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fuchsia / third_party / rust / 75b2ae5ec50a3fb3cadd297b7d524935afa9faad / . / src / tools / rustfmt / src / items.rs
blob: 2483d0570d9eaf1c27358646918b8bd56c50bfcb [file] [log] [blame]
// Formatting top-level items - functions, structs, enums, traits, impls.
use std::borrow::Cow;
use std::cmp::{max, min, Ordering};
use regex::Regex;
use rustc_ast::visit;
use rustc_ast::{ast, ptr};
use rustc_span::{symbol, BytePos, Span};
use crate::attr::filter_inline_attrs;
use crate::comment::{
combine_strs_with_missing_comments, contains_comment, is_last_comment_block,
recover_comment_removed, recover_missing_comment_in_span, rewrite_missing_comment,
FindUncommented,
};
use crate::config::lists::*;
use crate::config::{BraceStyle, Config, IndentStyle, Version};
use crate::expr::{
is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
rewrite_assign_rhs_with_comments, RhsTactics,
};
use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
use crate::macros::{rewrite_macro, MacroPosition};
use crate::overflow;
use crate::rewrite::{Rewrite, RewriteContext};
use crate::shape::{Indent, Shape};
use crate::source_map::{LineRangeUtils, SpanUtils};
use crate::spanned::Spanned;
use crate::stmt::Stmt;
use crate::utils::*;
use crate::vertical::rewrite_with_alignment;
use crate::visitor::FmtVisitor;
use crate::DEFAULT_VISIBILITY;
fn type_annotation_separator(config: &Config) -> &str {
colon_spaces(config)
}
// Statements of the form
// let pat: ty = init;
impl Rewrite for ast::Local {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
debug!(
"Local::rewrite {:?} {} {:?}",
self, shape.width, shape.indent
);
skip_out_of_file_lines_range!(context, self.span);
if contains_skip(&self.attrs) || matches!(self.kind, ast::LocalKind::InitElse(..)) {
return None;
}
let attrs_str = self.attrs.rewrite(context, shape)?;
let mut result = if attrs_str.is_empty() {
"let ".to_owned()
} else {
combine_strs_with_missing_comments(
context,
&attrs_str,
"let ",
mk_sp(
self.attrs.last().map(|a| a.span.hi()).unwrap(),
self.span.lo(),
),
shape,
false,
)?
};
// 4 = "let ".len()
let pat_shape = shape.offset_left(4)?;
// 1 = ;
let pat_shape = pat_shape.sub_width(1)?;
let pat_str = self.pat.rewrite(context, pat_shape)?;
result.push_str(&pat_str);
// String that is placed within the assignment pattern and expression.
let infix = {
let mut infix = String::with_capacity(32);
if let Some(ref ty) = self.ty {
let separator = type_annotation_separator(context.config);
let ty_shape = if pat_str.contains('\n') {
shape.with_max_width(context.config)
} else {
shape
}
.offset_left(last_line_width(&result) + separator.len())?
// 2 = ` =`
.sub_width(2)?;
let rewrite = ty.rewrite(context, ty_shape)?;
infix.push_str(separator);
infix.push_str(&rewrite);
}
if self.kind.init().is_some() {
infix.push_str(" =");
}
infix
};
result.push_str(&infix);
if let Some((init, _els)) = self.kind.init_else_opt() {
// 1 = trailing semicolon;
let nested_shape = shape.sub_width(1)?;
result = rewrite_assign_rhs(context, result, init, nested_shape)?;
// todo else
}
result.push(';');
Some(result)
}
}
// FIXME convert to using rewrite style rather than visitor
// FIXME format modules in this style
#[allow(dead_code)]
#[derive(Debug)]
struct Item<'a> {
unsafety: ast::Unsafe,
abi: Cow<'static, str>,
vis: Option<&'a ast::Visibility>,
body: Vec<BodyElement<'a>>,
span: Span,
}
impl<'a> Item<'a> {
fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
Item {
unsafety: fm.unsafety,
abi: format_extern(
ast::Extern::from_abi(fm.abi),
config.force_explicit_abi(),
true,
),
vis: None,
body: fm
.items
.iter()
.map(|i| BodyElement::ForeignItem(i))
.collect(),
span,
}
}
}
#[derive(Debug)]
enum BodyElement<'a> {
// Stmt(&'a ast::Stmt),
// Field(&'a ast::ExprField),
// Variant(&'a ast::Variant),
// Item(&'a ast::Item),
ForeignItem(&'a ast::ForeignItem),
}
/// Represents a fn's signature.
pub(crate) struct FnSig<'a> {
decl: &'a ast::FnDecl,
generics: &'a ast::Generics,
ext: ast::Extern,
is_async: Cow<'a, ast::Async>,
constness: ast::Const,
defaultness: ast::Defaultness,
unsafety: ast::Unsafe,
visibility: ast::Visibility,
}
impl<'a> FnSig<'a> {
pub(crate) fn from_method_sig(
method_sig: &'a ast::FnSig,
generics: &'a ast::Generics,
visibility: ast::Visibility,
) -> FnSig<'a> {
FnSig {
unsafety: method_sig.header.unsafety,
is_async: Cow::Borrowed(&method_sig.header.asyncness),
constness: method_sig.header.constness,
defaultness: ast::Defaultness::Final,
ext: method_sig.header.ext,
decl: &*method_sig.decl,
generics,
visibility,
}
}
pub(crate) fn from_fn_kind(
fn_kind: &'a visit::FnKind<'_>,
generics: &'a ast::Generics,
decl: &'a ast::FnDecl,
defaultness: ast::Defaultness,
) -> FnSig<'a> {
match *fn_kind {
visit::FnKind::Fn(fn_ctxt, _, fn_sig, vis, _) => match fn_ctxt {
visit::FnCtxt::Assoc(..) => {
let mut fn_sig = FnSig::from_method_sig(fn_sig, generics, vis.clone());
fn_sig.defaultness = defaultness;
fn_sig
}
_ => FnSig {
decl,
generics,
ext: fn_sig.header.ext,
constness: fn_sig.header.constness,
is_async: Cow::Borrowed(&fn_sig.header.asyncness),
defaultness,
unsafety: fn_sig.header.unsafety,
visibility: vis.clone(),
},
},
_ => unreachable!(),
}
}
fn to_str(&self, context: &RewriteContext<'_>) -> String {
let mut result = String::with_capacity(128);
// Vis defaultness constness unsafety abi.
result.push_str(&*format_visibility(context, &self.visibility));
result.push_str(format_defaultness(self.defaultness));
result.push_str(format_constness(self.constness));
result.push_str(format_async(&self.is_async));
result.push_str(format_unsafety(self.unsafety));
result.push_str(&format_extern(
self.ext,
context.config.force_explicit_abi(),
false,
));
result
}
}
impl<'a> FmtVisitor<'a> {
fn format_item(&mut self, item: &Item<'_>) {
self.buffer.push_str(format_unsafety(item.unsafety));
self.buffer.push_str(&item.abi);
let snippet = self.snippet(item.span);
let brace_pos = snippet.find_uncommented("{").unwrap();
self.push_str("{");
if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
// FIXME: this skips comments between the extern keyword and the opening
// brace.
self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
self.block_indent = self.block_indent.block_indent(self.config);
if !item.body.is_empty() {
for item in &item.body {
self.format_body_element(item);
}
}
self.format_missing_no_indent(item.span.hi() - BytePos(1));
self.block_indent = self.block_indent.block_unindent(self.config);
let indent_str = self.block_indent.to_string(self.config);
self.push_str(&indent_str);
}
self.push_str("}");
self.last_pos = item.span.hi();
}
fn format_body_element(&mut self, element: &BodyElement<'_>) {
match *element {
BodyElement::ForeignItem(item) => self.format_foreign_item(item),
}
}
pub(crate) fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
let item = Item::from_foreign_mod(fm, span, self.config);
self.format_item(&item);
}
fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
let rewrite = item.rewrite(&self.get_context(), self.shape());
let hi = item.span.hi();
let span = if item.attrs.is_empty() {
item.span
} else {
mk_sp(item.attrs[0].span.lo(), hi)
};
self.push_rewrite(span, rewrite);
self.last_pos = hi;
}
pub(crate) fn rewrite_fn_before_block(
&mut self,
indent: Indent,
ident: symbol::Ident,
fn_sig: &FnSig<'_>,
span: Span,
) -> Option<(String, FnBraceStyle)> {
let context = self.get_context();
let mut fn_brace_style = newline_for_brace(self.config, &fn_sig.generics.where_clause);
let (result, _, force_newline_brace) =
rewrite_fn_base(&context, indent, ident, fn_sig, span, fn_brace_style)?;
// 2 = ` {`
if self.config.brace_style() == BraceStyle::AlwaysNextLine
|| force_newline_brace
|| last_line_width(&result) + 2 > self.shape().width
{
fn_brace_style = FnBraceStyle::NextLine
}
Some((result, fn_brace_style))
}
pub(crate) fn rewrite_required_fn(
&mut self,
indent: Indent,
ident: symbol::Ident,
sig: &ast::FnSig,
generics: &ast::Generics,
span: Span,
) -> Option<String> {
// Drop semicolon or it will be interpreted as comment.
