src/types.rs

   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.
   4 //
   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.
  10
  11 use std::iter::ExactSizeIterator;
  12 use std::ops::Deref;
  13
  14 use syntax::ast::{self, FunctionRetTy, Mutability};
  15 use syntax::codemap::{self, BytePos, Span};
  16 use syntax::print::pprust;
  17 use syntax::symbol::keywords;
  18
  19 use spanned::Spanned;
  20 use codemap::SpanUtils;
  21 use config::{IndentStyle, Style, TypeDensity};
  22 use expr::{rewrite_pair, rewrite_tuple, rewrite_unary_prefix, wrap_args_with_parens};
  23 use items::{format_generics_item_list, generics_shape_from_config};
  24 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListTactic, Separator,
  25             SeparatorPlace, SeparatorTactic};
  26 use rewrite::{Rewrite, RewriteContext};
  27 use shape::Shape;
  28 use utils::{colon_spaces, extra_offset, format_abi, format_mutability, last_line_width, mk_sp};
  29
  30 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
  31 pub enum PathContext {
  32     Expr,
  33     Type,
  34     Import,
  35 }
  36
  37 // Does not wrap on simple segments.
  38 pub fn rewrite_path(
  39     context: &RewriteContext,
  40     path_context: PathContext,
  41     qself: Option<&ast::QSelf>,
  42     path: &ast::Path,
  43     shape: Shape,
  44 ) -> Option<String> {
  45     let skip_count = qself.map_or(0, |x| x.position);
  46
  47     let mut result = if path.is_global() && qself.is_none() && path_context != PathContext::Import {
  48         "::".to_owned()
  49     } else {
  50         String::new()
  51     };
  52
  53     let mut span_lo = path.span.lo();
  54
  55     if let Some(qself) = qself {
  56         result.push('<');
  57         if context.config.spaces_within_angle_brackets() {
  58             result.push_str(" ")
  59         }
  60
  61         let fmt_ty = qself.ty.rewrite(context, shape)?;
  62         result.push_str(&fmt_ty);
  63
  64         if skip_count > 0 {
  65             result.push_str(" as ");
  66             if path.is_global() && path_context != PathContext::Import {
  67                 result.push_str("::");
  68             }
  69
  70             let extra_offset = extra_offset(&result, shape);
  71             // 3 = ">::".len()
  72             let shape = shape.shrink_left(extra_offset)?.sub_width(3)?;
  73
  74             result = rewrite_path_segments(
  75                 PathContext::Type,
  76                 result,
  77                 path.segments.iter().take(skip_count),
  78                 span_lo,
  79                 path.span.hi(),
  80                 context,
  81                 shape,
  82             )?;
  83         }
  84
  85         if context.config.spaces_within_angle_brackets() {
  86             result.push_str(" ")
  87         }
  88
  89         result.push_str(">::");
  90         span_lo = qself.ty.span.hi() + BytePos(1);
  91     }
  92
  93     rewrite_path_segments(
  94         path_context,
  95         result,
  96         path.segments.iter().skip(skip_count),
  97         span_lo,
  98         path.span.hi(),
  99         context,
 100         shape,
 101     )
 102 }
 103
 104 fn rewrite_path_segments<'a, I>(
 105     path_context: PathContext,
 106     mut buffer: String,
 107     iter: I,
 108     mut span_lo: BytePos,
 109     span_hi: BytePos,
 110     context: &RewriteContext,
 111     shape: Shape,
 112 ) -> Option<String>
 113 where
 114     I: Iterator<Item = &'a ast::PathSegment>,
 115 {
 116     let mut first = true;
 117     let shape = shape.visual_indent(0);
 118
 119     for segment in iter {
 120         // Indicates a global path, shouldn't be rendered.
