blob: 97ba58c72a932adc64a7241a95d348396e43f612 [file] [log] [blame]
use super::*;
use punctuated::Punctuated;
ast_struct! {
/// A path at which a named item is exported: `std::collections::HashMap`.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct Path {
pub leading_colon: Option<Token![::]>,
pub segments: Punctuated<PathSegment, Token![::]>,
}
}
impl<T> From<T> for Path
where
T: Into<PathSegment>,
{
fn from(segment: T) -> Self {
let mut path = Path {
leading_colon: None,
segments: Punctuated::new(),
};
path.segments.push_value(segment.into());
path
}
}
ast_struct! {
/// A segment of a path together with any path arguments on that segment.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct PathSegment {
pub ident: Ident,
pub arguments: PathArguments,
}
}
impl<T> From<T> for PathSegment
where
T: Into<Ident>,
{
fn from(ident: T) -> Self {
PathSegment {
ident: ident.into(),
arguments: PathArguments::None,
}
}
}
ast_enum! {
/// Angle bracketed or parenthesized arguments of a path segment.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
///
/// ## Angle bracketed
///
/// The `<'a, T>` in `std::slice::iter<'a, T>`.
///
/// ## Parenthesized
///
/// The `(A, B) -> C` in `Fn(A, B) -> C`.
pub enum PathArguments {
None,
/// The `<'a, T>` in `std::slice::iter<'a, T>`.
AngleBracketed(AngleBracketedGenericArguments),
/// The `(A, B) -> C` in `Fn(A, B) -> C`.
Parenthesized(ParenthesizedGenericArguments),
}
}
impl Default for PathArguments {
fn default() -> Self {
PathArguments::None
}
}
impl PathArguments {
pub fn is_empty(&self) -> bool {
match *self {
PathArguments::None => true,
PathArguments::AngleBracketed(ref bracketed) => bracketed.args.is_empty(),
PathArguments::Parenthesized(_) => false,
}
}
fn is_none(&self) -> bool {
match *self {
PathArguments::None => true,
PathArguments::AngleBracketed(_) | PathArguments::Parenthesized(_) => false,
}
}
}
ast_enum! {
/// An individual generic argument, like `'a`, `T`, or `Item = T`.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub enum GenericArgument {
/// A lifetime argument.
Lifetime(Lifetime),
/// A type argument.
Type(Type),
/// A binding (equality constraint) on an associated type: the `Item =
/// u8` in `Iterator<Item = u8>`.
Binding(Binding),
/// An associated type bound: `Iterator<Item: Display>`.
Constraint(Constraint),
/// A const expression. Must be inside of a block.
///
/// NOTE: Identity expressions are represented as Type arguments, as
/// they are indistinguishable syntactically.
Const(Expr),
}
}
ast_struct! {
/// Angle bracketed arguments of a path segment: the `<K, V>` in `HashMap<K,
/// V>`.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct AngleBracketedGenericArguments {
pub colon2_token: Option<Token![::]>,
pub lt_token: Token![<],
pub args: Punctuated<GenericArgument, Token![,]>,
pub gt_token: Token![>],
}
}
ast_struct! {
/// A binding (equality constraint) on an associated type: `Item = u8`.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct Binding {
pub ident: Ident,
pub eq_token: Token![=],
pub ty: Type,
}
}
ast_struct! {
/// An associated type bound: `Iterator<Item: Display>`.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct Constraint {
pub ident: Ident,
pub colon_token: Token![:],
pub bounds: Punctuated<TypeParamBound, Token![+]>,
}
}
ast_struct! {
/// Arguments of a function path segment: the `(A, B) -> C` in `Fn(A,B) ->
/// C`.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct ParenthesizedGenericArguments {
pub paren_token: token::Paren,
/// `(A, B)`
pub inputs: Punctuated<Type, Token![,]>,
/// `C`
pub output: ReturnType,
}
}
ast_struct! {
/// The explicit Self type in a qualified path: the `T` in `<T as
/// Display>::fmt`.
///
/// The actual path, including the trait and the associated item, is stored
/// separately. The `position` field represents the index of the associated
/// item qualified with this Self type.