let span = mk_sp(span.lo(), span.hi() - BytePos(1));
let context = self.get_context();
let (mut result, ends_with_comment, _) = rewrite_fn_base(
&context,
indent,
ident,
&FnSig::from_method_sig(sig, generics, DEFAULT_VISIBILITY),
span,
FnBraceStyle::None,
)?;
// If `result` ends with a comment, then remember to add a newline
if ends_with_comment {
result.push_str(&indent.to_string_with_newline(context.config));
}
// Re-attach semicolon
result.push(';');
Some(result)
}
pub(crate) fn single_line_fn(
&self,
fn_str: &str,
block: &ast::Block,
inner_attrs: Option<&[ast::Attribute]>,
) -> Option<String> {
if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
return None;
}
let context = self.get_context();
if self.config.empty_item_single_line()
&& is_empty_block(&context, block, None)
&& self.block_indent.width() + fn_str.len() + 3 <= self.config.max_width()
&& !last_line_contains_single_line_comment(fn_str)
{
return Some(format!("{} {{}}", fn_str));
}
if !self.config.fn_single_line() || !is_simple_block_stmt(&context, block, None) {
return None;
}
let res = Stmt::from_ast_node(block.stmts.first()?, true)
.rewrite(&self.get_context(), self.shape())?;
let width = self.block_indent.width() + fn_str.len() + res.len() + 5;
if !res.contains('\n') && width <= self.config.max_width() {
Some(format!("{} {{ {} }}", fn_str, res))
} else {
None
}
}
pub(crate) fn visit_static(&mut self, static_parts: &StaticParts<'_>) {
let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
self.push_rewrite(static_parts.span, rewrite);
}
pub(crate) fn visit_struct(&mut self, struct_parts: &StructParts<'_>) {
let is_tuple = match struct_parts.def {
ast::VariantData::Tuple(..) => true,
_ => false,
};
let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
.map(|s| if is_tuple { s + ";" } else { s });
self.push_rewrite(struct_parts.span, rewrite);
}
pub(crate) fn visit_enum(
&mut self,
ident: symbol::Ident,
vis: &ast::Visibility,
enum_def: &ast::EnumDef,
generics: &ast::Generics,
span: Span,
) {
let enum_header =
format_header(&self.get_context(), "enum ", ident, vis, self.block_indent);
self.push_str(&enum_header);
let enum_snippet = self.snippet(span);
let brace_pos = enum_snippet.find_uncommented("{").unwrap();
let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
let generics_str = format_generics(
&self.get_context(),
generics,
self.config.brace_style(),
if enum_def.variants.is_empty() {
BracePos::ForceSameLine
} else {
BracePos::Auto
},
self.block_indent,
// make a span that starts right after `enum Foo`
mk_sp(ident.span.hi(), body_start),
last_line_width(&enum_header),
)
.unwrap();
self.push_str(&generics_str);
self.last_pos = body_start;
match self.format_variant_list(enum_def, body_start, span.hi()) {
Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
rw => {
self.push_rewrite(mk_sp(body_start, span.hi()), rw);
self.block_indent = self.block_indent.block_unindent(self.config);
}
}
}
// Format the body of an enum definition
fn format_variant_list(
&mut self,
enum_def: &ast::EnumDef,
body_lo: BytePos,
body_hi: BytePos,
) -> Option<String> {
if enum_def.variants.is_empty() {
let mut buffer = String::with_capacity(128);
// 1 = "}"
let span = mk_sp(body_lo, body_hi - BytePos(1));
format_empty_struct_or_tuple(
&self.get_context(),
span,
self.block_indent,
&mut buffer,
"",
"}",
);
return Some(buffer);
}
let mut result = String::with_capacity(1024);
let original_offset = self.block_indent;
self.block_indent = self.block_indent.block_indent(self.config);
// If enum variants have discriminants, try to vertically align those,
// provided the discrims are not shifted too much to the right
let align_threshold: usize = self.config.enum_discrim_align_threshold();
let discr_ident_lens: Vec<usize> = enum_def
.variants
.iter()
.filter(|var| var.disr_expr.is_some())
.map(|var| rewrite_ident(&self.get_context(), var.ident).len())
.collect();
// cut the list at the point of longest discrim shorter than the threshold
// All of the discrims under the threshold will get padded, and all above - left as is.
let pad_discrim_ident_to = *discr_ident_lens
.iter()
.filter(|&l| *l <= align_threshold)
.max()
.unwrap_or(&0);
let itemize_list_with = |one_line_width: usize| {
itemize_list(
self.snippet_provider,
enum_def.variants.iter(),
"}",
",",
|f| {
if !f.attrs.is_empty() {
f.attrs[0].span.lo()
} else {
f.span.lo()
}
},
|f| f.span.hi(),
|f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
body_lo,
body_hi,
false,
)
.collect()
};
let mut items: Vec<_> = itemize_list_with(self.config.struct_variant_width());
// If one of the variants use multiple lines, use multi-lined formatting for all variants.
let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
if has_multiline_variant && has_single_line_variant {
items = itemize_list_with(0);
}
let shape = self.shape().sub_width(2)?;
let fmt = ListFormatting::new(shape, self.config)
.trailing_separator(self.config.trailing_comma())
.preserve_newline(true);
let list = write_list(&items, &fmt)?;
result.push_str(&list);
result.push_str(&original_offset.to_string_with_newline(self.config));
result.push('}');
Some(result)
}
// Variant of an enum.
fn format_variant(
&self,
field: &ast::Variant,
one_line_width: usize,
pad_discrim_ident_to: usize,
) -> Option<String> {
if contains_skip(&field.attrs) {
let lo = field.attrs[0].span.lo();
let span = mk_sp(lo, field.span.hi());
return Some(self.snippet(span).to_owned());
}
let context = self.get_context();
// 1 = ','
let shape = self.shape().sub_width(1)?;
let attrs_str = field.attrs.rewrite(&context, shape)?;
let lo = field
.attrs
.last()
.map_or(field.span.lo(), |attr| attr.span.hi());
let span = mk_sp(lo, field.span.lo());
let variant_body = match field.data {
ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
&context,
&StructParts::from_variant(field),
self.block_indent,
Some(one_line_width),
)?,
ast::VariantData::Unit(..) => rewrite_ident(&context, field.ident).to_owned(),
};
let variant_body = if let Some(ref expr) = field.disr_expr {
let lhs = format!("{:1$} =", variant_body, pad_discrim_ident_to);
rewrite_assign_rhs_with(
&context,
lhs,
&*expr.value,
shape,
RhsTactics::AllowOverflow,
)?
} else {
variant_body
};
combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
}
fn visit_impl_items(&mut self, items: &[ptr::P<ast::AssocItem>]) {
if self.get_context().config.reorder_impl_items() {
// Create visitor for each items, then reorder them.
let mut buffer = vec![];
for item in items {
self.visit_impl_item(item);
buffer.push((self.buffer.clone(), item.clone()));
self.buffer.clear();
}
fn is_type(ty: &Option<rustc_ast::ptr::P<ast::Ty>>) -> bool {
if let Some(lty) = ty {
if let ast::TyKind::ImplTrait(..) = lty.kind {
return false;
}
}
true
}
fn is_opaque(ty: &Option<rustc_ast::ptr::P<ast::Ty>>) -> bool {
!is_type(ty)
}
fn both_type(
a: &Option<rustc_ast::ptr::P<ast::Ty>>,
b: &Option<rustc_ast::ptr::P<ast::Ty>>,
) -> bool {
is_type(a) && is_type(b)
}
fn both_opaque(
a: &Option<rustc_ast::ptr::P<ast::Ty>>,
b: &Option<rustc_ast::ptr::P<ast::Ty>>,
) -> bool {
is_opaque(a) && is_opaque(b)
}
// In rustc-ap-v638 the `OpaqueTy` AssocItemKind variant was removed but
// we still need to differentiate to maintain sorting order.
// type -> opaque -> const -> macro -> method
use crate::ast::AssocItemKind::*;
fn need_empty_line(a: &ast::AssocItemKind, b: &ast::AssocItemKind) -> bool {
match (a, b) {
(TyAlias(lty), TyAlias(rty))
if both_type(&lty.3, &rty.3) || both_opaque(&lty.3, &rty.3) =>
{
false
}
(Const(..), Const(..)) => false,
_ => true,
}
}
buffer.sort_by(|(_, a), (_, b)| match (&a.kind, &b.kind) {
(TyAlias(lty), TyAlias(rty))
if both_type(&lty.3, &rty.3) || both_opaque(&lty.3, &rty.3) =>
{
a.ident.as_str().cmp(&b.ident.as_str())
}
(Const(..), Const(..)) | (MacCall(..), MacCall(..)) => {
a.ident.as_str().cmp(&b.ident.as_str())
}
(Fn(..), Fn(..)) => a.span.lo().cmp(&b.span.lo()),
(TyAlias(ty), _) if is_type(&ty.3) => Ordering::Less,
(_, TyAlias(ty)) if is_type(&ty.3) => Ordering::Greater,
(TyAlias(..), _) => Ordering::Less,
(_, TyAlias(..)) => Ordering::Greater,
(Const(..), _) => Ordering::Less,
(_, Const(..)) => Ordering::Greater,
(MacCall(..), _) => Ordering::Less,
(_, MacCall(..)) => Ordering::Greater,
});
let mut prev_kind = None;
for (buf, item) in buffer {
// Make sure that there are at least a single empty line between
// different impl items.
if prev_kind
.as_ref()
.map_or(false, |prev_kind| need_empty_line(prev_kind, &item.kind))
{
self.push_str("\n");
}
let indent_str = self.block_indent.to_string_with_newline(self.config);
self.push_str(&indent_str);
self.push_str(buf.trim());
prev_kind = Some(item.kind.clone());
}
} else {
for item in items {
self.visit_impl_item(item);
}
}
}
}
pub(crate) fn format_impl(
context: &RewriteContext<'_>,
item: &ast::Item,
offset: Indent,
) -> Option<String> {
if let ast::ItemKind::Impl(impl_kind) = &item.kind {
let ast::ImplKind {
ref generics,
ref self_ty,
ref items,
..
} = **impl_kind;
let mut result = String::with_capacity(128);
let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
let sep = offset.to_string_with_newline(context.config);
result.push_str(&ref_and_type);
let where_budget = if result.contains('\n') {
context.config.max_width()
} else {
context.budget(last_line_width(&result))
};
let mut option = WhereClauseOption::snuggled(&ref_and_type);
let snippet = context.snippet(item.span);
let open_pos = snippet.find_uncommented("{")? + 1;
if !contains_comment(&snippet[open_pos..])
&& items.is_empty()
&& generics.where_clause.predicates.len() == 1
&& !result.contains('\n')
{
option.suppress_comma();
option.snuggle();
option.allow_single_line();
}
let missing_span = mk_sp(self_ty.span.hi(), item.span.hi());
let where_span_end = context.snippet_provider.opt_span_before(missing_span, "{");
let where_clause_str = rewrite_where_clause(
context,
&generics.where_clause,
context.config.brace_style(),
Shape::legacy(where_budget, offset.block_only()),
false,
"{",
where_span_end,
self_ty.span.hi(),
option,
)?;
// If there is no where-clause, we may have missing comments between the trait name and
// the opening brace.
if generics.where_clause.predicates.is_empty() {
if let Some(hi) = where_span_end {
match recover_missing_comment_in_span(
mk_sp(self_ty.span.hi(), hi),
Shape::indented(offset, context.config),
context,
last_line_width(&result),
) {
Some(ref missing_comment) if !missing_comment.is_empty() => {
result.push_str(missing_comment);
}
_ => (),
}
}
}
if is_impl_single_line(context, items.as_slice(), &result, &where_clause_str, item)? {
result.push_str(&where_clause_str);
if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
// if the where_clause contains extra comments AND
// there is only one where-clause predicate
// recover the suppressed comma in single line where_clause formatting
if generics.where_clause.predicates.len() == 1 {
result.push(',');
}
result.push_str(&format!("{}{{{}}}", sep, sep));
} else {
result.push_str(" {}");
}
return Some(result);
}
result.push_str(&where_clause_str);
let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
match context.config.brace_style() {
_ if need_newline => result.push_str(&sep),
BraceStyle::AlwaysNextLine => result.push_str(&sep),
BraceStyle::PreferSameLine => result.push(' '),
BraceStyle::SameLineWhere => {
if !where_clause_str.is_empty() {
result.push_str(&sep);
} else {
result.push(' ');
}
}
}
result.push('{');
// this is an impl body snippet(impl SampleImpl { /* here */ })
let lo = max(self_ty.span.hi(), generics.where_clause.span.hi());
let snippet = context.snippet(mk_sp(lo, item.span.hi()));
let open_pos = snippet.find_uncommented("{")? + 1;
if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
let mut visitor = FmtVisitor::from_context(context);
let item_indent = offset.block_only().block_indent(context.config);
visitor.block_indent = item_indent;
visitor.last_pos = lo + BytePos(open_pos as u32);
visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
visitor.visit_impl_items(items);
visitor.format_missing(item.span.hi() - BytePos(1));
let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
result.push_str(&inner_indent_str);
result.push_str(visitor.buffer.trim());
result.push_str(&outer_indent_str);
} else if need_newline || !context.config.empty_item_single_line() {
result.push_str(&sep);
}
result.push('}');
Some(result)
} else {
unreachable!();
}
}
fn is_impl_single_line(
context: &RewriteContext<'_>,
items: &[ptr::P<ast::AssocItem>],
result: &str,
where_clause_str: &str,
item: &ast::Item,
) -> Option<bool> {
let snippet = context.snippet(item.span);
let open_pos = snippet.find_uncommented("{")? + 1;
Some(
context.config.empty_item_single_line()
&& items.is_empty()
&& !result.contains('\n')
&& result.len() + where_clause_str.len() <= context.config.max_width()
&& !contains_comment(&snippet[open_pos..]),
)
}
fn format_impl_ref_and_type(
context: &RewriteContext<'_>,
item: &ast::Item,
offset: Indent,
) -> Option<String> {
if let ast::ItemKind::Impl(impl_kind) = &item.kind {
let ast::ImplKind {
unsafety,
polarity,
defaultness,
constness,
ref generics,
of_trait: ref trait_ref,
ref self_ty,
..