 121         if segment.identifier.name == keywords::CrateRoot.name() {
 122             continue;
 123         }
 124         if first {
 125             first = false;
 126         } else {
 127             buffer.push_str("::");
 128         }
 129
 130         let extra_offset = extra_offset(&buffer, shape);
 131         let new_shape = shape.shrink_left(extra_offset)?;
 132         let segment_string = rewrite_segment(
 133             path_context,
 134             segment,
 135             &mut span_lo,
 136             span_hi,
 137             context,
 138             new_shape,
 139         )?;
 140
 141         buffer.push_str(&segment_string);
 142     }
 143
 144     Some(buffer)
 145 }
 146
 147 #[derive(Debug)]
 148 enum SegmentParam<'a> {
 149     LifeTime(&'a ast::Lifetime),
 150     Type(&'a ast::Ty),
 151     Binding(&'a ast::TypeBinding),
 152 }
 153
 154 impl<'a> SegmentParam<'a> {
 155     fn get_span(&self) -> Span {
 156         match *self {
 157             SegmentParam::LifeTime(lt) => lt.span,
 158             SegmentParam::Type(ty) => ty.span,
 159             SegmentParam::Binding(binding) => binding.span,
 160         }
 161     }
 162 }
 163
 164 impl<'a> Rewrite for SegmentParam<'a> {
 165     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 166         match *self {
 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),
 173                 };
 174                 let budget = shape.width.checked_sub(result.len())?;
 175                 let rewrite = binding
 176                     .ty
 177                     .rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
 178                 result.push_str(&rewrite);
 179                 Some(result)
 180             }
 181         }
 182     }
 183 }
 184
 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.
 187 //
 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.
 190 //
 191 // span_hi is assumed equal to the end of the entire path.
 192 //
 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.
 195 fn rewrite_segment(
 196     path_context: PathContext,
 197     segment: &ast::PathSegment,
 198     span_lo: &mut BytePos,
 199     span_hi: BytePos,
 200     context: &RewriteContext,
 201     shape: Shape,
 202 ) -> Option<String> {
 203     let ident_len = segment.identifier.to_string().len();
 204     let shape = shape.shrink_left(ident_len)?;
 205
 206     let params = if let Some(ref params) = segment.parameters {
 207         match **params {
 208             ast::PathParameters::AngleBracketed(ref data)
 209                 if !data.lifetimes.is_empty() || !data.types.is_empty()
 210                     || !data.bindings.is_empty() =>
 211             {
 212                 let param_list = data.lifetimes
 213                     .iter()
 214                     .map(SegmentParam::LifeTime)
 215                     .chain(data.types.iter().map(|x| SegmentParam::Type(&*x)))
 216                     .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
 217                     .collect::<Vec<_>>();
 218
 219                 let next_span_lo = param_list.last().unwrap().get_span().hi() + BytePos(1);
 220                 let list_lo = context.codemap.span_after(mk_sp(*span_lo, span_hi), "<");
 221                 let separator = if path_context == PathContext::Expr {
 222                     "::"
 223                 } else {
 224                     ""
 225                 };
 226
 227                 let generics_shape =
 228                     generics_shape_from_config(context.config, shape, separator.len())?;
 229                 let one_line_width = shape.width.checked_sub(separator.len() + 2)?;
 230                 let items = itemize_list(
 231                     context.codemap,
 232                     param_list.into_iter(),
 233                     ">",
 234                     |param| param.get_span().lo(),
 235                     |param| param.get_span().hi(),
 236                     |seg| seg.rewrite(context, generics_shape),
 237                     list_lo,
 238                     span_hi,
 239                     false,
 240                 );
 241                 let generics_str =
 242                     format_generics_item_list(context, items, generics_shape, one_line_width)?;
 243
 244                 // Update position of last bracket.
 245                 *span_lo = next_span_lo;
 246
 247                 format!("{}{}", separator, generics_str)
 248             }
 249             ast::PathParameters::Parenthesized(ref data) => {
 250                 let output = match data.output {
 251                     Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
 252                     None => FunctionRetTy::Default(codemap::DUMMY_SP),
 253                 };
 254                 format_function_type(
 255                     data.inputs.iter().map(|x| &**x),
 256                     &output,
 257                     false,
 258                     data.span,
 259                     context,
 260                     shape,
 261                 )?
