1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use std::iter::ExactSizeIterator;
15 use syntax::ast::{self, FunctionRetTy, Mutability};
16 use syntax::source_map::{self, BytePos, Span};
17 use syntax::symbol::keywords;
19 use config::{IndentStyle, TypeDensity};
20 use expr::{rewrite_assign_rhs, rewrite_tuple, rewrite_unary_prefix};
21 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
22 use macros::{rewrite_macro, MacroPosition};
24 use pairs::{rewrite_pair, PairParts};
25 use rewrite::{Rewrite, RewriteContext};
27 use source_map::SpanUtils;
30 colon_spaces, extra_offset, first_line_width, format_abi, format_mutability,
31 last_line_extendable, last_line_width, mk_sp, rewrite_ident,
34 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
35 pub enum PathContext {
41 // Does not wrap on simple segments.
43 context: &RewriteContext,
44 path_context: PathContext,
45 qself: Option<&ast::QSelf>,
49 let skip_count = qself.map_or(0, |x| x.position);
51 let mut result = if path.is_global() && qself.is_none() && path_context != PathContext::Import {
57 let mut span_lo = path.span.lo();
59 if let Some(qself) = qself {
62 let fmt_ty = qself.ty.rewrite(context, shape)?;
63 result.push_str(&fmt_ty);
66 result.push_str(" as ");
67 if path.is_global() && path_context != PathContext::Import {
68 result.push_str("::");
72 let shape = shape.sub_width(3)?;
74 result = rewrite_path_segments(
77 path.segments.iter().take(skip_count),
85 result.push_str(">::");
86 span_lo = qself.ty.span.hi() + BytePos(1);
89 rewrite_path_segments(
92 path.segments.iter().skip(skip_count),
100 fn rewrite_path_segments<'a, I>(
101 path_context: PathContext,
104 mut span_lo: BytePos,
106 context: &RewriteContext,
110 I: Iterator<Item = &'a ast::PathSegment>,
112 let mut first = true;
113 let shape = shape.visual_indent(0);
115 for segment in iter {
116 // Indicates a global path, shouldn't be rendered.
117 if segment.ident.name == keywords::PathRoot.name() {
123 buffer.push_str("::");
126 let extra_offset = extra_offset(&buffer, shape);
127 let new_shape = shape.shrink_left(extra_offset)?;
128 let segment_string = rewrite_segment(
137 buffer.push_str(&segment_string);
144 pub enum SegmentParam<'a> {
145 LifeTime(&'a ast::Lifetime),
147 Binding(&'a ast::TypeBinding),
150 impl<'a> SegmentParam<'a> {
151 fn from_generic_arg(arg: &ast::GenericArg) -> SegmentParam {
153 ast::GenericArg::Lifetime(ref lt) => SegmentParam::LifeTime(lt),
154 ast::GenericArg::Type(ref ty) => SegmentParam::Type(ty),
159 impl<'a> Spanned for SegmentParam<'a> {
160 fn span(&self) -> Span {
162 SegmentParam::LifeTime(lt) => lt.ident.span,
163 SegmentParam::Type(ty) => ty.span,
164 SegmentParam::Binding(binding) => binding.span,
169 impl<'a> Rewrite for SegmentParam<'a> {
170 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
172 SegmentParam::LifeTime(lt) => lt.rewrite(context, shape),
173 SegmentParam::Type(ty) => ty.rewrite(context, shape),
174 SegmentParam::Binding(binding) => {
175 let mut result = match context.config.type_punctuation_density() {
176 TypeDensity::Wide => format!("{} = ", rewrite_ident(context, binding.ident)),
177 TypeDensity::Compressed => {
178 format!("{}=", rewrite_ident(context, binding.ident))
181 let budget = shape.width.checked_sub(result.len())?;
182 let rewrite = binding
184 .rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
185 result.push_str(&rewrite);
192 // Formats a path segment. There are some hacks involved to correctly determine
193 // the segment's associated span since it's not part of the AST.
195 // The span_lo is assumed to be greater than the end of any previous segment's
196 // parameters and lesser or equal than the start of current segment.
198 // span_hi is assumed equal to the end of the entire path.
200 // When the segment contains a positive number of parameters, we update span_lo
201 // so that invariants described above will hold for the next segment.