} = **impl_kind;
let mut result = String::with_capacity(128);
result.push_str(&format_visibility(context, &item.vis));
result.push_str(format_defaultness(defaultness));
result.push_str(format_unsafety(unsafety));
let shape = if context.config.version() == Version::Two {
Shape::indented(offset + last_line_width(&result), context.config)
} else {
generics_shape_from_config(
context.config,
Shape::indented(offset + last_line_width(&result), context.config),
0,
)?
};
let generics_str = rewrite_generics(context, "impl", generics, shape)?;
result.push_str(&generics_str);
result.push_str(format_constness_right(constness));
let polarity_str = match polarity {
ast::ImplPolarity::Negative(_) => "!",
ast::ImplPolarity::Positive => "",
};
let polarity_overhead;
let trait_ref_overhead;
if let Some(ref trait_ref) = *trait_ref {
let result_len = last_line_width(&result);
result.push_str(&rewrite_trait_ref(
context,
trait_ref,
offset,
polarity_str,
result_len,
)?);
polarity_overhead = 0; // already written
trait_ref_overhead = " for".len();
} else {
polarity_overhead = polarity_str.len();
trait_ref_overhead = 0;
}
// Try to put the self type in a single line.
let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
// If there is no where-clause adapt budget for type formatting to take space and curly
// brace into account.
match context.config.brace_style() {
BraceStyle::AlwaysNextLine => 0,
_ => 2,
}
} else {
0
};
let used_space = last_line_width(&result)
+ polarity_overhead
+ trait_ref_overhead
+ curly_brace_overhead;
// 1 = space before the type.
let budget = context.budget(used_space + 1);
if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
if !self_ty_str.contains('\n') {
if trait_ref.is_some() {
result.push_str(" for ");
} else {
result.push(' ');
result.push_str(polarity_str);
}
result.push_str(&self_ty_str);
return Some(result);
}
}
// Couldn't fit the self type on a single line, put it on a new line.
result.push('\n');
// Add indentation of one additional tab.
let new_line_offset = offset.block_indent(context.config);
result.push_str(&new_line_offset.to_string(context.config));
if trait_ref.is_some() {
result.push_str("for ");
} else {
result.push_str(polarity_str);
}
let budget = context.budget(last_line_width(&result) + polarity_overhead);
let type_offset = match context.config.indent_style() {
IndentStyle::Visual => new_line_offset + trait_ref_overhead,
IndentStyle::Block => new_line_offset,
};
result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
Some(result)
} else {
unreachable!();
}
}
fn rewrite_trait_ref(
context: &RewriteContext<'_>,
trait_ref: &ast::TraitRef,
offset: Indent,
polarity_str: &str,
result_len: usize,
) -> Option<String> {
// 1 = space between generics and trait_ref
let used_space = 1 + polarity_str.len() + result_len;
let shape = Shape::indented(offset + used_space, context.config);
if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
if !trait_ref_str.contains('\n') {
return Some(format!(" {}{}", polarity_str, trait_ref_str));
}
}
// We could not make enough space for trait_ref, so put it on new line.
let offset = offset.block_indent(context.config);
let shape = Shape::indented(offset, context.config);
let trait_ref_str = trait_ref.rewrite(context, shape)?;
Some(format!(
"{}{}{}",
offset.to_string_with_newline(context.config),
polarity_str,
trait_ref_str
))
}
pub(crate) struct StructParts<'a> {
prefix: &'a str,
ident: symbol::Ident,
vis: &'a ast::Visibility,
def: &'a ast::VariantData,
generics: Option<&'a ast::Generics>,
span: Span,
}
impl<'a> StructParts<'a> {
fn format_header(&self, context: &RewriteContext<'_>, offset: Indent) -> String {
format_header(context, self.prefix, self.ident, self.vis, offset)
}
pub(crate) fn from_variant(variant: &'a ast::Variant) -> Self {
StructParts {
prefix: "",
ident: variant.ident,
vis: &DEFAULT_VISIBILITY,
def: &variant.data,
generics: None,
span: variant.span,
}
}
pub(crate) fn from_item(item: &'a ast::Item) -> Self {
let (prefix, def, generics) = match item.kind {
ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
_ => unreachable!(),
};
StructParts {
prefix,
ident: item.ident,
vis: &item.vis,
def,
generics: Some(generics),
span: item.span,
}
}
}
fn format_struct(
context: &RewriteContext<'_>,
struct_parts: &StructParts<'_>,
offset: Indent,
one_line_width: Option<usize>,
) -> Option<String> {
match *struct_parts.def {
ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
ast::VariantData::Tuple(ref fields, _) => {
format_tuple_struct(context, struct_parts, fields, offset)
}
ast::VariantData::Struct(ref fields, _) => {
format_struct_struct(context, struct_parts, fields, offset, one_line_width)
}
}
}
pub(crate) fn format_trait(
context: &RewriteContext<'_>,
item: &ast::Item,
offset: Indent,
) -> Option<String> {
if let ast::ItemKind::Trait(trait_kind) = &item.kind {
let ast::TraitKind(is_auto, unsafety, ref generics, ref generic_bounds, ref trait_items) =
**trait_kind;
let mut result = String::with_capacity(128);
let header = format!(
"{}{}{}trait ",
format_visibility(context, &item.vis),
format_unsafety(unsafety),
format_auto(is_auto),
);
result.push_str(&header);
let body_lo = context.snippet_provider.span_after(item.span, "{");
let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
let generics_str =
rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
result.push_str(&generics_str);
// FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
if !generic_bounds.is_empty() {
let ident_hi = context
.snippet_provider
.span_after(item.span, &item.ident.as_str());
let bound_hi = generic_bounds.last().unwrap().span().hi();
let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
if contains_comment(snippet) {
return None;
}
result = rewrite_assign_rhs_with(
context,
result + ":",
generic_bounds,
shape,
RhsTactics::ForceNextLineWithoutIndent,
)?;
}
// Rewrite where-clause.
if !generics.where_clause.predicates.is_empty() {
let where_on_new_line = context.config.indent_style() != IndentStyle::Block;
let where_budget = context.budget(last_line_width(&result));
let pos_before_where = if generic_bounds.is_empty() {
generics.where_clause.span.lo()
} else {
generic_bounds[generic_bounds.len() - 1].span().hi()
};
let option = WhereClauseOption::snuggled(&generics_str);
let where_clause_str = rewrite_where_clause(
context,
&generics.where_clause,
context.config.brace_style(),
Shape::legacy(where_budget, offset.block_only()),
where_on_new_line,
"{",
None,
pos_before_where,
option,
)?;
// If the where-clause cannot fit on the same line,
// put the where-clause on a new line
if !where_clause_str.contains('\n')
&& last_line_width(&result) + where_clause_str.len() + offset.width()
> context.config.comment_width()
{
let width = offset.block_indent + context.config.tab_spaces() - 1;
let where_indent = Indent::new(0, width);
result.push_str(&where_indent.to_string_with_newline(context.config));
}
result.push_str(&where_clause_str);
} else {
let item_snippet = context.snippet(item.span);
if let Some(lo) = item_snippet.find('/') {
// 1 = `{`
let comment_hi = body_lo - BytePos(1);
let comment_lo = item.span.lo() + BytePos(lo as u32);
if comment_lo < comment_hi {
match recover_missing_comment_in_span(
mk_sp(comment_lo, comment_hi),
Shape::indented(offset, context.config),
context,
last_line_width(&result),
) {
Some(ref missing_comment) if !missing_comment.is_empty() => {
result.push_str(missing_comment);
}
_ => (),
}
}
}
}
match context.config.brace_style() {
_ if last_line_contains_single_line_comment(&result)
|| last_line_width(&result) + 2 > context.budget(offset.width()) =>
{
result.push_str(&offset.to_string_with_newline(context.config));
}
BraceStyle::AlwaysNextLine => {
result.push_str(&offset.to_string_with_newline(context.config));
}
BraceStyle::PreferSameLine => result.push(' '),
BraceStyle::SameLineWhere => {
if result.contains('\n')
|| (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
{
result.push_str(&offset.to_string_with_newline(context.config));
} else {
result.push(' ');
}
}
}
result.push('{');
let block_span = mk_sp(generics.where_clause.span.hi(), item.span.hi());
let snippet = context.snippet(block_span);
let open_pos = snippet.find_uncommented("{")? + 1;
let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
let mut visitor = FmtVisitor::from_context(context);
visitor.block_indent = offset.block_only().block_indent(context.config);
visitor.last_pos = block_span.lo() + BytePos(open_pos as u32);
for item in trait_items {
visitor.visit_trait_item(item);
}
visitor.format_missing(item.span.hi() - BytePos(1));
let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
result.push_str(&inner_indent_str);
result.push_str(visitor.buffer.trim());
result.push_str(&outer_indent_str);
} else if result.contains('\n') {
result.push_str(&outer_indent_str);
}
result.push('}');
Some(result)
} else {
unreachable!();
}
}
struct OpaqueTypeBounds<'a> {
generic_bounds: &'a ast::GenericBounds,
}
impl<'a> Rewrite for OpaqueTypeBounds<'a> {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
self.generic_bounds
.rewrite(context, shape)
.map(|s| format!("impl {}", s))
}
}
pub(crate) struct TraitAliasBounds<'a> {
generic_bounds: &'a ast::GenericBounds,
generics: &'a ast::Generics,
}
impl<'a> Rewrite for TraitAliasBounds<'a> {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
let generic_bounds_str = self.generic_bounds.rewrite(context, shape)?;
let mut option = WhereClauseOption::new(true, WhereClauseSpace::None);
option.allow_single_line();
let where_str = rewrite_where_clause(
context,
&self.generics.where_clause,
context.config.brace_style(),
shape,
false,
";",
None,
self.generics.where_clause.span.lo(),
option,
)?;
let fits_single_line = !generic_bounds_str.contains('\n')
&& !where_str.contains('\n')
&& generic_bounds_str.len() + where_str.len() < shape.width;
let space = if generic_bounds_str.is_empty() || where_str.is_empty() {
Cow::from("")
} else if fits_single_line {
Cow::from(" ")
} else {
shape.indent.to_string_with_newline(&context.config)
};
Some(format!("{}{}{}", generic_bounds_str, space, where_str))
}
}
pub(crate) fn format_trait_alias(
context: &RewriteContext<'_>,
ident: symbol::Ident,
vis: &ast::Visibility,
generics: &ast::Generics,
generic_bounds: &ast::GenericBounds,
shape: Shape,
) -> Option<String> {
let alias = rewrite_ident(context, ident);
// 6 = "trait ", 2 = " ="
let g_shape = shape.offset_left(6)?.sub_width(2)?;
let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
let vis_str = format_visibility(context, vis);
let lhs = format!("{}trait {} =", vis_str, generics_str);
// 1 = ";"
let trait_alias_bounds = TraitAliasBounds {
generic_bounds,
generics,
};
rewrite_assign_rhs(context, lhs, &trait_alias_bounds, shape.sub_width(1)?).map(|s| s + ";")
}
fn format_unit_struct(
context: &RewriteContext<'_>,
p: &StructParts<'_>,
offset: Indent,
) -> Option<String> {
let header_str = format_header(context, p.prefix, p.ident, p.vis, offset);
let generics_str = if let Some(generics) = p.generics {
let hi = context.snippet_provider.span_before(p.span, ";");
format_generics(
context,
generics,
context.config.brace_style(),
BracePos::None,
offset,
// make a span that starts right after `struct Foo`
mk_sp(p.ident.span.hi(), hi),
last_line_width(&header_str),
)?