 262             }
 263             _ => String::new(),
 264         }
 265     } else {
 266         String::new()
 267     };
 268
 269     Some(format!("{}{}", segment.identifier, params))
 270 }
 271
 272 fn format_function_type<'a, I>(
 273     inputs: I,
 274     output: &FunctionRetTy,
 275     variadic: bool,
 276     span: Span,
 277     context: &RewriteContext,
 278     shape: Shape,
 279 ) -> Option<String>
 280 where
 281     I: ExactSizeIterator,
 282     <I as Iterator>::Item: Deref,
 283     <I::Item as Deref>::Target: Rewrite + Spanned + 'a,
 284 {
 285     // Code for handling variadics is somewhat duplicated for items, but they
 286     // are different enough to need some serious refactoring to share code.
 287     enum ArgumentKind<T>
 288     where
 289         T: Deref,
 290         <T as Deref>::Target: Rewrite + Spanned,
 291     {
 292         Regular(Box<T>),
 293         Variadic(BytePos),
 294     }
 295
 296     let variadic_arg = if variadic {
 297         let variadic_start = context.codemap.span_before(span, "...");
 298         Some(ArgumentKind::Variadic(variadic_start))
 299     } else {
 300         None
 301     };
 302
 303     // 2 for ()
 304     let budget = shape.width.checked_sub(2)?;
 305     // 1 for (
 306     let offset = match context.config.fn_args_layout() {
 307         IndentStyle::Block => {
 308             shape
 309                 .block()
 310                 .block_indent(context.config.tab_spaces())
 311                 .indent
 312         }
 313         IndentStyle::Visual => shape.indent + 1,
 314     };
 315     let list_shape = Shape::legacy(budget, offset);
 316     let list_lo = context.codemap.span_after(span, "(");
 317     let items = itemize_list(
 318         context.codemap,
 319         // FIXME Would be nice to avoid this allocation,
 320         // but I couldn't get the types to work out.
 321         inputs
 322             .map(|i| ArgumentKind::Regular(Box::new(i)))
 323             .chain(variadic_arg),
 324         ")",
 325         |arg| match *arg {
 326             ArgumentKind::Regular(ref ty) => ty.span().lo(),
 327             ArgumentKind::Variadic(start) => start,
 328         },
 329         |arg| match *arg {
 330             ArgumentKind::Regular(ref ty) => ty.span().hi(),
 331             ArgumentKind::Variadic(start) => start + BytePos(3),
 332         },
 333         |arg| match *arg {
 334             ArgumentKind::Regular(ref ty) => ty.rewrite(context, list_shape),
 335             ArgumentKind::Variadic(_) => Some("...".to_owned()),
 336         },
 337         list_lo,
 338         span.hi(),
 339         false,
 340     );
 341
 342     let item_vec: Vec<_> = items.collect();
 343
 344     let tactic = definitive_tactic(
 345         &*item_vec,
 346         ListTactic::HorizontalVertical,
 347         Separator::Comma,
 348         budget,
 349     );
 350
 351     let fmt = ListFormatting {
 352         tactic: tactic,
 353         separator: ",",
 354         trailing_separator: if !context.use_block_indent() || variadic {
 355             SeparatorTactic::Never
 356         } else {
 357             context.config.trailing_comma()
 358         },
 359         separator_place: SeparatorPlace::Back,
 360         shape: list_shape,
 361         ends_with_newline: tactic.ends_with_newline(context.config.fn_call_style()),
 362         preserve_newline: true,
 363         config: context.config,
 364     };
 365
 366     let list_str = write_list(&item_vec, &fmt)?;
 367
 368     let ty_shape = match context.config.fn_args_layout() {
 369         IndentStyle::Block => shape.block().block_indent(context.config.tab_spaces()),
 370         IndentStyle::Visual => shape.block_left(4)?,
 371     };
 372     let output = match *output {
 373         FunctionRetTy::Ty(ref ty) => {
 374             let type_str = ty.rewrite(context, ty_shape)?;
 375             format!(" -> {}", type_str)
 376         }
 377         FunctionRetTy::Default(..) => String::new(),
 378     };
 379
 380     let shape = shape.sub_width(output.len())?;
 381     let extendable = !list_str.contains('\n') || list_str.is_empty();
 382     let args = wrap_args_with_parens(
 383         context,
 384         &list_str,
 385         extendable,
 386         shape,
 387         Shape::indented(offset, context.config),
 388     );
 389     if last_line_width(&args) + output.len() > shape.width {
 390         Some(format!(
 391             "{}\n{}{}",
 392             args,
 393             offset.to_string(context.config),
 394             output.trim_left()
 395         ))
 396     } else {
 397         Some(format!("{}{}", args, output))
 398     }
 399 }
 400
 401 fn type_bound_colon(context: &RewriteContext) -> &'static str {
 402     colon_spaces(
 403         context.config.space_before_bound(),
 404         context.config.space_after_bound_colon(),
 405     )
 406 }
 407
 408 impl Rewrite for ast::WherePredicate {
 409     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 410         // TODO: dead spans?
