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fuchsia / third_party / rust / 1.7.0 / . / src / libsyntax / parse / parser.rs
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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
pub use self::PathParsingMode::*;
use abi;
use ast::BareFnTy;
use ast::{RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
use ast::{Public, Unsafety};
use ast::{Mod, BiAdd, Arg, Arm, Attribute, BindingMode};
use ast::{BiBitAnd, BiBitOr, BiBitXor, BiRem, BiLt, Block};
use ast::{BlockCheckMode, CaptureByRef, CaptureByValue, CaptureClause};
use ast::{Constness, ConstTraitItem, Crate, CrateConfig};
use ast::{Decl, DeclItem, DeclLocal, DefaultBlock, DefaultReturn};
use ast::{UnDeref, BiDiv, EMPTY_CTXT, EnumDef, ExplicitSelf};
use ast::{Expr, Expr_, ExprAddrOf, ExprMatch, ExprAgain};
use ast::{ExprAssign, ExprAssignOp, ExprBinary, ExprBlock, ExprBox};
use ast::{ExprBreak, ExprCall, ExprCast, ExprInPlace};
use ast::{ExprField, ExprTupField, ExprClosure, ExprIf, ExprIfLet, ExprIndex};
use ast::{ExprLit, ExprLoop, ExprMac, ExprRange};
use ast::{ExprMethodCall, ExprParen, ExprPath};
use ast::{ExprRepeat, ExprRet, ExprStruct, ExprTup, ExprType, ExprUnary};
use ast::{ExprVec, ExprWhile, ExprWhileLet, ExprForLoop, Field, FnDecl};
use ast::{ForeignItem, ForeignItemStatic, ForeignItemFn, FunctionRetTy};
use ast::{Ident, Inherited, ImplItem, Item, Item_, ItemStatic};
use ast::{ItemEnum, ItemFn, ItemForeignMod, ItemImpl, ItemConst};
use ast::{ItemMac, ItemMod, ItemStruct, ItemTrait, ItemTy, ItemDefaultImpl};
use ast::{ItemExternCrate, ItemUse};
use ast::{Lit, Lit_};
use ast::{LitBool, LitChar, LitByte, LitByteStr};
use ast::{LitStr, LitInt, Local};
use ast::{MacStmtWithBraces, MacStmtWithSemicolon, MacStmtWithoutBraces};
use ast::{MutImmutable, MutMutable, Mac_};
use ast::{MutTy, BiMul, Mutability};
use ast::{NamedField, UnNeg, NoReturn, UnNot};
use ast::{Pat, PatBox, PatEnum, PatIdent, PatLit, PatQPath, PatMac, PatRange};
use ast::{PatRegion, PatStruct, PatTup, PatVec, PatWild};
use ast::{PolyTraitRef, QSelf};
use ast::{Return, BiShl, BiShr, Stmt, StmtDecl};
use ast::{StmtExpr, StmtSemi, StmtMac, VariantData, StructField};
use ast::{BiSub, StrStyle};
use ast::{SelfExplicit, SelfRegion, SelfStatic, SelfValue};
use ast::{Delimited, SequenceRepetition, TokenTree, TraitItem, TraitRef};
use ast::{Ty, Ty_, TypeBinding, TyMac};
use ast::{TyFixedLengthVec, TyBareFn, TyTypeof, TyInfer};
use ast::{TyParam, TyParamBounds, TyParen, TyPath, TyPtr};
use ast::{TyRptr, TyTup, TyU32, TyVec};
use ast::TypeTraitItem;
use ast::{UnnamedField, UnsafeBlock};
use ast::{ViewPath, ViewPathGlob, ViewPathList, ViewPathSimple};
use ast::{Visibility, WhereClause};
use attr::{ThinAttributes, ThinAttributesExt, AttributesExt};
use ast;
use ast_util::{self, ident_to_path};
use codemap::{self, Span, BytePos, Spanned, spanned, mk_sp, CodeMap};
use errors::{self, DiagnosticBuilder};
use ext::tt::macro_parser;
use parse;
use parse::classify;
use parse::common::{SeqSep, seq_sep_none, seq_sep_trailing_allowed};
use parse::lexer::{Reader, TokenAndSpan};
use parse::obsolete::{ParserObsoleteMethods, ObsoleteSyntax};
use parse::token::{self, intern, MatchNt, SubstNt, SpecialVarNt, InternedString};
use parse::token::{keywords, special_idents, SpecialMacroVar};
use parse::{new_sub_parser_from_file, ParseSess};
use util::parser::{AssocOp, Fixity};
use print::pprust;
use ptr::P;
use parse::PResult;
use std::collections::HashSet;
use std::io::prelude::*;
use std::mem;
use std::path::{Path, PathBuf};
use std::rc::Rc;
use std::slice;
bitflags! {
flags Restrictions: u8 {
const RESTRICTION_STMT_EXPR = 1 << 0,
const RESTRICTION_NO_STRUCT_LITERAL = 1 << 1,
}
}
type ItemInfo = (Ident, Item_, Option<Vec<Attribute> >);
/// How to parse a path. There are four different kinds of paths, all of which
/// are parsed somewhat differently.
#[derive(Copy, Clone, PartialEq)]
pub enum PathParsingMode {
/// A path with no type parameters; e.g. `foo::bar::Baz`
NoTypesAllowed,
/// A path with a lifetime and type parameters, with no double colons
/// before the type parameters; e.g. `foo::bar<'a>::Baz<T>`
LifetimeAndTypesWithoutColons,
/// A path with a lifetime and type parameters with double colons before
/// the type parameters; e.g. `foo::bar::<'a>::Baz::<T>`
LifetimeAndTypesWithColons,
}
/// How to parse a bound, whether to allow bound modifiers such as `?`.
#[derive(Copy, Clone, PartialEq)]
pub enum BoundParsingMode {
Bare,
Modified,
}
/// `pub` should be parsed in struct fields and not parsed in variant fields
#[derive(Clone, Copy, PartialEq)]
pub enum ParsePub {
Yes,
No,
}
/// Possibly accept an `token::Interpolated` expression (a pre-parsed expression
/// dropped into the token stream, which happens while parsing the result of
/// macro expansion). Placement of these is not as complex as I feared it would
/// be. The important thing is to make sure that lookahead doesn't balk at
/// `token::Interpolated` tokens.
macro_rules! maybe_whole_expr {
($p:expr) => (
{
let found = match $p.token {
token::Interpolated(token::NtExpr(ref e)) => {
Some((*e).clone())
}
token::Interpolated(token::NtPath(_)) => {
// FIXME: The following avoids an issue with lexical borrowck scopes,
// but the clone is unfortunate.
let pt = match $p.token {
token::Interpolated(token::NtPath(ref pt)) => (**pt).clone(),
_ => unreachable!()
};
let span = $p.span;
Some($p.mk_expr(span.lo, span.hi, ExprPath(None, pt), None))
}
token::Interpolated(token::NtBlock(_)) => {
// FIXME: The following avoids an issue with lexical borrowck scopes,
// but the clone is unfortunate.
let b = match $p.token {
token::Interpolated(token::NtBlock(ref b)) => (*b).clone(),
_ => unreachable!()
};
let span = $p.span;
Some($p.mk_expr(span.lo, span.hi, ExprBlock(b), None))
}
_ => None
};
match found {
Some(e) => {
$p.bump();
return Ok(e);
}
None => ()
}
}
)
}
/// As maybe_whole_expr, but for things other than expressions
macro_rules! maybe_whole {
($p:expr, $constructor:ident) => (
{
let found = match ($p).token {
token::Interpolated(token::$constructor(_)) => {
Some(($p).bump_and_get())
}
_ => None
};
if let Some(token::Interpolated(token::$constructor(x))) = found {
return Ok(x.clone());
}
}
);
(no_clone $p:expr, $constructor:ident) => (
{
let found = match ($p).token {
token::Interpolated(token::$constructor(_)) => {
Some(($p).bump_and_get())
}
_ => None
};
if let Some(token::Interpolated(token::$constructor(x))) = found {
return Ok(x);
}
}
);
(deref $p:expr, $constructor:ident) => (
{
let found = match ($p).token {
token::Interpolated(token::$constructor(_)) => {
Some(($p).bump_and_get())
}
_ => None
};
if let Some(token::Interpolated(token::$constructor(x))) = found {
return Ok((*x).clone());
}
}
);
(Some deref $p:expr, $constructor:ident) => (
{
let found = match ($p).token {
token::Interpolated(token::$constructor(_)) => {
Some(($p).bump_and_get())
}
_ => None
};
if let Some(token::Interpolated(token::$constructor(x))) = found {
return Ok(Some((*x).clone()));
}
}
);
(pair_empty $p:expr, $constructor:ident) => (
{
let found = match ($p).token {
token::Interpolated(token::$constructor(_)) => {
Some(($p).bump_and_get())
}
_ => None
};
if let Some(token::Interpolated(token::$constructor(x))) = found {
return Ok((Vec::new(), x));
}
}
)
}
fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>)
-> Vec<Attribute> {
if let Some(ref attrs) = rhs {
lhs.extend(attrs.iter().cloned())
}
lhs
}
/* ident is handled by common.rs */
pub struct Parser<'a> {
pub sess: &'a ParseSess,
/// the current token:
pub token: token::Token,
/// the span of the current token:
pub span: Span,
/// the span of the prior token:
pub last_span: Span,
pub cfg: CrateConfig,
/// the previous token or None (only stashed sometimes).
pub last_token: Option<Box<token::Token>>,
pub buffer: [TokenAndSpan; 4],
pub buffer_start: isize,
pub buffer_end: isize,
pub tokens_consumed: usize,
pub restrictions: Restrictions,
pub quote_depth: usize, // not (yet) related to the quasiquoter
pub reader: Box<Reader+'a>,
pub interner: Rc<token::IdentInterner>,
/// The set of seen errors about obsolete syntax. Used to suppress
/// extra detail when the same error is seen twice
pub obsolete_set: HashSet<ObsoleteSyntax>,
/// Used to determine the path to externally loaded source files
pub mod_path_stack: Vec<InternedString>,
/// Stack of spans of open delimiters. Used for error message.
pub open_braces: Vec<Span>,
/// Flag if this parser "owns" the directory that it is currently parsing
/// in. This will affect how nested files are looked up.
pub owns_directory: bool,
/// Name of the root module this parser originated from. If `None`, then the
/// name is not known. This does not change while the parser is descending
/// into modules, and sub-parsers have new values for this name.
pub root_module_name: Option<String>,
pub expected_tokens: Vec<TokenType>,
}
#[derive(PartialEq, Eq, Clone)]
pub enum TokenType {
Token(token::Token),
Keyword(keywords::Keyword),
Operator,
}
impl TokenType {
fn to_string(&self) -> String {
match *self {
TokenType::Token(ref t) => format!("`{}`", Parser::token_to_string(t)),
TokenType::Operator => "an operator".to_string(),
TokenType::Keyword(kw) => format!("`{}`", kw.to_name()),
}
}
}
fn is_plain_ident_or_underscore(t: &token::Token) -> bool {
t.is_plain_ident() || *t == token::Underscore
}
/// Information about the path to a module.
pub struct ModulePath {
pub name: String,
pub path_exists: bool,
pub result: Result<ModulePathSuccess, ModulePathError>,
}
pub struct ModulePathSuccess {
pub path: ::std::path::PathBuf,
pub owns_directory: bool,
}
pub struct ModulePathError {
pub err_msg: String,
pub help_msg: String,
}
pub enum LhsExpr {
NotYetParsed,
AttributesParsed(ThinAttributes),
AlreadyParsed(P<Expr>),
}
impl From<Option<ThinAttributes>> for LhsExpr {
fn from(o: Option<ThinAttributes>) -> Self {
if let Some(attrs) = o {
LhsExpr::AttributesParsed(attrs)
} else {
LhsExpr::NotYetParsed
}
}
}
impl From<P<Expr>> for LhsExpr {
fn from(expr: P<Expr>) -> Self {
LhsExpr::AlreadyParsed(expr)
}
}
impl<'a> Parser<'a> {
pub fn new(sess: &'a ParseSess,
cfg: ast::CrateConfig,
mut rdr: Box<Reader+'a>)
-> Parser<'a>
{
let tok0 = rdr.real_token();
let span = tok0.sp;
let placeholder = TokenAndSpan {
tok: token::Underscore,
sp: span,
};
Parser {
reader: rdr,
interner: token::get_ident_interner(),
sess: sess,
cfg: cfg,
token: tok0.tok,
span: span,
last_span: span,
last_token: None,
buffer: [
placeholder.clone(),
placeholder.clone(),
placeholder.clone(),
placeholder.clone(),
],
buffer_start: 0,
buffer_end: 0,
tokens_consumed: 0,
restrictions: Restrictions::empty(),
quote_depth: 0,
obsolete_set: HashSet::new(),
mod_path_stack: Vec::new(),
open_braces: Vec::new(),
owns_directory: true,
root_module_name: None,
expected_tokens: Vec::new(),
}
}
/// Convert a token to a string using self's reader
pub fn token_to_string(token: &token::Token) -> String {
pprust::token_to_string(token)
}
/// Convert the current token to a string using self's reader
pub fn this_token_to_string(&self) -> String {
Parser::token_to_string(&self.token)
}
pub fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> {
let token_str = Parser::token_to_string(t);
let last_span = self.last_span;
Err(self.span_fatal(last_span, &format!("unexpected token: `{}`", token_str)))
}
pub fn unexpected<T>(&mut self) -> PResult<'a, T> {
match self.expect_one_of(&[], &[]) {
Err(e) => Err(e),
Ok(_) => unreachable!(),
}
}
/// Expect and consume the token t. Signal an error if
/// the next token is not t.
pub fn expect(&mut self, t: &token::Token) -> PResult<'a, ()> {
if self.expected_tokens.is_empty() {
if self.token == *t {
self.bump();
Ok(())
} else {
let token_str = Parser::token_to_string(t);
let this_token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected `{}`, found `{}`",
token_str,
this_token_str)))
}
} else {
self.expect_one_of(unsafe { slice::from_raw_parts(t, 1) }, &[])
}
}
/// Expect next token to be edible or inedible token. If edible,
/// then consume it; if inedible, then return without consuming
/// anything. Signal a fatal error if next token is unexpected.
pub fn expect_one_of(&mut self,
edible: &[token::Token],
inedible: &[token::Token]) -> PResult<'a, ()>{
fn tokens_to_string(tokens: &[TokenType]) -> String {
let mut i = tokens.iter();
// This might be a sign we need a connect method on Iterator.
let b = i.next()
.map_or("".to_string(), |t| t.to_string());
i.enumerate().fold(b, |mut b, (i, ref a)| {
if tokens.len() > 2 && i == tokens.len() - 2 {
b.push_str(", or ");
} else if tokens.len() == 2 && i == tokens.len() - 2 {
b.push_str(" or ");
} else {
b.push_str(", ");
}
b.push_str(&*a.to_string());
b
})
}
if edible.contains(&self.token) {
self.bump();
Ok(())
} else if inedible.contains(&self.token) {
// leave it in the input
Ok(())
} else {
let mut expected = edible.iter()
.map(|x| TokenType::Token(x.clone()))
.chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
.chain(self.expected_tokens.iter().cloned())
.collect::<Vec<_>>();
expected.sort_by(|a, b| a.to_string().cmp(&b.to_string()));
expected.dedup();
let expect = tokens_to_string(&expected[..]);
let actual = self.this_token_to_string();
Err(self.fatal(
&(if expected.len() > 1 {
(format!("expected one of {}, found `{}`",
expect,
actual))
} else if expected.is_empty() {
(format!("unexpected token: `{}`",
actual))
} else {
(format!("expected {}, found `{}`",
expect,
actual))
})[..]
))
}
}
/// Check for erroneous `ident { }`; if matches, signal error and
/// recover (without consuming any expected input token). Returns
/// true if and only if input was consumed for recovery.
pub fn check_for_erroneous_unit_struct_expecting(&mut self,
expected: &[token::Token])
-> bool {
if self.token == token::OpenDelim(token::Brace)
&& expected.iter().all(|t| *t != token::OpenDelim(token::Brace))
&& self.look_ahead(1, |t| *t == token::CloseDelim(token::Brace)) {
// matched; signal non-fatal error and recover.
let span = self.span;
self.span_err(span, "unit-like struct construction is written with no trailing `{ }`");
self.eat(&token::OpenDelim(token::Brace));
self.eat(&token::CloseDelim(token::Brace));
true
} else {
false
}
}
/// Commit to parsing a complete expression `e` expected to be
/// followed by some token from the set edible + inedible. Recover
/// from anticipated input errors, discarding erroneous characters.
pub fn commit_expr(&mut self, e: &Expr, edible: &[token::Token],
inedible: &[token::Token]) -> PResult<'a, ()> {
debug!("commit_expr {:?}", e);
if let ExprPath(..) = e.node {
// might be unit-struct construction; check for recoverableinput error.
let expected = edible.iter()
.cloned()
.chain(inedible.iter().cloned())
.collect::<Vec<_>>();
self.check_for_erroneous_unit_struct_expecting(&expected[..]);
}
self.expect_one_of(edible, inedible)
}
pub fn commit_expr_expecting(&mut self, e: &Expr, edible: token::Token) -> PResult<'a, ()> {
self.commit_expr(e, &[edible], &[])
}
/// Commit to parsing a complete statement `s`, which expects to be
/// followed by some token from the set edible + inedible. Check
/// for recoverable input errors, discarding erroneous characters.
pub fn commit_stmt(&mut self, edible: &[token::Token],
inedible: &[token::Token]) -> PResult<'a, ()> {
if self.last_token
.as_ref()
.map_or(false, |t| t.is_ident() || t.is_path()) {
let expected = edible.iter()
.cloned()
.chain(inedible.iter().cloned())
.collect::<Vec<_>>();
self.check_for_erroneous_unit_struct_expecting(&expected);
}
self.expect_one_of(edible, inedible)
}
pub fn commit_stmt_expecting(&mut self, edible: token::Token) -> PResult<'a, ()> {
self.commit_stmt(&[edible], &[])
}
pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
self.check_strict_keywords();
self.check_reserved_keywords();
match self.token {
token::Ident(i, _) => {
self.bump();
Ok(i)
}
token::Interpolated(token::NtIdent(..)) => {
self.bug("ident interpolation not converted to real token");
}
_ => {
let token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected ident, found `{}`",
token_str)))
}
}
}
pub fn parse_ident_or_self_type(&mut self) -> PResult<'a, ast::Ident> {
if self.is_self_type_ident() {
self.expect_self_type_ident()
} else {
self.parse_ident()
}
}
pub fn parse_path_list_item(&mut self) -> PResult<'a, ast::PathListItem> {
let lo = self.span.lo;
let node = if self.eat_keyword(keywords::SelfValue) {
let rename = try!(self.parse_rename());
ast::PathListMod { id: ast::DUMMY_NODE_ID, rename: rename }
} else {
let ident = try!(self.parse_ident());
let rename = try!(self.parse_rename());
ast::PathListIdent { name: ident, rename: rename, id: ast::DUMMY_NODE_ID }
};
let hi = self.last_span.hi;
Ok(spanned(lo, hi, node))
}
/// Check if the next token is `tok`, and return `true` if so.
///
/// This method is will automatically add `tok` to `expected_tokens` if `tok` is not
/// encountered.
pub fn check(&mut self, tok: &token::Token) -> bool {
let is_present = self.token == *tok;
if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
is_present
}
/// Consume token 'tok' if it exists. Returns true if the given
/// token was present, false otherwise.
pub fn eat(&mut self, tok: &token::Token) -> bool {
let is_present = self.check(tok);
if is_present { self.bump() }
is_present
}
pub fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
self.expected_tokens.push(TokenType::Keyword(kw));
self.token.is_keyword(kw)
}
/// If the next token is the given keyword, eat it and return
/// true. Otherwise, return false.
pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
if self.check_keyword(kw) {
self.bump();
true
} else {
false
}
}
pub fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
if self.token.is_keyword(kw) {
self.bump();
true
} else {
false
}
}
/// If the given word is not a keyword, signal an error.
/// If the next token is not the given word, signal an error.
/// Otherwise, eat it.
pub fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
if !self.eat_keyword(kw) {
self.unexpected()
} else {
Ok(())
}
}
/// Signal an error if the given string is a strict keyword
pub fn check_strict_keywords(&mut self) {
if self.token.is_strict_keyword() {
let token_str = self.this_token_to_string();
let span = self.span;
self.span_err(span,
&format!("expected identifier, found keyword `{}`",
token_str));
}
}
/// Signal an error if the current token is a reserved keyword
pub fn check_reserved_keywords(&mut self) {
if self.token.is_reserved_keyword() {
let token_str = self.this_token_to_string();
self.fatal(&format!("`{}` is a reserved keyword", token_str)).emit()
}
}
/// Expect and consume an `&`. If `&&` is seen, replace it with a single
/// `&` and continue. If an `&` is not seen, signal an error.
fn expect_and(&mut self) -> PResult<'a, ()> {
self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
match self.token {
token::BinOp(token::And) => {
self.bump();
Ok(())
}
token::AndAnd => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.replace_token(token::BinOp(token::And), lo, span.hi))
}
_ => self.unexpected()
}
}
pub fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
match suffix {
None => {/* everything ok */}
Some(suf) => {
let text = suf.as_str();
if text.is_empty() {
self.span_bug(sp, "found empty literal suffix in Some")
}
self.span_err(sp, &*format!("{} with a suffix is invalid", kind));
}
}
}
/// Attempt to consume a `<`. If `<<` is seen, replace it with a single
/// `<` and continue. If a `<` is not seen, return false.