203 path_context: PathContext,
204 segment: &ast::PathSegment,
205 span_lo: &mut BytePos,
207 context: &RewriteContext,
209 ) -> Option<String> {
210 let mut result = String::with_capacity(128);
211 result.push_str(rewrite_ident(context, segment.ident));
213 let ident_len = result.len();
214 let shape = if context.use_block_indent() {
215 shape.offset_left(ident_len)?
217 shape.shrink_left(ident_len)?
220 if let Some(ref args) = segment.args {
222 ast::GenericArgs::AngleBracketed(ref data)
223 if !data.args.is_empty() || !data.bindings.is_empty() =>
225 let param_list = data
228 .map(SegmentParam::from_generic_arg)
229 .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
230 .collect::<Vec<_>>();
232 let force_separator =
233 context.inside_macro() && context.snippet(data.span).starts_with("::");
234 let separator = if path_context == PathContext::Expr || force_separator {
239 result.push_str(separator);
241 let generics_str = overflow::rewrite_with_angle_brackets(
246 mk_sp(*span_lo, span_hi),
249 // Update position of last bracket.
252 .span_after(mk_sp(*span_lo, span_hi), "<");
254 result.push_str(&generics_str)
256 ast::GenericArgs::Parenthesized(ref data) => {
257 let output = match data.output {
258 Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
259 None => FunctionRetTy::Default(source_map::DUMMY_SP),
261 result.push_str(&format_function_type(
262 data.inputs.iter().map(|x| &**x),
277 fn format_function_type<'a, I>(
279 output: &FunctionRetTy,
282 context: &RewriteContext,
286 I: ExactSizeIterator,
287 <I as Iterator>::Item: Deref,
288 <I::Item as Deref>::Target: Rewrite + Spanned + 'a,
290 debug!("format_function_type {:#?}", shape);
292 let ty_shape = match context.config.indent_style() {
294 IndentStyle::Block => shape.offset_left(4)?,
295 IndentStyle::Visual => shape.block_left(4)?,
297 let output = match *output {
298 FunctionRetTy::Ty(ref ty) => {
299 let type_str = ty.rewrite(context, ty_shape)?;
300 format!(" -> {}", type_str)
302 FunctionRetTy::Default(..) => String::new(),
305 // Code for handling variadics is somewhat duplicated for items, but they
306 // are different enough to need some serious refactoring to share code.
310 <T as Deref>::Target: Rewrite + Spanned,
316 let variadic_arg = if variadic {
317 let variadic_start = context.snippet_provider.span_before(span, "...");
318 Some(ArgumentKind::Variadic(variadic_start))
323 let list_shape = if context.use_block_indent() {
325 shape.block().indent.block_indent(context.config),
330 let budget = shape.width.checked_sub(2)?;
332 let offset = shape.indent + 1;
333 Shape::legacy(budget, offset)
335 let list_lo = context.snippet_provider.span_after(span, "(");
336 let items = itemize_list(
337 context.snippet_provider,
338 inputs.map(ArgumentKind::Regular).chain(variadic_arg),
342 ArgumentKind::Regular(ref ty) => ty.span().lo(),
343 ArgumentKind::Variadic(start) => start,
346 ArgumentKind::Regular(ref ty) => ty.span().hi(),
347 ArgumentKind::Variadic(start) => start + BytePos(3),
350 ArgumentKind::Regular(ref ty) => ty.rewrite(context, list_shape),
351 ArgumentKind::Variadic(_) => Some("...".to_owned()),
358 let item_vec: Vec<_> = items.collect();
360 // If the return type is multi-lined, then force to use multiple lines for
361 // arguments as well.