 411         let result = match *self {
 412             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
 413                 ref bound_lifetimes,
 414                 ref bounded_ty,
 415                 ref bounds,
 416                 ..
 417             }) => {
 418                 let type_str = bounded_ty.rewrite(context, shape)?;
 419
 420                 let colon = type_bound_colon(context);
 421
 422                 if !bound_lifetimes.is_empty() {
 423                     let lifetime_str: String = bound_lifetimes
 424                         .iter()
 425                         .map(|lt| lt.rewrite(context, shape))
 426                         .collect::<Option<Vec<_>>>()?
 427                         .join(", ");
 428
 429                     // 6 = "for<> ".len()
 430                     let used_width = lifetime_str.len() + type_str.len() + colon.len() + 6;
 431                     let ty_shape = shape.offset_left(used_width)?;
 432                     let bounds = bounds
 433                         .iter()
 434                         .map(|ty_bound| ty_bound.rewrite(context, ty_shape))
 435                         .collect::<Option<Vec<_>>>()?;
 436                     let bounds_str = join_bounds(context, ty_shape, &bounds);
 437
 438                     if context.config.spaces_within_angle_brackets() && !lifetime_str.is_empty() {
 439                         format!(
 440                             "for< {} > {}{}{}",
 441                             lifetime_str,
 442                             type_str,
 443                             colon,
 444                             bounds_str
 445                         )
 446                     } else {
 447                         format!("for<{}> {}{}{}", lifetime_str, type_str, colon, bounds_str)
 448                     }
 449                 } else {
 450                     let used_width = type_str.len() + colon.len();
 451                     let ty_shape = match context.config.where_style() {
 452                         Style::Legacy => shape.block_left(used_width)?,
 453                         Style::Rfc => shape,
 454                     };
 455                     let bounds = bounds
 456                         .iter()
 457                         .map(|ty_bound| ty_bound.rewrite(context, ty_shape))
 458                         .collect::<Option<Vec<_>>>()?;
 459                     let overhead = type_str.len() + colon.len();
 460                     let bounds_str = join_bounds(context, ty_shape.sub_width(overhead)?, &bounds);
 461
 462                     format!("{}{}{}", type_str, colon, bounds_str)
 463                 }
 464             }
 465             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
 466                 ref lifetime,
 467                 ref bounds,
 468                 ..
 469             }) => rewrite_bounded_lifetime(lifetime, bounds.iter(), context, shape)?,
 470             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
 471                 ref lhs_ty,
 472                 ref rhs_ty,
 473                 ..