///
/// This is meant to be used when parsing generics on a path to get the
/// starting token.
fn eat_lt(&mut self) -> bool {
self.expected_tokens.push(TokenType::Token(token::Lt));
match self.token {
token::Lt => {
self.bump();
true
}
token::BinOp(token::Shl) => {
let span = self.span;
let lo = span.lo + BytePos(1);
self.replace_token(token::Lt, lo, span.hi);
true
}
_ => false,
}
}
fn expect_lt(&mut self) -> PResult<'a, ()> {
if !self.eat_lt() {
self.unexpected()
} else {
Ok(())
}
}
/// Expect and consume a GT. if a >> is seen, replace it
/// with a single > and continue. If a GT is not seen,
/// signal an error.
pub fn expect_gt(&mut self) -> PResult<'a, ()> {
self.expected_tokens.push(TokenType::Token(token::Gt));
match self.token {
token::Gt => {
self.bump();
Ok(())
}
token::BinOp(token::Shr) => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.replace_token(token::Gt, lo, span.hi))
}
token::BinOpEq(token::Shr) => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.replace_token(token::Ge, lo, span.hi))
}
token::Ge => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.replace_token(token::Eq, lo, span.hi))
}
_ => {
let gt_str = Parser::token_to_string(&token::Gt);
let this_token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected `{}`, found `{}`",
gt_str,
this_token_str)))
}
}
}
pub fn parse_seq_to_before_gt_or_return<T, F>(&mut self,
sep: Option<token::Token>,
mut f: F)
-> PResult<'a, (P<[T]>, bool)>
where F: FnMut(&mut Parser<'a>) -> PResult<'a, Option<T>>,
{
let mut v = Vec::new();
// This loop works by alternating back and forth between parsing types
// and commas. For example, given a string `A, B,>`, the parser would
// first parse `A`, then a comma, then `B`, then a comma. After that it
// would encounter a `>` and stop. This lets the parser handle trailing
// commas in generic parameters, because it can stop either after
// parsing a type or after parsing a comma.
for i in 0.. {
if self.check(&token::Gt)
|| self.token == token::BinOp(token::Shr)
|| self.token == token::Ge
|| self.token == token::BinOpEq(token::Shr) {
break;
}
if i % 2 == 0 {
match try!(f(self)) {
Some(result) => v.push(result),
None => return Ok((P::from_vec(v), true))
}
} else {
if let Some(t) = sep.as_ref() {
try!(self.expect(t));
}
}
}
return Ok((P::from_vec(v), false));
}
/// Parse a sequence bracketed by '<' and '>', stopping
/// before the '>'.
pub fn parse_seq_to_before_gt<T, F>(&mut self,
sep: Option<token::Token>,
mut f: F)
-> PResult<'a, P<[T]>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let (result, returned) = try!(self.parse_seq_to_before_gt_or_return(sep,
|p| Ok(Some(try!(f(p))))));
assert!(!returned);
return Ok(result);
}
pub fn parse_seq_to_gt<T, F>(&mut self,
sep: Option<token::Token>,
f: F)
-> PResult<'a, P<[T]>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let v = try!(self.parse_seq_to_before_gt(sep, f));
try!(self.expect_gt());
return Ok(v);
}
pub fn parse_seq_to_gt_or_return<T, F>(&mut self,
sep: Option<token::Token>,
f: F)
-> PResult<'a, (P<[T]>, bool)> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, Option<T>>,
{
let (v, returned) = try!(self.parse_seq_to_before_gt_or_return(sep, f));
if !returned {
try!(self.expect_gt());
}
return Ok((v, returned));
}
/// Parse a sequence, including the closing delimiter. The function
/// f must consume tokens until reaching the next separator or
/// closing bracket.
pub fn parse_seq_to_end<T, F>(&mut self,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let val = try!(self.parse_seq_to_before_end(ket, sep, f));
self.bump();
Ok(val)
}
/// Parse a sequence, not including the closing delimiter. The function
/// f must consume tokens until reaching the next separator or
/// closing bracket.
pub fn parse_seq_to_before_end<T, F>(&mut self,
ket: &token::Token,
sep: SeqSep,
mut f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let mut first: bool = true;
let mut v = vec!();
while self.token != *ket {
match sep.sep {
Some(ref t) => {
if first { first = false; }
else { try!(self.expect(t)); }
}
_ => ()
}
if sep.trailing_sep_allowed && self.check(ket) { break; }
v.push(try!(f(self)));
}
return Ok(v);
}
/// Parse a sequence, including the closing delimiter. The function
/// f must consume tokens until reaching the next separator or
/// closing bracket.
pub fn parse_unspanned_seq<T, F>(&mut self,
bra: &token::Token,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
try!(self.expect(bra));
let result = try!(self.parse_seq_to_before_end(ket, sep, f));
self.bump();
Ok(result)
}
/// Parse a sequence parameter of enum variant. For consistency purposes,
/// these should not be empty.
pub fn parse_enum_variant_seq<T, F>(&mut self,
bra: &token::Token,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let result = try!(self.parse_unspanned_seq(bra, ket, sep, f));
if result.is_empty() {
let last_span = self.last_span;
self.span_err(last_span,
"nullary enum variants are written with no trailing `( )`");
}
Ok(result)
}
// NB: Do not use this function unless you actually plan to place the
// spanned list in the AST.
pub fn parse_seq<T, F>(&mut self,
bra: &token::Token,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Spanned<Vec<T>>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let lo = self.span.lo;
try!(self.expect(bra));
let result = try!(self.parse_seq_to_before_end(ket, sep, f));
let hi = self.span.hi;
self.bump();
Ok(spanned(lo, hi, result))
}
/// Advance the parser by one token
pub fn bump(&mut self) {
self.last_span = self.span;
// Stash token for error recovery (sometimes; clone is not necessarily cheap).
self.last_token = if self.token.is_ident() ||
self.token.is_path() ||
self.token == token::Comma {
Some(Box::new(self.token.clone()))
} else {
None
};
let next = if self.buffer_start == self.buffer_end {
self.reader.real_token()
} else {
// Avoid token copies with `replace`.
let buffer_start = self.buffer_start as usize;
let next_index = (buffer_start + 1) & 3;
self.buffer_start = next_index as isize;
let placeholder = TokenAndSpan {
tok: token::Underscore,
sp: self.span,
};
mem::replace(&mut self.buffer[buffer_start], placeholder)
};
self.span = next.sp;
self.token = next.tok;
self.tokens_consumed += 1;
self.expected_tokens.clear();
// check after each token
self.check_unknown_macro_variable();
}
/// Advance the parser by one token and return the bumped token.
pub fn bump_and_get(&mut self) -> token::Token {
let old_token = mem::replace(&mut self.token, token::Underscore);
self.bump();
old_token
}
/// EFFECT: replace the current token and span with the given one
pub fn replace_token(&mut self,
next: token::Token,
lo: BytePos,
hi: BytePos) {
self.last_span = mk_sp(self.span.lo, lo);
self.token = next;
self.span = mk_sp(lo, hi);
}
pub fn buffer_length(&mut self) -> isize {
if self.buffer_start <= self.buffer_end {
return self.buffer_end - self.buffer_start;
}
return (4 - self.buffer_start) + self.buffer_end;
}
pub fn look_ahead<R, F>(&mut self, distance: usize, f: F) -> R where
F: FnOnce(&token::Token) -> R,
{
let dist = distance as isize;
while self.buffer_length() < dist {
self.buffer[self.buffer_end as usize] = self.reader.real_token();
self.buffer_end = (self.buffer_end + 1) & 3;
}
f(&self.buffer[((self.buffer_start + dist - 1) & 3) as usize].tok)
}
pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_fatal(self.span, m)
}
pub fn span_fatal(&self, sp: Span, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_fatal(sp, m)
}
pub fn span_fatal_help(&self, sp: Span, m: &str, help: &str) -> DiagnosticBuilder<'a> {
let mut err = self.sess.span_diagnostic.struct_span_fatal(sp, m);
err.fileline_help(sp, help);
err
}
pub fn bug(&self, m: &str) -> ! {
self.sess.span_diagnostic.span_bug(self.span, m)
}
pub fn warn(&self, m: &str) {
self.sess.span_diagnostic.span_warn(self.span, m)
}
pub fn span_warn(&self, sp: Span, m: &str) {
self.sess.span_diagnostic.span_warn(sp, m)
}
pub fn span_err(&self, sp: Span, m: &str) {
self.sess.span_diagnostic.span_err(sp, m)
}
pub fn span_bug(&self, sp: Span, m: &str) -> ! {
self.sess.span_diagnostic.span_bug(sp, m)
}
pub fn abort_if_errors(&self) {
self.sess.span_diagnostic.abort_if_errors();
}
pub fn diagnostic(&self) -> &'a errors::Handler {
&self.sess.span_diagnostic
}
pub fn id_to_interned_str(&mut self, id: Ident) -> InternedString {
id.name.as_str()
}
/// Is the current token one of the keywords that signals a bare function
/// type?
pub fn token_is_bare_fn_keyword(&mut self) -> bool {
self.check_keyword(keywords::Fn) ||
self.check_keyword(keywords::Unsafe) ||
self.check_keyword(keywords::Extern)
}
pub fn get_lifetime(&mut self) -> ast::Ident {
match self.token {
token::Lifetime(ref ident) => *ident,
_ => self.bug("not a lifetime"),
}
}
pub fn parse_for_in_type(&mut self) -> PResult<'a, Ty_> {
/*
Parses whatever can come after a `for` keyword in a type.
The `for` has already been consumed.
Deprecated:
- for <'lt> |S| -> T
Eventually:
- for <'lt> [unsafe] [extern "ABI"] fn (S) -> T
- for <'lt> path::foo(a, b)
*/
// parse <'lt>
let lo = self.span.lo;
let lifetime_defs = try!(self.parse_late_bound_lifetime_defs());
// examine next token to decide to do
if self.token_is_bare_fn_keyword() {
self.parse_ty_bare_fn(lifetime_defs)
} else {
let hi = self.span.hi;
let trait_ref = try!(self.parse_trait_ref());
let poly_trait_ref = ast::PolyTraitRef { bound_lifetimes: lifetime_defs,
trait_ref: trait_ref,
span: mk_sp(lo, hi)};
let other_bounds = if self.eat(&token::BinOp(token::Plus)) {
try!(self.parse_ty_param_bounds(BoundParsingMode::Bare))
} else {
P::empty()
};
let all_bounds =
Some(TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None)).into_iter()
.chain(other_bounds.into_vec())
.collect();
Ok(ast::TyPolyTraitRef(all_bounds))
}
}
pub fn parse_ty_path(&mut self) -> PResult<'a, Ty_> {
Ok(TyPath(None, try!(self.parse_path(LifetimeAndTypesWithoutColons))))
}
/// parse a TyBareFn type:
pub fn parse_ty_bare_fn(&mut self, lifetime_defs: Vec<ast::LifetimeDef>) -> PResult<'a, Ty_> {
/*
[unsafe] [extern "ABI"] fn <'lt> (S) -> T
^~~~^ ^~~~^ ^~~~^ ^~^ ^
| | | | |
| | | | Return type
| | | Argument types
| | Lifetimes
| ABI
Function Style
*/
let unsafety = try!(self.parse_unsafety());
let abi = if self.eat_keyword(keywords::Extern) {
try!(self.parse_opt_abi()).unwrap_or(abi::C)
} else {
abi::Rust
};
try!(self.expect_keyword(keywords::Fn));
let (inputs, variadic) = try!(self.parse_fn_args(false, true));
let ret_ty = try!(self.parse_ret_ty());
let decl = P(FnDecl {
inputs: inputs,
output: ret_ty,
variadic: variadic
});
Ok(TyBareFn(P(BareFnTy {
abi: abi,
unsafety: unsafety,
lifetimes: lifetime_defs,
decl: decl
})))
}
/// Parses an obsolete closure kind (`&:`, `&mut:`, or `:`).
pub fn parse_obsolete_closure_kind(&mut self) -> PResult<'a, ()> {
let lo = self.span.lo;
if
self.check(&token::BinOp(token::And)) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
self.look_ahead(2, |t| *t == token::Colon)
{
self.bump();
self.bump();
self.bump();
} else if
self.token == token::BinOp(token::And) &&
self.look_ahead(1, |t| *t == token::Colon)
{
self.bump();
self.bump();
} else if
self.eat(&token::Colon)
{
/* nothing */
} else {
return Ok(());
}
let span = mk_sp(lo, self.span.hi);
self.obsolete(span, ObsoleteSyntax::ClosureKind);
Ok(())
}
pub fn parse_unsafety(&mut self) -> PResult<'a, Unsafety> {
if self.eat_keyword(keywords::Unsafe) {
return Ok(Unsafety::Unsafe);
} else {
return Ok(Unsafety::Normal);
}
}
/// Parse the items in a trait declaration
pub fn parse_trait_items(&mut self) -> PResult<'a, Vec<P<TraitItem>>> {
self.parse_unspanned_seq(
&token::OpenDelim(token::Brace),
&token::CloseDelim(token::Brace),
seq_sep_none(),
|p| -> PResult<'a, P<TraitItem>> {
maybe_whole!(no_clone p, NtTraitItem);
let mut attrs = try!(p.parse_outer_attributes());
let lo = p.span.lo;
let (name, node) = if p.eat_keyword(keywords::Type) {
let TyParam {ident, bounds, default, ..} = try!(p.parse_ty_param());
try!(p.expect(&token::Semi));
(ident, TypeTraitItem(bounds, default))
} else if p.is_const_item() {
try!(p.expect_keyword(keywords::Const));
let ident = try!(p.parse_ident());
try!(p.expect(&token::Colon));
let ty = try!(p.parse_ty_sum());
let default = if p.check(&token::Eq) {
p.bump();
let expr = try!(p.parse_expr());
try!(p.commit_expr_expecting(&expr, token::Semi));
Some(expr)
} else {
try!(p.expect(&token::Semi));
None
};
(ident, ConstTraitItem(ty, default))
} else {
let (constness, unsafety, abi) = try!(p.parse_fn_front_matter());
let ident = try!(p.parse_ident());
let mut generics = try!(p.parse_generics());
let (explicit_self, d) = try!(p.parse_fn_decl_with_self(|p: &mut Parser<'a>|{
// This is somewhat dubious; We don't want to allow
// argument names to be left off if there is a
// definition...
p.parse_arg_general(false)
}));
generics.where_clause = try!(p.parse_where_clause());
let sig = ast::MethodSig {
unsafety: unsafety,
constness: constness,
decl: d,
generics: generics,
abi: abi,
explicit_self: explicit_self,
};
let body = match p.token {
token::Semi => {
p.bump();
debug!("parse_trait_methods(): parsing required method");
None
}
token::OpenDelim(token::Brace) => {
debug!("parse_trait_methods(): parsing provided method");
let (inner_attrs, body) =
try!(p.parse_inner_attrs_and_block());
attrs.extend(inner_attrs.iter().cloned());
Some(body)
}
_ => {
let token_str = p.this_token_to_string();
return Err(p.fatal(&format!("expected `;` or `{{`, found `{}`",
token_str)[..]))
}
};
(ident, ast::MethodTraitItem(sig, body))
};
Ok(P(TraitItem {
id: ast::DUMMY_NODE_ID,
ident: name,
attrs: attrs,
node: node,
span: mk_sp(lo, p.last_span.hi),
}))
})
}
/// Parse a possibly mutable type
pub fn parse_mt(&mut self) -> PResult<'a, MutTy> {
let mutbl = try!(self.parse_mutability());
let t = try!(self.parse_ty());
Ok(MutTy { ty: t, mutbl: mutbl })
}
/// Parse optional return type [ -> TY ] in function decl
pub fn parse_ret_ty(&mut self) -> PResult<'a, FunctionRetTy> {
if self.eat(&token::RArrow) {
if self.eat(&token::Not) {
Ok(NoReturn(self.last_span))
} else {
Ok(Return(try!(self.parse_ty())))
}
} else {
let pos = self.span.lo;
Ok(DefaultReturn(mk_sp(pos, pos)))
}
}
/// Parse a type in a context where `T1+T2` is allowed.
pub fn parse_ty_sum(&mut self) -> PResult<'a, P<Ty>> {
let lo = self.span.lo;
let lhs = try!(self.parse_ty());
if !self.eat(&token::BinOp(token::Plus)) {
return Ok(lhs);
}
let bounds = try!(self.parse_ty_param_bounds(BoundParsingMode::Bare));
// In type grammar, `+` is treated like a binary operator,
// and hence both L and R side are required.
if bounds.is_empty() {
let last_span = self.last_span;
self.span_err(last_span,
"at least one type parameter bound \
must be specified");
}
let sp = mk_sp(lo, self.last_span.hi);
let sum = ast::TyObjectSum(lhs, bounds);
Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: sum, span: sp}))
}
/// Parse a type.
pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
maybe_whole!(no_clone self, NtTy);
let lo = self.span.lo;
let t = if self.check(&token::OpenDelim(token::Paren)) {
self.bump();
// (t) is a parenthesized ty
// (t,) is the type of a tuple with only one field,
// of type t
let mut ts = vec![];
let mut last_comma = false;
while self.token != token::CloseDelim(token::Paren) {
ts.push(try!(self.parse_ty_sum()));
if self.check(&token::Comma) {
last_comma = true;
self.bump();
} else {
last_comma = false;
break;
}
}
try!(self.expect(&token::CloseDelim(token::Paren)));
if ts.len() == 1 && !last_comma {
TyParen(ts.into_iter().nth(0).unwrap())
} else {
TyTup(ts)
}
} else if self.check(&token::BinOp(token::Star)) {
// STAR POINTER (bare pointer?)
self.bump();
TyPtr(try!(self.parse_ptr()))
} else if self.check(&token::OpenDelim(token::Bracket)) {
// VECTOR
try!(self.expect(&token::OpenDelim(token::Bracket)));
let t = try!(self.parse_ty_sum());
// Parse the `; e` in `[ i32; e ]`
// where `e` is a const expression
let t = match try!(self.maybe_parse_fixed_length_of_vec()) {
None => TyVec(t),
Some(suffix) => TyFixedLengthVec(t, suffix)
};
try!(self.expect(&token::CloseDelim(token::Bracket)));
t
} else if self.check(&token::BinOp(token::And)) ||
self.token == token::AndAnd {
// BORROWED POINTER
try!(self.expect_and());
try!(self.parse_borrowed_pointee())
} else if self.check_keyword(keywords::For) {
try!(self.parse_for_in_type())
} else if self.token_is_bare_fn_keyword() {
// BARE FUNCTION
try!(self.parse_ty_bare_fn(Vec::new()))
} else if self.eat_keyword_noexpect(keywords::Typeof) {
// TYPEOF
// In order to not be ambiguous, the type must be surrounded by parens.
try!(self.expect(&token::OpenDelim(token::Paren)));
let e = try!(self.parse_expr());
try!(self.expect(&token::CloseDelim(token::Paren)));
TyTypeof(e)
} else if self.eat_lt() {
let (qself, path) =
try!(self.parse_qualified_path(NoTypesAllowed));
TyPath(Some(qself), path)
} else if self.check(&token::ModSep) ||
self.token.is_ident() ||
self.token.is_path() {
let path = try!(self.parse_path(LifetimeAndTypesWithoutColons));
if self.check(&token::Not) {
// MACRO INVOCATION
self.bump();
let delim = try!(self.expect_open_delim());
let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
seq_sep_none(),
|p| p.parse_token_tree()));
let hi = self.span.hi;
TyMac(spanned(lo, hi, Mac_ { path: path, tts: tts, ctxt: EMPTY_CTXT }))
} else {
// NAMED TYPE
TyPath(None, path)
}
} else if self.eat(&token::Underscore) {
// TYPE TO BE INFERRED
TyInfer
} else {
let this_token_str = self.this_token_to_string();
let msg = format!("expected type, found `{}`", this_token_str);
return Err(self.fatal(&msg[..]));
};
let sp = mk_sp(lo, self.last_span.hi);
Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: t, span: sp}))
}
pub fn parse_borrowed_pointee(&mut self) -> PResult<'a, Ty_> {
// look for `&'lt` or `&'foo ` and interpret `foo` as the region name:
let opt_lifetime = try!(self.parse_opt_lifetime());
let mt = try!(self.parse_mt());
return Ok(TyRptr(opt_lifetime, mt));
}
pub fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
let mutbl = if self.eat_keyword(keywords::Mut) {
MutMutable
} else if self.eat_keyword(keywords::Const) {
MutImmutable
} else {
let span = self.last_span;
self.span_err(span,
"bare raw pointers are no longer allowed, you should \
likely use `*mut T`, but otherwise `*T` is now \
known as `*const T`");
MutImmutable
};
let t = try!(self.parse_ty());
Ok(MutTy { ty: t, mutbl: mutbl })
}
pub fn is_named_argument(&mut self) -> bool {
let offset = match self.token {
token::BinOp(token::And) => 1,
token::AndAnd => 1,
_ if self.token.is_keyword(keywords::Mut) => 1,
_ => 0
};
debug!("parser is_named_argument offset:{}", offset);
if offset == 0 {
is_plain_ident_or_underscore(&self.token)
&& self.look_ahead(1, |t| *t == token::Colon)
} else {
self.look_ahead(offset, |t| is_plain_ident_or_underscore(t))
&& self.look_ahead(offset + 1, |t| *t == token::Colon)
}
}
/// This version of parse arg doesn't necessarily require
/// identifier names.