///
/// ```text
/// <Vec<T> as a::b::Trait>::AssociatedItem
/// ^~~~~~ ~~~~~~~~~~~~~~^
/// ty position = 3
///
/// <Vec<T>>::AssociatedItem
/// ^~~~~~ ^
/// ty position = 0
/// ```
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
pub struct QSelf {
pub lt_token: Token![<],
pub ty: Box<Type>,
pub position: usize,
pub as_token: Option<Token![as]>,
pub gt_token: Token![>],
}
}
#[cfg(feature = "parsing")]
pub mod parsing {
use super::*;
#[cfg(feature = "full")]
use expr;
use ext::IdentExt;
use parse::{Parse, ParseStream, Result};
impl Parse for Path {
fn parse(input: ParseStream) -> Result<Self> {
Self::parse_helper(input, false)
}
}
impl Parse for GenericArgument {
fn parse(input: ParseStream) -> Result<Self> {
if input.peek(Lifetime) && !input.peek2(Token![+]) {
return Ok(GenericArgument::Lifetime(input.parse()?));
}
if input.peek(Ident) && input.peek2(Token![=]) {
return Ok(GenericArgument::Binding(input.parse()?));
}
#[cfg(feature = "full")]
{
if input.peek(Ident) && input.peek2(Token![:]) && !input.peek2(Token![::]) {
return Ok(GenericArgument::Constraint(input.parse()?));
}
if input.peek(Lit) {
let lit = input.call(expr::parsing::expr_lit)?;
return Ok(GenericArgument::Const(Expr::Lit(lit)));
}
if input.peek(token::Brace) {
let block = input.call(expr::parsing::expr_block)?;
return Ok(GenericArgument::Const(Expr::Block(block)));
}
}
input.parse().map(GenericArgument::Type)
}
}
impl Parse for AngleBracketedGenericArguments {
fn parse(input: ParseStream) -> Result<Self> {
Ok(AngleBracketedGenericArguments {
colon2_token: input.parse()?,
lt_token: input.parse()?,
args: {
let mut args = Punctuated::new();
loop {
if input.peek(Token![>]) {
break;
}
let value = input.parse()?;
args.push_value(value);
if input.peek(Token![>]) {
break;
}
let punct = input.parse()?;
args.push_punct(punct);
}
args
},
gt_token: input.parse()?,
})
}
}
impl Parse for ParenthesizedGenericArguments {
fn parse(input: ParseStream) -> Result<Self> {
let content;
Ok(ParenthesizedGenericArguments {
paren_token: parenthesized!(content in input),
inputs: content.parse_terminated(Type::parse)?,
output: input.call(ReturnType::without_plus)?,
})
}
}
impl Parse for PathSegment {
fn parse(input: ParseStream) -> Result<Self> {
Self::parse_helper(input, false)
}
}
impl PathSegment {
fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
if input.peek(Token![super])
|| input.peek(Token![self])
|| input.peek(Token![Self])
|| input.peek(Token![crate])
|| input.peek(Token![extern])
{
let ident = input.call(Ident::parse_any)?;
return Ok(PathSegment::from(ident));
}
let ident = input.parse()?;
if !expr_style && input.peek(Token![<]) && !input.peek(Token![<=])
|| input.peek(Token![::]) && input.peek3(Token![<])
{
Ok(PathSegment {
ident: ident,
arguments: PathArguments::AngleBracketed(input.parse()?),
})
} else {
Ok(PathSegment::from(ident))
}
}
}
impl Parse for Binding {
fn parse(input: ParseStream) -> Result<Self> {
Ok(Binding {
ident: input.parse()?,
eq_token: input.parse()?,
ty: input.parse()?,
})
}
}
#[cfg(feature = "full")]
impl Parse for Constraint {
fn parse(input: ParseStream) -> Result<Self> {
Ok(Constraint {
ident: input.parse()?,
colon_token: input.parse()?,
bounds: {
let mut bounds = Punctuated::new();
loop {
if input.peek(Token![,]) || input.peek(Token![>]) {
break;
}
let value = input.parse()?;
bounds.push_value(value);
if !input.peek(Token![+]) {
break;
}
let punct = input.parse()?;
bounds.push_punct(punct);
}
bounds
},
})
}
}
impl Path {
/// Parse a `Path` containing no path arguments on any of its segments.
///
/// *This function is available if Syn is built with the `"parsing"`
/// feature.*
///
/// # Example
///
/// ```
/// #[macro_use]
/// extern crate syn;
///
/// use syn::{Path, Result};
/// use syn::parse::{Parse, ParseStream};
///
/// // A simplified single `use` statement like:
/// //
/// // use std::collections::HashMap;
/// //
/// // Note that generic parameters are not allowed in a `use` statement
/// // so the following must not be accepted.