} else {
String::new()
};
Some(format!("{}{};", header_str, generics_str))
}
pub(crate) fn format_struct_struct(
context: &RewriteContext<'_>,
struct_parts: &StructParts<'_>,
fields: &[ast::FieldDef],
offset: Indent,
one_line_width: Option<usize>,
) -> Option<String> {
let mut result = String::with_capacity(1024);
let span = struct_parts.span;
let header_str = struct_parts.format_header(context, offset);
result.push_str(&header_str);
let header_hi = struct_parts.ident.span.hi();
let body_lo = context.snippet_provider.span_after(span, "{");
let generics_str = match struct_parts.generics {
Some(g) => format_generics(
context,
g,
context.config.brace_style(),
if fields.is_empty() {
BracePos::ForceSameLine
} else {
BracePos::Auto
},
offset,
// make a span that starts right after `struct Foo`
mk_sp(header_hi, body_lo),
last_line_width(&result),
)?,
None => {
// 3 = ` {}`, 2 = ` {`.
let overhead = if fields.is_empty() { 3 } else { 2 };
if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
|| context.config.max_width() < overhead + result.len()
{
format!("\n{}{{", offset.block_only().to_string(context.config))
} else {
" {".to_owned()
}
}
};
// 1 = `}`
let overhead = if fields.is_empty() { 1 } else { 0 };
let total_width = result.len() + generics_str.len() + overhead;
if !generics_str.is_empty()
&& !generics_str.contains('\n')
&& total_width > context.config.max_width()
{
result.push('\n');
result.push_str(&offset.to_string(context.config));
result.push_str(generics_str.trim_start());
} else {
result.push_str(&generics_str);
}
if fields.is_empty() {
let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
return Some(result);
}
// 3 = ` ` and ` }`
let one_line_budget = context.budget(result.len() + 3 + offset.width());
let one_line_budget =
one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
let items_str = rewrite_with_alignment(
fields,
context,
Shape::indented(offset.block_indent(context.config), context.config).sub_width(1)?,
mk_sp(body_lo, span.hi()),
one_line_budget,
)?;
if !items_str.contains('\n')
&& !result.contains('\n')
&& items_str.len() <= one_line_budget
&& !last_line_contains_single_line_comment(&items_str)
{
Some(format!("{} {} }}", result, items_str))
} else {
Some(format!(
"{}\n{}{}\n{}}}",
result,
offset
.block_indent(context.config)
.to_string(context.config),
items_str,
offset.to_string(context.config)
))
}
}
fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
match vis.kind {
ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
_ => default_span.lo(),
}
}
// Format tuple or struct without any fields. We need to make sure that the comments
// inside the delimiters are preserved.
fn format_empty_struct_or_tuple(
context: &RewriteContext<'_>,
span: Span,
offset: Indent,
result: &mut String,
opener: &str,
closer: &str,
) {
// 3 = " {}" or "();"
let used_width = last_line_used_width(&result, offset.width()) + 3;
if used_width > context.config.max_width() {
result.push_str(&offset.to_string_with_newline(context.config))
}
result.push_str(opener);
match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
Some(ref s) if s.is_empty() => (),
Some(ref s) => {
if !is_single_line(s) || first_line_contains_single_line_comment(s) {
let nested_indent_str = offset
.block_indent(context.config)
.to_string_with_newline(context.config);
result.push_str(&nested_indent_str);
}
result.push_str(s);
if last_line_contains_single_line_comment(s) {
result.push_str(&offset.to_string_with_newline(context.config));
}
}
None => result.push_str(context.snippet(span)),
}
result.push_str(closer);
}
fn format_tuple_struct(
context: &RewriteContext<'_>,
struct_parts: &StructParts<'_>,
fields: &[ast::FieldDef],
offset: Indent,
) -> Option<String> {
let mut result = String::with_capacity(1024);
let span = struct_parts.span;
let header_str = struct_parts.format_header(context, offset);
result.push_str(&header_str);
let body_lo = if fields.is_empty() {
let lo = get_bytepos_after_visibility(struct_parts.vis, span);
context
.snippet_provider
.span_after(mk_sp(lo, span.hi()), "(")
} else {
fields[0].span.lo()
};
let body_hi = if fields.is_empty() {
context
.snippet_provider
.span_after(mk_sp(body_lo, span.hi()), ")")
} else {
// This is a dirty hack to work around a missing `)` from the span of the last field.
let last_arg_span = fields[fields.len() - 1].span;
context
.snippet_provider
.opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
.unwrap_or_else(|| last_arg_span.hi())
};
let where_clause_str = match struct_parts.generics {
Some(generics) => {
let budget = context.budget(last_line_width(&header_str));
let shape = Shape::legacy(budget, offset);
let generics_str = rewrite_generics(context, "", generics, shape)?;
result.push_str(&generics_str);
let where_budget = context.budget(last_line_width(&result));
let option = WhereClauseOption::new(true, WhereClauseSpace::Newline);
rewrite_where_clause(
context,
&generics.where_clause,
context.config.brace_style(),
Shape::legacy(where_budget, offset.block_only()),
false,
";",
None,
body_hi,
option,
)?
}
None => "".to_owned(),
};
if fields.is_empty() {
let body_hi = context
.snippet_provider
.span_before(mk_sp(body_lo, span.hi()), ")");
let inner_span = mk_sp(body_lo, body_hi);
format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
} else {
let shape = Shape::indented(offset, context.config).sub_width(1)?;
result = overflow::rewrite_with_parens(
context,
&result,
fields.iter(),
shape,
span,
context.config.fn_call_width(),
None,
)?;
}
if !where_clause_str.is_empty()
&& !where_clause_str.contains('\n')
&& (result.contains('\n')
|| offset.block_indent + result.len() + where_clause_str.len() + 1
> context.config.max_width())
{
// We need to put the where-clause on a new line, but we didn't
// know that earlier, so the where-clause will not be indented properly.
result.push('\n');
result.push_str(
&(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
);
}
result.push_str(&where_clause_str);
Some(result)
}
fn rewrite_type<R: Rewrite>(
context: &RewriteContext<'_>,
indent: Indent,
ident: symbol::Ident,
vis: &ast::Visibility,
generics: &ast::Generics,
generic_bounds_opt: Option<&ast::GenericBounds>,
rhs: Option<&R>,
span: Span,
) -> Option<String> {
let mut result = String::with_capacity(128);
result.push_str(&format!("{}type ", format_visibility(context, vis)));
let ident_str = rewrite_ident(context, ident);
if generics.params.is_empty() {
result.push_str(ident_str)
} else {
// 2 = `= `
let g_shape = Shape::indented(indent, context.config)
.offset_left(result.len())?
.sub_width(2)?;
let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
result.push_str(&generics_str);
}
if let Some(bounds) = generic_bounds_opt {
if !bounds.is_empty() {
// 2 = `: `
let shape = Shape::indented(indent, context.config).offset_left(result.len() + 2)?;
let type_bounds = bounds.rewrite(context, shape).map(|s| format!(": {}", s))?;
result.push_str(&type_bounds);
}
}
let where_budget = context.budget(last_line_width(&result));
let mut option = WhereClauseOption::snuggled(&result);
if rhs.is_none() {
option.suppress_comma();
}
let where_clause_str = rewrite_where_clause(
context,
&generics.where_clause,
context.config.brace_style(),
Shape::legacy(where_budget, indent),
false,
"=",
None,
generics.span.hi(),
option,
)?;
result.push_str(&where_clause_str);
if let Some(ty) = rhs {
// If there's a where clause, add a newline before the assignment. Otherwise just add a
// space.
let has_where = !generics.where_clause.predicates.is_empty();
if has_where {
result.push_str(&indent.to_string_with_newline(context.config));
} else {
result.push(' ');
}
let comment_span = context
.snippet_provider
.opt_span_before(span, "=")
.map(|op_lo| mk_sp(generics.where_clause.span.hi(), op_lo));
let lhs = match comment_span {
Some(comment_span)
if contains_comment(context.snippet_provider.span_to_snippet(comment_span)?) =>
{
let comment_shape = if has_where {
Shape::indented(indent, context.config)
} else {
Shape::indented(indent, context.config)
.block_left(context.config.tab_spaces())?
};
combine_strs_with_missing_comments(
context,
result.trim_end(),
"=",
comment_span,
comment_shape,
true,
)?