pub fn parse_arg_general(&mut self, require_name: bool) -> PResult<'a, Arg> {
maybe_whole!(no_clone self, NtArg);
let pat = if require_name || self.is_named_argument() {
debug!("parse_arg_general parse_pat (require_name:{})",
require_name);
let pat = try!(self.parse_pat());
try!(self.expect(&token::Colon));
pat
} else {
debug!("parse_arg_general ident_to_pat");
ast_util::ident_to_pat(ast::DUMMY_NODE_ID,
self.last_span,
special_idents::invalid)
};
let t = try!(self.parse_ty_sum());
Ok(Arg {
ty: t,
pat: pat,
id: ast::DUMMY_NODE_ID,
})
}
/// Parse a single function argument
pub fn parse_arg(&mut self) -> PResult<'a, Arg> {
self.parse_arg_general(true)
}
/// Parse an argument in a lambda header e.g. |arg, arg|
pub fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
let pat = try!(self.parse_pat());
let t = if self.eat(&token::Colon) {
try!(self.parse_ty_sum())
} else {
P(Ty {
id: ast::DUMMY_NODE_ID,
node: TyInfer,
span: mk_sp(self.span.lo, self.span.hi),
})
};
Ok(Arg {
ty: t,
pat: pat,
id: ast::DUMMY_NODE_ID
})
}
pub fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
if self.check(&token::Semi) {
self.bump();
Ok(Some(try!(self.parse_expr())))
} else {
Ok(None)
}
}
/// Matches token_lit = LIT_INTEGER | ...
pub fn lit_from_token(&self, tok: &token::Token) -> PResult<'a, Lit_> {
match *tok {
token::Interpolated(token::NtExpr(ref v)) => {
match v.node {
ExprLit(ref lit) => { Ok(lit.node.clone()) }
_ => { return self.unexpected_last(tok); }
}
}
token::Literal(lit, suf) => {
let (suffix_illegal, out) = match lit {
token::Byte(i) => (true, LitByte(parse::byte_lit(&i.as_str()).0)),
token::Char(i) => (true, LitChar(parse::char_lit(&i.as_str()).0)),
// there are some valid suffixes for integer and
// float literals, so all the handling is done
// internally.
token::Integer(s) => {
(false, parse::integer_lit(&s.as_str(),
suf.as_ref().map(|s| s.as_str()),
&self.sess.span_diagnostic,
self.last_span))
}
token::Float(s) => {
(false, parse::float_lit(&s.as_str(),
suf.as_ref().map(|s| s.as_str()),
&self.sess.span_diagnostic,
self.last_span))
}
token::Str_(s) => {
(true,
LitStr(token::intern_and_get_ident(&parse::str_lit(&s.as_str())),
ast::CookedStr))
}
token::StrRaw(s, n) => {
(true,
LitStr(
token::intern_and_get_ident(&parse::raw_str_lit(&s.as_str())),
ast::RawStr(n)))
}
token::ByteStr(i) =>
(true, LitByteStr(parse::byte_str_lit(&i.as_str()))),
token::ByteStrRaw(i, _) =>
(true,
LitByteStr(Rc::new(i.to_string().into_bytes()))),
};
if suffix_illegal {
let sp = self.last_span;
self.expect_no_suffix(sp, &*format!("{} literal", lit.short_name()), suf)
}
Ok(out)
}
_ => { return self.unexpected_last(tok); }
}
}
/// Matches lit = true | false | token_lit
pub fn parse_lit(&mut self) -> PResult<'a, Lit> {
let lo = self.span.lo;
let lit = if self.eat_keyword(keywords::True) {
LitBool(true)
} else if self.eat_keyword(keywords::False) {
LitBool(false)
} else {
let token = self.bump_and_get();
let lit = try!(self.lit_from_token(&token));
lit
};
Ok(codemap::Spanned { node: lit, span: mk_sp(lo, self.last_span.hi) })
}
/// matches '-' lit | lit
pub fn parse_pat_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
let minus_lo = self.span.lo;
let minus_present = self.eat(&token::BinOp(token::Minus));
let lo = self.span.lo;
let literal = P(try!(self.parse_lit()));
let hi = self.last_span.hi;
let expr = self.mk_expr(lo, hi, ExprLit(literal), None);
if minus_present {
let minus_hi = self.last_span.hi;
let unary = self.mk_unary(UnNeg, expr);
Ok(self.mk_expr(minus_lo, minus_hi, unary, None))
} else {
Ok(expr)
}
}
/// Parses qualified path.
///
/// Assumes that the leading `<` has been parsed already.
///
/// Qualifed paths are a part of the universal function call
/// syntax (UFCS).
///
/// `qualified_path = <type [as trait_ref]>::path`
///
/// See `parse_path` for `mode` meaning.
///
/// # Examples:
///
/// `<T as U>::a`
/// `<T as U>::F::a::<S>`
pub fn parse_qualified_path(&mut self, mode: PathParsingMode)
-> PResult<'a, (QSelf, ast::Path)> {
let span = self.last_span;
let self_type = try!(self.parse_ty_sum());
let mut path = if self.eat_keyword(keywords::As) {
try!(self.parse_path(LifetimeAndTypesWithoutColons))
} else {
ast::Path {
span: span,
global: false,
segments: vec![]
}
};
let qself = QSelf {
ty: self_type,
position: path.segments.len()
};
try!(self.expect(&token::Gt));
try!(self.expect(&token::ModSep));
let segments = match mode {
LifetimeAndTypesWithoutColons => {
try!(self.parse_path_segments_without_colons())
}
LifetimeAndTypesWithColons => {
try!(self.parse_path_segments_with_colons())
}
NoTypesAllowed => {
try!(self.parse_path_segments_without_types())
}
};
path.segments.extend(segments);
path.span.hi = self.last_span.hi;
Ok((qself, path))
}
/// Parses a path and optional type parameter bounds, depending on the
/// mode. The `mode` parameter determines whether lifetimes, types, and/or
/// bounds are permitted and whether `::` must precede type parameter
/// groups.
pub fn parse_path(&mut self, mode: PathParsingMode) -> PResult<'a, ast::Path> {
// Check for a whole path...
let found = match self.token {
token::Interpolated(token::NtPath(_)) => Some(self.bump_and_get()),
_ => None,
};
if let Some(token::Interpolated(token::NtPath(path))) = found {
return Ok(*path);
}
let lo = self.span.lo;
let is_global = self.eat(&token::ModSep);
// Parse any number of segments and bound sets. A segment is an
// identifier followed by an optional lifetime and a set of types.
// A bound set is a set of type parameter bounds.
let segments = match mode {
LifetimeAndTypesWithoutColons => {
try!(self.parse_path_segments_without_colons())
}
LifetimeAndTypesWithColons => {
try!(self.parse_path_segments_with_colons())
}
NoTypesAllowed => {
try!(self.parse_path_segments_without_types())
}
};
// Assemble the span.
let span = mk_sp(lo, self.last_span.hi);
// Assemble the result.
Ok(ast::Path {
span: span,
global: is_global,
segments: segments,
})
}
/// Examples:
/// - `a::b<T,U>::c<V,W>`
/// - `a::b<T,U>::c(V) -> W`
/// - `a::b<T,U>::c(V)`
pub fn parse_path_segments_without_colons(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
let mut segments = Vec::new();
loop {
// First, parse an identifier.
let identifier = try!(self.parse_ident_or_self_type());
// Parse types, optionally.
let parameters = if self.eat_lt() {
let (lifetimes, types, bindings) = try!(self.parse_generic_values_after_lt());
ast::PathParameters::AngleBracketed(ast::AngleBracketedParameterData {
lifetimes: lifetimes,
types: P::from_vec(types),
bindings: P::from_vec(bindings),
})
} else if self.eat(&token::OpenDelim(token::Paren)) {
let lo = self.last_span.lo;
let inputs = try!(self.parse_seq_to_end(
&token::CloseDelim(token::Paren),
seq_sep_trailing_allowed(token::Comma),
|p| p.parse_ty_sum()));
let output_ty = if self.eat(&token::RArrow) {
Some(try!(self.parse_ty()))
} else {
None
};
let hi = self.last_span.hi;
ast::PathParameters::Parenthesized(ast::ParenthesizedParameterData {
span: mk_sp(lo, hi),
inputs: inputs,
output: output_ty,
})
} else {
ast::PathParameters::none()
};
// Assemble and push the result.
segments.push(ast::PathSegment { identifier: identifier,
parameters: parameters });
// Continue only if we see a `::`
if !self.eat(&token::ModSep) {
return Ok(segments);
}
}
}
/// Examples:
/// - `a::b::<T,U>::c`
pub fn parse_path_segments_with_colons(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
let mut segments = Vec::new();
loop {
// First, parse an identifier.
let identifier = try!(self.parse_ident_or_self_type());
// If we do not see a `::`, stop.
if !self.eat(&token::ModSep) {
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none()
});
return Ok(segments);
}
// Check for a type segment.
if self.eat_lt() {
// Consumed `a::b::<`, go look for types
let (lifetimes, types, bindings) = try!(self.parse_generic_values_after_lt());
let parameters = ast::AngleBracketedParameterData {
lifetimes: lifetimes,
types: P::from_vec(types),
bindings: P::from_vec(bindings),
};
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::AngleBracketed(parameters),
});
// Consumed `a::b::<T,U>`, check for `::` before proceeding
if !self.eat(&token::ModSep) {
return Ok(segments);
}
} else {
// Consumed `a::`, go look for `b`
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none(),
});
}
}
}
/// Examples:
/// - `a::b::c`
pub fn parse_path_segments_without_types(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
let mut segments = Vec::new();
loop {
// First, parse an identifier.
let identifier = try!(self.parse_ident_or_self_type());
// Assemble and push the result.
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none()
});
// If we do not see a `::`, stop.
if !self.eat(&token::ModSep) {
return Ok(segments);
}
}
}
/// parses 0 or 1 lifetime
pub fn parse_opt_lifetime(&mut self) -> PResult<'a, Option<ast::Lifetime>> {
match self.token {
token::Lifetime(..) => {
Ok(Some(try!(self.parse_lifetime())))
}
_ => {
Ok(None)
}
}
}
/// Parses a single lifetime
/// Matches lifetime = LIFETIME
pub fn parse_lifetime(&mut self) -> PResult<'a, ast::Lifetime> {
match self.token {
token::Lifetime(i) => {
let span = self.span;
self.bump();
return Ok(ast::Lifetime {
id: ast::DUMMY_NODE_ID,
span: span,
name: i.name
});
}
_ => {
return Err(self.fatal("expected a lifetime name"));
}
}
}
/// Parses `lifetime_defs = [ lifetime_defs { ',' lifetime_defs } ]` where `lifetime_def =
/// lifetime [':' lifetimes]`
pub fn parse_lifetime_defs(&mut self) -> PResult<'a, Vec<ast::LifetimeDef>> {
let mut res = Vec::new();
loop {
match self.token {
token::Lifetime(_) => {
let lifetime = try!(self.parse_lifetime());
let bounds =
if self.eat(&token::Colon) {
try!(self.parse_lifetimes(token::BinOp(token::Plus)))
} else {
Vec::new()
};
res.push(ast::LifetimeDef { lifetime: lifetime,
bounds: bounds });
}
_ => {
return Ok(res);
}
}
match self.token {
token::Comma => { self.bump();}
token::Gt => { return Ok(res); }
token::BinOp(token::Shr) => { return Ok(res); }
_ => {
let this_token_str = self.this_token_to_string();
let msg = format!("expected `,` or `>` after lifetime \
name, found `{}`",
this_token_str);
return Err(self.fatal(&msg[..]));
}
}
}
}
/// matches lifetimes = ( lifetime ) | ( lifetime , lifetimes ) actually, it matches the empty
/// one too, but putting that in there messes up the grammar....
///
/// Parses zero or more comma separated lifetimes. Expects each lifetime to be followed by
/// either a comma or `>`. Used when parsing type parameter lists, where we expect something
/// like `<'a, 'b, T>`.
pub fn parse_lifetimes(&mut self, sep: token::Token) -> PResult<'a, Vec<ast::Lifetime>> {
let mut res = Vec::new();
loop {
match self.token {
token::Lifetime(_) => {
res.push(try!(self.parse_lifetime()));
}
_ => {
return Ok(res);
}
}
if self.token != sep {
return Ok(res);
}
self.bump();
}
}
/// Parse mutability declaration (mut/const/imm)
pub fn parse_mutability(&mut self) -> PResult<'a, Mutability> {
if self.eat_keyword(keywords::Mut) {
Ok(MutMutable)
} else {
Ok(MutImmutable)
}
}
/// Parse ident COLON expr
pub fn parse_field(&mut self) -> PResult<'a, Field> {
let lo = self.span.lo;
let i = try!(self.parse_ident());
let hi = self.last_span.hi;
try!(self.expect(&token::Colon));
let e = try!(self.parse_expr());
Ok(ast::Field {
ident: spanned(lo, hi, i),
span: mk_sp(lo, e.span.hi),
expr: e,
})
}
pub fn mk_expr(&mut self, lo: BytePos, hi: BytePos,
node: Expr_, attrs: ThinAttributes) -> P<Expr> {
P(Expr {
id: ast::DUMMY_NODE_ID,
node: node,
span: mk_sp(lo, hi),
attrs: attrs,
})
}
pub fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::Expr_ {
ExprUnary(unop, expr)
}
pub fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::Expr_ {
ExprBinary(binop, lhs, rhs)
}
pub fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::Expr_ {
ExprCall(f, args)
}
fn mk_method_call(&mut self,
ident: ast::SpannedIdent,
tps: Vec<P<Ty>>,
args: Vec<P<Expr>>)
-> ast::Expr_ {
ExprMethodCall(ident, tps, args)
}
pub fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::Expr_ {
ExprIndex(expr, idx)
}
pub fn mk_range(&mut self,
start: Option<P<Expr>>,
end: Option<P<Expr>>)
-> ast::Expr_ {
ExprRange(start, end)
}
pub fn mk_field(&mut self, expr: P<Expr>, ident: ast::SpannedIdent) -> ast::Expr_ {
ExprField(expr, ident)
}
pub fn mk_tup_field(&mut self, expr: P<Expr>, idx: codemap::Spanned<usize>) -> ast::Expr_ {
ExprTupField(expr, idx)
}
pub fn mk_assign_op(&mut self, binop: ast::BinOp,
lhs: P<Expr>, rhs: P<Expr>) -> ast::Expr_ {
ExprAssignOp(binop, lhs, rhs)
}
pub fn mk_mac_expr(&mut self, lo: BytePos, hi: BytePos,
m: Mac_, attrs: ThinAttributes) -> P<Expr> {
P(Expr {
id: ast::DUMMY_NODE_ID,
node: ExprMac(codemap::Spanned {node: m, span: mk_sp(lo, hi)}),
span: mk_sp(lo, hi),
attrs: attrs,
})
}
pub fn mk_lit_u32(&mut self, i: u32, attrs: ThinAttributes) -> P<Expr> {
let span = &self.span;
let lv_lit = P(codemap::Spanned {
node: LitInt(i as u64, ast::UnsignedIntLit(TyU32)),
span: *span
});
P(Expr {
id: ast::DUMMY_NODE_ID,
node: ExprLit(lv_lit),
span: *span,
attrs: attrs,
})
}
fn expect_open_delim(&mut self) -> PResult<'a, token::DelimToken> {
self.expected_tokens.push(TokenType::Token(token::Gt));
match self.token {
token::OpenDelim(delim) => {
self.bump();
Ok(delim)
},
_ => Err(self.fatal("expected open delimiter")),
}
}
/// At the bottom (top?) of the precedence hierarchy,
/// parse things like parenthesized exprs,
/// macros, return, etc.
///
/// NB: This does not parse outer attributes,
/// and is private because it only works
/// correctly if called from parse_dot_or_call_expr().
fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
maybe_whole_expr!(self);
// Outer attributes are already parsed and will be
// added to the return value after the fact.
//
// Therefore, prevent sub-parser from parsing
// attributes by giving them a empty "already parsed" list.
let mut attrs = None;
let lo = self.span.lo;
let mut hi = self.span.hi;
let ex: Expr_;
// Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
match self.token {
token::OpenDelim(token::Paren) => {
self.bump();
let attrs = try!(self.parse_inner_attributes())
.into_thin_attrs()
.prepend(attrs);
// (e) is parenthesized e
// (e,) is a tuple with only one field, e
let mut es = vec![];
let mut trailing_comma = false;
while self.token != token::CloseDelim(token::Paren) {
es.push(try!(self.parse_expr()));
try!(self.commit_expr(&**es.last().unwrap(), &[],
&[token::Comma, token::CloseDelim(token::Paren)]));
if self.check(&token::Comma) {
trailing_comma = true;
self.bump();
} else {
trailing_comma = false;
break;
}
}
self.bump();
hi = self.last_span.hi;
return if es.len() == 1 && !trailing_comma {
Ok(self.mk_expr(lo, hi, ExprParen(es.into_iter().nth(0).unwrap()), attrs))
} else {
Ok(self.mk_expr(lo, hi, ExprTup(es), attrs))
}
},
token::OpenDelim(token::Brace) => {
return self.parse_block_expr(lo, DefaultBlock, attrs);
},
token::BinOp(token::Or) | token::OrOr => {
let lo = self.span.lo;
return self.parse_lambda_expr(lo, CaptureByRef, attrs);
},
token::Ident(id @ ast::Ident {
name: token::SELF_KEYWORD_NAME,
ctxt: _
}, token::Plain) => {
self.bump();
let path = ast_util::ident_to_path(mk_sp(lo, hi), id);
ex = ExprPath(None, path);
hi = self.last_span.hi;
}
token::OpenDelim(token::Bracket) => {
self.bump();
let inner_attrs = try!(self.parse_inner_attributes())
.into_thin_attrs();
attrs.update(|attrs| attrs.append(inner_attrs));
if self.check(&token::CloseDelim(token::Bracket)) {
// Empty vector.
self.bump();
ex = ExprVec(Vec::new());
} else {
// Nonempty vector.
let first_expr = try!(self.parse_expr());
if self.check(&token::Semi) {
// Repeating array syntax: [ 0; 512 ]
self.bump();
let count = try!(self.parse_expr());
try!(self.expect(&token::CloseDelim(token::Bracket)));
ex = ExprRepeat(first_expr, count);
} else if self.check(&token::Comma) {
// Vector with two or more elements.
self.bump();
let remaining_exprs = try!(self.parse_seq_to_end(
&token::CloseDelim(token::Bracket),
seq_sep_trailing_allowed(token::Comma),
|p| Ok(try!(p.parse_expr()))
));
let mut exprs = vec!(first_expr);
exprs.extend(remaining_exprs);
ex = ExprVec(exprs);
} else {
// Vector with one element.
try!(self.expect(&token::CloseDelim(token::Bracket)));
ex = ExprVec(vec!(first_expr));
}
}
hi = self.last_span.hi;
}
_ => {
if self.eat_lt() {
let (qself, path) =
try!(self.parse_qualified_path(LifetimeAndTypesWithColons));
hi = path.span.hi;
return Ok(self.mk_expr(lo, hi, ExprPath(Some(qself), path), attrs));
}
if self.eat_keyword(keywords::Move) {
let lo = self.last_span.lo;
return self.parse_lambda_expr(lo, CaptureByValue, attrs);
}
if self.eat_keyword(keywords::If) {
return self.parse_if_expr(attrs);
}
if self.eat_keyword(keywords::For) {
let lo = self.last_span.lo;
return self.parse_for_expr(None, lo, attrs);
}
if self.eat_keyword(keywords::While) {
let lo = self.last_span.lo;
return self.parse_while_expr(None, lo, attrs);
}
if self.token.is_lifetime() {
let lifetime = self.get_lifetime();
let lo = self.span.lo;
self.bump();
try!(self.expect(&token::Colon));
if self.eat_keyword(keywords::While) {
return self.parse_while_expr(Some(lifetime), lo, attrs)
}
if self.eat_keyword(keywords::For) {
return self.parse_for_expr(Some(lifetime), lo, attrs)
}
if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(Some(lifetime), lo, attrs)
}
return Err(self.fatal("expected `while`, `for`, or `loop` after a label"))
}
if self.eat_keyword(keywords::Loop) {
let lo = self.last_span.lo;
return self.parse_loop_expr(None, lo, attrs);
}
if self.eat_keyword(keywords::Continue) {
let ex = if self.token.is_lifetime() {
let ex = ExprAgain(Some(Spanned{
node: self.get_lifetime(),
span: self.span
}));
self.bump();
ex
} else {
ExprAgain(None)
};
let hi = self.last_span.hi;
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
if self.eat_keyword(keywords::Match) {
return self.parse_match_expr(attrs);
}
if self.eat_keyword(keywords::Unsafe) {
return self.parse_block_expr(
lo,
UnsafeBlock(ast::UserProvided),
attrs);
}
if self.eat_keyword(keywords::Return) {
if self.token.can_begin_expr() {
let e = try!(self.parse_expr());
hi = e.span.hi;
ex = ExprRet(Some(e));
} else {
ex = ExprRet(None);
}
} else if self.eat_keyword(keywords::Break) {
if self.token.is_lifetime() {
ex = ExprBreak(Some(Spanned {
node: self.get_lifetime(),
span: self.span
}));
self.bump();
} else {
ex = ExprBreak(None);
}
hi = self.last_span.hi;
} else if self.check(&token::ModSep) ||
self.token.is_ident() &&
!self.check_keyword(keywords::True) &&
!self.check_keyword(keywords::False) {
let pth =
try!(self.parse_path(LifetimeAndTypesWithColons));
// `!`, as an operator, is prefix, so we know this isn't that
if self.check(&token::Not) {
// MACRO INVOCATION expression
self.bump();
let delim = try!(self.expect_open_delim());
let tts = try!(self.parse_seq_to_end(
&token::CloseDelim(delim),
seq_sep_none(),
|p| p.parse_token_tree()));
let hi = self.last_span.hi;
return Ok(self.mk_mac_expr(lo,
hi,
Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT },
attrs));
}
if self.check(&token::OpenDelim(token::Brace)) {
// This is a struct literal, unless we're prohibited
// from parsing struct literals here.