 474             }) => {
 475                 let lhs_ty_str = lhs_ty.rewrite(context, shape)?;
 476                 // 3 = " = ".len()
 477                 let used_width = 3 + lhs_ty_str.len();
 478                 let budget = shape.width.checked_sub(used_width)?;
 479                 let rhs_ty_str =
 480                     rhs_ty.rewrite(context, Shape::legacy(budget, shape.indent + used_width))?;
 481                 format!("{} = {}", lhs_ty_str, rhs_ty_str)
 482             }
 483         };
 484
 485         Some(result)
 486     }
 487 }
 488
 489 impl Rewrite for ast::LifetimeDef {
 490     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 491         rewrite_bounded_lifetime(&self.lifetime, self.bounds.iter(), context, shape)
 492     }
 493 }
 494
 495 fn rewrite_bounded_lifetime<'b, I>(
 496     lt: &ast::Lifetime,
 497     bounds: I,
 498     context: &RewriteContext,
 499     shape: Shape,
 500 ) -> Option<String>
 501 where
 502     I: ExactSizeIterator<Item = &'b ast::Lifetime>,
 503 {
 504     let result = lt.rewrite(context, shape)?;
 505
 506     if bounds.len() == 0 {
 507         Some(result)
 508     } else {
 509         let appendix = bounds
 510             .into_iter()
 511             .map(|b| b.rewrite(context, shape))
 512             .collect::<Option<Vec<_>>>()?;
 513         let colon = type_bound_colon(context);
 514         let overhead = last_line_width(&result) + colon.len();
 515         let result = format!(
 516             "{}{}{}",
 517             result,
 518             colon,
 519             join_bounds(context, shape.sub_width(overhead)?, &appendix)
 520         );
 521         Some(result)
 522     }
 523 }
 524
 525 impl Rewrite for ast::TyParamBound {
 526     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 527         match *self {
 528             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::None) => {
 529                 tref.rewrite(context, shape)
 530             }
 531             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::Maybe) => {
 532                 Some(format!(
 533                     "?{}",
 534                     tref.rewrite(context, shape.offset_left(1)?)?
 535                 ))
 536             }
 537             ast::TyParamBound::RegionTyParamBound(ref l) => l.rewrite(context, shape),
 538         }
 539     }
 540 }
 541
 542 impl Rewrite for ast::Lifetime {
 543     fn rewrite(&self, _: &RewriteContext, _: Shape) -> Option<String> {
 544         Some(pprust::lifetime_to_string(self))
 545     }
 546 }
 547
 548 impl Rewrite for ast::TyParamBounds {
 549     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 550         let strs = self.iter()
 551             .map(|b| b.rewrite(context, shape))
 552             .collect::<Option<Vec<_>>>()?;
 553         Some(join_bounds(context, shape, &strs))
 554     }
 555 }
 556
 557 impl Rewrite for ast::TyParam {
 558     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 559         let mut result = String::with_capacity(128);
 560         // FIXME: If there are more than one attributes, this will force multiline.
 561         match self.attrs.rewrite(context, shape) {
 562             Some(ref rw) if !rw.is_empty() => result.push_str(&format!("{} ", rw)),
 563             _ => (),
 564         }
 565         result.push_str(&self.ident.to_string());
 566         if !self.bounds.is_empty() {
 567             result.push_str(type_bound_colon(context));
 568             let strs = self.bounds
 569                 .iter()
 570                 .map(|ty_bound| ty_bound.rewrite(context, shape))
 571                 .collect::<Option<Vec<_>>>()?;
 572             result.push_str(&join_bounds(context, shape, &strs));
 573         }
 574         if let Some(ref def) = self.default {
 575             let eq_str = match context.config.type_punctuation_density() {
 576                 TypeDensity::Compressed => "=",
 577                 TypeDensity::Wide => " = ",
 578             };
 579             result.push_str(eq_str);
 580             let budget = shape.width.checked_sub(result.len())?;
 581             let rewrite = def.rewrite(context, Shape::legacy(budget, shape.indent + result.len()))?;
 582             result.push_str(&rewrite);
 583         }
 584
 585         Some(result)
 586     }
 587 }
 588
 589 impl Rewrite for ast::PolyTraitRef {
 590     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 591         if !self.bound_lifetimes.is_empty() {
 592             let lifetime_str: String = self.bound_lifetimes
 593                 .iter()
 594                 .map(|lt| lt.rewrite(context, shape))
 595                 .collect::<Option<Vec<_>>>()?