}
_ => format!("{}=", result),
};
// 1 = `;`
let shape = Shape::indented(indent, context.config).sub_width(1)?;
rewrite_assign_rhs(context, lhs, &*ty, shape).map(|s| s + ";")
} else {
Some(format!("{};", result))
}
}
pub(crate) fn rewrite_opaque_type(
context: &RewriteContext<'_>,
indent: Indent,
ident: symbol::Ident,
generic_bounds: &ast::GenericBounds,
generics: &ast::Generics,
vis: &ast::Visibility,
span: Span,
) -> Option<String> {
let opaque_type_bounds = OpaqueTypeBounds { generic_bounds };
rewrite_type(
context,
indent,
ident,
vis,
generics,
Some(generic_bounds),
Some(&opaque_type_bounds),
span,
)
}
fn type_annotation_spacing(config: &Config) -> (&str, &str) {
(
if config.space_before_colon() { " " } else { "" },
if config.space_after_colon() { " " } else { "" },
)
}
pub(crate) fn rewrite_struct_field_prefix(
context: &RewriteContext<'_>,
field: &ast::FieldDef,
) -> Option<String> {
let vis = format_visibility(context, &field.vis);
let type_annotation_spacing = type_annotation_spacing(context.config);
Some(match field.ident {
Some(name) => format!(
"{}{}{}:",
vis,
rewrite_ident(context, name),
type_annotation_spacing.0
),
None => vis.to_string(),
})
}
impl Rewrite for ast::FieldDef {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
rewrite_struct_field(context, self, shape, 0)
}
}
pub(crate) fn rewrite_struct_field(
context: &RewriteContext<'_>,
field: &ast::FieldDef,
shape: Shape,
lhs_max_width: usize,
) -> Option<String> {
if contains_skip(&field.attrs) {
return Some(context.snippet(field.span()).to_owned());
}
let type_annotation_spacing = type_annotation_spacing(context.config);
let prefix = rewrite_struct_field_prefix(context, field)?;
let attrs_str = field.attrs.rewrite(context, shape)?;
let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
let missing_span = if field.attrs.is_empty() {
mk_sp(field.span.lo(), field.span.lo())
} else {
mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
};
let mut spacing = String::from(if field.ident.is_some() {
type_annotation_spacing.1
} else {
""
});
// Try to put everything on a single line.
let attr_prefix = combine_strs_with_missing_comments(
context,
&attrs_str,
&prefix,
missing_span,
shape,
attrs_extendable,
)?;
let overhead = trimmed_last_line_width(&attr_prefix);
let lhs_offset = lhs_max_width.saturating_sub(overhead);
for _ in 0..lhs_offset {
spacing.push(' ');
}
// In this extreme case we will be missing a space between an attribute and a field.
if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
spacing.push(' ');
}
let orig_ty = shape
.offset_left(overhead + spacing.len())
.and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
if let Some(ref ty) = orig_ty {
if !ty.contains('\n') {
return Some(attr_prefix + &spacing + ty);
}
}
let is_prefix_empty = prefix.is_empty();
// We must use multiline. We are going to put attributes and a field on different lines.
let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
// Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
let field_str = if is_prefix_empty {
field_str.trim_start()
} else {
&field_str
};
combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
}
pub(crate) struct StaticParts<'a> {
prefix: &'a str,
vis: &'a ast::Visibility,
ident: symbol::Ident,
ty: &'a ast::Ty,
mutability: ast::Mutability,
expr_opt: Option<&'a ptr::P<ast::Expr>>,
defaultness: Option<ast::Defaultness>,
span: Span,
}
impl<'a> StaticParts<'a> {
pub(crate) fn from_item(item: &'a ast::Item) -> Self {
let (defaultness, prefix, ty, mutability, expr) = match item.kind {
ast::ItemKind::Static(ref ty, mutability, ref expr) => {
(None, "static", ty, mutability, expr)
}
ast::ItemKind::Const(defaultness, ref ty, ref expr) => {
(Some(defaultness), "const", ty, ast::Mutability::Not, expr)
}
_ => unreachable!(),
};
StaticParts {
prefix,
vis: &item.vis,
ident: item.ident,
ty,
mutability,
expr_opt: expr.as_ref(),
defaultness,
span: item.span,
}
}
pub(crate) fn from_trait_item(ti: &'a ast::AssocItem) -> Self {
let (defaultness, ty, expr_opt) = match ti.kind {
ast::AssocItemKind::Const(defaultness, ref ty, ref expr_opt) => {
(defaultness, ty, expr_opt)
}
_ => unreachable!(),
};
StaticParts {
prefix: "const",
vis: &DEFAULT_VISIBILITY,
ident: ti.ident,
ty,
mutability: ast::Mutability::Not,
expr_opt: expr_opt.as_ref(),
defaultness: Some(defaultness),
span: ti.span,
}
}
pub(crate) fn from_impl_item(ii: &'a ast::AssocItem) -> Self {
let (defaultness, ty, expr) = match ii.kind {
ast::AssocItemKind::Const(defaultness, ref ty, ref expr) => (defaultness, ty, expr),
_ => unreachable!(),
};
StaticParts {
prefix: "const",
vis: &ii.vis,
ident: ii.ident,
ty,
mutability: ast::Mutability::Not,
expr_opt: expr.as_ref(),
defaultness: Some(defaultness),
span: ii.span,
}
}
}
fn rewrite_static(
context: &RewriteContext<'_>,
static_parts: &StaticParts<'_>,
offset: Indent,
) -> Option<String> {
let colon = colon_spaces(context.config);
let mut prefix = format!(
"{}{}{} {}{}{}",
format_visibility(context, static_parts.vis),
static_parts.defaultness.map_or("", format_defaultness),
static_parts.prefix,
format_mutability(static_parts.mutability),
rewrite_ident(context, static_parts.ident),
colon,
);
// 2 = " =".len()
let ty_shape =
Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
Some(ty_str) => ty_str,
None => {
if prefix.ends_with(' ') {
prefix.pop();
}
let nested_indent = offset.block_indent(context.config);
let nested_shape = Shape::indented(nested_indent, context.config);
let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
format!(
"{}{}",
nested_indent.to_string_with_newline(context.config),
ty_str
)
}
};
if let Some(expr) = static_parts.expr_opt {
let comments_lo = context.snippet_provider.span_after(static_parts.span, "=");
let expr_lo = expr.span.lo();
let comments_span = mk_sp(comments_lo, expr_lo);
let lhs = format!("{}{} =", prefix, ty_str);
// 1 = ;
let remaining_width = context.budget(offset.block_indent + 1);
rewrite_assign_rhs_with_comments(
context,
&lhs,
&**expr,
Shape::legacy(remaining_width, offset.block_only()),
RhsTactics::Default,
comments_span,
true,
)
.and_then(|res| recover_comment_removed(res, static_parts.span, context))
.map(|s| if s.ends_with(';') { s } else { s + ";" })
} else {
Some(format!("{}{};", prefix, ty_str))
}
}
pub(crate) fn rewrite_type_alias(
ident: symbol::Ident,
ty_opt: Option<&ptr::P<ast::Ty>>,
generics: &ast::Generics,
generic_bounds_opt: Option<&ast::GenericBounds>,
context: &RewriteContext<'_>,
indent: Indent,
vis: &ast::Visibility,
span: Span,
) -> Option<String> {
rewrite_type(
context,
indent,
ident,
vis,
generics,
generic_bounds_opt,
ty_opt,
span,
)
}
struct OpaqueType<'a> {
bounds: &'a ast::GenericBounds,
}
impl<'a> Rewrite for OpaqueType<'a> {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
let shape = shape.offset_left(5)?; // `impl `
self.bounds
.rewrite(context, shape)
.map(|s| format!("impl {}", s))
}
}
pub(crate) fn rewrite_opaque_impl_type(
context: &RewriteContext<'_>,
ident: symbol::Ident,
generics: &ast::Generics,
generic_bounds: &ast::GenericBounds,
indent: Indent,
) -> Option<String> {
let ident_str = rewrite_ident(context, ident);
// 5 = "type "
let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
let prefix = format!("type {} =", generics_str);
let rhs = OpaqueType {
bounds: generic_bounds,
};
rewrite_assign_rhs(
context,
&prefix,
&rhs,
Shape::indented(indent, context.config).sub_width(1)?,
)
.map(|s| s + ";")
}
pub(crate) fn rewrite_associated_impl_type(
ident: symbol::Ident,
vis: &ast::Visibility,
defaultness: ast::Defaultness,
ty_opt: Option<&ptr::P<ast::Ty>>,
generics: &ast::Generics,
context: &RewriteContext<'_>,
indent: Indent,
span: Span,
) -> Option<String> {
let result = rewrite_type_alias(ident, ty_opt, generics, None, context, indent, vis, span)?;
match defaultness {
ast::Defaultness::Default(..) => Some(format!("default {}", result)),
_ => Some(result),
}
}
impl Rewrite for ast::FnRetTy {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
match *self {
ast::FnRetTy::Default(_) => Some(String::new()),
ast::FnRetTy::Ty(ref ty) => {
if context.config.version() == Version::One
|| context.config.indent_style() == IndentStyle::Visual
{
let inner_width = shape.width.checked_sub(3)?;
return ty
.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
.map(|r| format!("-> {}", r));
}
ty.rewrite(context, shape.offset_left(3)?)
.map(|s| format!("-> {}", s))
}
}
}
}
fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
match ty.kind {
ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
_ => false,
}
}
/// Recover any missing comments between the param and the type.
///
/// # Returns
///
/// A 2-len tuple with the comment before the colon in first position, and the comment after the
/// colon in second position.
fn get_missing_param_comments(
context: &RewriteContext<'_>,
pat_span: Span,
ty_span: Span,
shape: Shape,
) -> (String, String) {
let missing_comment_span = mk_sp(pat_span.hi(), ty_span.lo());
let span_before_colon = {
let missing_comment_span_hi = context
.snippet_provider
.span_before(missing_comment_span, ":");
mk_sp(pat_span.hi(), missing_comment_span_hi)
};
let span_after_colon = {
let missing_comment_span_lo = context
.snippet_provider
.span_after(missing_comment_span, ":");
mk_sp(missing_comment_span_lo, ty_span.lo())
};
let comment_before_colon = rewrite_missing_comment(span_before_colon, shape, context)
.filter(|comment| !comment.is_empty())
.map_or(String::new(), |comment| format!(" {}", comment));
let comment_after_colon = rewrite_missing_comment(span_after_colon, shape, context)
.filter(|comment| !comment.is_empty())
.map_or(String::new(), |comment| format!("{} ", comment));
(comment_before_colon, comment_after_colon)
}
impl Rewrite for ast::Param {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
let param_attrs_result = self
.attrs
.rewrite(context, Shape::legacy(shape.width, shape.indent))?;
let (span, has_multiple_attr_lines) = if !self.attrs.is_empty() {
let num_attrs = self.attrs.len();
(
mk_sp(self.attrs[num_attrs - 1].span.hi(), self.pat.span.lo()),
param_attrs_result.contains('\n'),
)
} else {
(mk_sp(self.span.lo(), self.span.lo()), false)
};
if let Some(ref explicit_self) = self.to_self() {
rewrite_explicit_self(
context,
explicit_self,
&param_attrs_result,
span,
shape,
has_multiple_attr_lines,
)
} else if is_named_param(self) {
let mut result = combine_strs_with_missing_comments(
context,
&param_attrs_result,
&self
.pat
.rewrite(context, Shape::legacy(shape.width, shape.indent))?,
span,
shape,
!has_multiple_attr_lines,
)?;
if !is_empty_infer(&*self.ty, self.pat.span) {
let (before_comment, after_comment) =
get_missing_param_comments(context, self.pat.span, self.ty.span, shape);
result.push_str(&before_comment);
result.push_str(colon_spaces(context.config));
result.push_str(&after_comment);
let overhead = last_line_width(&result);
let max_width = shape.width.checked_sub(overhead)?;
let ty_str = self
.ty
.rewrite(context, Shape::legacy(max_width, shape.indent))?;
result.push_str(&ty_str);
}
Some(result)
} else {
self.ty.rewrite(context, shape)
}
}
}
fn rewrite_explicit_self(
context: &RewriteContext<'_>,
explicit_self: &ast::ExplicitSelf,
param_attrs: &str,
span: Span,
shape: Shape,
has_multiple_attr_lines: bool,
) -> Option<String> {
match explicit_self.node {
ast::SelfKind::Region(lt, m) => {
let mut_str = format_mutability(m);
match lt {
Some(ref l) => {
let lifetime_str = l.rewrite(
context,
Shape::legacy(context.config.max_width(), Indent::empty()),
)?;
Some(combine_strs_with_missing_comments(
context,
&param_attrs,
&format!("&{} {}self", lifetime_str, mut_str),
span,
shape,
!has_multiple_attr_lines,
)?)