let prohibited = self.restrictions.contains(
Restrictions::RESTRICTION_NO_STRUCT_LITERAL
);
if !prohibited {
// It's a struct literal.
self.bump();
let mut fields = Vec::new();
let mut base = None;
let attrs = attrs.append(
try!(self.parse_inner_attributes())
.into_thin_attrs());
while self.token != token::CloseDelim(token::Brace) {
if self.eat(&token::DotDot) {
base = Some(try!(self.parse_expr()));
break;
}
fields.push(try!(self.parse_field()));
try!(self.commit_expr(&*fields.last().unwrap().expr,
&[token::Comma],
&[token::CloseDelim(token::Brace)]));
}
hi = self.span.hi;
try!(self.expect(&token::CloseDelim(token::Brace)));
ex = ExprStruct(pth, fields, base);
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
}
hi = pth.span.hi;
ex = ExprPath(None, pth);
} else {
// other literal expression
let lit = try!(self.parse_lit());
hi = lit.span.hi;
ex = ExprLit(P(lit));
}
}
}
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
fn parse_or_use_outer_attributes(&mut self,
already_parsed_attrs: Option<ThinAttributes>)
-> PResult<'a, ThinAttributes> {
if let Some(attrs) = already_parsed_attrs {
Ok(attrs)
} else {
self.parse_outer_attributes().map(|a| a.into_thin_attrs())
}
}
/// Parse a block or unsafe block
pub fn parse_block_expr(&mut self, lo: BytePos, blk_mode: BlockCheckMode,
attrs: ThinAttributes)
-> PResult<'a, P<Expr>> {
let outer_attrs = attrs;
try!(self.expect(&token::OpenDelim(token::Brace)));
let inner_attrs = try!(self.parse_inner_attributes()).into_thin_attrs();
let attrs = outer_attrs.append(inner_attrs);
let blk = try!(self.parse_block_tail(lo, blk_mode));
return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk), attrs));
}
/// parse a.b or a(13) or a[4] or just a
pub fn parse_dot_or_call_expr(&mut self,
already_parsed_attrs: Option<ThinAttributes>)
-> PResult<'a, P<Expr>> {
let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
let b = try!(self.parse_bottom_expr());
self.parse_dot_or_call_expr_with(b, attrs)
}
pub fn parse_dot_or_call_expr_with(&mut self,
e0: P<Expr>,
attrs: ThinAttributes)
-> PResult<'a, P<Expr>> {
// Stitch the list of outer attributes onto the return value.
// A little bit ugly, but the best way given the current code
// structure
self.parse_dot_or_call_expr_with_(e0)
.map(|expr|
expr.map(|mut expr| {
expr.attrs.update(|a| a.prepend(attrs));
match expr.node {
ExprIf(..) | ExprIfLet(..) => {
if !expr.attrs.as_attr_slice().is_empty() {
// Just point to the first attribute in there...
let span = expr.attrs.as_attr_slice()[0].span;
self.span_err(span,
"attributes are not yet allowed on `if` \
expressions");
}
}
_ => {}
}
expr
})
)
}
fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>) -> PResult<'a, P<Expr>> {
let mut e = e0;
let lo = e.span.lo;
let mut hi;
loop {
// expr.f
if self.eat(&token::Dot) {
match self.token {
token::Ident(i, _) => {
let dot = self.last_span.hi;
hi = self.span.hi;
self.bump();
let (_, tys, bindings) = if self.eat(&token::ModSep) {
try!(self.expect_lt());
try!(self.parse_generic_values_after_lt())
} else {
(Vec::new(), Vec::new(), Vec::new())
};
if !bindings.is_empty() {
let last_span = self.last_span;
self.span_err(last_span, "type bindings are only permitted on trait paths");
}
// expr.f() method call
match self.token {
token::OpenDelim(token::Paren) => {
let mut es = try!(self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
seq_sep_trailing_allowed(token::Comma),
|p| Ok(try!(p.parse_expr()))
));
hi = self.last_span.hi;
es.insert(0, e);
let id = spanned(dot, hi, i);
let nd = self.mk_method_call(id, tys, es);
e = self.mk_expr(lo, hi, nd, None);
}
_ => {
if !tys.is_empty() {
let last_span = self.last_span;
self.span_err(last_span,
"field expressions may not \
have type parameters");
}
let id = spanned(dot, hi, i);
let field = self.mk_field(e, id);
e = self.mk_expr(lo, hi, field, None);
}
}
}
token::Literal(token::Integer(n), suf) => {
let sp = self.span;
// A tuple index may not have a suffix
self.expect_no_suffix(sp, "tuple index", suf);
let dot = self.last_span.hi;
hi = self.span.hi;
self.bump();
let index = n.as_str().parse::<usize>().ok();
match index {
Some(n) => {
let id = spanned(dot, hi, n);
let field = self.mk_tup_field(e, id);
e = self.mk_expr(lo, hi, field, None);
}
None => {
let last_span = self.last_span;
self.span_err(last_span, "invalid tuple or tuple struct index");
}
}
}
token::Literal(token::Float(n), _suf) => {
self.bump();
let last_span = self.last_span;
let fstr = n.as_str();
let mut err = self.diagnostic().struct_span_err(last_span,
&format!("unexpected token: `{}`", n.as_str()));
if fstr.chars().all(|x| "0123456789.".contains(x)) {
let float = match fstr.parse::<f64>().ok() {
Some(f) => f,
None => continue,
};
err.fileline_help(last_span,
&format!("try parenthesizing the first index; e.g., `(foo.{}){}`",
float.trunc() as usize,
format!(".{}", fstr.splitn(2, ".").last().unwrap())));
}
err.emit();
self.abort_if_errors();
}
_ => return self.unexpected()
}
continue;
}
if self.expr_is_complete(&*e) { break; }
match self.token {
// expr(...)
token::OpenDelim(token::Paren) => {
let es = try!(self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
seq_sep_trailing_allowed(token::Comma),
|p| Ok(try!(p.parse_expr()))
));
hi = self.last_span.hi;
let nd = self.mk_call(e, es);
e = self.mk_expr(lo, hi, nd, None);
}
// expr[...]
// Could be either an index expression or a slicing expression.
token::OpenDelim(token::Bracket) => {
self.bump();
let ix = try!(self.parse_expr());
hi = self.span.hi;
try!(self.commit_expr_expecting(&*ix, token::CloseDelim(token::Bracket)));
let index = self.mk_index(e, ix);
e = self.mk_expr(lo, hi, index, None)
}
_ => return Ok(e)
}
}
return Ok(e);
}
// Parse unquoted tokens after a `$` in a token tree
fn parse_unquoted(&mut self) -> PResult<'a, TokenTree> {
let mut sp = self.span;
let (name, namep) = match self.token {
token::Dollar => {
self.bump();
if self.token == token::OpenDelim(token::Paren) {
let Spanned { node: seq, span: seq_span } = try!(self.parse_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
seq_sep_none(),
|p| p.parse_token_tree()
));
let (sep, repeat) = try!(self.parse_sep_and_kleene_op());
let name_num = macro_parser::count_names(&seq);
return Ok(TokenTree::Sequence(mk_sp(sp.lo, seq_span.hi),
Rc::new(SequenceRepetition {
tts: seq,
separator: sep,
op: repeat,
num_captures: name_num
})));
} else if self.token.is_keyword_allow_following_colon(keywords::Crate) {
self.bump();
return Ok(TokenTree::Token(sp, SpecialVarNt(SpecialMacroVar::CrateMacroVar)));
} else {
sp = mk_sp(sp.lo, self.span.hi);
let namep = match self.token { token::Ident(_, p) => p, _ => token::Plain };
let name = try!(self.parse_ident());
(name, namep)
}
}
token::SubstNt(name, namep) => {
self.bump();
(name, namep)
}
_ => unreachable!()
};
// continue by trying to parse the `:ident` after `$name`
if self.token == token::Colon && self.look_ahead(1, |t| t.is_ident() &&
!t.is_strict_keyword() &&
!t.is_reserved_keyword()) {
self.bump();
sp = mk_sp(sp.lo, self.span.hi);
let kindp = match self.token { token::Ident(_, p) => p, _ => token::Plain };
let nt_kind = try!(self.parse_ident());
Ok(TokenTree::Token(sp, MatchNt(name, nt_kind, namep, kindp)))
} else {
Ok(TokenTree::Token(sp, SubstNt(name, namep)))
}
}
pub fn check_unknown_macro_variable(&mut self) {
if self.quote_depth == 0 {
match self.token {
token::SubstNt(name, _) =>
self.fatal(&format!("unknown macro variable `{}`", name)).emit(),
_ => {}
}
}
}
/// Parse an optional separator followed by a Kleene-style
/// repetition token (+ or *).
pub fn parse_sep_and_kleene_op(&mut self)
-> PResult<'a, (Option<token::Token>, ast::KleeneOp)> {
fn parse_kleene_op<'a>(parser: &mut Parser<'a>) -> PResult<'a, Option<ast::KleeneOp>> {
match parser.token {
token::BinOp(token::Star) => {
parser.bump();
Ok(Some(ast::ZeroOrMore))
},
token::BinOp(token::Plus) => {
parser.bump();
Ok(Some(ast::OneOrMore))
},
_ => Ok(None)
}
};
match try!(parse_kleene_op(self)) {
Some(kleene_op) => return Ok((None, kleene_op)),
None => {}
}
let separator = self.bump_and_get();
match try!(parse_kleene_op(self)) {
Some(zerok) => Ok((Some(separator), zerok)),
None => return Err(self.fatal("expected `*` or `+`"))
}
}
/// parse a single token tree from the input.
pub fn parse_token_tree(&mut self) -> PResult<'a, TokenTree> {
// FIXME #6994: currently, this is too eager. It
// parses token trees but also identifies TokenType::Sequence's
// and token::SubstNt's; it's too early to know yet
// whether something will be a nonterminal or a seq
// yet.
maybe_whole!(deref self, NtTT);
// this is the fall-through for the 'match' below.
// invariants: the current token is not a left-delimiter,
// not an EOF, and not the desired right-delimiter (if
// it were, parse_seq_to_before_end would have prevented
// reaching this point.
fn parse_non_delim_tt_tok<'b>(p: &mut Parser<'b>) -> PResult<'b, TokenTree> {
maybe_whole!(deref p, NtTT);
match p.token {
token::CloseDelim(_) => {
let token_str = p.this_token_to_string();
let mut err = p.fatal(
&format!("incorrect close delimiter: `{}`", token_str));
// This is a conservative error: only report the last unclosed delimiter. The
// previous unclosed delimiters could actually be closed! The parser just hasn't
// gotten to them yet.
if let Some(&sp) = p.open_braces.last() {
err.span_note(sp, "unclosed delimiter");
};
Err(err)
},
/* we ought to allow different depths of unquotation */
token::Dollar | token::SubstNt(..) if p.quote_depth > 0 => {
p.parse_unquoted()
}
_ => {
Ok(TokenTree::Token(p.span, p.bump_and_get()))
}
}
}
match self.token {
token::Eof => {
let open_braces = self.open_braces.clone();
let mut err: DiagnosticBuilder<'a> =
self.fatal("this file contains an un-closed delimiter");
for sp in &open_braces {
err.span_help(*sp, "did you mean to close this delimiter?");
}
return Err(err);
},
token::OpenDelim(delim) => {
// The span for beginning of the delimited section
let pre_span = self.span;
// Parse the open delimiter.
self.open_braces.push(self.span);
let open_span = self.span;
self.bump();
// Parse the token trees within the delimiters
let tts = try!(self.parse_seq_to_before_end(
&token::CloseDelim(delim),
seq_sep_none(),
|p| p.parse_token_tree()
));
// Parse the close delimiter.
let close_span = self.span;
self.bump();
self.open_braces.pop().unwrap();
// Expand to cover the entire delimited token tree
let span = Span { hi: close_span.hi, ..pre_span };
Ok(TokenTree::Delimited(span, Rc::new(Delimited {
delim: delim,
open_span: open_span,
tts: tts,
close_span: close_span,
})))
},
_ => parse_non_delim_tt_tok(self),
}
}
// parse a stream of tokens into a list of TokenTree's,
// up to EOF.
pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
let mut tts = Vec::new();
while self.token != token::Eof {
tts.push(try!(self.parse_token_tree()));
}
Ok(tts)
}
/// Parse a prefix-unary-operator expr
pub fn parse_prefix_expr(&mut self,
already_parsed_attrs: Option<ThinAttributes>)
-> PResult<'a, P<Expr>> {
let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
let lo = self.span.lo;
let hi;
// Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
let ex = match self.token {
token::Not => {
self.bump();
let e = try!(self.parse_prefix_expr(None));
hi = e.span.hi;
self.mk_unary(UnNot, e)
}
token::BinOp(token::Minus) => {
self.bump();
let e = try!(self.parse_prefix_expr(None));
hi = e.span.hi;
self.mk_unary(UnNeg, e)
}
token::BinOp(token::Star) => {
self.bump();
let e = try!(self.parse_prefix_expr(None));
hi = e.span.hi;
self.mk_unary(UnDeref, e)
}
token::BinOp(token::And) | token::AndAnd => {
try!(self.expect_and());
let m = try!(self.parse_mutability());
let e = try!(self.parse_prefix_expr(None));
hi = e.span.hi;
ExprAddrOf(m, e)
}
token::Ident(..) if self.token.is_keyword(keywords::In) => {
self.bump();
let place = try!(self.parse_expr_res(
Restrictions::RESTRICTION_NO_STRUCT_LITERAL,
None,
));
let blk = try!(self.parse_block());
let span = blk.span;
hi = span.hi;
let blk_expr = self.mk_expr(span.lo, span.hi, ExprBlock(blk),
None);
ExprInPlace(place, blk_expr)
}
token::Ident(..) if self.token.is_keyword(keywords::Box) => {
self.bump();
let subexpression = try!(self.parse_prefix_expr(None));
hi = subexpression.span.hi;
ExprBox(subexpression)
}
_ => return self.parse_dot_or_call_expr(Some(attrs))
};
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
/// Parse an associative expression
///
/// This parses an expression accounting for associativity and precedence of the operators in
/// the expression.
pub fn parse_assoc_expr(&mut self,
already_parsed_attrs: Option<ThinAttributes>)
-> PResult<'a, P<Expr>> {
self.parse_assoc_expr_with(0, already_parsed_attrs.into())
}
/// Parse an associative expression with operators of at least `min_prec` precedence
pub fn parse_assoc_expr_with(&mut self,
min_prec: usize,
lhs: LhsExpr)
-> PResult<'a, P<Expr>> {
let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
expr
} else {
let attrs = match lhs {
LhsExpr::AttributesParsed(attrs) => Some(attrs),
_ => None,
};
if self.token == token::DotDot {
return self.parse_prefix_range_expr(attrs);
} else {
try!(self.parse_prefix_expr(attrs))
}
};
if self.expr_is_complete(&*lhs) {
// Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
return Ok(lhs);
}
self.expected_tokens.push(TokenType::Operator);
while let Some(op) = AssocOp::from_token(&self.token) {
let cur_op_span = self.span;
let restrictions = if op.is_assign_like() {
self.restrictions & Restrictions::RESTRICTION_NO_STRUCT_LITERAL
} else {
self.restrictions
};
if op.precedence() < min_prec {
break;
}
self.bump();
if op.is_comparison() {
self.check_no_chained_comparison(&*lhs, &op);
}
// Special cases:
if op == AssocOp::As {
let rhs = try!(self.parse_ty());
lhs = self.mk_expr(lhs.span.lo, rhs.span.hi,
ExprCast(lhs, rhs), None);
continue
} else if op == AssocOp::Colon {
let rhs = try!(self.parse_ty());
lhs = self.mk_expr(lhs.span.lo, rhs.span.hi,
ExprType(lhs, rhs), None);
continue
} else if op == AssocOp::DotDot {
// If we didn’t have to handle `x..`, it would be pretty easy to generalise
// it to the Fixity::None code.
//
// We have 2 alternatives here: `x..y` and `x..` The other two variants are
// handled with `parse_prefix_range_expr` call above.
let rhs = if self.is_at_start_of_range_notation_rhs() {
let rhs = self.parse_assoc_expr_with(op.precedence() + 1,
LhsExpr::NotYetParsed);
match rhs {
Ok(e) => Some(e),
Err(mut e) => {
e.cancel();
None
}
}
} else {
None
};
let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
x.span
} else {
cur_op_span
});
let r = self.mk_range(Some(lhs), rhs);
lhs = self.mk_expr(lhs_span.lo, rhs_span.hi, r, None);
break
}
let rhs = try!(match op.fixity() {
Fixity::Right => self.with_res(
restrictions - Restrictions::RESTRICTION_STMT_EXPR,
|this| {
this.parse_assoc_expr_with(op.precedence(),
LhsExpr::NotYetParsed)
}),
Fixity::Left => self.with_res(
restrictions - Restrictions::RESTRICTION_STMT_EXPR,
|this| {
this.parse_assoc_expr_with(op.precedence() + 1,
LhsExpr::NotYetParsed)
}),
// We currently have no non-associative operators that are not handled above by
// the special cases. The code is here only for future convenience.
Fixity::None => self.with_res(
restrictions - Restrictions::RESTRICTION_STMT_EXPR,
|this| {
this.parse_assoc_expr_with(op.precedence() + 1,
LhsExpr::NotYetParsed)
}),
});
lhs = match op {
AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
AssocOp::Greater | AssocOp::GreaterEqual => {
let ast_op = op.to_ast_binop().unwrap();
let (lhs_span, rhs_span) = (lhs.span, rhs.span);
let binary = self.mk_binary(codemap::respan(cur_op_span, ast_op), lhs, rhs);
self.mk_expr(lhs_span.lo, rhs_span.hi, binary, None)
}
AssocOp::Assign =>
self.mk_expr(lhs.span.lo, rhs.span.hi, ExprAssign(lhs, rhs), None),
AssocOp::Inplace =>
self.mk_expr(lhs.span.lo, rhs.span.hi, ExprInPlace(lhs, rhs), None),
AssocOp::AssignOp(k) => {
let aop = match k {
token::Plus => BiAdd,
token::Minus => BiSub,
token::Star => BiMul,
token::Slash => BiDiv,
token::Percent => BiRem,
token::Caret => BiBitXor,
token::And => BiBitAnd,
token::Or => BiBitOr,
token::Shl => BiShl,
token::Shr => BiShr
};
let (lhs_span, rhs_span) = (lhs.span, rhs.span);
let aopexpr = self.mk_assign_op(codemap::respan(cur_op_span, aop), lhs, rhs);
self.mk_expr(lhs_span.lo, rhs_span.hi, aopexpr, None)
}
AssocOp::As | AssocOp::Colon | AssocOp::DotDot => {
self.bug("As, Colon or DotDot branch reached")
}
};
if op.fixity() == Fixity::None { break }
}
Ok(lhs)
}
/// Produce an error if comparison operators are chained (RFC #558).