 596                 .join(", ");
 597
 598             // 6 is "for<> ".len()
 599             let extra_offset = lifetime_str.len() + 6;
 600             let path_str = self.trait_ref
 601                 .rewrite(context, shape.offset_left(extra_offset)?)?;
 602
 603             Some(
 604                 if context.config.spaces_within_angle_brackets() && !lifetime_str.is_empty() {
 605                     format!("for< {} > {}", lifetime_str, path_str)
 606                 } else {
 607                     format!("for<{}> {}", lifetime_str, path_str)
 608                 },
 609             )
 610         } else {
 611             self.trait_ref.rewrite(context, shape)
 612         }
 613     }
 614 }
 615
 616 impl Rewrite for ast::TraitRef {
 617     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 618         rewrite_path(context, PathContext::Type, None, &self.path, shape)
 619     }
 620 }
 621
 622 impl Rewrite for ast::Ty {
 623     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 624         match self.node {
 625             ast::TyKind::TraitObject(ref bounds, ..) => bounds.rewrite(context, shape),
 626             ast::TyKind::Ptr(ref mt) => {
 627                 let prefix = match mt.mutbl {
 628                     Mutability::Mutable => "*mut ",
 629                     Mutability::Immutable => "*const ",
 630                 };
 631
 632                 rewrite_unary_prefix(context, prefix, &*mt.ty, shape)
 633             }
 634             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 635                 let mut_str = format_mutability(mt.mutbl);
 636                 let mut_len = mut_str.len();
 637                 Some(match *lifetime {
 638                     Some(ref lifetime) => {
 639                         let lt_budget = shape.width.checked_sub(2 + mut_len)?;
 640                         let lt_str = lifetime.rewrite(
 641                             context,
 642                             Shape::legacy(lt_budget, shape.indent + 2 + mut_len),
 643                         )?;
 644                         let lt_len = lt_str.len();
 645                         let budget = shape.width.checked_sub(2 + mut_len + lt_len)?;
 646                         format!(
 647                             "&{} {}{}",
 648                             lt_str,
 649                             mut_str,
 650                             mt.ty.rewrite(
 651                                 context,
 652                                 Shape::legacy(budget, shape.indent + 2 + mut_len + lt_len)
 653                             )?
 654                         )
 655                     }
 656                     None => {
 657                         let budget = shape.width.checked_sub(1 + mut_len)?;
 658                         format!(
 659                             "&{}{}",
 660                             mut_str,
 661                             mt.ty.rewrite(
 662                                 context,
 663                                 Shape::legacy(budget, shape.indent + 1 + mut_len)
 664                             )?
 665                         )
 666                     }
 667                 })
 668             }
 669             // FIXME: we drop any comments here, even though it's a silly place to put
 670             // comments.
 671             ast::TyKind::Paren(ref ty) => {
 672                 let budget = shape.width.checked_sub(2)?;
 673                 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
 674                     .map(|ty_str| if context.config.spaces_within_parens() {
 675                         format!("( {} )", ty_str)
 676                     } else {
 677                         format!("({})", ty_str)
 678                     })
 679             }
 680             ast::TyKind::Slice(ref ty) => {
 681                 let budget = if context.config.spaces_within_square_brackets() {
 682                     shape.width.checked_sub(4)?
 683                 } else {
 684                     shape.width.checked_sub(2)?
