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::codemap::{self, BytePos, Span};
17 use syntax::symbol::keywords;
19 use codemap::SpanUtils;
20 use config::{IndentStyle, TypeDensity};
21 use expr::{rewrite_pair, rewrite_tuple, rewrite_unary_prefix, wrap_args_with_parens, PairParts};
22 use items::{format_generics_item_list, generics_shape_from_config};
23 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
24 use macros::{rewrite_macro, MacroPosition};
25 use rewrite::{Rewrite, RewriteContext};
28 use utils::{colon_spaces, extra_offset, first_line_width, format_abi, format_mutability,
29 last_line_width, mk_sp};
31 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
32 pub enum PathContext {
38 // Does not wrap on simple segments.
40 context: &RewriteContext,
41 path_context: PathContext,
42 qself: Option<&ast::QSelf>,
46 let skip_count = qself.map_or(0, |x| x.position);
48 let mut result = if path.is_global() && qself.is_none() && path_context != PathContext::Import {
54 let mut span_lo = path.span.lo();
56 if let Some(qself) = qself {
58 if context.config.spaces_within_parens_and_brackets() {
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 if context.config.spaces_within_parens_and_brackets() {
89 result.push_str(">::");
90 span_lo = qself.ty.span.hi() + BytePos(1);
93 rewrite_path_segments(
96 path.segments.iter().skip(skip_count),
104 fn rewrite_path_segments<'a, I>(
105 path_context: PathContext,
108 mut span_lo: BytePos,
110 context: &RewriteContext,
114 I: Iterator<Item = &'a ast::PathSegment>,
116 let mut first = true;
117 let shape = shape.visual_indent(0);
119 for segment in iter {
120 // Indicates a global path, shouldn't be rendered.
121 if segment.identifier.name == keywords::CrateRoot.name() {
127 buffer.push_str("::");
130 let extra_offset = extra_offset(&buffer, shape);
131 let new_shape = shape.shrink_left(extra_offset)?;
132 let segment_string = rewrite_segment(
141 buffer.push_str(&segment_string);
148 enum SegmentParam<'a> {
149 LifeTime(&'a ast::Lifetime),
151 Binding(&'a ast::TypeBinding),
154 impl<'a> SegmentParam<'a> {
155 fn get_span(&self) -> Span {
157 SegmentParam::LifeTime(lt) => lt.span,
158 SegmentParam::Type(ty) => ty.span,
159 SegmentParam::Binding(binding) => binding.span,
164 impl<'a> Rewrite for SegmentParam<'a> {
165 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
167 SegmentParam::LifeTime(lt) => lt.rewrite(context, shape),
168 SegmentParam::Type(ty) => ty.rewrite(context, shape),
169 SegmentParam::Binding(binding) => {
170 let mut result = match context.config.type_punctuation_density() {
171 TypeDensity::Wide => format!("{} = ", binding.ident),
172 TypeDensity::Compressed => format!("{}=", binding.ident),
174 let budget = shape.width.checked_sub(result.len())?;
175 let rewrite = binding
177 .rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
178 result.push_str(&rewrite);
185 // Formats a path segment. There are some hacks involved to correctly determine
186 // the segment's associated span since it's not part of the AST.
188 // The span_lo is assumed to be greater than the end of any previous segment's
189 // parameters and lesser or equal than the start of current segment.
191 // span_hi is assumed equal to the end of the entire path.
193 // When the segment contains a positive number of parameters, we update span_lo
194 // so that invariants described above will hold for the next segment.
