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, ToExpr};
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::CrateRoot.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 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> ToExpr for SegmentParam<'a> {
170 fn to_expr(&self) -> Option<&ast::Expr> {
174 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
176 SegmentParam::Type(ty) => ty.can_be_overflowed(context, len),
182 impl<'a> Rewrite for SegmentParam<'a> {
183 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
185 SegmentParam::LifeTime(lt) => lt.rewrite(context, shape),
186 SegmentParam::Type(ty) => ty.rewrite(context, shape),
187 SegmentParam::Binding(binding) => {
188 let mut result = match context.config.type_punctuation_density() {
189 TypeDensity::Wide => format!("{} = ", rewrite_ident(context, binding.ident)),
190 TypeDensity::Compressed => {
191 format!("{}=", rewrite_ident(context, binding.ident))
194 let budget = shape.width.checked_sub(result.len())?;
195 let rewrite = binding
197 .rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
198 result.push_str(&rewrite);
205 // Formats a path segment. There are some hacks involved to correctly determine
206 // the segment's associated span since it's not part of the AST.
208 // The span_lo is assumed to be greater than the end of any previous segment's
209 // parameters and lesser or equal than the start of current segment.
211 // span_hi is assumed equal to the end of the entire path.
213 // When the segment contains a positive number of parameters, we update span_lo
214 // so that invariants described above will hold for the next segment.
216 path_context: PathContext,
217 segment: &ast::PathSegment,
218 span_lo: &mut BytePos,
220 context: &RewriteContext,
222 ) -> Option<String> {
223 let mut result = String::with_capacity(128);
224 result.push_str(rewrite_ident(context, segment.ident));
226 let ident_len = result.len();
227 let shape = if context.use_block_indent() {
228 shape.offset_left(ident_len)?
230 shape.shrink_left(ident_len)?
233 if let Some(ref args) = segment.args {
235 ast::GenericArgs::AngleBracketed(ref data)
236 if !data.args.is_empty() || !data.bindings.is_empty() =>
238 let param_list = data
241 .map(SegmentParam::from_generic_arg)
242 .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
243 .collect::<Vec<_>>();
245 let separator = if path_context == PathContext::Expr {
250 result.push_str(separator);
252 let generics_str = overflow::rewrite_with_angle_brackets(
255 ¶m_list.iter().map(|e| &*e).collect::<Vec<_>>(),
257 mk_sp(*span_lo, span_hi),
260 // Update position of last bracket.
263 .span_after(mk_sp(*span_lo, span_hi), "<");
265 result.push_str(&generics_str)
267 ast::GenericArgs::Parenthesized(ref data) => {
268 let output = match data.output {
269 Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
270 None => FunctionRetTy::Default(source_map::DUMMY_SP),
272 result.push_str(&format_function_type(
273 data.inputs.iter().map(|x| &**x),
288 fn format_function_type<'a, I>(
290 output: &FunctionRetTy,
293 context: &RewriteContext,
297 I: ExactSizeIterator,
298 <I as Iterator>::Item: Deref,
299 <I::Item as Deref>::Target: Rewrite + Spanned + 'a,
301 debug!("format_function_type {:#?}", shape);
303 // Code for handling variadics is somewhat duplicated for items, but they
304 // are different enough to need some serious refactoring to share code.