/// //
/// // use a::<b>::c;
/// struct SingleUse {
/// use_token: Token![use],
/// path: Path,
/// }
///
/// impl Parse for SingleUse {
/// fn parse(input: ParseStream) -> Result<Self> {
/// Ok(SingleUse {
/// use_token: input.parse()?,
/// path: input.call(Path::parse_mod_style)?,
/// })
/// }
/// }
/// #
/// # fn main() {}
/// ```
pub fn parse_mod_style(input: ParseStream) -> Result<Self> {
Ok(Path {
leading_colon: input.parse()?,
segments: {
let mut segments = Punctuated::new();
loop {
if !input.peek(Ident)
&& !input.peek(Token![super])
&& !input.peek(Token![self])
&& !input.peek(Token![Self])
&& !input.peek(Token![crate])
&& !input.peek(Token![extern])
{
break;
}
let ident = Ident::parse_any(input)?;
segments.push_value(PathSegment::from(ident));
if !input.peek(Token![::]) {
break;
}
let punct = input.parse()?;
segments.push_punct(punct);
}
if segments.is_empty() {
return Err(input.error("expected path"));
} else if segments.trailing_punct() {
return Err(input.error("expected path segment"));
}
segments
},
})
}
/// Determines whether this is a path of length 1 equal to the given
/// ident.
///
/// For them to compare equal, it must be the case that:
///
/// - the path has no leading colon,
/// - the number of path segments is 1,
/// - the first path segment has no angle bracketed or parenthesized
/// path arguments
/// - and the ident of the first path segment is equal to the given one.
pub fn is_ident<I>(&self, ident: I) -> bool
where
Ident: PartialEq<I>,
{
self.leading_colon.is_none()
&& self.segments.len() == 1
&& self.segments[0].arguments.is_none()
&& self.segments[0].ident == ident
}
fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
if input.peek(Token![dyn]) {
return Err(input.error("expected path"));
}
Ok(Path {
leading_colon: input.parse()?,
segments: {
let mut segments = Punctuated::new();
let value = PathSegment::parse_helper(input, expr_style)?;
segments.push_value(value);
while input.peek(Token![::]) {
let punct: Token![::] = input.parse()?;
segments.push_punct(punct);
let value = PathSegment::parse_helper(input, expr_style)?;
segments.push_value(value);
}
segments
},
})
}
}
pub fn qpath(input: ParseStream, expr_style: bool) -> Result<(Option<QSelf>, Path)> {
if input.peek(Token![<]) {
let lt_token: Token![<] = input.parse()?;
let this: Type = input.parse()?;
let path = if input.peek(Token![as]) {
let as_token: Token![as] = input.parse()?;
let path: Path = input.parse()?;
Some((as_token, path))
} else {
None
};
let gt_token: Token![>] = input.parse()?;
let colon2_token: Token![::] = input.parse()?;
let mut rest = Punctuated::new();
loop {
let path = PathSegment::parse_helper(input, expr_style)?;
rest.push_value(path);
if !input.peek(Token![::]) {
break;
}
let punct: Token![::] = input.parse()?;
rest.push_punct(punct);
}
let (position, as_token, path) = match path {
Some((as_token, mut path)) => {
let pos = path.segments.len();
path.segments.push_punct(colon2_token);
path.segments.extend(rest.into_pairs());
(pos, Some(as_token), path)
}
None => {
let path = Path {
leading_colon: Some(colon2_token),
segments: rest,
};
(0, None, path)
}
};
let qself = QSelf {
lt_token: lt_token,
ty: Box::new(this),
position: position,
as_token: as_token,
gt_token: gt_token,
};
Ok((Some(qself), path))
} else {
let path = Path::parse_helper(input, expr_style)?;
Ok((None, path))
}
}
}
#[cfg(feature = "printing")]
mod printing {
use super::*;
use proc_macro2::TokenStream;
use quote::ToTokens;
use print::TokensOrDefault;
impl ToTokens for Path {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.leading_colon.to_tokens(tokens);
self.segments.to_tokens(tokens);
}
}
impl ToTokens for PathSegment {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
self.arguments.to_tokens(tokens);
}
}
impl ToTokens for PathArguments {
fn to_tokens(&self, tokens: &mut TokenStream) {
match *self {
PathArguments::None => {}
PathArguments::AngleBracketed(ref arguments) => {
arguments.to_tokens(tokens);
}
PathArguments::Parenthesized(ref arguments) => {
arguments.to_tokens(tokens);
}
}
}
}
impl ToTokens for GenericArgument {
#[cfg_attr(feature = "cargo-clippy", allow(match_same_arms))]
fn to_tokens(&self, tokens: &mut TokenStream) {
match *self {
GenericArgument::Lifetime(ref lt) => lt.to_tokens(tokens),
GenericArgument::Type(ref ty) => ty.to_tokens(tokens),
GenericArgument::Binding(ref tb) => tb.to_tokens(tokens),
GenericArgument::Constraint(ref tc) => tc.to_tokens(tokens),
GenericArgument::Const(ref e) => match *e {
Expr::Lit(_) => e.to_tokens(tokens),
// NOTE: We should probably support parsing blocks with only
// expressions in them without the full feature for const
// generics.