}
None => Some(combine_strs_with_missing_comments(
context,
&param_attrs,
&format!("&{}self", mut_str),
span,
shape,
!has_multiple_attr_lines,
)?),
}
}
ast::SelfKind::Explicit(ref ty, mutability) => {
let type_str = ty.rewrite(
context,
Shape::legacy(context.config.max_width(), Indent::empty()),
)?;
Some(combine_strs_with_missing_comments(
context,
&param_attrs,
&format!("{}self: {}", format_mutability(mutability), type_str),
span,
shape,
!has_multiple_attr_lines,
)?)
}
ast::SelfKind::Value(mutability) => Some(combine_strs_with_missing_comments(
context,
&param_attrs,
&format!("{}self", format_mutability(mutability)),
span,
shape,
!has_multiple_attr_lines,
)?),
}
}
pub(crate) fn span_lo_for_param(param: &ast::Param) -> BytePos {
if param.attrs.is_empty() {
if is_named_param(param) {
param.pat.span.lo()
} else {
param.ty.span.lo()
}
} else {
param.attrs[0].span.lo()
}
}
pub(crate) fn span_hi_for_param(context: &RewriteContext<'_>, param: &ast::Param) -> BytePos {
match param.ty.kind {
ast::TyKind::Infer if context.snippet(param.ty.span) == "_" => param.ty.span.hi(),
ast::TyKind::Infer if is_named_param(param) => param.pat.span.hi(),
_ => param.ty.span.hi(),
}
}
pub(crate) fn is_named_param(param: &ast::Param) -> bool {
if let ast::PatKind::Ident(_, ident, _) = param.pat.kind {
ident.name != symbol::kw::Empty
} else {
true
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub(crate) enum FnBraceStyle {
SameLine,
NextLine,
None,
}
// Return type is (result, force_new_line_for_brace)
fn rewrite_fn_base(
context: &RewriteContext<'_>,
indent: Indent,
ident: symbol::Ident,
fn_sig: &FnSig<'_>,
span: Span,
fn_brace_style: FnBraceStyle,
) -> Option<(String, bool, bool)> {
let mut force_new_line_for_brace = false;
let where_clause = &fn_sig.generics.where_clause;
let mut result = String::with_capacity(1024);
result.push_str(&fn_sig.to_str(context));
// fn foo
result.push_str("fn ");
// Generics.
let overhead = if let FnBraceStyle::SameLine = fn_brace_style {
// 4 = `() {`
4
} else {
// 2 = `()`
2
};
let used_width = last_line_used_width(&result, indent.width());
let one_line_budget = context.budget(used_width + overhead);
let shape = Shape {
width: one_line_budget,
indent,
offset: used_width,
};
let fd = fn_sig.decl;
let generics_str = rewrite_generics(
context,
rewrite_ident(context, ident),
fn_sig.generics,
shape,
)?;
result.push_str(&generics_str);
let snuggle_angle_bracket = generics_str
.lines()
.last()
.map_or(false, |l| l.trim_start().len() == 1);
// Note that the width and indent don't really matter, we'll re-layout the
// return type later anyway.
let ret_str = fd
.output
.rewrite(context, Shape::indented(indent, context.config))?;
let multi_line_ret_str = ret_str.contains('\n');
let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
// Params.
let (one_line_budget, multi_line_budget, mut param_indent) = compute_budgets_for_params(
context,
&result,
indent,
ret_str_len,
fn_brace_style,
multi_line_ret_str,
)?;
debug!(
"rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, param_indent: {:?}",
one_line_budget, multi_line_budget, param_indent
);
result.push('(');
// Check if vertical layout was forced.
if one_line_budget == 0
&& !snuggle_angle_bracket
&& context.config.indent_style() == IndentStyle::Visual
{
result.push_str(&param_indent.to_string_with_newline(context.config));
}
// Skip `pub(crate)`.
let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
// A conservative estimation, the goal is to be over all parens in generics
let params_start = fn_sig
.generics
.params
.last()
.map_or(lo_after_visibility, |param| param.span().hi());
let params_end = if fd.inputs.is_empty() {
context
.snippet_provider
.span_after(mk_sp(params_start, span.hi()), ")")
} else {
let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
context.snippet_provider.span_after(last_span, ")")
};
let params_span = mk_sp(
context
.snippet_provider
.span_after(mk_sp(params_start, span.hi()), "("),
params_end,
);
let param_str = rewrite_params(
context,
&fd.inputs,
one_line_budget,
multi_line_budget,
indent,
param_indent,
params_span,
fd.c_variadic(),
)?;
let put_params_in_block = match context.config.indent_style() {
IndentStyle::Block => param_str.contains('\n') || param_str.len() > one_line_budget,
_ => false,
} && !fd.inputs.is_empty();
let mut params_last_line_contains_comment = false;
let mut no_params_and_over_max_width = false;
if put_params_in_block {
param_indent = indent.block_indent(context.config);
result.push_str(&param_indent.to_string_with_newline(context.config));
result.push_str(&param_str);
result.push_str(&indent.to_string_with_newline(context.config));
result.push(')');
} else {
result.push_str(&param_str);
let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
// Put the closing brace on the next line if it overflows the max width.
// 1 = `)`
let closing_paren_overflow_max_width =
fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
// If the last line of params contains comment, we cannot put the closing paren
// on the same line.
params_last_line_contains_comment = param_str
.lines()
.last()
.map_or(false, |last_line| last_line.contains("//"));
if context.config.version() == Version::Two {
if closing_paren_overflow_max_width {
result.push(')');
result.push_str(&indent.to_string_with_newline(context.config));
no_params_and_over_max_width = true;
} else if params_last_line_contains_comment {
result.push_str(&indent.to_string_with_newline(context.config));
result.push(')');
no_params_and_over_max_width = true;
} else {
result.push(')');
}
} else {
if closing_paren_overflow_max_width || params_last_line_contains_comment {
result.push_str(&indent.to_string_with_newline(context.config));
}
result.push(')');
}
}
// Return type.
if let ast::FnRetTy::Ty(..) = fd.output {
let ret_should_indent = match context.config.indent_style() {
// If our params are block layout then we surely must have space.
IndentStyle::Block if put_params_in_block || fd.inputs.is_empty() => false,
_ if params_last_line_contains_comment => false,
_ if result.contains('\n') || multi_line_ret_str => true,
_ => {
// If the return type would push over the max width, then put the return type on
// a new line. With the +1 for the signature length an additional space between
// the closing parenthesis of the param and the arrow '->' is considered.
let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
// If there is no where-clause, take into account the space after the return type
// and the brace.
if where_clause.predicates.is_empty() {
sig_length += 2;
}
sig_length > context.config.max_width()
}
};
let ret_shape = if ret_should_indent {
if context.config.version() == Version::One
|| context.config.indent_style() == IndentStyle::Visual
{
let indent = if param_str.is_empty() {
// Aligning with non-existent params looks silly.
force_new_line_for_brace = true;
indent + 4
} else {
// FIXME: we might want to check that using the param indent
// doesn't blow our budget, and if it does, then fallback to
// the where-clause indent.
param_indent
};
result.push_str(&indent.to_string_with_newline(context.config));
Shape::indented(indent, context.config)
} else {
let mut ret_shape = Shape::indented(indent, context.config);
if param_str.is_empty() {
// Aligning with non-existent params looks silly.
force_new_line_for_brace = true;
ret_shape = if context.use_block_indent() {
ret_shape.offset_left(4).unwrap_or(ret_shape)
} else {
ret_shape.indent = ret_shape.indent + 4;
ret_shape
};
}
result.push_str(&ret_shape.indent.to_string_with_newline(context.config));
ret_shape
}
} else {
if context.config.version() == Version::Two {
if !param_str.is_empty() || !no_params_and_over_max_width {
result.push(' ');
}
} else {
result.push(' ');
}
let ret_shape = Shape::indented(indent, context.config);
ret_shape
.offset_left(last_line_width(&result))
.unwrap_or(ret_shape)
};
if multi_line_ret_str || ret_should_indent {
// Now that we know the proper indent and width, we need to
// re-layout the return type.
let ret_str = fd.output.rewrite(context, ret_shape)?;
result.push_str(&ret_str);
} else {
result.push_str(&ret_str);
}
// Comment between return type and the end of the decl.
let snippet_lo = fd.output.span().hi();
if where_clause.predicates.is_empty() {
let snippet_hi = span.hi();
let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
// Try to preserve the layout of the original snippet.
let original_starts_with_newline = snippet
.find(|c| c != ' ')
.map_or(false, |i| starts_with_newline(&snippet[i..]));
let original_ends_with_newline = snippet
.rfind(|c| c != ' ')
.map_or(false, |i| snippet[i..].ends_with('\n'));
let snippet = snippet.trim();
if !snippet.is_empty() {
result.push(if original_starts_with_newline {
'\n'
} else {
' '
});
result.push_str(snippet);
if original_ends_with_newline {
force_new_line_for_brace = true;
}
}
}
}
let pos_before_where = match fd.output {
ast::FnRetTy::Default(..) => params_span.hi(),
ast::FnRetTy::Ty(ref ty) => ty.span.hi(),
};
let is_params_multi_lined = param_str.contains('\n');
let space = if put_params_in_block && ret_str.is_empty() {
WhereClauseSpace::Space
} else {
WhereClauseSpace::Newline
};
let mut option = WhereClauseOption::new(fn_brace_style == FnBraceStyle::None, space);
if is_params_multi_lined {
option.veto_single_line();
}
let where_clause_str = rewrite_where_clause(
context,
where_clause,
context.config.brace_style(),
Shape::indented(indent, context.config),
true,
"{",
Some(span.hi()),
pos_before_where,
option,
)?;
// If there are neither where-clause nor return type, we may be missing comments between
// params and `{`.
if where_clause_str.is_empty() {
if let ast::FnRetTy::Default(ret_span) = fd.output {
match recover_missing_comment_in_span(
mk_sp(params_span.hi(), ret_span.hi()),
shape,
context,
last_line_width(&result),
) {
Some(ref missing_comment) if !missing_comment.is_empty() => {
result.push_str(missing_comment);
force_new_line_for_brace = true;
}
_ => (),
}
}
}
result.push_str(&where_clause_str);
let ends_with_comment = last_line_contains_single_line_comment(&result);
force_new_line_for_brace |= ends_with_comment;
force_new_line_for_brace |=
is_params_multi_lined && context.config.where_single_line() && !where_clause_str.is_empty();
Some((result, ends_with_comment, force_new_line_for_brace))
}
/// Kind of spaces to put before `where`.