/// We only need to check lhs, not rhs, because all comparison ops
/// have same precedence and are left-associative
fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
debug_assert!(outer_op.is_comparison());
match lhs.node {
ExprBinary(op, _, _) if op.node.is_comparison() => {
// respan to include both operators
let op_span = mk_sp(op.span.lo, self.span.hi);
let mut err = self.diagnostic().struct_span_err(op_span,
"chained comparison operators require parentheses");
if op.node == BiLt && *outer_op == AssocOp::Greater {
err.fileline_help(op_span,
"use `::<...>` instead of `<...>` if you meant to specify type arguments");
}
err.emit();
}
_ => {}
}
}
/// Parse prefix-forms of range notation: `..expr` and `..`
fn parse_prefix_range_expr(&mut self,
already_parsed_attrs: Option<ThinAttributes>)
-> PResult<'a, P<Expr>> {
debug_assert!(self.token == token::DotDot);
let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
let lo = self.span.lo;
let mut hi = self.span.hi;
self.bump();
let opt_end = if self.is_at_start_of_range_notation_rhs() {
// RHS must be parsed with more associativity than DotDot.
let next_prec = AssocOp::from_token(&token::DotDot).unwrap().precedence() + 1;
Some(try!(self.parse_assoc_expr_with(next_prec,
LhsExpr::NotYetParsed)
.map(|x|{
hi = x.span.hi;
x
})))
} else {
None
};
let r = self.mk_range(None, opt_end);
Ok(self.mk_expr(lo, hi, r, attrs))
}
fn is_at_start_of_range_notation_rhs(&self) -> bool {
if self.token.can_begin_expr() {
// parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
if self.token == token::OpenDelim(token::Brace) {
return !self.restrictions.contains(Restrictions::RESTRICTION_NO_STRUCT_LITERAL);
}
true
} else {
false
}
}
/// Parse an 'if' or 'if let' expression ('if' token already eaten)
pub fn parse_if_expr(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
if self.check_keyword(keywords::Let) {
return self.parse_if_let_expr(attrs);
}
let lo = self.last_span.lo;
let cond = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
let thn = try!(self.parse_block());
let mut els: Option<P<Expr>> = None;
let mut hi = thn.span.hi;
if self.eat_keyword(keywords::Else) {
let elexpr = try!(self.parse_else_expr());
hi = elexpr.span.hi;
els = Some(elexpr);
}
Ok(self.mk_expr(lo, hi, ExprIf(cond, thn, els), attrs))
}
/// Parse an 'if let' expression ('if' token already eaten)
pub fn parse_if_let_expr(&mut self, attrs: ThinAttributes)
-> PResult<'a, P<Expr>> {
let lo = self.last_span.lo;
try!(self.expect_keyword(keywords::Let));
let pat = try!(self.parse_pat());
try!(self.expect(&token::Eq));
let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
let thn = try!(self.parse_block());
let (hi, els) = if self.eat_keyword(keywords::Else) {
let expr = try!(self.parse_else_expr());
(expr.span.hi, Some(expr))
} else {
(thn.span.hi, None)
};
Ok(self.mk_expr(lo, hi, ExprIfLet(pat, expr, thn, els), attrs))
}
// `|args| expr`
pub fn parse_lambda_expr(&mut self, lo: BytePos,
capture_clause: CaptureClause,
attrs: ThinAttributes)
-> PResult<'a, P<Expr>>
{
let decl = try!(self.parse_fn_block_decl());
let body = match decl.output {
DefaultReturn(_) => {
// If no explicit return type is given, parse any
// expr and wrap it up in a dummy block:
let body_expr = try!(self.parse_expr());
P(ast::Block {
id: ast::DUMMY_NODE_ID,
stmts: vec![],
span: body_expr.span,
expr: Some(body_expr),
rules: DefaultBlock,
})
}
_ => {
// If an explicit return type is given, require a
// block to appear (RFC 968).
try!(self.parse_block())
}
};
Ok(self.mk_expr(
lo,
body.span.hi,
ExprClosure(capture_clause, decl, body), attrs))
}
// `else` token already eaten
pub fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
if self.eat_keyword(keywords::If) {
return self.parse_if_expr(None);
} else {
let blk = try!(self.parse_block());
return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk), None));
}
}
/// Parse a 'for' .. 'in' expression ('for' token already eaten)
pub fn parse_for_expr(&mut self, opt_ident: Option<ast::Ident>,
span_lo: BytePos,
attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
// Parse: `for <src_pat> in <src_expr> <src_loop_block>`
let pat = try!(self.parse_pat());
try!(self.expect_keyword(keywords::In));
let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
let (iattrs, loop_block) = try!(self.parse_inner_attrs_and_block());
let attrs = attrs.append(iattrs.into_thin_attrs());
let hi = self.last_span.hi;
Ok(self.mk_expr(span_lo, hi,
ExprForLoop(pat, expr, loop_block, opt_ident),
attrs))
}
/// Parse a 'while' or 'while let' expression ('while' token already eaten)
pub fn parse_while_expr(&mut self, opt_ident: Option<ast::Ident>,
span_lo: BytePos,
attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
if self.token.is_keyword(keywords::Let) {
return self.parse_while_let_expr(opt_ident, span_lo, attrs);
}
let cond = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
let (iattrs, body) = try!(self.parse_inner_attrs_and_block());
let attrs = attrs.append(iattrs.into_thin_attrs());
let hi = body.span.hi;
return Ok(self.mk_expr(span_lo, hi, ExprWhile(cond, body, opt_ident),
attrs));
}
/// Parse a 'while let' expression ('while' token already eaten)
pub fn parse_while_let_expr(&mut self, opt_ident: Option<ast::Ident>,
span_lo: BytePos,
attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
try!(self.expect_keyword(keywords::Let));
let pat = try!(self.parse_pat());
try!(self.expect(&token::Eq));
let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
let (iattrs, body) = try!(self.parse_inner_attrs_and_block());
let attrs = attrs.append(iattrs.into_thin_attrs());
let hi = body.span.hi;
return Ok(self.mk_expr(span_lo, hi, ExprWhileLet(pat, expr, body, opt_ident), attrs));
}
// parse `loop {...}`, `loop` token already eaten
pub fn parse_loop_expr(&mut self, opt_ident: Option<ast::Ident>,
span_lo: BytePos,
attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
let (iattrs, body) = try!(self.parse_inner_attrs_and_block());
let attrs = attrs.append(iattrs.into_thin_attrs());
let hi = body.span.hi;
Ok(self.mk_expr(span_lo, hi, ExprLoop(body, opt_ident), attrs))
}
// `match` token already eaten
fn parse_match_expr(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
let match_span = self.last_span;
let lo = self.last_span.lo;
let discriminant = try!(self.parse_expr_res(
Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
if let Err(mut e) = self.commit_expr_expecting(&*discriminant,
token::OpenDelim(token::Brace)) {
if self.token == token::Token::Semi {
e.span_note(match_span, "did you mean to remove this `match` keyword?");
}
return Err(e)
}
let attrs = attrs.append(
try!(self.parse_inner_attributes()).into_thin_attrs());
let mut arms: Vec<Arm> = Vec::new();
while self.token != token::CloseDelim(token::Brace) {
arms.push(try!(self.parse_arm()));
}
let hi = self.span.hi;
self.bump();
return Ok(self.mk_expr(lo, hi, ExprMatch(discriminant, arms), attrs));
}
pub fn parse_arm(&mut self) -> PResult<'a, Arm> {
maybe_whole!(no_clone self, NtArm);
let attrs = try!(self.parse_outer_attributes());
let pats = try!(self.parse_pats());
let mut guard = None;
if self.eat_keyword(keywords::If) {
guard = Some(try!(self.parse_expr()));
}
try!(self.expect(&token::FatArrow));
let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_STMT_EXPR, None));
let require_comma =
!classify::expr_is_simple_block(&*expr)
&& self.token != token::CloseDelim(token::Brace);
if require_comma {
try!(self.commit_expr(&*expr, &[token::Comma], &[token::CloseDelim(token::Brace)]));
} else {
self.eat(&token::Comma);
}
Ok(ast::Arm {
attrs: attrs,
pats: pats,
guard: guard,
body: expr,
})
}
/// Parse an expression
pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
self.parse_expr_res(Restrictions::empty(), None)
}
/// Evaluate the closure with restrictions in place.
///
/// After the closure is evaluated, restrictions are reset.
pub fn with_res<F>(&mut self, r: Restrictions, f: F) -> PResult<'a, P<Expr>>
where F: FnOnce(&mut Self) -> PResult<'a, P<Expr>>
{
let old = self.restrictions;
self.restrictions = r;
let r = f(self);
self.restrictions = old;
return r;
}
/// Parse an expression, subject to the given restrictions
pub fn parse_expr_res(&mut self, r: Restrictions,
already_parsed_attrs: Option<ThinAttributes>)
-> PResult<'a, P<Expr>> {
self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
}
/// Parse the RHS of a local variable declaration (e.g. '= 14;')
fn parse_initializer(&mut self) -> PResult<'a, Option<P<Expr>>> {
if self.check(&token::Eq) {
self.bump();
Ok(Some(try!(self.parse_expr())))
} else {
Ok(None)
}
}
/// Parse patterns, separated by '|' s
fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
let mut pats = Vec::new();
loop {
pats.push(try!(self.parse_pat()));
if self.check(&token::BinOp(token::Or)) { self.bump();}
else { return Ok(pats); }
};
}
fn parse_pat_tuple_elements(&mut self) -> PResult<'a, Vec<P<Pat>>> {
let mut fields = vec![];
if !self.check(&token::CloseDelim(token::Paren)) {
fields.push(try!(self.parse_pat()));
if self.look_ahead(1, |t| *t != token::CloseDelim(token::Paren)) {
while self.eat(&token::Comma) &&
!self.check(&token::CloseDelim(token::Paren)) {
fields.push(try!(self.parse_pat()));
}
}
if fields.len() == 1 {
try!(self.expect(&token::Comma));
}
}
Ok(fields)
}
fn parse_pat_vec_elements(
&mut self,
) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
let mut before = Vec::new();
let mut slice = None;
let mut after = Vec::new();
let mut first = true;
let mut before_slice = true;
while self.token != token::CloseDelim(token::Bracket) {
if first {
first = false;
} else {
try!(self.expect(&token::Comma));
if self.token == token::CloseDelim(token::Bracket)
&& (before_slice || !after.is_empty()) {
break
}
}
if before_slice {
if self.check(&token::DotDot) {
self.bump();
if self.check(&token::Comma) ||
self.check(&token::CloseDelim(token::Bracket)) {
slice = Some(P(ast::Pat {
id: ast::DUMMY_NODE_ID,
node: PatWild,
span: self.span,
}));
before_slice = false;
}
continue
}
}
let subpat = try!(self.parse_pat());
if before_slice && self.check(&token::DotDot) {
self.bump();
slice = Some(subpat);
before_slice = false;
} else if before_slice {
before.push(subpat);
} else {
after.push(subpat);
}
}
Ok((before, slice, after))
}
/// Parse the fields of a struct-like pattern
fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<codemap::Spanned<ast::FieldPat>> , bool)> {
let mut fields = Vec::new();
let mut etc = false;
let mut first = true;
while self.token != token::CloseDelim(token::Brace) {
if first {
first = false;
} else {
try!(self.expect(&token::Comma));
// accept trailing commas
if self.check(&token::CloseDelim(token::Brace)) { break }
}
let lo = self.span.lo;
let hi;
if self.check(&token::DotDot) {
self.bump();
if self.token != token::CloseDelim(token::Brace) {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `{}`, found `{}`", "}",
token_str)))
}
etc = true;
break;
}
// Check if a colon exists one ahead. This means we're parsing a fieldname.
let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
// Parsing a pattern of the form "fieldname: pat"
let fieldname = try!(self.parse_ident());
self.bump();
let pat = try!(self.parse_pat());
hi = pat.span.hi;
(pat, fieldname, false)
} else {
// Parsing a pattern of the form "(box) (ref) (mut) fieldname"
let is_box = self.eat_keyword(keywords::Box);
let boxed_span_lo = self.span.lo;
let is_ref = self.eat_keyword(keywords::Ref);
let is_mut = self.eat_keyword(keywords::Mut);
let fieldname = try!(self.parse_ident());
hi = self.last_span.hi;
let bind_type = match (is_ref, is_mut) {
(true, true) => BindingMode::ByRef(MutMutable),
(true, false) => BindingMode::ByRef(MutImmutable),
(false, true) => BindingMode::ByValue(MutMutable),
(false, false) => BindingMode::ByValue(MutImmutable),
};
let fieldpath = codemap::Spanned{span:self.last_span, node:fieldname};
let fieldpat = P(ast::Pat{
id: ast::DUMMY_NODE_ID,
node: PatIdent(bind_type, fieldpath, None),
span: mk_sp(boxed_span_lo, hi),
});
let subpat = if is_box {
P(ast::Pat{
id: ast::DUMMY_NODE_ID,
node: PatBox(fieldpat),
span: mk_sp(lo, hi),
})
} else {
fieldpat
};
(subpat, fieldname, true)
};
fields.push(codemap::Spanned { span: mk_sp(lo, hi),
node: ast::FieldPat { ident: fieldname,
pat: subpat,
is_shorthand: is_shorthand }});
}
return Ok((fields, etc));
}
fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
if self.is_path_start() {
let lo = self.span.lo;
let (qself, path) = if self.eat_lt() {
// Parse a qualified path
let (qself, path) =
try!(self.parse_qualified_path(NoTypesAllowed));
(Some(qself), path)
} else {
// Parse an unqualified path
(None, try!(self.parse_path(LifetimeAndTypesWithColons)))
};
let hi = self.last_span.hi;
Ok(self.mk_expr(lo, hi, ExprPath(qself, path), None))
} else {
self.parse_pat_literal_maybe_minus()
}
}
fn is_path_start(&self) -> bool {
(self.token == token::Lt || self.token == token::ModSep
|| self.token.is_ident() || self.token.is_path())
&& !self.token.is_keyword(keywords::True) && !self.token.is_keyword(keywords::False)
}
/// Parse a pattern.
pub fn parse_pat(&mut self) -> PResult<'a, P<Pat>> {
maybe_whole!(self, NtPat);
let lo = self.span.lo;
let pat;
match self.token {
token::Underscore => {
// Parse _
self.bump();
pat = PatWild;
}
token::BinOp(token::And) | token::AndAnd => {
// Parse &pat / &mut pat
try!(self.expect_and());
let mutbl = try!(self.parse_mutability());
if let token::Lifetime(ident) = self.token {
return Err(self.fatal(&format!("unexpected lifetime `{}` in pattern", ident)));
}
let subpat = try!(self.parse_pat());
pat = PatRegion(subpat, mutbl);
}
token::OpenDelim(token::Paren) => {
// Parse (pat,pat,pat,...) as tuple pattern
self.bump();
let fields = try!(self.parse_pat_tuple_elements());
try!(self.expect(&token::CloseDelim(token::Paren)));
pat = PatTup(fields);
}
token::OpenDelim(token::Bracket) => {
// Parse [pat,pat,...] as slice pattern
self.bump();
let (before, slice, after) = try!(self.parse_pat_vec_elements());
try!(self.expect(&token::CloseDelim(token::Bracket)));
pat = PatVec(before, slice, after);
}
_ => {
// At this point, token != _, &, &&, (, [
if self.eat_keyword(keywords::Mut) {
// Parse mut ident @ pat
pat = try!(self.parse_pat_ident(BindingMode::ByValue(MutMutable)));
} else if self.eat_keyword(keywords::Ref) {
// Parse ref ident @ pat / ref mut ident @ pat
let mutbl = try!(self.parse_mutability());
pat = try!(self.parse_pat_ident(BindingMode::ByRef(mutbl)));
} else if self.eat_keyword(keywords::Box) {
// Parse box pat
let subpat = try!(self.parse_pat());
pat = PatBox(subpat);
} else if self.is_path_start() {
// Parse pattern starting with a path
if self.token.is_plain_ident() && self.look_ahead(1, |t| *t != token::DotDotDot &&
*t != token::OpenDelim(token::Brace) &&
*t != token::OpenDelim(token::Paren) &&
// Contrary to its definition, a plain ident can be followed by :: in macros
*t != token::ModSep) {
// Plain idents have some extra abilities here compared to general paths
if self.look_ahead(1, |t| *t == token::Not) {
// Parse macro invocation
let ident = try!(self.parse_ident());
let ident_span = self.last_span;
let path = ident_to_path(ident_span, ident);
self.bump();
let delim = try!(self.expect_open_delim());
let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
seq_sep_none(), |p| p.parse_token_tree()));
let mac = Mac_ { path: path, tts: tts, ctxt: EMPTY_CTXT };
pat = PatMac(codemap::Spanned {node: mac,
span: mk_sp(lo, self.last_span.hi)});
} else {
// Parse ident @ pat
// This can give false positives and parse nullary enums,
// they are dealt with later in resolve
pat = try!(self.parse_pat_ident(BindingMode::ByValue(MutImmutable)));
}
} else {
let (qself, path) = if self.eat_lt() {
// Parse a qualified path
let (qself, path) =
try!(self.parse_qualified_path(NoTypesAllowed));
(Some(qself), path)
} else {
// Parse an unqualified path
(None, try!(self.parse_path(LifetimeAndTypesWithColons)))
};
match self.token {
token::DotDotDot => {
// Parse range
let hi = self.last_span.hi;
let begin = self.mk_expr(lo, hi, ExprPath(qself, path), None);
self.bump();
let end = try!(self.parse_pat_range_end());
pat = PatRange(begin, end);
}
token::OpenDelim(token::Brace) => {
if qself.is_some() {
return Err(self.fatal("unexpected `{` after qualified path"));
}
// Parse struct pattern
self.bump();
let (fields, etc) = try!(self.parse_pat_fields());
self.bump();
pat = PatStruct(path, fields, etc);
}
token::OpenDelim(token::Paren) => {
if qself.is_some() {
return Err(self.fatal("unexpected `(` after qualified path"));
}
// Parse tuple struct or enum pattern
if self.look_ahead(1, |t| *t == token::DotDot) {
// This is a "top constructor only" pat
self.bump();
self.bump();
try!(self.expect(&token::CloseDelim(token::Paren)));
pat = PatEnum(path, None);
} else {
let args = try!(self.parse_enum_variant_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
seq_sep_trailing_allowed(token::Comma),
|p| p.parse_pat()));
pat = PatEnum(path, Some(args));
}
}
_ => {
pat = match qself {
// Parse qualified path
Some(qself) => PatQPath(qself, path),
// Parse nullary enum
None => PatEnum(path, Some(vec![]))
};
}
}
}
} else {
// Try to parse everything else as literal with optional minus
let begin = try!(self.parse_pat_literal_maybe_minus());
if self.eat(&token::DotDotDot) {
let end = try!(self.parse_pat_range_end());
pat = PatRange(begin, end);
} else {
pat = PatLit(begin);
}
}
}
}
let hi = self.last_span.hi;
Ok(P(ast::Pat {
id: ast::DUMMY_NODE_ID,
node: pat,
span: mk_sp(lo, hi),
}))
}
/// Parse ident or ident @ pat
/// used by the copy foo and ref foo patterns to give a good
/// error message when parsing mistakes like ref foo(a,b)
fn parse_pat_ident(&mut self,
binding_mode: ast::BindingMode)
-> PResult<'a, ast::Pat_> {
if !self.token.is_plain_ident() {
let span = self.span;
let tok_str = self.this_token_to_string();
return Err(self.span_fatal(span,
&format!("expected identifier, found `{}`", tok_str)))
}
let ident = try!(self.parse_ident());
let last_span = self.last_span;
let name = codemap::Spanned{span: last_span, node: ident};
let sub = if self.eat(&token::At) {
Some(try!(self.parse_pat()))
} else {
None
};
// just to be friendly, if they write something like
// ref Some(i)
// we end up here with ( as the current token. This shortly
// leads to a parse error. Note that if there is no explicit
// binding mode then we do not end up here, because the lookahead
// will direct us over to parse_enum_variant()
if self.token == token::OpenDelim(token::Paren) {
let last_span = self.last_span;
return Err(self.span_fatal(
last_span,
"expected identifier, found enum pattern"))
}
Ok(PatIdent(binding_mode, name, sub))
}
/// Parse a local variable declaration
fn parse_local(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Local>> {
let lo = self.span.lo;
let pat = try!(self.parse_pat());
let mut ty = None;
if self.eat(&token::Colon) {
ty = Some(try!(self.parse_ty_sum()));
}
let init = try!(self.parse_initializer());
Ok(P(ast::Local {
ty: ty,
pat: pat,
init: init,
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, self.last_span.hi),
attrs: attrs,
}))
}
/// Parse a "let" stmt
fn parse_let(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Decl>> {
let lo = self.span.lo;
let local = try!(self.parse_local(attrs));
Ok(P(spanned(lo, self.last_span.hi, DeclLocal(local))))
}
/// Parse a structure field
fn parse_name_and_ty(&mut self, pr: Visibility,
attrs: Vec<Attribute> ) -> PResult<'a, StructField> {
let lo = match pr {
Inherited => self.span.lo,
Public => self.last_span.lo,
};
if !self.token.is_plain_ident() {
return Err(self.fatal("expected ident"));
}
let name = try!(self.parse_ident());
try!(self.expect(&token::Colon));
let ty = try!(self.parse_ty_sum());
Ok(spanned(lo, self.last_span.hi, ast::StructField_ {
kind: NamedField(name, pr),
id: ast::DUMMY_NODE_ID,
ty: ty,
attrs: attrs,
}))
}
/// Emit an expected item after attributes error.
fn expected_item_err(&self, attrs: &[Attribute]) {
let message = match attrs.last() {
Some(&Attribute { node: ast::Attribute_ { is_sugared_doc: true, .. }, .. }) => {
"expected item after doc comment"
}
_ => "expected item after attributes",
};
self.span_err(self.last_span, message);
}
/// Parse a statement. may include decl.