362 let tactic = if output.contains('\n') {
363 DefinitiveListTactic::Vertical
367 ListTactic::HorizontalVertical,
369 shape.width.saturating_sub(2 + output.len()),
372 let trailing_separator = if !context.use_block_indent() || variadic {
373 SeparatorTactic::Never
375 context.config.trailing_comma()
378 let fmt = ListFormatting::new(list_shape, context.config)
380 .trailing_separator(trailing_separator)
381 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
382 .preserve_newline(true);
383 let list_str = write_list(&item_vec, &fmt)?;
385 let args = if tactic == DefinitiveListTactic::Horizontal || !context.use_block_indent() {
386 format!("({})", list_str)
390 list_shape.indent.to_string_with_newline(context.config),
392 shape.block().indent.to_string_with_newline(context.config),
395 if output.is_empty() || last_line_width(&args) + first_line_width(&output) <= shape.width {
396 Some(format!("{}{}", args, output))
401 list_shape.indent.to_string(context.config),
407 fn type_bound_colon(context: &RewriteContext) -> &'static str {
409 context.config.space_before_colon(),
410 context.config.space_after_colon(),
414 impl Rewrite for ast::WherePredicate {
415 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
416 // FIXME: dead spans?
417 let result = match *self {
418 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
419 ref bound_generic_params,
424 let type_str = bounded_ty.rewrite(context, shape)?;
425 let colon = type_bound_colon(context).trim_end();
426 let lhs = if let Some(lifetime_str) =
427 rewrite_lifetime_param(context, shape, bound_generic_params)
429 format!("for<{}> {}{}", lifetime_str, type_str, colon)
431 format!("{}{}", type_str, colon)
434 rewrite_assign_rhs(context, lhs, bounds, shape)?
436 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
440 }) => rewrite_bounded_lifetime(lifetime, bounds, context, shape)?,
441 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
446 let lhs_ty_str = lhs_ty.rewrite(context, shape).map(|lhs| lhs + " =")?;
447 rewrite_assign_rhs(context, lhs_ty_str, &**rhs_ty, shape)?
455 impl Rewrite for ast::GenericArg {
456 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
458 ast::GenericArg::Lifetime(ref lt) => lt.rewrite(context, shape),
459 ast::GenericArg::Type(ref ty) => ty.rewrite(context, shape),
464 fn rewrite_bounded_lifetime(
466 bounds: &[ast::GenericBound],
467 context: &RewriteContext,
469 ) -> Option<String> {
470 let result = lt.rewrite(context, shape)?;
472 if bounds.is_empty() {
475 let colon = type_bound_colon(context);
476 let overhead = last_line_width(&result) + colon.len();
477 let result = format!(
481 join_bounds(context, shape.sub_width(overhead)?, bounds, true)?
487 impl Rewrite for ast::Lifetime {
488 fn rewrite(&self, context: &RewriteContext, _: Shape) -> Option<String> {
489 Some(rewrite_ident(context, self.ident).to_owned())
493 impl Rewrite for ast::GenericBound {
494 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
496 ast::GenericBound::Trait(ref poly_trait_ref, trait_bound_modifier) => {
497 let snippet = context.snippet(self.span());
498 let has_paren = snippet.starts_with('(') && snippet.ends_with(')');
499 let rewrite = match trait_bound_modifier {
500 ast::TraitBoundModifier::None => poly_trait_ref.rewrite(context, shape),
501 ast::TraitBoundModifier::Maybe => poly_trait_ref
502 .rewrite(context, shape.offset_left(1)?)
503 .map(|s| format!("?{}", s)),
505 rewrite.map(|s| if has_paren { format!("({})", s) } else { s })
507 ast::GenericBound::Outlives(ref lifetime) => lifetime.rewrite(context, shape),
512 impl Rewrite for ast::GenericBounds {
513 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
515 return Some(String::new());
518 join_bounds(context, shape, self, true)
522 impl Rewrite for ast::GenericParam {
523 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
524 let mut result = String::with_capacity(128);
525 // FIXME: If there are more than one attributes, this will force multiline.
526 match self.attrs.rewrite(context, shape) {
527 Some(ref rw) if !rw.is_empty() => result.push_str(&format!("{} ", rw)),
530 result.push_str(rewrite_ident(context, self.ident));
531 if !self.bounds.is_empty() {
532 result.push_str(type_bound_colon(context));
533 result.push_str(&self.bounds.rewrite(context, shape)?)