308 <T as Deref>::Target: Rewrite + Spanned,
314 let variadic_arg = if variadic {
315 let variadic_start = context.snippet_provider.span_before(span, "...");
316 Some(ArgumentKind::Variadic(variadic_start))
322 let budget = shape.width.checked_sub(2)?;
324 let offset = match context.config.indent_style() {
325 IndentStyle::Block => {
328 .block_indent(context.config.tab_spaces())
331 IndentStyle::Visual => shape.indent + 1,
333 let list_shape = Shape::legacy(budget, offset);
334 let list_lo = context.snippet_provider.span_after(span, "(");
335 let items = itemize_list(
336 context.snippet_provider,
337 inputs.map(ArgumentKind::Regular).chain(variadic_arg),
341 ArgumentKind::Regular(ref ty) => ty.span().lo(),
342 ArgumentKind::Variadic(start) => start,
345 ArgumentKind::Regular(ref ty) => ty.span().hi(),
346 ArgumentKind::Variadic(start) => start + BytePos(3),
349 ArgumentKind::Regular(ref ty) => ty.rewrite(context, list_shape),
350 ArgumentKind::Variadic(_) => Some("...".to_owned()),
357 let item_vec: Vec<_> = items.collect();
359 let tactic = definitive_tactic(
361 ListTactic::HorizontalVertical,
365 let trailing_separator = if !context.use_block_indent() || variadic {
366 SeparatorTactic::Never
368 context.config.trailing_comma()
371 let fmt = ListFormatting::new(list_shape, context.config)
373 .trailing_separator(trailing_separator)
374 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
375 .preserve_newline(true);
376 let list_str = write_list(&item_vec, &fmt)?;
378 let ty_shape = match context.config.indent_style() {
380 IndentStyle::Block => shape.offset_left(4)?,
381 IndentStyle::Visual => shape.block_left(4)?,
383 let output = match *output {
384 FunctionRetTy::Ty(ref ty) => {
385 let type_str = ty.rewrite(context, ty_shape)?;
386 format!(" -> {}", type_str)
388 FunctionRetTy::Default(..) => String::new(),
391 let args = if (!list_str.contains('\n') || list_str.is_empty()) && !output.contains('\n')
392 || !context.use_block_indent()
394 format!("({})", list_str)
398 offset.to_string_with_newline(context.config),
400 shape.block().indent.to_string_with_newline(context.config),
403 if output.is_empty() || last_line_width(&args) + first_line_width(&output) <= shape.width {
404 Some(format!("{}{}", args, output))
409 offset.to_string(context.config),
415 fn type_bound_colon(context: &RewriteContext) -> &'static str {
417 context.config.space_before_colon(),
418 context.config.space_after_colon(),
422 impl Rewrite for ast::WherePredicate {
423 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
424 // FIXME: dead spans?
425 let result = match *self {
426 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
427 ref bound_generic_params,
432 let type_str = bounded_ty.rewrite(context, shape)?;
433 let colon = type_bound_colon(context).trim_right();
434 let lhs = if let Some(lifetime_str) =
435 rewrite_lifetime_param(context, shape, bound_generic_params)
437 format!("for<{}> {}{}", lifetime_str, type_str, colon)
439 format!("{}{}", type_str, colon)
442 rewrite_assign_rhs(context, lhs, bounds, shape)?
444 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
448 }) => rewrite_bounded_lifetime(lifetime, bounds, context, shape)?,
449 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
454 let lhs_ty_str = lhs_ty.rewrite(context, shape).map(|lhs| lhs + " =")?;
455 rewrite_assign_rhs(context, lhs_ty_str, &**rhs_ty, shape)?
463 impl Rewrite for ast::GenericArg {
464 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
466 ast::GenericArg::Lifetime(ref lt) => lt.rewrite(context, shape),
467 ast::GenericArg::Type(ref ty) => ty.rewrite(context, shape),
472 fn rewrite_bounded_lifetime(
474 bounds: &[ast::GenericBound],
475 context: &RewriteContext,
477 ) -> Option<String> {
478 let result = lt.rewrite(context, shape)?;
480 if bounds.is_empty() {
483 let colon = type_bound_colon(context);
484 let overhead = last_line_width(&result) + colon.len();
485 let result = format!(
489 join_bounds(context, shape.sub_width(overhead)?, bounds, true)?
495 impl Rewrite for ast::Lifetime {
496 fn rewrite(&self, context: &RewriteContext, _: Shape) -> Option<String> {
497 Some(rewrite_ident(context, self.ident).to_owned())
501 impl Rewrite for ast::GenericBound {
502 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
504 ast::GenericBound::Trait(ref poly_trait_ref, trait_bound_modifier) => {
505 match trait_bound_modifier {
506 ast::TraitBoundModifier::None => poly_trait_ref.rewrite(context, shape),
507 ast::TraitBoundModifier::Maybe => {
508 let rw = poly_trait_ref.rewrite(context, shape.offset_left(1)?)?;
509 Some(format!("?{}", rw))
513 ast::GenericBound::Outlives(ref lifetime) => lifetime.rewrite(context, shape),
518 impl Rewrite for ast::GenericBounds {
519 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
521 return Some(String::new());
524 let span = mk_sp(self.get(0)?.span().lo(), self.last()?.span().hi());
525 let has_paren = context.snippet(span).starts_with('(');
526 let bounds_shape = if has_paren {
527 shape.offset_left(1)?.sub_width(1)?
531 join_bounds(context, bounds_shape, self, true).map(|s| {
541 impl Rewrite for ast::GenericParam {
542 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
543 let mut result = String::with_capacity(128);
544 // FIXME: If there are more than one attributes, this will force multiline.