pub fn parse_stmt(&mut self) -> PResult<'a, Option<P<Stmt>>> {
Ok(try!(self.parse_stmt_()).map(P))
}
fn parse_stmt_(&mut self) -> PResult<'a, Option<Stmt>> {
maybe_whole!(Some deref self, NtStmt);
let attrs = try!(self.parse_outer_attributes());
let lo = self.span.lo;
Ok(Some(if self.check_keyword(keywords::Let) {
try!(self.expect_keyword(keywords::Let));
let decl = try!(self.parse_let(attrs.into_thin_attrs()));
let hi = decl.span.hi;
let stmt = StmtDecl(decl, ast::DUMMY_NODE_ID);
spanned(lo, hi, stmt)
} else if self.token.is_ident()
&& !self.token.is_any_keyword()
&& self.look_ahead(1, |t| *t == token::Not) {
// it's a macro invocation:
// Potential trouble: if we allow macros with paths instead of
// idents, we'd need to look ahead past the whole path here...
let pth = try!(self.parse_path(NoTypesAllowed));
self.bump();
let id = match self.token {
token::OpenDelim(_) => token::special_idents::invalid, // no special identifier
_ => try!(self.parse_ident()),
};
// check that we're pointing at delimiters (need to check
// again after the `if`, because of `parse_ident`
// consuming more tokens).
let delim = match self.token {
token::OpenDelim(delim) => delim,
_ => {
// we only expect an ident if we didn't parse one
// above.
let ident_str = if id.name == token::special_idents::invalid.name {
"identifier, "
} else {
""
};
let tok_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected {}`(` or `{{`, found `{}`",
ident_str,
tok_str)))
},
};
let tts = try!(self.parse_unspanned_seq(
&token::OpenDelim(delim),
&token::CloseDelim(delim),
seq_sep_none(),
|p| p.parse_token_tree()
));
let hi = self.last_span.hi;
let style = if delim == token::Brace {
MacStmtWithBraces
} else {
MacStmtWithoutBraces
};
if id.name == token::special_idents::invalid.name {
let stmt = StmtMac(P(spanned(lo,
hi,
Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT })),
style,
attrs.into_thin_attrs());
spanned(lo, hi, stmt)
} else {
// if it has a special ident, it's definitely an item
//
// Require a semicolon or braces.
if style != MacStmtWithBraces {
if !self.eat(&token::Semi) {
let last_span = self.last_span;
self.span_err(last_span,
"macros that expand to items must \
either be surrounded with braces or \
followed by a semicolon");
}
}
spanned(lo, hi, StmtDecl(
P(spanned(lo, hi, DeclItem(
self.mk_item(
lo, hi, id /*id is good here*/,
ItemMac(spanned(lo, hi,
Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT })),
Inherited, attrs)))),
ast::DUMMY_NODE_ID))
}
} else {
// FIXME: Bad copy of attrs
match try!(self.parse_item_(attrs.clone(), false, true)) {
Some(i) => {
let hi = i.span.hi;
let decl = P(spanned(lo, hi, DeclItem(i)));
spanned(lo, hi, StmtDecl(decl, ast::DUMMY_NODE_ID))
}
None => {
let unused_attrs = |attrs: &[_], s: &mut Self| {
if attrs.len() > 0 {
s.span_err(s.span,
"expected statement after outer attribute");
}
};
// Do not attempt to parse an expression if we're done here.
if self.token == token::Semi {
unused_attrs(&attrs, self);
self.bump();
return Ok(None);
}
if self.token == token::CloseDelim(token::Brace) {
unused_attrs(&attrs, self);
return Ok(None);
}
// Remainder are line-expr stmts.
let e = try!(self.parse_expr_res(
Restrictions::RESTRICTION_STMT_EXPR, Some(attrs.into_thin_attrs())));
let hi = e.span.hi;
let stmt = StmtExpr(e, ast::DUMMY_NODE_ID);
spanned(lo, hi, stmt)
}
}
}))
}
/// Is this expression a successfully-parsed statement?
fn expr_is_complete(&mut self, e: &Expr) -> bool {
self.restrictions.contains(Restrictions::RESTRICTION_STMT_EXPR) &&
!classify::expr_requires_semi_to_be_stmt(e)
}
/// Parse a block. No inner attrs are allowed.
pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
maybe_whole!(no_clone self, NtBlock);
let lo = self.span.lo;
if !self.eat(&token::OpenDelim(token::Brace)) {
let sp = self.span;
let tok = self.this_token_to_string();
return Err(self.span_fatal_help(sp,
&format!("expected `{{`, found `{}`", tok),
"place this code inside a block"));
}
self.parse_block_tail(lo, DefaultBlock)
}
/// Parse a block. Inner attrs are allowed.
fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
maybe_whole!(pair_empty self, NtBlock);
let lo = self.span.lo;
try!(self.expect(&token::OpenDelim(token::Brace)));
Ok((try!(self.parse_inner_attributes()),
try!(self.parse_block_tail(lo, DefaultBlock))))
}
/// Parse the rest of a block expression or function body
/// Precondition: already parsed the '{'.
fn parse_block_tail(&mut self, lo: BytePos, s: BlockCheckMode) -> PResult<'a, P<Block>> {
let mut stmts = vec![];
let mut expr = None;
while !self.eat(&token::CloseDelim(token::Brace)) {
let Spanned {node, span} = if let Some(s) = try!(self.parse_stmt_()) {
s
} else {
// Found only `;` or `}`.
continue;
};
match node {
StmtExpr(e, _) => {
try!(self.handle_expression_like_statement(e, span, &mut stmts, &mut expr));
}
StmtMac(mac, MacStmtWithoutBraces, attrs) => {
// statement macro without braces; might be an
// expr depending on whether a semicolon follows
match self.token {
token::Semi => {
stmts.push(P(Spanned {
node: StmtMac(mac, MacStmtWithSemicolon, attrs),
span: mk_sp(span.lo, self.span.hi),
}));
self.bump();
}
_ => {
let e = self.mk_mac_expr(span.lo, span.hi,
mac.and_then(|m| m.node),
None);
let e = try!(self.parse_dot_or_call_expr_with(e, attrs));
let e = try!(self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e)));
try!(self.handle_expression_like_statement(
e,
span,
&mut stmts,
&mut expr));
}
}
}
StmtMac(m, style, attrs) => {
// statement macro; might be an expr
match self.token {
token::Semi => {
stmts.push(P(Spanned {
node: StmtMac(m, MacStmtWithSemicolon, attrs),
span: mk_sp(span.lo, self.span.hi),
}));
self.bump();
}
token::CloseDelim(token::Brace) => {
// if a block ends in `m!(arg)` without
// a `;`, it must be an expr
expr = Some(self.mk_mac_expr(span.lo, span.hi,
m.and_then(|x| x.node),
attrs));
}
_ => {
stmts.push(P(Spanned {
node: StmtMac(m, style, attrs),
span: span
}));
}
}
}
_ => { // all other kinds of statements:
let mut hi = span.hi;
if classify::stmt_ends_with_semi(&node) {
try!(self.commit_stmt_expecting(token::Semi));
hi = self.last_span.hi;
}
stmts.push(P(Spanned {
node: node,
span: mk_sp(span.lo, hi)
}));
}
}
}
Ok(P(ast::Block {
stmts: stmts,
expr: expr,
id: ast::DUMMY_NODE_ID,
rules: s,
span: mk_sp(lo, self.last_span.hi),
}))
}
fn handle_expression_like_statement(
&mut self,
e: P<Expr>,
span: Span,
stmts: &mut Vec<P<Stmt>>,
last_block_expr: &mut Option<P<Expr>>) -> PResult<'a, ()> {
// expression without semicolon
if classify::expr_requires_semi_to_be_stmt(&*e) {
// Just check for errors and recover; do not eat semicolon yet.
try!(self.commit_stmt(&[],
&[token::Semi, token::CloseDelim(token::Brace)]));
}
match self.token {
token::Semi => {
self.bump();
let span_with_semi = Span {
lo: span.lo,
hi: self.last_span.hi,
expn_id: span.expn_id,
};
stmts.push(P(Spanned {
node: StmtSemi(e, ast::DUMMY_NODE_ID),
span: span_with_semi,
}));
}
token::CloseDelim(token::Brace) => *last_block_expr = Some(e),
_ => {
stmts.push(P(Spanned {
node: StmtExpr(e, ast::DUMMY_NODE_ID),
span: span
}));
}
}
Ok(())
}
// Parses a sequence of bounds if a `:` is found,
// otherwise returns empty list.
fn parse_colon_then_ty_param_bounds(&mut self,
mode: BoundParsingMode)
-> PResult<'a, TyParamBounds>
{
if !self.eat(&token::Colon) {
Ok(P::empty())
} else {
self.parse_ty_param_bounds(mode)
}
}
// matches bounds = ( boundseq )?
// where boundseq = ( polybound + boundseq ) | polybound
// and polybound = ( 'for' '<' 'region '>' )? bound
// and bound = 'region | trait_ref
fn parse_ty_param_bounds(&mut self,
mode: BoundParsingMode)
-> PResult<'a, TyParamBounds>
{
let mut result = vec!();
loop {
let question_span = self.span;
let ate_question = self.eat(&token::Question);
match self.token {
token::Lifetime(lifetime) => {
if ate_question {
self.span_err(question_span,
"`?` may only modify trait bounds, not lifetime bounds");
}
result.push(RegionTyParamBound(ast::Lifetime {
id: ast::DUMMY_NODE_ID,
span: self.span,
name: lifetime.name
}));
self.bump();
}
token::ModSep | token::Ident(..) => {
let poly_trait_ref = try!(self.parse_poly_trait_ref());
let modifier = if ate_question {
if mode == BoundParsingMode::Modified {
TraitBoundModifier::Maybe
} else {
self.span_err(question_span,
"unexpected `?`");
TraitBoundModifier::None
}
} else {
TraitBoundModifier::None
};
result.push(TraitTyParamBound(poly_trait_ref, modifier))
}
_ => break,
}
if !self.eat(&token::BinOp(token::Plus)) {
break;
}
}
return Ok(P::from_vec(result));
}
/// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
fn parse_ty_param(&mut self) -> PResult<'a, TyParam> {
let span = self.span;
let ident = try!(self.parse_ident());
let bounds = try!(self.parse_colon_then_ty_param_bounds(BoundParsingMode::Modified));
let default = if self.check(&token::Eq) {
self.bump();
Some(try!(self.parse_ty_sum()))
} else {
None
};
Ok(TyParam {
ident: ident,
id: ast::DUMMY_NODE_ID,
bounds: bounds,
default: default,
span: span,
})
}
/// Parse a set of optional generic type parameter declarations. Where
/// clauses are not parsed here, and must be added later via
/// `parse_where_clause()`.
///
/// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
/// | ( < lifetimes , typaramseq ( , )? > )
/// where typaramseq = ( typaram ) | ( typaram , typaramseq )
pub fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
maybe_whole!(self, NtGenerics);
if self.eat(&token::Lt) {
let lifetime_defs = try!(self.parse_lifetime_defs());
let mut seen_default = false;
let ty_params = try!(self.parse_seq_to_gt(Some(token::Comma), |p| {
try!(p.forbid_lifetime());
let ty_param = try!(p.parse_ty_param());
if ty_param.default.is_some() {
seen_default = true;
} else if seen_default {
let last_span = p.last_span;
p.span_err(last_span,
"type parameters with a default must be trailing");
}
Ok(ty_param)
}));
Ok(ast::Generics {
lifetimes: lifetime_defs,
ty_params: ty_params,
where_clause: WhereClause {
id: ast::DUMMY_NODE_ID,
predicates: Vec::new(),
}
})
} else {
Ok(ast::Generics::default())
}
}
fn parse_generic_values_after_lt(&mut self) -> PResult<'a, (Vec<ast::Lifetime>,
Vec<P<Ty>>,
Vec<P<TypeBinding>>)> {
let span_lo = self.span.lo;
let lifetimes = try!(self.parse_lifetimes(token::Comma));
let missing_comma = !lifetimes.is_empty() &&
!self.token.is_like_gt() &&
self.last_token
.as_ref().map_or(true,
|x| &**x != &token::Comma);
if missing_comma {
let msg = format!("expected `,` or `>` after lifetime \
name, found `{}`",
self.this_token_to_string());
let mut err = self.diagnostic().struct_span_err(self.span, &msg);
let span_hi = self.span.hi;
let span_hi = match self.parse_ty() {
Ok(..) => self.span.hi,
Err(ref mut err) => {
err.cancel();
span_hi
}
};
let msg = format!("did you mean a single argument type &'a Type, \
or did you mean the comma-separated arguments \
'a, Type?");
err.span_note(mk_sp(span_lo, span_hi), &msg);
err.emit();
self.abort_if_errors()
}
// First parse types.
let (types, returned) = try!(self.parse_seq_to_gt_or_return(
Some(token::Comma),
|p| {
try!(p.forbid_lifetime());
if p.look_ahead(1, |t| t == &token::Eq) {
Ok(None)
} else {
Ok(Some(try!(p.parse_ty_sum())))
}
}
));
// If we found the `>`, don't continue.
if !returned {
return Ok((lifetimes, types.into_vec(), Vec::new()));
}
// Then parse type bindings.
let bindings = try!(self.parse_seq_to_gt(
Some(token::Comma),
|p| {
try!(p.forbid_lifetime());
let lo = p.span.lo;
let ident = try!(p.parse_ident());
let found_eq = p.eat(&token::Eq);
if !found_eq {
let span = p.span;
p.span_warn(span, "whoops, no =?");
}
let ty = try!(p.parse_ty());
let hi = ty.span.hi;
let span = mk_sp(lo, hi);
return Ok(P(TypeBinding{id: ast::DUMMY_NODE_ID,
ident: ident,
ty: ty,
span: span,
}));
}
));
Ok((lifetimes, types.into_vec(), bindings.into_vec()))
}
fn forbid_lifetime(&mut self) -> PResult<'a, ()> {
if self.token.is_lifetime() {
let span = self.span;
return Err(self.span_fatal(span, "lifetime parameters must be declared \
prior to type parameters"))
}
Ok(())
}
/// Parses an optional `where` clause and places it in `generics`.
///
/// ```ignore
/// where T : Trait<U, V> + 'b, 'a : 'b
/// ```
pub fn parse_where_clause(&mut self) -> PResult<'a, ast::WhereClause> {
maybe_whole!(self, NtWhereClause);
let mut where_clause = WhereClause {
id: ast::DUMMY_NODE_ID,
predicates: Vec::new(),
};
if !self.eat_keyword(keywords::Where) {
return Ok(where_clause);
}
let mut parsed_something = false;
loop {
let lo = self.span.lo;
match self.token {
token::OpenDelim(token::Brace) => {
break
}
token::Lifetime(..) => {
let bounded_lifetime =
try!(self.parse_lifetime());
self.eat(&token::Colon);
let bounds =
try!(self.parse_lifetimes(token::BinOp(token::Plus)));
let hi = self.last_span.hi;
let span = mk_sp(lo, hi);
where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
ast::WhereRegionPredicate {
span: span,
lifetime: bounded_lifetime,
bounds: bounds
}
));
parsed_something = true;
}
_ => {
let bound_lifetimes = if self.eat_keyword(keywords::For) {
// Higher ranked constraint.
try!(self.expect(&token::Lt));
let lifetime_defs = try!(self.parse_lifetime_defs());
try!(self.expect_gt());
lifetime_defs
} else {
vec![]
};
let bounded_ty = try!(self.parse_ty());
if self.eat(&token::Colon) {
let bounds = try!(self.parse_ty_param_bounds(BoundParsingMode::Bare));
let hi = self.last_span.hi;
let span = mk_sp(lo, hi);
if bounds.is_empty() {
self.span_err(span,
"each predicate in a `where` clause must have \
at least one bound in it");
}
where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
ast::WhereBoundPredicate {
span: span,
bound_lifetimes: bound_lifetimes,
bounded_ty: bounded_ty,
bounds: bounds,
}));
parsed_something = true;
} else if self.eat(&token::Eq) {
// let ty = try!(self.parse_ty());
let hi = self.last_span.hi;
let span = mk_sp(lo, hi);
// where_clause.predicates.push(
// ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
// id: ast::DUMMY_NODE_ID,
// span: span,
// path: panic!("NYI"), //bounded_ty,
// ty: ty,
// }));
// parsed_something = true;
// // FIXME(#18433)
self.span_err(span,
"equality constraints are not yet supported \
in where clauses (#20041)");
} else {
let last_span = self.last_span;
self.span_err(last_span,
"unexpected token in `where` clause");
}
}
};
if !self.eat(&token::Comma) {
break
}
}
if !parsed_something {
let last_span = self.last_span;
self.span_err(last_span,
"a `where` clause must have at least one predicate \
in it");
}
Ok(where_clause)
}
fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
-> PResult<'a, (Vec<Arg> , bool)> {
let sp = self.span;
let mut args: Vec<Option<Arg>> =
try!(self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
seq_sep_trailing_allowed(token::Comma),
|p| {
if p.token == token::DotDotDot {
p.bump();
if allow_variadic {
if p.token != token::CloseDelim(token::Paren) {
let span = p.span;
return Err(p.span_fatal(span,
"`...` must be last in argument list for variadic function"))
}
} else {
let span = p.span;
return Err(p.span_fatal(span,
"only foreign functions are allowed to be variadic"))
}
Ok(None)
} else {
Ok(Some(try!(p.parse_arg_general(named_args))))
}
}
));
let variadic = match args.pop() {
Some(None) => true,
Some(x) => {
// Need to put back that last arg
args.push(x);
false
}
None => false
};
if variadic && args.is_empty() {
self.span_err(sp,
"variadic function must be declared with at least one named argument");
}
let args = args.into_iter().map(|x| x.unwrap()).collect();
Ok((args, variadic))
}
/// Parse the argument list and result type of a function declaration
pub fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
let (args, variadic) = try!(self.parse_fn_args(true, allow_variadic));
let ret_ty = try!(self.parse_ret_ty());
Ok(P(FnDecl {
inputs: args,
output: ret_ty,
variadic: variadic
}))
}
fn is_self_ident(&mut self) -> bool {
match self.token {
token::Ident(id, token::Plain) => id.name == special_idents::self_.name,
_ => false
}
}
fn expect_self_ident(&mut self) -> PResult<'a, ast::Ident> {
match self.token {
token::Ident(id, token::Plain) if id.name == special_idents::self_.name => {
self.bump();
Ok(id)
},
_ => {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `self`, found `{}`",
token_str)))
}
}
}
fn is_self_type_ident(&mut self) -> bool {
match self.token {
token::Ident(id, token::Plain) => id.name == special_idents::type_self.name,
_ => false
}
}
fn expect_self_type_ident(&mut self) -> PResult<'a, ast::Ident> {
match self.token {
token::Ident(id, token::Plain) if id.name == special_idents::type_self.name => {
self.bump();
Ok(id)
},
_ => {
let token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected `Self`, found `{}`",
token_str)))
}
}
}
/// Parse the argument list and result type of a function
/// that may have a self type.
fn parse_fn_decl_with_self<F>(&mut self,
parse_arg_fn: F) -> PResult<'a, (ExplicitSelf, P<FnDecl>)> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
{
fn maybe_parse_borrowed_explicit_self<'b>(this: &mut Parser<'b>)
-> PResult<'b, ast::ExplicitSelf_> {
// The following things are possible to see here:
//
// fn(&mut self)
// fn(&mut self)
// fn(&'lt self)
// fn(&'lt mut self)
//
// We already know that the current token is `&`.
if this.look_ahead(1, |t| t.is_keyword(keywords::SelfValue)) {
this.bump();
Ok(SelfRegion(None, MutImmutable, try!(this.expect_self_ident())))
} else if this.look_ahead(1, |t| t.is_mutability()) &&
this.look_ahead(2, |t| t.is_keyword(keywords::SelfValue)) {
this.bump();
let mutability = try!(this.parse_mutability());
Ok(SelfRegion(None, mutability, try!(this.expect_self_ident())))
} else if this.look_ahead(1, |t| t.is_lifetime()) &&
this.look_ahead(2, |t| t.is_keyword(keywords::SelfValue)) {
this.bump();
let lifetime = try!(this.parse_lifetime());
Ok(SelfRegion(Some(lifetime), MutImmutable, try!(this.expect_self_ident())))
} else if this.look_ahead(1, |t| t.is_lifetime()) &&
this.look_ahead(2, |t| t.is_mutability()) &&
this.look_ahead(3, |t| t.is_keyword(keywords::SelfValue)) {
this.bump();
let lifetime = try!(this.parse_lifetime());
let mutability = try!(this.parse_mutability());
Ok(SelfRegion(Some(lifetime), mutability, try!(this.expect_self_ident())))
} else {
Ok(SelfStatic)
}
}
try!(self.expect(&token::OpenDelim(token::Paren)));
// A bit of complexity and lookahead is needed here in order to be
// backwards compatible.
let lo = self.span.lo;
let mut self_ident_lo = self.span.lo;
let mut self_ident_hi = self.span.hi;
let mut mutbl_self = MutImmutable;
let explicit_self = match self.token {
token::BinOp(token::And) => {
let eself = try!(maybe_parse_borrowed_explicit_self(self));
self_ident_lo = self.last_span.lo;
self_ident_hi = self.last_span.hi;
eself
}
token::BinOp(token::Star) => {
// Possibly "*self" or "*mut self" -- not supported. Try to avoid
// emitting cryptic "unexpected token" errors.