535 if let ast::GenericParamKind::Type {
536 default: Some(ref def),
539 let eq_str = match context.config.type_punctuation_density() {
540 TypeDensity::Compressed => "=",
541 TypeDensity::Wide => " = ",
543 result.push_str(eq_str);
544 let budget = shape.width.checked_sub(result.len())?;
546 def.rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
547 result.push_str(&rewrite);
554 impl Rewrite for ast::PolyTraitRef {
555 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
556 if let Some(lifetime_str) =
557 rewrite_lifetime_param(context, shape, &self.bound_generic_params)
559 // 6 is "for<> ".len()
560 let extra_offset = lifetime_str.len() + 6;
563 .rewrite(context, shape.offset_left(extra_offset)?)?;
565 Some(format!("for<{}> {}", lifetime_str, path_str))
567 self.trait_ref.rewrite(context, shape)
572 impl Rewrite for ast::TraitRef {
573 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
574 rewrite_path(context, PathContext::Type, None, &self.path, shape)
578 impl Rewrite for ast::Ty {
579 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
581 ast::TyKind::TraitObject(ref bounds, tobj_syntax) => {
582 // we have to consider 'dyn' keyword is used or not!!!
583 let is_dyn = tobj_syntax == ast::TraitObjectSyntax::Dyn;
584 // 4 is length of 'dyn '
585 let shape = if is_dyn { shape.offset_left(4)? } else { shape };
586 let res = bounds.rewrite(context, shape)?;
588 Some(format!("dyn {}", res))
593 ast::TyKind::Ptr(ref mt) => {
594 let prefix = match mt.mutbl {
595 Mutability::Mutable => "*mut ",
596 Mutability::Immutable => "*const ",
599 rewrite_unary_prefix(context, prefix, &*mt.ty, shape)
601 ast::TyKind::Rptr(ref lifetime, ref mt) => {
602 let mut_str = format_mutability(mt.mutbl);
603 let mut_len = mut_str.len();
604 Some(match *lifetime {
605 Some(ref lifetime) => {
606 let lt_budget = shape.width.checked_sub(2 + mut_len)?;
607 let lt_str = lifetime.rewrite(
609 Shape::legacy(lt_budget, shape.indent + 2 + mut_len),
611 let lt_len = lt_str.len();
612 let budget = shape.width.checked_sub(2 + mut_len + lt_len)?;
619 Shape::legacy(budget, shape.indent + 2 + mut_len + lt_len)
624 let budget = shape.width.checked_sub(1 + mut_len)?;
630 Shape::legacy(budget, shape.indent + 1 + mut_len)
636 // FIXME: we drop any comments here, even though it's a silly place to put
638 ast::TyKind::Paren(ref ty) => {
639 let budget = shape.width.checked_sub(2)?;
640 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
641 .map(|ty_str| format!("({})", ty_str))
643 ast::TyKind::Slice(ref ty) => {
644 let budget = shape.width.checked_sub(4)?;
645 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
646 .map(|ty_str| format!("[{}]", ty_str))
648 ast::TyKind::Tup(ref items) => {
649 rewrite_tuple(context, items.iter(), self.span, shape, items.len() == 1)
651 ast::TyKind::Path(ref q_self, ref path) => {
652 rewrite_path(context, PathContext::Type, q_self.as_ref(), path, shape)
654 ast::TyKind::Array(ref ty, ref repeats) => rewrite_pair(
657 PairParts::new("[", "; ", "]"),
660 SeparatorPlace::Back,
662 ast::TyKind::Infer => {
663 if shape.width >= 1 {
669 ast::TyKind::BareFn(ref bare_fn) => rewrite_bare_fn(bare_fn, self.span, context, shape),
670 ast::TyKind::Never => Some(String::from("!")),
671 ast::TyKind::Mac(ref mac) => {
672 rewrite_macro(mac, None, context, shape, MacroPosition::Expression)
674 ast::TyKind::ImplicitSelf => Some(String::from("")),
675 ast::TyKind::ImplTrait(_, ref it) => it
676 .rewrite(context, shape)
677 .map(|it_str| format!("impl {}", it_str)),
678 ast::TyKind::Err | ast::TyKind::Typeof(..) => unreachable!(),
684 bare_fn: &ast::BareFnTy,
686 context: &RewriteContext,
688 ) -> Option<String> {
689 debug!("rewrite_bare_fn {:#?}", shape);
691 let mut result = String::with_capacity(128);
693 if let Some(ref lifetime_str) = rewrite_lifetime_param(context, shape, &bare_fn.generic_params)
695 result.push_str("for<");
696 // 6 = "for<> ".len(), 4 = "for<".