196 path_context: PathContext,
197 segment: &ast::PathSegment,
198 span_lo: &mut BytePos,
200 context: &RewriteContext,
202 ) -> Option<String> {
203 let mut result = String::with_capacity(128);
204 result.push_str(&segment.identifier.name.as_str());
206 let ident_len = result.len();
207 let shape = shape.shrink_left(ident_len)?;
209 if let Some(ref params) = segment.parameters {
211 ast::PathParameters::AngleBracketed(ref data)
212 if !data.lifetimes.is_empty() || !data.types.is_empty()
213 || !data.bindings.is_empty() =>
215 let param_list = data.lifetimes
217 .map(SegmentParam::LifeTime)
218 .chain(data.types.iter().map(|x| SegmentParam::Type(&*x)))
219 .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
220 .collect::<Vec<_>>();
222 let next_span_lo = param_list.last().unwrap().get_span().hi() + BytePos(1);
223 let list_lo = context
225 .span_after(mk_sp(*span_lo, span_hi), "<");
226 let separator = if path_context == PathContext::Expr {
231 result.push_str(separator);
234 generics_shape_from_config(context.config, shape, separator.len())?;
235 let one_line_width = shape.width.checked_sub(separator.len() + 2)?;
236 let items = itemize_list(
237 context.snippet_provider,
238 param_list.into_iter(),
241 |param| param.get_span().lo(),
242 |param| param.get_span().hi(),
243 |seg| seg.rewrite(context, generics_shape),
249 format_generics_item_list(context, items, generics_shape, one_line_width)?;
251 // Update position of last bracket.
252 *span_lo = next_span_lo;
254 result.push_str(&generics_str)
256 ast::PathParameters::Parenthesized(ref data) => {
257 let output = match data.output {
258 Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
259 None => FunctionRetTy::Default(codemap::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 // Code for handling variadics is somewhat duplicated for items, but they
291 // are different enough to need some serious refactoring to share code.
295 <T as Deref>::Target: Rewrite + Spanned,
301 let variadic_arg = if variadic {
302 let variadic_start = context.snippet_provider.span_before(span, "...");
303 Some(ArgumentKind::Variadic(variadic_start))
309 let budget = shape.width.checked_sub(2)?;
311 let offset = match context.config.indent_style() {
312 IndentStyle::Block => {
315 .block_indent(context.config.tab_spaces())
318 IndentStyle::Visual => shape.indent + 1,
320 let list_shape = Shape::legacy(budget, offset);
321 let list_lo = context.snippet_provider.span_after(span, "(");
322 let items = itemize_list(
323 context.snippet_provider,
324 // FIXME Would be nice to avoid this allocation,
325 // but I couldn't get the types to work out.
327 .map(|i| ArgumentKind::Regular(Box::new(i)))
328 .chain(variadic_arg),
332 ArgumentKind::Regular(ref ty) => ty.span().lo(),
333 ArgumentKind::Variadic(start) => start,
336 ArgumentKind::Regular(ref ty) => ty.span().hi(),
337 ArgumentKind::Variadic(start) => start + BytePos(3),
340 ArgumentKind::Regular(ref ty) => ty.rewrite(context, list_shape),
341 ArgumentKind::Variadic(_) => Some("...".to_owned()),
348 let item_vec: Vec<_> = items.collect();
350 let tactic = definitive_tactic(
352 ListTactic::HorizontalVertical,
357 let fmt = ListFormatting {
360 trailing_separator: if !context.use_block_indent() || variadic {
361 SeparatorTactic::Never
363 context.config.trailing_comma()
365 separator_place: SeparatorPlace::Back,
367 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
368 preserve_newline: true,
369 config: context.config,
372 let list_str = write_list(&item_vec, &fmt)?;
374 let ty_shape = match context.config.indent_style() {
376 IndentStyle::Block => shape.offset_left(4)?,
377 IndentStyle::Visual => shape.block_left(4)?,
379 let output = match *output {
380 FunctionRetTy::Ty(ref ty) => {
381 let type_str = ty.rewrite(context, ty_shape)?;
382 format!(" -> {}", type_str)