545 match self.attrs.rewrite(context, shape) {
546 Some(ref rw) if !rw.is_empty() => result.push_str(&format!("{} ", rw)),
549 result.push_str(rewrite_ident(context, self.ident));
550 if !self.bounds.is_empty() {
551 result.push_str(type_bound_colon(context));
552 result.push_str(&self.bounds.rewrite(context, shape)?)
554 if let ast::GenericParamKind::Type {
555 default: Some(ref def),
558 let eq_str = match context.config.type_punctuation_density() {
559 TypeDensity::Compressed => "=",
560 TypeDensity::Wide => " = ",
562 result.push_str(eq_str);
563 let budget = shape.width.checked_sub(result.len())?;
565 def.rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
566 result.push_str(&rewrite);
573 impl Rewrite for ast::PolyTraitRef {
574 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
575 if let Some(lifetime_str) =
576 rewrite_lifetime_param(context, shape, &self.bound_generic_params)
578 // 6 is "for<> ".len()
579 let extra_offset = lifetime_str.len() + 6;
582 .rewrite(context, shape.offset_left(extra_offset)?)?;
584 Some(format!("for<{}> {}", lifetime_str, path_str))
586 self.trait_ref.rewrite(context, shape)
591 impl Rewrite for ast::TraitRef {
592 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
593 rewrite_path(context, PathContext::Type, None, &self.path, shape)
597 impl Rewrite for ast::Ty {
598 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
600 ast::TyKind::TraitObject(ref bounds, tobj_syntax) => {
601 // we have to consider 'dyn' keyword is used or not!!!
602 let is_dyn = tobj_syntax == ast::TraitObjectSyntax::Dyn;
603 // 4 is length of 'dyn '
604 let shape = if is_dyn { shape.offset_left(4)? } else { shape };
605 let res = bounds.rewrite(context, shape)?;
607 Some(format!("dyn {}", res))
612 ast::TyKind::Ptr(ref mt) => {
613 let prefix = match mt.mutbl {
614 Mutability::Mutable => "*mut ",
615 Mutability::Immutable => "*const ",
618 rewrite_unary_prefix(context, prefix, &*mt.ty, shape)
620 ast::TyKind::Rptr(ref lifetime, ref mt) => {
621 let mut_str = format_mutability(mt.mutbl);
622 let mut_len = mut_str.len();
623 Some(match *lifetime {
624 Some(ref lifetime) => {
625 let lt_budget = shape.width.checked_sub(2 + mut_len)?;
626 let lt_str = lifetime.rewrite(
628 Shape::legacy(lt_budget, shape.indent + 2 + mut_len),
630 let lt_len = lt_str.len();
631 let budget = shape.width.checked_sub(2 + mut_len + lt_len)?;
638 Shape::legacy(budget, shape.indent + 2 + mut_len + lt_len)
643 let budget = shape.width.checked_sub(1 + mut_len)?;
649 Shape::legacy(budget, shape.indent + 1 + mut_len)
655 // FIXME: we drop any comments here, even though it's a silly place to put
657 ast::TyKind::Paren(ref ty) => {
658 let budget = shape.width.checked_sub(2)?;
659 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
660 .map(|ty_str| format!("({})", ty_str))
662 ast::TyKind::Slice(ref ty) => {
663 let budget = shape.width.checked_sub(4)?;
664 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
665 .map(|ty_str| format!("[{}]", ty_str))
667 ast::TyKind::Tup(ref items) => rewrite_tuple(
669 &::utils::ptr_vec_to_ref_vec(items),
673 ast::TyKind::Path(ref q_self, ref path) => {
674 rewrite_path(context, PathContext::Type, q_self.as_ref(), path, shape)
676 ast::TyKind::Array(ref ty, ref repeats) => rewrite_pair(
679 PairParts::new("[", "; ", "]"),
682 SeparatorPlace::Back,
684 ast::TyKind::Infer => {
685 if shape.width >= 1 {
691 ast::TyKind::BareFn(ref bare_fn) => rewrite_bare_fn(bare_fn, self.span, context, shape),
692 ast::TyKind::Never => Some(String::from("!")),
693 ast::TyKind::Mac(ref mac) => {
694 rewrite_macro(mac, None, context, shape, MacroPosition::Expression)
696 ast::TyKind::ImplicitSelf => Some(String::from("")),
697 ast::TyKind::ImplTrait(_, ref it) => it
698 .rewrite(context, shape)
699 .map(|it_str| format!("impl {}", it_str)),
700 ast::TyKind::Err | ast::TyKind::Typeof(..) => unreachable!(),
706 bare_fn: &ast::BareFnTy,
708 context: &RewriteContext,
710 ) -> Option<String> {
711 debug!("rewrite_bare_fn {:#?}", shape);
713 let mut result = String::with_capacity(128);
715 if let Some(ref lifetime_str) = rewrite_lifetime_param(context, shape, &bare_fn.generic_params)
717 result.push_str("for<");
718 // 6 = "for<> ".len(), 4 = "for<".