#[cfg(feature = "full")]
Expr::Block(_) => e.to_tokens(tokens),
// ERROR CORRECTION: Add braces to make sure that the
// generated code is valid.
_ => token::Brace::default().surround(tokens, |tokens| {
e.to_tokens(tokens);
}),
},
}
}
}
impl ToTokens for AngleBracketedGenericArguments {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.colon2_token.to_tokens(tokens);
self.lt_token.to_tokens(tokens);
// Print lifetimes before types and consts, all before bindings,
// regardless of their order in self.args.
//
// TODO: ordering rules for const arguments vs type arguments have
// not been settled yet. https://github.com/rust-lang/rust/issues/44580
let mut trailing_or_empty = true;
for param in self.args.pairs() {
match **param.value() {
GenericArgument::Lifetime(_) => {
param.to_tokens(tokens);
trailing_or_empty = param.punct().is_some();
}
GenericArgument::Type(_)
| GenericArgument::Binding(_)
| GenericArgument::Constraint(_)
| GenericArgument::Const(_) => {}
}
}
for param in self.args.pairs() {
match **param.value() {
GenericArgument::Type(_) | GenericArgument::Const(_) => {
if !trailing_or_empty {
<Token![,]>::default().to_tokens(tokens);
}
param.to_tokens(tokens);
trailing_or_empty = param.punct().is_some();
}
GenericArgument::Lifetime(_)
| GenericArgument::Binding(_)
| GenericArgument::Constraint(_) => {}
}
}
for param in self.args.pairs() {
match **param.value() {
GenericArgument::Binding(_) | GenericArgument::Constraint(_) => {
if !trailing_or_empty {
<Token![,]>::default().to_tokens(tokens);
trailing_or_empty = true;
}
param.to_tokens(tokens);
}
GenericArgument::Lifetime(_)
| GenericArgument::Type(_)
| GenericArgument::Const(_) => {}
}
}
self.gt_token.to_tokens(tokens);
}
}
impl ToTokens for Binding {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
self.eq_token.to_tokens(tokens);
self.ty.to_tokens(tokens);
}
}
impl ToTokens for Constraint {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
self.colon_token.to_tokens(tokens);
self.bounds.to_tokens(tokens);
}
}
impl ToTokens for ParenthesizedGenericArguments {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.paren_token.surround(tokens, |tokens| {
self.inputs.to_tokens(tokens);
});
self.output.to_tokens(tokens);
}
}
impl private {
pub fn print_path(tokens: &mut TokenStream, qself: &Option<QSelf>, path: &Path) {
let qself = match *qself {
Some(ref qself) => qself,
None => {
path.to_tokens(tokens);
return;
}
};
qself.lt_token.to_tokens(tokens);
qself.ty.to_tokens(tokens);
let pos = if qself.position > 0 && qself.position >= path.segments.len() {
path.segments.len() - 1
} else {
qself.position
};
let mut segments = path.segments.pairs();
if pos > 0 {
TokensOrDefault(&qself.as_token).to_tokens(tokens);
path.leading_colon.to_tokens(tokens);
for (i, segment) in segments.by_ref().take(pos).enumerate() {
if i + 1 == pos {
segment.value().to_tokens(tokens);
qself.gt_token.to_tokens(tokens);
segment.punct().to_tokens(tokens);
} else {
segment.to_tokens(tokens);
}
}
} else {
qself.gt_token.to_tokens(tokens);
path.leading_colon.to_tokens(tokens);
}
for segment in segments {
segment.to_tokens(tokens);
}
}
}
}