384 FunctionRetTy::Default(..) => String::new(),
387 let extendable = (!list_str.contains('\n') || list_str.is_empty()) && !output.contains('\n');
388 let args = wrap_args_with_parens(
392 shape.sub_width(first_line_width(&output))?,
393 Shape::indented(offset, context.config),
395 if last_line_width(&args) + first_line_width(&output) <= shape.width {
396 Some(format!("{}{}", args, output))
401 offset.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> {
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)?;
426 let colon = type_bound_colon(context);
428 if let Some(lifetime_str) =
429 rewrite_lifetime_param(context, shape, bound_generic_params)
431 // 6 = "for<> ".len()
432 let used_width = lifetime_str.len() + type_str.len() + colon.len() + 6;
433 let ty_shape = shape.offset_left(used_width)?;
436 .map(|ty_bound| ty_bound.rewrite(context, ty_shape))
437 .collect::<Option<Vec<_>>>()?;
438 let bounds_str = join_bounds(context, ty_shape, &bounds);
440 if context.config.spaces_within_parens_and_brackets()
441 && !lifetime_str.is_empty()
445 lifetime_str, type_str, colon, bounds_str
448 format!("for<{}> {}{}{}", lifetime_str, type_str, colon, bounds_str)
451 let used_width = type_str.len() + colon.len();
452 let ty_shape = match context.config.indent_style() {
453 IndentStyle::Visual => shape.block_left(used_width)?,
454 IndentStyle::Block => shape,
458 .map(|ty_bound| ty_bound.rewrite(context, ty_shape))
459 .collect::<Option<Vec<_>>>()?;
460 let overhead = type_str.len() + colon.len();
461 let bounds_str = join_bounds(context, ty_shape.sub_width(overhead)?, &bounds);
463 format!("{}{}{}", type_str, colon, bounds_str)
466 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
470 }) => rewrite_bounded_lifetime(lifetime, bounds.iter(), context, shape)?,
471 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
476 let lhs_ty_str = lhs_ty.rewrite(context, shape)?;
478 let used_width = 3 + lhs_ty_str.len();
479 let budget = shape.width.checked_sub(used_width)?;
481 rhs_ty.rewrite(context, Shape::legacy(budget, shape.indent + used_width))?;
482 format!("{} = {}", lhs_ty_str, rhs_ty_str)
490 impl Rewrite for ast::LifetimeDef {
491 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
492 rewrite_bounded_lifetime(&self.lifetime, self.bounds.iter(), context, shape)
496 fn rewrite_bounded_lifetime<'b, I>(
499 context: &RewriteContext,
503 I: ExactSizeIterator<Item = &'b ast::Lifetime>,
505 let result = lt.rewrite(context, shape)?;
507 if bounds.len() == 0 {
510 let appendix = bounds
512 .map(|b| b.rewrite(context, shape))
513 .collect::<Option<Vec<_>>>()?;
514 let colon = type_bound_colon(context);
515 let overhead = last_line_width(&result) + colon.len();
516 let result = format!(
520 join_bounds(context, shape.sub_width(overhead)?, &appendix)
526 impl Rewrite for ast::TyParamBound {
527 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
529 ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::None) => {
530 tref.rewrite(context, shape)
532 ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::Maybe) => Some(
533 format!("?{}", tref.rewrite(context, shape.offset_left(1)?)?),
535 ast::TyParamBound::RegionTyParamBound(ref l) => l.rewrite(context, shape),
540 impl Rewrite for ast::Lifetime {
541 fn rewrite(&self, _: &RewriteContext, _: Shape) -> Option<String> {
542 Some(self.ident.to_string())
546 impl Rewrite for ast::TyParamBounds {
547 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
548 let strs = self.iter()
549 .map(|b| b.rewrite(context, shape))
550 .collect::<Option<Vec<_>>>()?;
551 Some(join_bounds(context, shape, &strs))
555 impl Rewrite for ast::TyParam {
556 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
557 let mut result = String::with_capacity(128);
558 // FIXME: If there are more than one attributes, this will force multiline.