 685                 };
 686                 ty.rewrite(context, Shape::legacy(budget, shape.indent + 1))
 687                     .map(|ty_str| if context.config.spaces_within_square_brackets() {
 688                         format!("[ {} ]", ty_str)
 689                     } else {
 690                         format!("[{}]", ty_str)
 691                     })
 692             }
 693             ast::TyKind::Tup(ref items) => rewrite_tuple(
 694                 context,
 695                 &::utils::ptr_vec_to_ref_vec(&items),
 696                 self.span,
 697                 shape,
 698             ),
 699             ast::TyKind::Path(ref q_self, ref path) => {
 700                 rewrite_path(context, PathContext::Type, q_self.as_ref(), path, shape)
 701             }
 702             ast::TyKind::Array(ref ty, ref repeats) => {
 703                 let use_spaces = context.config.spaces_within_square_brackets();
 704                 let lbr = if use_spaces { "[ " } else { "[" };
 705                 let rbr = if use_spaces { " ]" } else { "]" };
 706                 rewrite_pair(
 707                     &**ty,
 708                     &**repeats,
 709                     lbr,
 710                     "; ",
 711                     rbr,
 712                     context,
 713                     shape,
 714                     SeparatorPlace::Back,
 715                 )
 716             }
 717             ast::TyKind::Infer => if shape.width >= 1 {
 718                 Some("_".to_owned())
 719             } else {
 720                 None
 721             },
 722             ast::TyKind::BareFn(ref bare_fn) => rewrite_bare_fn(bare_fn, self.span, context, shape),
 723             ast::TyKind::Never => Some(String::from("!")),
 724             ast::TyKind::Mac(..) => None,
 725             ast::TyKind::ImplicitSelf => Some(String::from("")),
 726             ast::TyKind::ImplTrait(ref it) => it.rewrite(context, shape)
 727                 .map(|it_str| format!("impl {}", it_str)),
 728             ast::TyKind::Err | ast::TyKind::Typeof(..) => unreachable!(),
 729         }
 730     }
 731 }
 732
 733 fn rewrite_bare_fn(
 734     bare_fn: &ast::BareFnTy,
 735     span: Span,
 736     context: &RewriteContext,
 737     shape: Shape,
 738 ) -> Option<String> {
 739     let mut result = String::with_capacity(128);
 740
 741     if !bare_fn.lifetimes.is_empty() {
 742         result.push_str("for<");
 743         // 6 = "for<> ".len(), 4 = "for<".
 744         // This doesn't work out so nicely for mutliline situation with lots of
 745         // rightward drift. If that is a problem, we could use the list stuff.
 746         result.push_str(&bare_fn
 747             .lifetimes
 748             .iter()
 749             .map(|l| {
 750                 l.rewrite(
 751                     context,
 752                     Shape::legacy(shape.width.checked_sub(6)?, shape.indent + 4),
 753                 )
 754             })
 755             .collect::<Option<Vec<_>>>()?
 756             .join(", "));
 757         result.push_str("> ");
 758     }
 759
 760     result.push_str(::utils::format_unsafety(bare_fn.unsafety));
 761
 762     result.push_str(&format_abi(
 763         bare_fn.abi,
 764         context.config.force_explicit_abi(),
 765         false,
 766     ));
 767
 768     result.push_str("fn");
 769
 770     let func_ty_shape = shape.offset_left(result.len())?;
 771
 772     let rewrite = format_function_type(
 773         bare_fn.decl.inputs.iter(),
 774         &bare_fn.decl.output,
 775         bare_fn.decl.variadic,
 776         span,
 777         context,
 778         func_ty_shape,
 779     )?;
 780
 781     result.push_str(&rewrite);
 782
 783     Some(result)
 784 }
 785
 786 pub fn join_bounds(context: &RewriteContext, shape: Shape, type_strs: &[String]) -> String {
 787     // Try to join types in a single line
 788     let joiner = match context.config.type_punctuation_density() {
 789         TypeDensity::Compressed => "+",
 790         TypeDensity::Wide => " + ",
 791     };
 792     let result = type_strs.join(joiner);
 793     if result.contains('\n') || result.len() > shape.width {
 794         let joiner_indent = shape.indent.block_indent(context.config);
 795         let joiner = format!("\n{}+ ", joiner_indent.to_string(context.config));
 796         type_strs.join(&joiner)
 797     } else {
 798         result
 799     }
 800 }
 801
 802 pub fn can_be_overflowed_type(context: &RewriteContext, ty: &ast::Ty, len: usize) -> bool {
 803     match ty.node {
 804         ast::TyKind::Path(..) | ast::TyKind::Tup(..) => context.use_block_indent() && len == 1,
 805         ast::TyKind::Rptr(_, ref mutty) | ast::TyKind::Ptr(ref mutty) => {
 806             can_be_overflowed_type(context, &*mutty.ty, len)
 807         }
 808         _ => false,
 809     }
 810 }