719 // This doesn't work out so nicely for multiline situation with lots of
720 // rightward drift. If that is a problem, we could use the list stuff.
721 result.push_str(lifetime_str);
722 result.push_str("> ");
725 result.push_str(::utils::format_unsafety(bare_fn.unsafety));
727 result.push_str(&format_abi(
729 context.config.force_explicit_abi(),
733 result.push_str("fn");
735 let func_ty_shape = if context.use_block_indent() {
736 shape.offset_left(result.len())?
738 shape.visual_indent(result.len()).sub_width(result.len())?
741 let rewrite = format_function_type(
742 bare_fn.decl.inputs.iter(),
743 &bare_fn.decl.output,
744 bare_fn.decl.variadic,
750 result.push_str(&rewrite);
755 fn is_generic_bounds_in_order(generic_bounds: &[ast::GenericBound]) -> bool {
756 let is_trait = |b: &ast::GenericBound| match b {
757 ast::GenericBound::Outlives(..) => false,
758 ast::GenericBound::Trait(..) => true,
760 let is_lifetime = |b: &ast::GenericBound| !is_trait(b);
761 let last_trait_index = generic_bounds.iter().rposition(is_trait);
762 let first_lifetime_index = generic_bounds.iter().position(is_lifetime);
763 match (last_trait_index, first_lifetime_index) {
764 (Some(last_trait_index), Some(first_lifetime_index)) => {
765 last_trait_index < first_lifetime_index
772 context: &RewriteContext,
774 items: &[ast::GenericBound],
776 ) -> Option<String> {
777 // Try to join types in a single line
778 let joiner = match context.config.type_punctuation_density() {
779 TypeDensity::Compressed => "+",
780 TypeDensity::Wide => " + ",
782 let type_strs = items
784 .map(|item| item.rewrite(context, shape))
785 .collect::<Option<Vec<_>>>()?;
786 let result = type_strs.join(joiner);
787 if items.len() <= 1 || (!result.contains('\n') && result.len() <= shape.width) {
791 // We need to use multiple lines.
792 let (type_strs, offset) = if need_indent {
793 // Rewrite with additional indentation.
794 let nested_shape = shape.block_indent(context.config.tab_spaces());
795 let type_strs = items
797 .map(|item| item.rewrite(context, nested_shape))
798 .collect::<Option<Vec<_>>>()?;
799 (type_strs, nested_shape.indent)
801 (type_strs, shape.indent)
804 let is_bound_extendable = |s: &str, b: &ast::GenericBound| match b {
805 ast::GenericBound::Outlives(..) => true,
806 ast::GenericBound::Trait(..) => last_line_extendable(s),
808 let mut result = String::with_capacity(128);
809 result.push_str(&type_strs[0]);
810 let mut can_be_put_on_the_same_line = is_bound_extendable(&result, &items[0]);
811 let generic_bounds_in_order = is_generic_bounds_in_order(items);
812 for (bound, bound_str) in items[1..].iter().zip(type_strs[1..].iter()) {
813 if generic_bounds_in_order && can_be_put_on_the_same_line {
814 result.push_str(joiner);
816 result.push_str(&offset.to_string_with_newline(context.config));
817 result.push_str("+ ");
819 result.push_str(bound_str);
820 can_be_put_on_the_same_line = is_bound_extendable(bound_str, bound);
826 pub fn can_be_overflowed_type(context: &RewriteContext, ty: &ast::Ty, len: usize) -> bool {
828 ast::TyKind::Tup(..) => context.use_block_indent() && len == 1,
829 ast::TyKind::Rptr(_, ref mutty) | ast::TyKind::Ptr(ref mutty) => {
830 can_be_overflowed_type(context, &*mutty.ty, len)
836 /// Returns `None` if there is no `LifetimeDef` in the given generic parameters.
837 fn rewrite_lifetime_param(
838 context: &RewriteContext,
840 generic_params: &[ast::GenericParam],
841 ) -> Option<String> {
842 let result = generic_params
844 .filter(|p| match p.kind {
845 ast::GenericParamKind::Lifetime => true,
848 .map(|lt| lt.rewrite(context, shape))
849 .collect::<Option<Vec<_>>>()?
851 if result.is_empty() {