self.bump();
let _mutability = if self.token.is_mutability() {
try!(self.parse_mutability())
} else {
MutImmutable
};
if self.is_self_ident() {
let span = self.span;
self.span_err(span, "cannot pass self by raw pointer");
self.bump();
}
// error case, making bogus self ident:
SelfValue(special_idents::self_)
}
token::Ident(..) => {
if self.is_self_ident() {
let self_ident = try!(self.expect_self_ident());
// Determine whether this is the fully explicit form, `self:
// TYPE`.
if self.eat(&token::Colon) {
SelfExplicit(try!(self.parse_ty_sum()), self_ident)
} else {
SelfValue(self_ident)
}
} else if self.token.is_mutability() &&
self.look_ahead(1, |t| t.is_keyword(keywords::SelfValue)) {
mutbl_self = try!(self.parse_mutability());
let self_ident = try!(self.expect_self_ident());
// Determine whether this is the fully explicit form,
// `self: TYPE`.
if self.eat(&token::Colon) {
SelfExplicit(try!(self.parse_ty_sum()), self_ident)
} else {
SelfValue(self_ident)
}
} else {
SelfStatic
}
}
_ => SelfStatic,
};
let explicit_self_sp = mk_sp(self_ident_lo, self_ident_hi);
// shared fall-through for the three cases below. borrowing prevents simply
// writing this as a closure
macro_rules! parse_remaining_arguments {
($self_id:ident) =>
{
// If we parsed a self type, expect a comma before the argument list.
match self.token {
token::Comma => {
self.bump();
let sep = seq_sep_trailing_allowed(token::Comma);
let mut fn_inputs = try!(self.parse_seq_to_before_end(
&token::CloseDelim(token::Paren),
sep,
parse_arg_fn
));
fn_inputs.insert(0, Arg::new_self(explicit_self_sp, mutbl_self, $self_id));
fn_inputs
}
token::CloseDelim(token::Paren) => {
vec!(Arg::new_self(explicit_self_sp, mutbl_self, $self_id))
}
_ => {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `,` or `)`, found `{}`",
token_str)))
}
}
}
}
let fn_inputs = match explicit_self {
SelfStatic => {
let sep = seq_sep_trailing_allowed(token::Comma);
try!(self.parse_seq_to_before_end(&token::CloseDelim(token::Paren),
sep, parse_arg_fn))
}
SelfValue(id) => parse_remaining_arguments!(id),
SelfRegion(_,_,id) => parse_remaining_arguments!(id),
SelfExplicit(_,id) => parse_remaining_arguments!(id),
};
try!(self.expect(&token::CloseDelim(token::Paren)));
let hi = self.span.hi;
let ret_ty = try!(self.parse_ret_ty());
let fn_decl = P(FnDecl {
inputs: fn_inputs,
output: ret_ty,
variadic: false
});
Ok((spanned(lo, hi, explicit_self), fn_decl))
}
// parse the |arg, arg| header on a lambda
fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
let inputs_captures = {
if self.eat(&token::OrOr) {
Vec::new()
} else {
try!(self.expect(&token::BinOp(token::Or)));
try!(self.parse_obsolete_closure_kind());
let args = try!(self.parse_seq_to_before_end(
&token::BinOp(token::Or),
seq_sep_trailing_allowed(token::Comma),
|p| p.parse_fn_block_arg()
));
self.bump();
args
}
};
let output = try!(self.parse_ret_ty());
Ok(P(FnDecl {
inputs: inputs_captures,
output: output,
variadic: false
}))
}
/// Parse the name and optional generic types of a function header.
fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
let id = try!(self.parse_ident());
let generics = try!(self.parse_generics());
Ok((id, generics))
}
fn mk_item(&mut self, lo: BytePos, hi: BytePos, ident: Ident,
node: Item_, vis: Visibility,
attrs: Vec<Attribute>) -> P<Item> {
P(Item {
ident: ident,
attrs: attrs,
id: ast::DUMMY_NODE_ID,
node: node,
vis: vis,
span: mk_sp(lo, hi)
})
}
/// Parse an item-position function declaration.
fn parse_item_fn(&mut self,
unsafety: Unsafety,
constness: Constness,
abi: abi::Abi)
-> PResult<'a, ItemInfo> {
let (ident, mut generics) = try!(self.parse_fn_header());
let decl = try!(self.parse_fn_decl(false));
generics.where_clause = try!(self.parse_where_clause());
let (inner_attrs, body) = try!(self.parse_inner_attrs_and_block());
Ok((ident, ItemFn(decl, unsafety, constness, abi, generics, body), Some(inner_attrs)))
}
/// true if we are looking at `const ID`, false for things like `const fn` etc
pub fn is_const_item(&mut self) -> bool {
self.token.is_keyword(keywords::Const) &&
!self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
!self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
}
/// parses all the "front matter" for a `fn` declaration, up to
/// and including the `fn` keyword:
///
/// - `const fn`
/// - `unsafe fn`
/// - `const unsafe fn`
/// - `extern fn`
/// - etc
pub fn parse_fn_front_matter(&mut self)
-> PResult<'a, (ast::Constness, ast::Unsafety, abi::Abi)> {
let is_const_fn = self.eat_keyword(keywords::Const);
let unsafety = try!(self.parse_unsafety());
let (constness, unsafety, abi) = if is_const_fn {
(Constness::Const, unsafety, abi::Rust)
} else {
let abi = if self.eat_keyword(keywords::Extern) {
try!(self.parse_opt_abi()).unwrap_or(abi::C)
} else {
abi::Rust
};
(Constness::NotConst, unsafety, abi)
};
try!(self.expect_keyword(keywords::Fn));
Ok((constness, unsafety, abi))
}
/// Parse an impl item.
pub fn parse_impl_item(&mut self) -> PResult<'a, P<ImplItem>> {
maybe_whole!(no_clone self, NtImplItem);
let mut attrs = try!(self.parse_outer_attributes());
let lo = self.span.lo;
let vis = try!(self.parse_visibility());
let (name, node) = if self.eat_keyword(keywords::Type) {
let name = try!(self.parse_ident());
try!(self.expect(&token::Eq));
let typ = try!(self.parse_ty_sum());
try!(self.expect(&token::Semi));
(name, ast::ImplItemKind::Type(typ))
} else if self.is_const_item() {
try!(self.expect_keyword(keywords::Const));
let name = try!(self.parse_ident());
try!(self.expect(&token::Colon));
let typ = try!(self.parse_ty_sum());
try!(self.expect(&token::Eq));
let expr = try!(self.parse_expr());
try!(self.commit_expr_expecting(&expr, token::Semi));
(name, ast::ImplItemKind::Const(typ, expr))
} else {
let (name, inner_attrs, node) = try!(self.parse_impl_method(vis));
attrs.extend(inner_attrs);
(name, node)
};
Ok(P(ImplItem {
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, self.last_span.hi),
ident: name,
vis: vis,
attrs: attrs,
node: node
}))
}
fn complain_if_pub_macro(&mut self, visa: Visibility, span: Span) {
match visa {
Public => {
let is_macro_rules: bool = match self.token {
token::Ident(sid, _) => sid.name == intern("macro_rules"),
_ => false,
};
if is_macro_rules {
self.diagnostic().struct_span_err(span, "can't qualify macro_rules \
invocation with `pub`")
.fileline_help(span, "did you mean #[macro_export]?")
.emit();
} else {
self.diagnostic().struct_span_err(span, "can't qualify macro \
invocation with `pub`")
.fileline_help(span, "try adjusting the macro to put `pub` \
inside the invocation")
.emit();
}
}
Inherited => (),
}
}
/// Parse a method or a macro invocation in a trait impl.
fn parse_impl_method(&mut self, vis: Visibility)
-> PResult<'a, (Ident, Vec<ast::Attribute>, ast::ImplItemKind)> {
// code copied from parse_macro_use_or_failure... abstraction!
if !self.token.is_any_keyword()
&& self.look_ahead(1, |t| *t == token::Not)
&& (self.look_ahead(2, |t| *t == token::OpenDelim(token::Paren))
|| self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))) {
// method macro.
let last_span = self.last_span;
self.complain_if_pub_macro(vis, last_span);
let lo = self.span.lo;
let pth = try!(self.parse_path(NoTypesAllowed));
try!(self.expect(&token::Not));
// eat a matched-delimiter token tree:
let delim = try!(self.expect_open_delim());
let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
seq_sep_none(),
|p| p.parse_token_tree()));
let m_ = Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT };
let m: ast::Mac = codemap::Spanned { node: m_,
span: mk_sp(lo,
self.last_span.hi) };
if delim != token::Brace {
try!(self.expect(&token::Semi))
}
Ok((token::special_idents::invalid, vec![], ast::ImplItemKind::Macro(m)))
} else {
let (constness, unsafety, abi) = try!(self.parse_fn_front_matter());
let ident = try!(self.parse_ident());
let mut generics = try!(self.parse_generics());
let (explicit_self, decl) = try!(self.parse_fn_decl_with_self(|p| {
p.parse_arg()
}));
generics.where_clause = try!(self.parse_where_clause());
let (inner_attrs, body) = try!(self.parse_inner_attrs_and_block());
Ok((ident, inner_attrs, ast::ImplItemKind::Method(ast::MethodSig {
generics: generics,
abi: abi,
explicit_self: explicit_self,
unsafety: unsafety,
constness: constness,
decl: decl
}, body)))
}
}
/// Parse trait Foo { ... }
fn parse_item_trait(&mut self, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
let ident = try!(self.parse_ident());
let mut tps = try!(self.parse_generics());
// Parse supertrait bounds.
let bounds = try!(self.parse_colon_then_ty_param_bounds(BoundParsingMode::Bare));
tps.where_clause = try!(self.parse_where_clause());
let meths = try!(self.parse_trait_items());
Ok((ident, ItemTrait(unsafety, tps, bounds, meths), None))
}
/// Parses items implementations variants
/// impl<T> Foo { ... }
/// impl<T> ToString for &'static T { ... }
/// impl Send for .. {}
fn parse_item_impl(&mut self, unsafety: ast::Unsafety) -> PResult<'a, ItemInfo> {
let impl_span = self.span;
// First, parse type parameters if necessary.
let mut generics = try!(self.parse_generics());
// Special case: if the next identifier that follows is '(', don't
// allow this to be parsed as a trait.
let could_be_trait = self.token != token::OpenDelim(token::Paren);
let neg_span = self.span;
let polarity = if self.eat(&token::Not) {
ast::ImplPolarity::Negative
} else {
ast::ImplPolarity::Positive
};
// Parse the trait.
let mut ty = try!(self.parse_ty_sum());
// Parse traits, if necessary.
let opt_trait = if could_be_trait && self.eat_keyword(keywords::For) {
// New-style trait. Reinterpret the type as a trait.
match ty.node {
TyPath(None, ref path) => {
Some(TraitRef {
path: (*path).clone(),
ref_id: ty.id,
})
}
_ => {
self.span_err(ty.span, "not a trait");
None
}
}
} else {
match polarity {
ast::ImplPolarity::Negative => {
// This is a negated type implementation
// `impl !MyType {}`, which is not allowed.
self.span_err(neg_span, "inherent implementation can't be negated");
},
_ => {}
}
None
};
if opt_trait.is_some() && self.eat(&token::DotDot) {
if generics.is_parameterized() {
self.span_err(impl_span, "default trait implementations are not \
allowed to have generics");
}
try!(self.expect(&token::OpenDelim(token::Brace)));
try!(self.expect(&token::CloseDelim(token::Brace)));
Ok((ast_util::impl_pretty_name(&opt_trait, None),
ItemDefaultImpl(unsafety, opt_trait.unwrap()), None))
} else {
if opt_trait.is_some() {
ty = try!(self.parse_ty_sum());
}
generics.where_clause = try!(self.parse_where_clause());
try!(self.expect(&token::OpenDelim(token::Brace)));
let attrs = try!(self.parse_inner_attributes());
let mut impl_items = vec![];
while !self.eat(&token::CloseDelim(token::Brace)) {
impl_items.push(try!(self.parse_impl_item()));
}
Ok((ast_util::impl_pretty_name(&opt_trait, Some(&*ty)),
ItemImpl(unsafety, polarity, generics, opt_trait, ty, impl_items),
Some(attrs)))
}
}
/// Parse a::B<String,i32>
fn parse_trait_ref(&mut self) -> PResult<'a, TraitRef> {
Ok(ast::TraitRef {
path: try!(self.parse_path(LifetimeAndTypesWithoutColons)),
ref_id: ast::DUMMY_NODE_ID,
})
}
fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<ast::LifetimeDef>> {
if self.eat_keyword(keywords::For) {
try!(self.expect(&token::Lt));
let lifetime_defs = try!(self.parse_lifetime_defs());
try!(self.expect_gt());
Ok(lifetime_defs)
} else {
Ok(Vec::new())
}
}
/// Parse for<'l> a::B<String,i32>
fn parse_poly_trait_ref(&mut self) -> PResult<'a, PolyTraitRef> {
let lo = self.span.lo;
let lifetime_defs = try!(self.parse_late_bound_lifetime_defs());
Ok(ast::PolyTraitRef {
bound_lifetimes: lifetime_defs,
trait_ref: try!(self.parse_trait_ref()),
span: mk_sp(lo, self.last_span.hi),
})
}
/// Parse struct Foo { ... }
fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
let class_name = try!(self.parse_ident());
let mut generics = try!(self.parse_generics());
// There is a special case worth noting here, as reported in issue #17904.
// If we are parsing a tuple struct it is the case that the where clause
// should follow the field list. Like so:
//
// struct Foo<T>(T) where T: Copy;
//
// If we are parsing a normal record-style struct it is the case
// that the where clause comes before the body, and after the generics.
// So if we look ahead and see a brace or a where-clause we begin
// parsing a record style struct.
//
// Otherwise if we look ahead and see a paren we parse a tuple-style
// struct.
let vdata = if self.token.is_keyword(keywords::Where) {
generics.where_clause = try!(self.parse_where_clause());
if self.eat(&token::Semi) {
// If we see a: `struct Foo<T> where T: Copy;` style decl.
VariantData::Unit(ast::DUMMY_NODE_ID)
} else {
// If we see: `struct Foo<T> where T: Copy { ... }`
VariantData::Struct(try!(self.parse_record_struct_body(ParsePub::Yes)),
ast::DUMMY_NODE_ID)
}
// No `where` so: `struct Foo<T>;`
} else if self.eat(&token::Semi) {
VariantData::Unit(ast::DUMMY_NODE_ID)
// Record-style struct definition
} else if self.token == token::OpenDelim(token::Brace) {
VariantData::Struct(try!(self.parse_record_struct_body(ParsePub::Yes)),
ast::DUMMY_NODE_ID)
// Tuple-style struct definition with optional where-clause.
} else if self.token == token::OpenDelim(token::Paren) {
let body = VariantData::Tuple(try!(self.parse_tuple_struct_body(ParsePub::Yes)),
ast::DUMMY_NODE_ID);
generics.where_clause = try!(self.parse_where_clause());
try!(self.expect(&token::Semi));
body
} else {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `where`, `{{`, `(`, or `;` after struct \
name, found `{}`", token_str)))
};
Ok((class_name, ItemStruct(vdata, generics), None))
}
pub fn parse_record_struct_body(&mut self,
parse_pub: ParsePub)
-> PResult<'a, Vec<StructField>> {
let mut fields = Vec::new();
if self.eat(&token::OpenDelim(token::Brace)) {
while self.token != token::CloseDelim(token::Brace) {
fields.push(try!(self.parse_struct_decl_field(parse_pub)));
}
self.bump();
} else {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `where`, or `{{` after struct \
name, found `{}`",
token_str)));
}
Ok(fields)
}
pub fn parse_tuple_struct_body(&mut self,
parse_pub: ParsePub)
-> PResult<'a, Vec<StructField>> {
// This is the case where we find `struct Foo<T>(T) where T: Copy;`
// Unit like structs are handled in parse_item_struct function
let fields = try!(self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
seq_sep_trailing_allowed(token::Comma),
|p| {
let attrs = try!(p.parse_outer_attributes());
let lo = p.span.lo;
let struct_field_ = ast::StructField_ {
kind: UnnamedField (
if parse_pub == ParsePub::Yes {
try!(p.parse_visibility())
} else {
Inherited
}
),
id: ast::DUMMY_NODE_ID,
ty: try!(p.parse_ty_sum()),
attrs: attrs,
};
Ok(spanned(lo, p.span.hi, struct_field_))
}));
Ok(fields)
}
/// Parse a structure field declaration
pub fn parse_single_struct_field(&mut self,
vis: Visibility,
attrs: Vec<Attribute> )
-> PResult<'a, StructField> {
let a_var = try!(self.parse_name_and_ty(vis, attrs));
match self.token {
token::Comma => {
self.bump();
}
token::CloseDelim(token::Brace) => {}
_ => {
let span = self.span;
let token_str = self.this_token_to_string();
return Err(self.span_fatal_help(span,
&format!("expected `,`, or `}}`, found `{}`",
token_str),
"struct fields should be separated by commas"))
}
}
Ok(a_var)
}
/// Parse an element of a struct definition
fn parse_struct_decl_field(&mut self, parse_pub: ParsePub) -> PResult<'a, StructField> {
let attrs = try!(self.parse_outer_attributes());
if self.eat_keyword(keywords::Pub) {
if parse_pub == ParsePub::No {
let span = self.last_span;
self.span_err(span, "`pub` is not allowed here");
}
return self.parse_single_struct_field(Public, attrs);
}
return self.parse_single_struct_field(Inherited, attrs);
}
/// Parse visibility: PUB or nothing
fn parse_visibility(&mut self) -> PResult<'a, Visibility> {
if self.eat_keyword(keywords::Pub) { Ok(Public) }
else { Ok(Inherited) }
}
/// Given a termination token, parse all of the items in a module
fn parse_mod_items(&mut self, term: &token::Token, inner_lo: BytePos) -> PResult<'a, Mod> {
let mut items = vec![];
while let Some(item) = try!(self.parse_item()) {
items.push(item);
}
if !self.eat(term) {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected item, found `{}`", token_str)));
}
let hi = if self.span == codemap::DUMMY_SP {
inner_lo
} else {
self.last_span.hi
};
Ok(ast::Mod {
inner: mk_sp(inner_lo, hi),
items: items
})
}
fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
let id = try!(self.parse_ident());
try!(self.expect(&token::Colon));
let ty = try!(self.parse_ty_sum());
try!(self.expect(&token::Eq));
let e = try!(self.parse_expr());
try!(self.commit_expr_expecting(&*e, token::Semi));
let item = match m {
Some(m) => ItemStatic(ty, m, e),
None => ItemConst(ty, e),
};
Ok((id, item, None))
}
/// Parse a `mod <foo> { ... }` or `mod <foo>;` item
fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
let id_span = self.span;
let id = try!(self.parse_ident());
if self.check(&token::Semi) {
self.bump();
// This mod is in an external file. Let's go get it!
let (m, attrs) = try!(self.eval_src_mod(id, outer_attrs, id_span));
Ok((id, m, Some(attrs)))
} else {
self.push_mod_path(id, outer_attrs);
try!(self.expect(&token::OpenDelim(token::Brace)));
let mod_inner_lo = self.span.lo;
let old_owns_directory = self.owns_directory;
self.owns_directory = true;
let attrs = try!(self.parse_inner_attributes());
let m = try!(self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo));
self.owns_directory = old_owns_directory;
self.pop_mod_path();
Ok((id, ItemMod(m), Some(attrs)))
}
}
fn push_mod_path(&mut self, id: Ident, attrs: &[Attribute]) {
let default_path = self.id_to_interned_str(id);
let file_path = match ::attr::first_attr_value_str_by_name(attrs, "path") {
Some(d) => d,
None => default_path,
};
self.mod_path_stack.push(file_path)
}
fn pop_mod_path(&mut self) {
self.mod_path_stack.pop().unwrap();
}
pub fn submod_path_from_attr(attrs: &[ast::Attribute], dir_path: &Path) -> Option<PathBuf> {
::attr::first_attr_value_str_by_name(attrs, "path").map(|d| dir_path.join(&*d))
}
/// Returns either a path to a module, or .