#[derive(Copy, Clone)]
enum WhereClauseSpace {
/// A single space.
Space,
/// A new line.
Newline,
/// Nothing.
None,
}
#[derive(Copy, Clone)]
struct WhereClauseOption {
suppress_comma: bool, // Force no trailing comma
snuggle: WhereClauseSpace,
allow_single_line: bool, // Try single line where-clause instead of vertical layout
veto_single_line: bool, // Disallow a single-line where-clause.
}
impl WhereClauseOption {
fn new(suppress_comma: bool, snuggle: WhereClauseSpace) -> WhereClauseOption {
WhereClauseOption {
suppress_comma,
snuggle,
allow_single_line: false,
veto_single_line: false,
}
}
fn snuggled(current: &str) -> WhereClauseOption {
WhereClauseOption {
suppress_comma: false,
snuggle: if last_line_width(current) == 1 {
WhereClauseSpace::Space
} else {
WhereClauseSpace::Newline
},
allow_single_line: false,
veto_single_line: false,
}
}
fn suppress_comma(&mut self) {
self.suppress_comma = true
}
fn allow_single_line(&mut self) {
self.allow_single_line = true
}
fn snuggle(&mut self) {
self.snuggle = WhereClauseSpace::Space
}
fn veto_single_line(&mut self) {
self.veto_single_line = true;
}
}
fn rewrite_params(
context: &RewriteContext<'_>,
params: &[ast::Param],
one_line_budget: usize,
multi_line_budget: usize,
indent: Indent,
param_indent: Indent,
span: Span,
variadic: bool,
) -> Option<String> {
if params.is_empty() {
let comment = context
.snippet(mk_sp(
span.lo(),
// to remove ')'
span.hi() - BytePos(1),
))
.trim();
return Some(comment.to_owned());
}
let param_items: Vec<_> = itemize_list(
context.snippet_provider,
params.iter(),
")",
",",
|param| span_lo_for_param(param),
|param| param.ty.span.hi(),
|param| {
param
.rewrite(context, Shape::legacy(multi_line_budget, param_indent))
.or_else(|| Some(context.snippet(param.span()).to_owned()))
},
span.lo(),
span.hi(),
false,
)
.collect();
let tactic = definitive_tactic(
&param_items,
context
.config
.fn_args_layout()
.to_list_tactic(param_items.len()),
Separator::Comma,
one_line_budget,
);
let budget = match tactic {
DefinitiveListTactic::Horizontal => one_line_budget,
_ => multi_line_budget,
};
let indent = match context.config.indent_style() {
IndentStyle::Block => indent.block_indent(context.config),
IndentStyle::Visual => param_indent,
};
let trailing_separator = if variadic {
SeparatorTactic::Never
} else {
match context.config.indent_style() {
IndentStyle::Block => context.config.trailing_comma(),
IndentStyle::Visual => SeparatorTactic::Never,
}
};
let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
.tactic(tactic)
.trailing_separator(trailing_separator)
.ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
.preserve_newline(true);
write_list(&param_items, &fmt)
}
fn compute_budgets_for_params(
context: &RewriteContext<'_>,
result: &str,
indent: Indent,
ret_str_len: usize,
fn_brace_style: FnBraceStyle,
force_vertical_layout: bool,
) -> Option<(usize, usize, Indent)> {
debug!(
"compute_budgets_for_params {} {:?}, {}, {:?}",
result.len(),
indent,
ret_str_len,
fn_brace_style,
);
// Try keeping everything on the same line.
if !result.contains('\n') && !force_vertical_layout {
// 2 = `()`, 3 = `() `, space is before ret_string.
let overhead = if ret_str_len == 0 { 2 } else { 3 };
let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
match fn_brace_style {
FnBraceStyle::None => used_space += 1, // 1 = `;`
FnBraceStyle::SameLine => used_space += 2, // 2 = `{}`
FnBraceStyle::NextLine => (),
}
let one_line_budget = context.budget(used_space);
if one_line_budget > 0 {
// 4 = "() {".len()
let (indent, multi_line_budget) = match context.config.indent_style() {
IndentStyle::Block => {
let indent = indent.block_indent(context.config);
(indent, context.budget(indent.width() + 1))
}
IndentStyle::Visual => {
let indent = indent + result.len() + 1;
let multi_line_overhead = match fn_brace_style {
FnBraceStyle::SameLine => 4,
_ => 2,
} + indent.width();
(indent, context.budget(multi_line_overhead))
}
};
return Some((one_line_budget, multi_line_budget, indent));
}
}
// Didn't work. we must force vertical layout and put params on a newline.
let new_indent = indent.block_indent(context.config);
let used_space = match context.config.indent_style() {
// 1 = `,`
IndentStyle::Block => new_indent.width() + 1,
// Account for `)` and possibly ` {`.
IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
};
Some((0, context.budget(used_space), new_indent))
}
fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> FnBraceStyle {
let predicate_count = where_clause.predicates.len();
if config.where_single_line() && predicate_count == 1 {
return FnBraceStyle::SameLine;
}
let brace_style = config.brace_style();
let use_next_line = brace_style == BraceStyle::AlwaysNextLine
|| (brace_style == BraceStyle::SameLineWhere && predicate_count > 0);
if use_next_line {
FnBraceStyle::NextLine
} else {
FnBraceStyle::SameLine
}
}
fn rewrite_generics(
context: &RewriteContext<'_>,
ident: &str,
generics: &ast::Generics,
shape: Shape,
) -> Option<String> {
// FIXME: convert bounds to where-clauses where they get too big or if
// there is a where-clause at all.
if generics.params.is_empty() {
return Some(ident.to_owned());
}
let params = generics.params.iter();
overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
}
fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
match config.indent_style() {
IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
IndentStyle::Block => {
// 1 = ","
shape
.block()
.block_indent(config.tab_spaces())
.with_max_width(config)
.sub_width(1)
}
}
}
fn rewrite_where_clause_rfc_style(
context: &RewriteContext<'_>,
where_clause: &ast::WhereClause,
shape: Shape,
terminator: &str,
span_end: Option<BytePos>,
span_end_before_where: BytePos,
where_clause_option: WhereClauseOption,
) -> Option<String> {
let (where_keyword, allow_single_line) = rewrite_where_keyword(
context,
where_clause,
shape,
span_end_before_where,
where_clause_option,
)?;
// 1 = `,`
let clause_shape = shape
.block()
.with_max_width(context.config)
.block_left(context.config.tab_spaces())?
.sub_width(1)?;
let force_single_line = context.config.where_single_line()
&& where_clause.predicates.len() == 1
&& !where_clause_option.veto_single_line;
let preds_str = rewrite_bounds_on_where_clause(
context,
where_clause,
clause_shape,
terminator,
span_end,
where_clause_option,
force_single_line,
)?;
// 6 = `where `
let clause_sep =
if allow_single_line && !preds_str.contains('\n') && 6 + preds_str.len() <= shape.width
|| force_single_line
{
Cow::from(" ")
} else {
clause_shape.indent.to_string_with_newline(context.config)
};
Some(format!("{}{}{}", where_keyword, clause_sep, preds_str))
}
/// Rewrite `where` and comment around it.
fn rewrite_where_keyword(
context: &RewriteContext<'_>,
where_clause: &ast::WhereClause,
shape: Shape,
span_end_before_where: BytePos,
where_clause_option: WhereClauseOption,
) -> Option<(String, bool)> {
let block_shape = shape.block().with_max_width(context.config);
// 1 = `,`
let clause_shape = block_shape
.block_left(context.config.tab_spaces())?
.sub_width(1)?;
let comment_separator = |comment: &str, shape: Shape| {
if comment.is_empty() {
Cow::from("")
} else {
shape.indent.to_string_with_newline(context.config)
}
};
let (span_before, span_after) =
missing_span_before_after_where(span_end_before_where, where_clause);
let (comment_before, comment_after) =
rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
let starting_newline = match where_clause_option.snuggle {
WhereClauseSpace::Space if comment_before.is_empty() => Cow::from(" "),
WhereClauseSpace::None => Cow::from(""),
_ => block_shape.indent.to_string_with_newline(context.config),
};
let newline_before_where = comment_separator(&comment_before, shape);
let newline_after_where = comment_separator(&comment_after, clause_shape);
let result = format!(
"{}{}{}where{}{}",
starting_newline, comment_before, newline_before_where, newline_after_where, comment_after
);
let allow_single_line = where_clause_option.allow_single_line
&& comment_before.is_empty()
&& comment_after.is_empty();
Some((result, allow_single_line))
}
/// Rewrite bounds on a where clause.
fn rewrite_bounds_on_where_clause(
context: &RewriteContext<'_>,
where_clause: &ast::WhereClause,
shape: Shape,
terminator: &str,
span_end: Option<BytePos>,
where_clause_option: WhereClauseOption,
force_single_line: bool,
) -> Option<String> {
let span_start = where_clause.predicates[0].span().lo();
// If we don't have the start of the next span, then use the end of the
// predicates, but that means we miss comments.
let len = where_clause.predicates.len();
let end_of_preds = where_clause.predicates[len - 1].span().hi();
let span_end = span_end.unwrap_or(end_of_preds);
let items = itemize_list(
context.snippet_provider,
where_clause.predicates.iter(),
terminator,
",",
|pred| pred.span().lo(),
|pred| pred.span().hi(),
|pred| pred.rewrite(context, shape),
span_start,
span_end,
false,
);
let comma_tactic = if where_clause_option.suppress_comma || force_single_line {
SeparatorTactic::Never
} else {
context.config.trailing_comma()
};
// shape should be vertical only and only if we have `force_single_line` option enabled
// and the number of items of the where-clause is equal to 1
let shape_tactic = if force_single_line {
DefinitiveListTactic::Horizontal
} else {
DefinitiveListTactic::Vertical
};
let fmt = ListFormatting::new(shape, context.config)
.tactic(shape_tactic)
.trailing_separator(comma_tactic)
.preserve_newline(true);
write_list(&items.collect::<Vec<_>>(), &fmt)
}
fn rewrite_where_clause(
context: &RewriteContext<'_>,
where_clause: &ast::WhereClause,
brace_style: BraceStyle,
shape: Shape,
on_new_line: bool,
terminator: &str,
span_end: Option<BytePos>,
span_end_before_where: BytePos,
where_clause_option: WhereClauseOption,
) -> Option<String> {
if where_clause.predicates.is_empty() {
return Some(String::new());
}
if context.config.indent_style() == IndentStyle::Block {
return rewrite_where_clause_rfc_style(
context,
where_clause,
shape,
terminator,
span_end,
span_end_before_where,
where_clause_option,
);
}
let extra_indent = Indent::new(context.config.tab_spaces(), 0);
let offset = match context.config.indent_style() {
IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
// 6 = "where ".len()
IndentStyle::Visual => shape.indent + extra_indent + 6,
};
// FIXME: if indent_style != Visual, then the budgets below might
// be out by a char or two.