697 // This doesn't work out so nicely for multiline situation with lots of
698 // rightward drift. If that is a problem, we could use the list stuff.
699 result.push_str(lifetime_str);
700 result.push_str("> ");
703 result.push_str(::utils::format_unsafety(bare_fn.unsafety));
705 result.push_str(&format_abi(
707 context.config.force_explicit_abi(),
711 result.push_str("fn");
713 let func_ty_shape = if context.use_block_indent() {
714 shape.offset_left(result.len())?
716 shape.visual_indent(result.len()).sub_width(result.len())?
719 let rewrite = format_function_type(
720 bare_fn.decl.inputs.iter(),
721 &bare_fn.decl.output,
722 bare_fn.decl.variadic,
728 result.push_str(&rewrite);
733 fn is_generic_bounds_in_order(generic_bounds: &[ast::GenericBound]) -> bool {
734 let is_trait = |b: &ast::GenericBound| match b {
735 ast::GenericBound::Outlives(..) => false,
736 ast::GenericBound::Trait(..) => true,
738 let is_lifetime = |b: &ast::GenericBound| !is_trait(b);
739 let last_trait_index = generic_bounds.iter().rposition(is_trait);
740 let first_lifetime_index = generic_bounds.iter().position(is_lifetime);
741 match (last_trait_index, first_lifetime_index) {
742 (Some(last_trait_index), Some(first_lifetime_index)) => {
743 last_trait_index < first_lifetime_index
750 context: &RewriteContext,
752 items: &[ast::GenericBound],
754 ) -> Option<String> {
755 debug_assert!(!items.is_empty());
757 // Try to join types in a single line
758 let joiner = match context.config.type_punctuation_density() {
759 TypeDensity::Compressed => "+",
760 TypeDensity::Wide => " + ",
762 let type_strs = items
764 .map(|item| item.rewrite(context, shape))
765 .collect::<Option<Vec<_>>>()?;
766 let result = type_strs.join(joiner);
767 if items.len() <= 1 || (!result.contains('\n') && result.len() <= shape.width) {
771 // We need to use multiple lines.
772 let (type_strs, offset) = if need_indent {
773 // Rewrite with additional indentation.
774 let nested_shape = shape.block_indent(context.config.tab_spaces());
775 let type_strs = items
777 .map(|item| item.rewrite(context, nested_shape))
778 .collect::<Option<Vec<_>>>()?;
779 (type_strs, nested_shape.indent)
781 (type_strs, shape.indent)
784 let is_bound_extendable = |s: &str, b: &ast::GenericBound| match b {
785 ast::GenericBound::Outlives(..) => true,
786 ast::GenericBound::Trait(..) => last_line_extendable(s),
788 let mut result = String::with_capacity(128);
789 result.push_str(&type_strs[0]);
790 let mut can_be_put_on_the_same_line = is_bound_extendable(&result, &items[0]);
791 let generic_bounds_in_order = is_generic_bounds_in_order(items);
792 for (bound, bound_str) in items[1..].iter().zip(type_strs[1..].iter()) {
793 if generic_bounds_in_order && can_be_put_on_the_same_line {
794 result.push_str(joiner);
796 result.push_str(&offset.to_string_with_newline(context.config));
797 result.push_str("+ ");
799 result.push_str(bound_str);
800 can_be_put_on_the_same_line = is_bound_extendable(bound_str, bound);
806 pub fn can_be_overflowed_type(context: &RewriteContext, ty: &ast::Ty, len: usize) -> bool {
808 ast::TyKind::Tup(..) => context.use_block_indent() && len == 1,
809 ast::TyKind::Rptr(_, ref mutty) | ast::TyKind::Ptr(ref mutty) => {
810 can_be_overflowed_type(context, &*mutty.ty, len)
816 /// Returns `None` if there is no `LifetimeDef` in the given generic parameters.
817 fn rewrite_lifetime_param(
818 context: &RewriteContext,
820 generic_params: &[ast::GenericParam],
821 ) -> Option<String> {
822 let result = generic_params
824 .filter(|p| match p.kind {
825 ast::GenericParamKind::Lifetime => true,
828 .map(|lt| lt.rewrite(context, shape))
829 .collect::<Option<Vec<_>>>()?
831 if result.is_empty() {