559 match self.attrs.rewrite(context, shape) {
560 Some(ref rw) if !rw.is_empty() => result.push_str(&format!("{} ", rw)),
563 result.push_str(&self.ident.to_string());
564 if !self.bounds.is_empty() {
565 result.push_str(type_bound_colon(context));
566 let strs = self.bounds
568 .map(|ty_bound| ty_bound.rewrite(context, shape))
569 .collect::<Option<Vec<_>>>()?;
570 result.push_str(&join_bounds(context, shape, &strs));
572 if let Some(ref def) = self.default {
573 let eq_str = match context.config.type_punctuation_density() {
574 TypeDensity::Compressed => "=",
575 TypeDensity::Wide => " = ",
577 result.push_str(eq_str);
578 let budget = shape.width.checked_sub(result.len())?;
579 let rewrite = def.rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
580 result.push_str(&rewrite);
587 impl Rewrite for ast::PolyTraitRef {
588 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
589 if let Some(lifetime_str) =
590 rewrite_lifetime_param(context, shape, &self.bound_generic_params)
592 // 6 is "for<> ".len()
593 let extra_offset = lifetime_str.len() + 6;
594 let path_str = self.trait_ref
595 .rewrite(context, shape.offset_left(extra_offset)?)?;
598 if context.config.spaces_within_parens_and_brackets() && !lifetime_str.is_empty() {
599 format!("for< {} > {}", lifetime_str, path_str)
601 format!("for<{}> {}", lifetime_str, path_str)
605 self.trait_ref.rewrite(context, shape)
610 impl Rewrite for ast::TraitRef {
611 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
612 rewrite_path(context, PathContext::Type, None, &self.path, shape)
616 impl Rewrite for ast::Ty {
617 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
619 ast::TyKind::TraitObject(ref bounds, tobj_syntax) => {
620 // we have to consider 'dyn' keyword is used or not!!!
621 let is_dyn = tobj_syntax == ast::TraitObjectSyntax::Dyn;
622 // 4 is length of 'dyn '
623 let shape = if is_dyn { shape.offset_left(4)? } else { shape };
624 let res = bounds.rewrite(context, shape)?;
626 Some(format!("dyn {}", res))
631 ast::TyKind::Ptr(ref mt) => {
632 let prefix = match mt.mutbl {
633 Mutability::Mutable => "*mut ",
634 Mutability::Immutable => "*const ",
637 rewrite_unary_prefix(context, prefix, &*mt.ty, shape)
639 ast::TyKind::Rptr(ref lifetime, ref mt) => {
640 let mut_str = format_mutability(mt.mutbl);
641 let mut_len = mut_str.len();
642 Some(match *lifetime {
643 Some(ref lifetime) => {
644 let lt_budget = shape.width.checked_sub(2 + mut_len)?;
645 let lt_str = lifetime.rewrite(
647 Shape::legacy(lt_budget, shape.indent + 2 + mut_len),
649 let lt_len = lt_str.len();
650 let budget = shape.width.checked_sub(2 + mut_len + lt_len)?;
657 Shape::legacy(budget, shape.indent + 2 + mut_len + lt_len)
662 let budget = shape.width.checked_sub(1 + mut_len)?;
668 Shape::legacy(budget, shape.indent + 1 + mut_len)
674 // FIXME: we drop any comments here, even though it's a silly place to put
676 ast::TyKind::Paren(ref ty) => {
677 let budget = shape.width.checked_sub(2)?;
678 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
680 if context.config.spaces_within_parens_and_brackets() {
681 format!("( {} )", ty_str)
683 format!("({})", ty_str)
687 ast::TyKind::Slice(ref ty) => {
688 let budget = if context.config.spaces_within_parens_and_brackets() {
689 shape.width.checked_sub(4)?
691 shape.width.checked_sub(2)?