let budget = context.config.max_width() - offset.width();
let span_start = where_clause.predicates[0].span().lo();
// If we don't have the start of the next span, then use the end of the
// predicates, but that means we miss comments.
let len = where_clause.predicates.len();
let end_of_preds = where_clause.predicates[len - 1].span().hi();
let span_end = span_end.unwrap_or(end_of_preds);
let items = itemize_list(
context.snippet_provider,
where_clause.predicates.iter(),
terminator,
",",
|pred| pred.span().lo(),
|pred| pred.span().hi(),
|pred| pred.rewrite(context, Shape::legacy(budget, offset)),
span_start,
span_end,
false,
);
let item_vec = items.collect::<Vec<_>>();
// FIXME: we don't need to collect here
let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
let mut comma_tactic = context.config.trailing_comma();
// Kind of a hack because we don't usually have trailing commas in where-clauses.
if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
comma_tactic = SeparatorTactic::Never;
}
let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
.tactic(tactic)
.trailing_separator(comma_tactic)
.ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
.preserve_newline(true);
let preds_str = write_list(&item_vec, &fmt)?;
let end_length = if terminator == "{" {
// If the brace is on the next line we don't need to count it otherwise it needs two
// characters " {"
match brace_style {
BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
BraceStyle::PreferSameLine => 2,
}
} else if terminator == "=" {
2
} else {
terminator.len()
};
if on_new_line
|| preds_str.contains('\n')
|| shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
{
Some(format!(
"\n{}where {}",
(shape.indent + extra_indent).to_string(context.config),
preds_str
))
} else {
Some(format!(" where {}", preds_str))
}
}
fn missing_span_before_after_where(
before_item_span_end: BytePos,
where_clause: &ast::WhereClause,
) -> (Span, Span) {
let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
// 5 = `where`
let pos_after_where = where_clause.span.lo() + BytePos(5);
let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
(missing_span_before, missing_span_after)
}
fn rewrite_comments_before_after_where(
context: &RewriteContext<'_>,
span_before_where: Span,
span_after_where: Span,
shape: Shape,
) -> Option<(String, String)> {
let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
let after_comment = rewrite_missing_comment(
span_after_where,
shape.block_indent(context.config.tab_spaces()),
context,
)?;
Some((before_comment, after_comment))
}
fn format_header(
context: &RewriteContext<'_>,
item_name: &str,
ident: symbol::Ident,
vis: &ast::Visibility,
offset: Indent,
) -> String {
let mut result = String::with_capacity(128);
let shape = Shape::indented(offset, context.config);
result.push_str(&format_visibility(context, vis).trim());
// Check for a missing comment between the visibility and the item name.
let after_vis = vis.span.hi();
if let Some(before_item_name) = context
.snippet_provider
.opt_span_before(mk_sp(vis.span.lo(), ident.span.hi()), item_name.trim())
{
let missing_span = mk_sp(after_vis, before_item_name);
if let Some(result_with_comment) = combine_strs_with_missing_comments(
context,
&result,
item_name,
missing_span,
shape,
/* allow_extend */ true,
) {
result = result_with_comment;
}
}
result.push_str(&rewrite_ident(context, ident));
result
}
#[derive(PartialEq, Eq, Clone, Copy)]
enum BracePos {
None,
Auto,
ForceSameLine,
}
fn format_generics(
context: &RewriteContext<'_>,
generics: &ast::Generics,
brace_style: BraceStyle,
brace_pos: BracePos,
offset: Indent,
span: Span,
used_width: usize,
) -> Option<String> {
let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
let mut result = rewrite_generics(context, "", generics, shape)?;
// If the generics are not parameterized then generics.span.hi() == 0,
// so we use span.lo(), which is the position after `struct Foo`.
let span_end_before_where = if !generics.params.is_empty() {
generics.span.hi()
} else {
span.lo()
};
let (same_line_brace, missed_comments) = if !generics.where_clause.predicates.is_empty() {
let budget = context.budget(last_line_used_width(&result, offset.width()));
let mut option = WhereClauseOption::snuggled(&result);
if brace_pos == BracePos::None {
option.suppress_comma = true;
}
let where_clause_str = rewrite_where_clause(
context,
&generics.where_clause,
brace_style,
Shape::legacy(budget, offset.block_only()),
true,
"{",
Some(span.hi()),
span_end_before_where,
option,
)?;
result.push_str(&where_clause_str);
(
brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine,
// missed comments are taken care of in #rewrite_where_clause
None,
)
} else {
(
brace_pos == BracePos::ForceSameLine
|| (result.contains('\n') && brace_style == BraceStyle::PreferSameLine
|| brace_style != BraceStyle::AlwaysNextLine)
|| trimmed_last_line_width(&result) == 1,
rewrite_missing_comment(
mk_sp(
span_end_before_where,
if brace_pos == BracePos::None {
span.hi()
} else {
context.snippet_provider.span_before(span, "{")
},
),
shape,
context,
),
)
};
// add missing comments
let missed_line_comments = missed_comments
.filter(|missed_comments| !missed_comments.is_empty())
.map_or(false, |missed_comments| {
let is_block = is_last_comment_block(&missed_comments);
let sep = if is_block { " " } else { "\n" };
result.push_str(sep);
result.push_str(&missed_comments);
!is_block
});
if brace_pos == BracePos::None {
return Some(result);
}
let total_used_width = last_line_used_width(&result, used_width);
let remaining_budget = context.budget(total_used_width);
// If the same line brace if forced, it indicates that we are rewriting an item with empty body,
// and hence we take the closer into account as well for one line budget.
// We assume that the closer has the same length as the opener.
let overhead = if brace_pos == BracePos::ForceSameLine {
// 3 = ` {}`
3
} else {
// 2 = ` {`
2
};
let forbid_same_line_brace = missed_line_comments || overhead > remaining_budget;
if !forbid_same_line_brace && same_line_brace {
result.push(' ');
} else {
result.push('\n');
result.push_str(&offset.block_only().to_string(context.config));
}
result.push('{');
Some(result)
}
impl Rewrite for ast::ForeignItem {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
let attrs_str = self.attrs.rewrite(context, shape)?;
// Drop semicolon or it will be interpreted as comment.
// FIXME: this may be a faulty span from libsyntax.
let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
let item_str = match self.kind {
ast::ForeignItemKind::Fn(ref fn_kind) => {
let ast::FnKind(defaultness, ref fn_sig, ref generics, ref block) = **fn_kind;
if let Some(ref body) = block {
let mut visitor = FmtVisitor::from_context(context);
visitor.block_indent = shape.indent;
visitor.last_pos = self.span.lo();
let inner_attrs = inner_attributes(&self.attrs);
let fn_ctxt = visit::FnCtxt::Foreign;
visitor.visit_fn(
visit::FnKind::Fn(fn_ctxt, self.ident, &fn_sig, &self.vis, Some(body)),
generics,
&fn_sig.decl,
self.span,
defaultness,
Some(&inner_attrs),
);
Some(visitor.buffer.to_owned())
} else {
rewrite_fn_base(
context,
shape.indent,
self.ident,
&FnSig::from_method_sig(&fn_sig, generics, self.vis.clone()),
span,
FnBraceStyle::None,
)
.map(|(s, _, _)| format!("{};", s))
}
}
ast::ForeignItemKind::Static(ref ty, mutability, _) => {
// FIXME(#21): we're dropping potential comments in between the
// function kw here.
let vis = format_visibility(context, &self.vis);
let mut_str = format_mutability(mutability);
let prefix = format!(
"{}static {}{}:",
vis,
mut_str,
rewrite_ident(context, self.ident)
);
// 1 = ;
rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
}
ast::ForeignItemKind::TyAlias(ref ty_alias_kind) => {
let ast::TyAliasKind(_, ref generics, ref generic_bounds, ref type_default) =
**ty_alias_kind;
rewrite_type_alias(
self.ident,
type_default.as_ref(),
generics,
Some(generic_bounds),
&context,
shape.indent,
&self.vis,
self.span,
)
}
ast::ForeignItemKind::MacCall(ref mac) => {
rewrite_macro(mac, None, context, shape, MacroPosition::Item)
}
}?;
let missing_span = if self.attrs.is_empty() {
mk_sp(self.span.lo(), self.span.lo())
} else {
mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
};
combine_strs_with_missing_comments(
context,
&attrs_str,
&item_str,
missing_span,
shape,
false,
)
}
}
/// Rewrite the attributes of an item.
fn rewrite_attrs(
context: &RewriteContext<'_>,
item: &ast::Item,
item_str: &str,
shape: Shape,
) -> Option<String> {
let attrs = filter_inline_attrs(&item.attrs, item.span());
let attrs_str = attrs.rewrite(context, shape)?;
let missed_span = if attrs.is_empty() {
mk_sp(item.span.lo(), item.span.lo())
} else {
mk_sp(attrs[attrs.len() - 1].span.hi(), item.span.lo())
};
let allow_extend = if attrs.len() == 1 {
let line_len = attrs_str.len() + 1 + item_str.len();
!attrs.first().unwrap().is_doc_comment()
&& context.config.inline_attribute_width() >= line_len
} else {
false
};
combine_strs_with_missing_comments(
context,
&attrs_str,
&item_str,
missed_span,
shape,
allow_extend,
)
}
/// Rewrite an inline mod.
/// The given shape is used to format the mod's attributes.
pub(crate) fn rewrite_mod(
context: &RewriteContext<'_>,
item: &ast::Item,
attrs_shape: Shape,
) -> Option<String> {
let mut result = String::with_capacity(32);
result.push_str(&*format_visibility(context, &item.vis));
result.push_str("mod ");
result.push_str(rewrite_ident(context, item.ident));
result.push(';');
rewrite_attrs(context, item, &result, attrs_shape)
}
/// Rewrite `extern crate foo;`.
/// The given shape is used to format the extern crate's attributes.
pub(crate) fn rewrite_extern_crate(
context: &RewriteContext<'_>,
item: &ast::Item,
attrs_shape: Shape,
) -> Option<String> {
assert!(is_extern_crate(item));
let new_str = context.snippet(item.span);
let item_str = if contains_comment(new_str) {
new_str.to_owned()
} else {
let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
};
rewrite_attrs(context, item, &item_str, attrs_shape)
}
/// Returns `true` for `mod foo;`, false for `mod foo { .. }`.
pub(crate) fn is_mod_decl(item: &ast::Item) -> bool {
!matches!(
item.kind,
ast::ItemKind::Mod(_, ast::ModKind::Loaded(_, ast::Inline::Yes, _))
)
}
pub(crate) fn is_use_item(item: &ast::Item) -> bool {
matches!(item.kind, ast::ItemKind::Use(_))
}
pub(crate) fn is_extern_crate(item: &ast::Item) -> bool {
matches!(item.kind, ast::ItemKind::ExternCrate(..))
}