pub fn default_submod_path(id: ast::Ident, dir_path: &Path, codemap: &CodeMap) -> ModulePath
{
let mod_name = id.to_string();
let default_path_str = format!("{}.rs", mod_name);
let secondary_path_str = format!("{}/mod.rs", mod_name);
let default_path = dir_path.join(&default_path_str);
let secondary_path = dir_path.join(&secondary_path_str);
let default_exists = codemap.file_exists(&default_path);
let secondary_exists = codemap.file_exists(&secondary_path);
let result = match (default_exists, secondary_exists) {
(true, false) => Ok(ModulePathSuccess { path: default_path, owns_directory: false }),
(false, true) => Ok(ModulePathSuccess { path: secondary_path, owns_directory: true }),
(false, false) => Err(ModulePathError {
err_msg: format!("file not found for module `{}`", mod_name),
help_msg: format!("name the file either {} or {} inside the directory {:?}",
default_path_str,
secondary_path_str,
dir_path.display()),
}),
(true, true) => Err(ModulePathError {
err_msg: format!("file for module `{}` found at both {} and {}",
mod_name,
default_path_str,
secondary_path_str),
help_msg: "delete or rename one of them to remove the ambiguity".to_owned(),
}),
};
ModulePath {
name: mod_name,
path_exists: default_exists || secondary_exists,
result: result,
}
}
fn submod_path(&mut self,
id: ast::Ident,
outer_attrs: &[ast::Attribute],
id_sp: Span) -> PResult<'a, ModulePathSuccess> {
let mut prefix = PathBuf::from(&self.sess.codemap().span_to_filename(self.span));
prefix.pop();
let mut dir_path = prefix;
for part in &self.mod_path_stack {
dir_path.push(&**part);
}
if let Some(p) = Parser::submod_path_from_attr(outer_attrs, &dir_path) {
return Ok(ModulePathSuccess { path: p, owns_directory: true });
}
let paths = Parser::default_submod_path(id, &dir_path, self.sess.codemap());
if !self.owns_directory {
let mut err = self.diagnostic().struct_span_err(id_sp,
"cannot declare a new module at this location");
let this_module = match self.mod_path_stack.last() {
Some(name) => name.to_string(),
None => self.root_module_name.as_ref().unwrap().clone(),
};
err.span_note(id_sp,
&format!("maybe move this module `{0}` to its own directory \
via `{0}/mod.rs`",
this_module));
if paths.path_exists {
err.span_note(id_sp,
&format!("... or maybe `use` the module `{}` instead \
of possibly redeclaring it",
paths.name));
}
err.emit();
self.abort_if_errors();
}
match paths.result {
Ok(succ) => Ok(succ),
Err(err) => Err(self.span_fatal_help(id_sp, &err.err_msg, &err.help_msg)),
}
}
/// Read a module from a source file.
fn eval_src_mod(&mut self,
id: ast::Ident,
outer_attrs: &[ast::Attribute],
id_sp: Span)
-> PResult<'a, (ast::Item_, Vec<ast::Attribute> )> {
let ModulePathSuccess { path, owns_directory } = try!(self.submod_path(id,
outer_attrs,
id_sp));
self.eval_src_mod_from_path(path,
owns_directory,
id.to_string(),
id_sp)
}
fn eval_src_mod_from_path(&mut self,
path: PathBuf,
owns_directory: bool,
name: String,
id_sp: Span) -> PResult<'a, (ast::Item_, Vec<ast::Attribute> )> {
let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
match included_mod_stack.iter().position(|p| *p == path) {
Some(i) => {
let mut err = String::from("circular modules: ");
let len = included_mod_stack.len();
for p in &included_mod_stack[i.. len] {
err.push_str(&p.to_string_lossy());
err.push_str(" -> ");
}
err.push_str(&path.to_string_lossy());
return Err(self.span_fatal(id_sp, &err[..]));
}
None => ()
}
included_mod_stack.push(path.clone());
drop(included_mod_stack);
let mut p0 = new_sub_parser_from_file(self.sess,
self.cfg.clone(),
&path,
owns_directory,
Some(name),
id_sp);
let mod_inner_lo = p0.span.lo;
let mod_attrs = try!(p0.parse_inner_attributes());
let m0 = try!(p0.parse_mod_items(&token::Eof, mod_inner_lo));
self.sess.included_mod_stack.borrow_mut().pop();
Ok((ast::ItemMod(m0), mod_attrs))
}
/// Parse a function declaration from a foreign module
fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: BytePos,
attrs: Vec<Attribute>) -> PResult<'a, P<ForeignItem>> {
try!(self.expect_keyword(keywords::Fn));
let (ident, mut generics) = try!(self.parse_fn_header());
let decl = try!(self.parse_fn_decl(true));
generics.where_clause = try!(self.parse_where_clause());
let hi = self.span.hi;
try!(self.expect(&token::Semi));
Ok(P(ast::ForeignItem {
ident: ident,
attrs: attrs,
node: ForeignItemFn(decl, generics),
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, hi),
vis: vis
}))
}
/// Parse a static item from a foreign module
fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: BytePos,
attrs: Vec<Attribute>) -> PResult<'a, P<ForeignItem>> {
try!(self.expect_keyword(keywords::Static));
let mutbl = self.eat_keyword(keywords::Mut);
let ident = try!(self.parse_ident());
try!(self.expect(&token::Colon));
let ty = try!(self.parse_ty_sum());
let hi = self.span.hi;
try!(self.expect(&token::Semi));
Ok(P(ForeignItem {
ident: ident,
attrs: attrs,
node: ForeignItemStatic(ty, mutbl),
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, hi),
vis: vis
}))
}
/// Parse extern crate links
///
/// # Examples
///
/// extern crate foo;
/// extern crate bar as foo;
fn parse_item_extern_crate(&mut self,
lo: BytePos,
visibility: Visibility,
attrs: Vec<Attribute>)
-> PResult<'a, P<Item>> {
let crate_name = try!(self.parse_ident());
let (maybe_path, ident) = if let Some(ident) = try!(self.parse_rename()) {
(Some(crate_name.name), ident)
} else {
(None, crate_name)
};
try!(self.expect(&token::Semi));
let last_span = self.last_span;
if visibility == ast::Public {
self.span_warn(mk_sp(lo, last_span.hi),
"`pub extern crate` does not work as expected and should not be used. \
Likely to become an error. Prefer `extern crate` and `pub use`.");
}
Ok(self.mk_item(lo,
last_span.hi,
ident,
ItemExternCrate(maybe_path),
visibility,
attrs))
}
/// Parse `extern` for foreign ABIs
/// modules.
///
/// `extern` is expected to have been
/// consumed before calling this method
///
/// # Examples:
///
/// extern "C" {}
/// extern {}
fn parse_item_foreign_mod(&mut self,
lo: BytePos,
opt_abi: Option<abi::Abi>,
visibility: Visibility,
mut attrs: Vec<Attribute>)
-> PResult<'a, P<Item>> {
try!(self.expect(&token::OpenDelim(token::Brace)));
let abi = opt_abi.unwrap_or(abi::C);
attrs.extend(try!(self.parse_inner_attributes()));
let mut foreign_items = vec![];
while let Some(item) = try!(self.parse_foreign_item()) {
foreign_items.push(item);
}
try!(self.expect(&token::CloseDelim(token::Brace)));
let last_span = self.last_span;
let m = ast::ForeignMod {
abi: abi,
items: foreign_items
};
Ok(self.mk_item(lo,
last_span.hi,
special_idents::invalid,
ItemForeignMod(m),
visibility,
attrs))
}
/// Parse type Foo = Bar;
fn parse_item_type(&mut self) -> PResult<'a, ItemInfo> {
let ident = try!(self.parse_ident());
let mut tps = try!(self.parse_generics());
tps.where_clause = try!(self.parse_where_clause());
try!(self.expect(&token::Eq));
let ty = try!(self.parse_ty_sum());
try!(self.expect(&token::Semi));
Ok((ident, ItemTy(ty, tps), None))
}
/// Parse the part of an "enum" decl following the '{'
fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
let mut variants = Vec::new();
let mut all_nullary = true;
let mut any_disr = None;
while self.token != token::CloseDelim(token::Brace) {
let variant_attrs = try!(self.parse_outer_attributes());
let vlo = self.span.lo;
let struct_def;
let mut disr_expr = None;
let ident = try!(self.parse_ident());
if self.check(&token::OpenDelim(token::Brace)) {
// Parse a struct variant.
all_nullary = false;
struct_def = VariantData::Struct(try!(self.parse_record_struct_body(ParsePub::No)),
ast::DUMMY_NODE_ID);
} else if self.check(&token::OpenDelim(token::Paren)) {
all_nullary = false;
struct_def = VariantData::Tuple(try!(self.parse_tuple_struct_body(ParsePub::No)),
ast::DUMMY_NODE_ID);
} else if self.eat(&token::Eq) {
disr_expr = Some(try!(self.parse_expr()));
any_disr = disr_expr.as_ref().map(|expr| expr.span);
struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
} else {
struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
}
let vr = ast::Variant_ {
name: ident,
attrs: variant_attrs,
data: struct_def,
disr_expr: disr_expr,
};
variants.push(P(spanned(vlo, self.last_span.hi, vr)));
if !self.eat(&token::Comma) { break; }
}
try!(self.expect(&token::CloseDelim(token::Brace)));
match any_disr {
Some(disr_span) if !all_nullary =>
self.span_err(disr_span,
"discriminator values can only be used with a c-like enum"),
_ => ()
}
Ok(ast::EnumDef { variants: variants })
}
/// Parse an "enum" declaration
fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
let id = try!(self.parse_ident());
let mut generics = try!(self.parse_generics());
generics.where_clause = try!(self.parse_where_clause());
try!(self.expect(&token::OpenDelim(token::Brace)));
let enum_definition = try!(self.parse_enum_def(&generics));
Ok((id, ItemEnum(enum_definition, generics), None))
}
/// Parses a string as an ABI spec on an extern type or module. Consumes
/// the `extern` keyword, if one is found.
fn parse_opt_abi(&mut self) -> PResult<'a, Option<abi::Abi>> {
match self.token {
token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
let sp = self.span;
self.expect_no_suffix(sp, "ABI spec", suf);
self.bump();
match abi::lookup(&s.as_str()) {
Some(abi) => Ok(Some(abi)),
None => {
let last_span = self.last_span;
self.span_err(
last_span,
&format!("invalid ABI: expected one of [{}], \
found `{}`",
abi::all_names().join(", "),
s));
Ok(None)
}
}
}
_ => Ok(None),
}
}
/// Parse one of the items allowed by the flags.
/// NB: this function no longer parses the items inside an
/// extern crate.
fn parse_item_(&mut self, attrs: Vec<Attribute>,
macros_allowed: bool, attributes_allowed: bool) -> PResult<'a, Option<P<Item>>> {
let nt_item = match self.token {
token::Interpolated(token::NtItem(ref item)) => {
Some((**item).clone())
}
_ => None
};
match nt_item {
Some(mut item) => {
self.bump();
let mut attrs = attrs;
mem::swap(&mut item.attrs, &mut attrs);
item.attrs.extend(attrs);
return Ok(Some(P(item)));
}
None => {}
}
let lo = self.span.lo;
let visibility = try!(self.parse_visibility());
if self.eat_keyword(keywords::Use) {
// USE ITEM
let item_ = ItemUse(try!(self.parse_view_path()));
try!(self.expect(&token::Semi));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
token::special_idents::invalid,
item_,
visibility,
attrs);
return Ok(Some(item));
}
if self.eat_keyword(keywords::Extern) {
if self.eat_keyword(keywords::Crate) {
return Ok(Some(try!(self.parse_item_extern_crate(lo, visibility, attrs))));
}
let opt_abi = try!(self.parse_opt_abi());
if self.eat_keyword(keywords::Fn) {
// EXTERN FUNCTION ITEM
let abi = opt_abi.unwrap_or(abi::C);
let (ident, item_, extra_attrs) =
try!(self.parse_item_fn(Unsafety::Normal, Constness::NotConst, abi));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
} else if self.check(&token::OpenDelim(token::Brace)) {
return Ok(Some(try!(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs))));
}
try!(self.unexpected());
}
if self.eat_keyword(keywords::Static) {
// STATIC ITEM
let m = if self.eat_keyword(keywords::Mut) {MutMutable} else {MutImmutable};
let (ident, item_, extra_attrs) = try!(self.parse_item_const(Some(m)));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Const) {
if self.check_keyword(keywords::Fn)
|| (self.check_keyword(keywords::Unsafe)
&& self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
// CONST FUNCTION ITEM
let unsafety = if self.eat_keyword(keywords::Unsafe) {
Unsafety::Unsafe
} else {
Unsafety::Normal
};
self.bump();
let (ident, item_, extra_attrs) =
try!(self.parse_item_fn(unsafety, Constness::Const, abi::Rust));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
// CONST ITEM
if self.eat_keyword(keywords::Mut) {
let last_span = self.last_span;
self.diagnostic().struct_span_err(last_span, "const globals cannot be mutable")
.fileline_help(last_span, "did you mean to declare a static?")
.emit();
}
let (ident, item_, extra_attrs) = try!(self.parse_item_const(None));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Unsafe) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
{
// UNSAFE TRAIT ITEM
try!(self.expect_keyword(keywords::Unsafe));
try!(self.expect_keyword(keywords::Trait));
let (ident, item_, extra_attrs) =
try!(self.parse_item_trait(ast::Unsafety::Unsafe));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Unsafe) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Impl))
{
// IMPL ITEM
try!(self.expect_keyword(keywords::Unsafe));
try!(self.expect_keyword(keywords::Impl));
let (ident, item_, extra_attrs) = try!(self.parse_item_impl(ast::Unsafety::Unsafe));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Fn) {
// FUNCTION ITEM
self.bump();
let (ident, item_, extra_attrs) =
try!(self.parse_item_fn(Unsafety::Normal, Constness::NotConst, abi::Rust));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Unsafe)
&& self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
// UNSAFE FUNCTION ITEM
self.bump();
let abi = if self.eat_keyword(keywords::Extern) {
try!(self.parse_opt_abi()).unwrap_or(abi::C)
} else {
abi::Rust
};
try!(self.expect_keyword(keywords::Fn));
let (ident, item_, extra_attrs) =
try!(self.parse_item_fn(Unsafety::Unsafe, Constness::NotConst, abi));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Mod) {
// MODULE ITEM
let (ident, item_, extra_attrs) =
try!(self.parse_item_mod(&attrs[..]));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Type) {
// TYPE ITEM
let (ident, item_, extra_attrs) = try!(self.parse_item_type());
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Enum) {
// ENUM ITEM
let (ident, item_, extra_attrs) = try!(self.parse_item_enum());
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Trait) {
// TRAIT ITEM
let (ident, item_, extra_attrs) =
try!(self.parse_item_trait(ast::Unsafety::Normal));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Impl) {
// IMPL ITEM
let (ident, item_, extra_attrs) = try!(self.parse_item_impl(ast::Unsafety::Normal));
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Struct) {
// STRUCT ITEM
let (ident, item_, extra_attrs) = try!(self.parse_item_struct());
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
self.parse_macro_use_or_failure(attrs,macros_allowed,attributes_allowed,lo,visibility)
}
/// Parse a foreign item.
fn parse_foreign_item(&mut self) -> PResult<'a, Option<P<ForeignItem>>> {
let attrs = try!(self.parse_outer_attributes());
let lo = self.span.lo;
let visibility = try!(self.parse_visibility());
if self.check_keyword(keywords::Static) {
// FOREIGN STATIC ITEM
return Ok(Some(try!(self.parse_item_foreign_static(visibility, lo, attrs))));
}
if self.check_keyword(keywords::Fn) || self.check_keyword(keywords::Unsafe) {
// FOREIGN FUNCTION ITEM
return Ok(Some(try!(self.parse_item_foreign_fn(visibility, lo, attrs))));
}
// FIXME #5668: this will occur for a macro invocation:
match try!(self.parse_macro_use_or_failure(attrs, true, false, lo, visibility)) {
Some(item) => {
return Err(self.span_fatal(item.span, "macros cannot expand to foreign items"));
}
None => Ok(None)
}
}
/// This is the fall-through for parsing items.
fn parse_macro_use_or_failure(
&mut self,
attrs: Vec<Attribute> ,
macros_allowed: bool,
attributes_allowed: bool,
lo: BytePos,
visibility: Visibility
) -> PResult<'a, Option<P<Item>>> {
if macros_allowed && !self.token.is_any_keyword()
&& self.look_ahead(1, |t| *t == token::Not)
&& (self.look_ahead(2, |t| t.is_plain_ident())
|| self.look_ahead(2, |t| *t == token::OpenDelim(token::Paren))
|| self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))) {
// MACRO INVOCATION ITEM
let last_span = self.last_span;
self.complain_if_pub_macro(visibility, last_span);
let mac_lo = self.span.lo;
// item macro.
let pth = try!(self.parse_path(NoTypesAllowed));
try!(self.expect(&token::Not));
// a 'special' identifier (like what `macro_rules!` uses)
// is optional. We should eventually unify invoc syntax
// and remove this.
let id = if self.token.is_plain_ident() {
try!(self.parse_ident())
} else {
token::special_idents::invalid // no special identifier
};
// eat a matched-delimiter token tree:
let delim = try!(self.expect_open_delim());
let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
seq_sep_none(),
|p| p.parse_token_tree()));
// single-variant-enum... :
let m = Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT };
let m: ast::Mac = codemap::Spanned { node: m,
span: mk_sp(mac_lo,
self.last_span.hi) };
if delim != token::Brace {
if !self.eat(&token::Semi) {
let last_span = self.last_span;
self.span_err(last_span,
"macros that expand to items must either \
be surrounded with braces or followed by \
a semicolon");
}
}
let item_ = ItemMac(m);
let last_span = self.last_span;
let item = self.mk_item(lo,
last_span.hi,
id,
item_,
visibility,
attrs);
return Ok(Some(item));
}
// FAILURE TO PARSE ITEM
match visibility {
Inherited => {}
Public => {
let last_span = self.last_span;
return Err(self.span_fatal(last_span, "unmatched visibility `pub`"));
}
}
if !attributes_allowed && !attrs.is_empty() {
self.expected_item_err(&attrs);
}
Ok(None)
}
pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
let attrs = try!(self.parse_outer_attributes());
self.parse_item_(attrs, true, false)
}
/// Matches view_path : MOD? non_global_path as IDENT
/// | MOD? non_global_path MOD_SEP LBRACE RBRACE
/// | MOD? non_global_path MOD_SEP LBRACE ident_seq RBRACE
/// | MOD? non_global_path MOD_SEP STAR
/// | MOD? non_global_path
fn parse_view_path(&mut self) -> PResult<'a, P<ViewPath>> {
let lo = self.span.lo;
// Allow a leading :: because the paths are absolute either way.
// This occurs with "use $crate::..." in macros.
self.eat(&token::ModSep);
if self.check(&token::OpenDelim(token::Brace)) {
// use {foo,bar}
let idents = try!(self.parse_unspanned_seq(
&token::OpenDelim(token::Brace),
&token::CloseDelim(token::Brace),
seq_sep_trailing_allowed(token::Comma),
|p| p.parse_path_list_item()));
let path = ast::Path {
span: mk_sp(lo, self.span.hi),
global: false,
segments: Vec::new()
};
return Ok(P(spanned(lo, self.span.hi, ViewPathList(path, idents))));
}
let first_ident = try!(self.parse_ident());
let mut path = vec!(first_ident);
if let token::ModSep = self.token {
// foo::bar or foo::{a,b,c} or foo::*
while self.check(&token::ModSep) {
self.bump();
match self.token {
token::Ident(..) => {
let ident = try!(self.parse_ident());
path.push(ident);
}
// foo::bar::{a,b,c}
token::OpenDelim(token::Brace) => {
let idents = try!(self.parse_unspanned_seq(
&token::OpenDelim(token::Brace),
&token::CloseDelim(token::Brace),
seq_sep_trailing_allowed(token::Comma),
|p| p.parse_path_list_item()
));
let path = ast::Path {
span: mk_sp(lo, self.span.hi),
global: false,
segments: path.into_iter().map(|identifier| {
ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none(),
}
}).collect()
};
return Ok(P(spanned(lo, self.span.hi, ViewPathList(path, idents))));
}
// foo::bar::*
token::BinOp(token::Star) => {
self.bump();
let path = ast::Path {
span: mk_sp(lo, self.span.hi),
global: false,
segments: path.into_iter().map(|identifier| {
ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none(),
}
}).collect()
};
return Ok(P(spanned(lo, self.span.hi, ViewPathGlob(path))));
}
// fall-through for case foo::bar::;
token::Semi => {
self.span_err(self.span, "expected identifier or `{` or `*`, found `;`");
}
_ => break
}
}
}
let mut rename_to = path[path.len() - 1];
let path = ast::Path {
span: mk_sp(lo, self.last_span.hi),
global: false,
segments: path.into_iter().map(|identifier| {
ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none(),
}
}).collect()
};
rename_to = try!(self.parse_rename()).unwrap_or(rename_to);
Ok(P(spanned(lo, self.last_span.hi, ViewPathSimple(rename_to, path))))
}
fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
if self.eat_keyword(keywords::As) {
self.parse_ident().map(Some)
} else {
Ok(None)
}
}
/// Parses a source module as a crate. This is the main
/// entry point for the parser.
pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
let lo = self.span.lo;
Ok(ast::Crate {
attrs: try!(self.parse_inner_attributes()),
module: try!(self.parse_mod_items(&token::Eof, lo)),
config: self.cfg.clone(),
span: mk_sp(lo, self.span.lo),
exported_macros: Vec::new(),
})
}
pub fn parse_optional_str(&mut self)
-> Option<(InternedString,
ast::StrStyle,
Option<ast::Name>)> {
let ret = match self.token {
token::Literal(token::Str_(s), suf) => {
(self.id_to_interned_str(ast::Ident::with_empty_ctxt(s)), ast::CookedStr, suf)
}
token::Literal(token::StrRaw(s, n), suf) => {
(self.id_to_interned_str(ast::Ident::with_empty_ctxt(s)), ast::RawStr(n), suf)
}
_ => return None
};
self.bump();
Some(ret)
}
pub fn parse_str(&mut self) -> PResult<'a, (InternedString, StrStyle)> {
match self.parse_optional_str() {
Some((s, style, suf)) => {
let sp = self.last_span;
self.expect_no_suffix(sp, "string literal", suf);
Ok((s, style))
}
_ => Err(self.fatal("expected string literal"))
}
}
}