693 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
695 if context.config.spaces_within_parens_and_brackets() {
696 format!("[ {} ]", ty_str)
698 format!("[{}]", ty_str)
702 ast::TyKind::Tup(ref items) => rewrite_tuple(
704 &::utils::ptr_vec_to_ref_vec(items),
708 ast::TyKind::Path(ref q_self, ref path) => {
709 rewrite_path(context, PathContext::Type, q_self.as_ref(), path, shape)
711 ast::TyKind::Array(ref ty, ref repeats) => {
712 let use_spaces = context.config.spaces_within_parens_and_brackets();
713 let lbr = if use_spaces { "[ " } else { "[" };
714 let rbr = if use_spaces { " ]" } else { "]" };
718 PairParts::new(lbr, "; ", rbr),
721 SeparatorPlace::Back,
724 ast::TyKind::Infer => {
725 if shape.width >= 1 {
731 ast::TyKind::BareFn(ref bare_fn) => rewrite_bare_fn(bare_fn, self.span, context, shape),
732 ast::TyKind::Never => Some(String::from("!")),
733 ast::TyKind::Mac(ref mac) => {
734 rewrite_macro(mac, None, context, shape, MacroPosition::Expression)
736 ast::TyKind::ImplicitSelf => Some(String::from("")),
737 ast::TyKind::ImplTrait(ref it) => it.rewrite(context, shape)
738 .map(|it_str| format!("impl {}", it_str)),
739 ast::TyKind::Err | ast::TyKind::Typeof(..) => unreachable!(),
745 bare_fn: &ast::BareFnTy,
747 context: &RewriteContext,
749 ) -> Option<String> {
750 let mut result = String::with_capacity(128);
752 if let Some(ref lifetime_str) = rewrite_lifetime_param(context, shape, &bare_fn.generic_params)
754 result.push_str("for<");
755 // 6 = "for<> ".len(), 4 = "for<".
756 // This doesn't work out so nicely for mutliline situation with lots of
757 // rightward drift. If that is a problem, we could use the list stuff.
758 result.push_str(lifetime_str);
759 result.push_str("> ");
762 result.push_str(::utils::format_unsafety(bare_fn.unsafety));
764 result.push_str(&format_abi(
766 context.config.force_explicit_abi(),
770 result.push_str("fn");
772 let func_ty_shape = shape.offset_left(result.len())?;
774 let rewrite = format_function_type(
775 bare_fn.decl.inputs.iter(),
776 &bare_fn.decl.output,
777 bare_fn.decl.variadic,
783 result.push_str(&rewrite);
788 pub fn join_bounds(context: &RewriteContext, shape: Shape, type_strs: &[String]) -> String {
789 // Try to join types in a single line
790 let joiner = match context.config.type_punctuation_density() {
791 TypeDensity::Compressed => "+",
792 TypeDensity::Wide => " + ",
794 let result = type_strs.join(joiner);
795 if result.contains('\n') || result.len() > shape.width {
796 let joiner_indent = shape.indent.block_indent(context.config);
797 let joiner = format!("{}+ ", joiner_indent.to_string_with_newline(context.config));
798 type_strs.join(&joiner)
804 pub fn can_be_overflowed_type(context: &RewriteContext, ty: &ast::Ty, len: usize) -> bool {
806 ast::TyKind::Path(..) | ast::TyKind::Tup(..) => context.use_block_indent() && len == 1,
807 ast::TyKind::Rptr(_, ref mutty) | ast::TyKind::Ptr(ref mutty) => {
808 can_be_overflowed_type(context, &*mutty.ty, len)
814 /// Returns `None` if there is no `LifetimeDef` in the given generic parameters.
815 fn rewrite_lifetime_param(
816 context: &RewriteContext,
818 generic_params: &[ast::GenericParam],
819 ) -> Option<String> {
820 let result = generic_params
822 .filter(|p| p.is_lifetime_param())
823 .map(|lt| lt.rewrite(context, shape))
824 .collect::<Option<Vec<_>>>()?
826 if result.is_empty() {