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::ops::Deref;
  12 use std::iter::ExactSizeIterator;
  13
  14 use syntax::ast::{self, Mutability, FunctionRetTy};
  15 use syntax::print::pprust;
  16 use syntax::codemap::{self, Span, BytePos};
  17 use syntax::abi;
  18
  19 use {Indent, Spanned};
  20 use lists::{format_item_list, itemize_list, format_fn_args};
  21 use rewrite::{Rewrite, RewriteContext};
  22 use utils::{extra_offset, span_after, format_mutability, wrap_str};
  23 use expr::{rewrite_unary_prefix, rewrite_pair, rewrite_tuple};
  24
  25 // Does not wrap on simple segments.
  26 pub fn rewrite_path(context: &RewriteContext,
  27                     expr_context: bool,
  28                     qself: Option<&ast::QSelf>,
  29                     path: &ast::Path,
  30                     width: usize,
  31                     offset: Indent)
  32                     -> Option<String> {
  33     let skip_count = qself.map(|x| x.position).unwrap_or(0);
  34
  35     let mut result = if path.global {
  36         "::".to_owned()
  37     } else {
  38         String::new()
  39     };
  40
  41     let mut span_lo = path.span.lo;
  42
  43     if let Some(ref qself) = qself {
  44         result.push('<');
  45         let fmt_ty = try_opt!(qself.ty.rewrite(context, width, offset));
  46         result.push_str(&fmt_ty);
  47
  48         if skip_count > 0 {
  49             result.push_str(" as ");
  50
  51             let extra_offset = extra_offset(&result, offset);
  52             // 3 = ">::".len()
  53             let budget = try_opt!(width.checked_sub(extra_offset + 3));
  54
  55             result = try_opt!(rewrite_path_segments(expr_context,
  56                                                     result,
  57                                                     path.segments.iter().take(skip_count),
  58                                                     span_lo,
  59                                                     path.span.hi,
  60                                                     context,
  61                                                     budget,
  62                                                     offset + extra_offset));
  63         }
  64
  65         result.push_str(">::");
  66         span_lo = qself.ty.span.hi + BytePos(1);
  67     }
  68
  69     let extra_offset = extra_offset(&result, offset);
  70     let budget = try_opt!(width.checked_sub(extra_offset));
  71     rewrite_path_segments(expr_context,
  72                           result,
  73                           path.segments.iter().skip(skip_count),
  74                           span_lo,
  75                           path.span.hi,
  76                           context,
  77                           budget,
  78                           offset + extra_offset)
  79 }
  80
  81 fn rewrite_path_segments<'a, I>(expr_context: bool,
  82                                 mut buffer: String,
  83                                 iter: I,
  84                                 mut span_lo: BytePos,
  85                                 span_hi: BytePos,
  86                                 context: &RewriteContext,
  87                                 width: usize,
  88                                 offset: Indent)
  89                                 -> Option<String>
  90     where I: Iterator<Item = &'a ast::PathSegment>
  91 {
  92     let mut first = true;
  93
  94     for segment in iter {
  95         if first {
  96             first = false;
  97         } else {
  98             buffer.push_str("::");
  99         }
 100
 101         let extra_offset = extra_offset(&buffer, offset);
 102         let remaining_width = try_opt!(width.checked_sub(extra_offset));
 103         let new_offset = offset + extra_offset;
 104         let segment_string = try_opt!(rewrite_segment(expr_context,
 105                                                       segment,
 106                                                       &mut span_lo,
 107                                                       span_hi,
 108                                                       context,
 109                                                       remaining_width,
 110                                                       new_offset));
 111
 112         buffer.push_str(&segment_string);
 113     }
 114
 115     Some(buffer)
 116 }
 117
 118 #[derive(Debug)]
 119 enum SegmentParam<'a> {
 120     LifeTime(&'a ast::Lifetime),
 121     Type(&'a ast::Ty),
 122     Binding(&'a ast::TypeBinding),
 123 }
 124
 125 impl<'a> SegmentParam<'a> {
 126     fn get_span(&self) -> Span {
 127         match *self {
 128             SegmentParam::LifeTime(ref lt) => lt.span,
 129             SegmentParam::Type(ref ty) => ty.span,
 130             SegmentParam::Binding(ref binding) => binding.span,
 131         }
 132     }
 133 }
 134
 135 impl<'a> Rewrite for SegmentParam<'a> {
 136     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 137         match *self {
 138             SegmentParam::LifeTime(ref lt) => {
 139                 wrap_str(pprust::lifetime_to_string(lt),
 140                          context.config.max_width,
 141                          width,
 142                          offset)
 143             }
 144             SegmentParam::Type(ref ty) => ty.rewrite(context, width, offset),
 145             SegmentParam::Binding(ref binding) => {
 146                 let mut result = format!("{} = ", binding.ident);
 147                 let budget = try_opt!(width.checked_sub(result.len()));
 148                 let rewrite = try_opt!(binding.ty.rewrite(context, budget, offset + result.len()));
 149                 result.push_str(&rewrite);
 150                 Some(result)
 151             }
 152         }
 153     }
 154 }
 155
 156 // Formats a path segment. There are some hacks involved to correctly determine
 157 // the segment's associated span since it's not part of the AST.
 158 //
 159 // The span_lo is assumed to be greater than the end of any previous segment's
 160 // parameters and lesser or equal than the start of current segment.
 161 //
 162 // span_hi is assumed equal to the end of the entire path.
 163 //
 164 // When the segment contains a positive number of parameters, we update span_lo
 165 // so that invariants described above will hold for the next segment.
 166 fn rewrite_segment(expr_context: bool,
 167                    segment: &ast::PathSegment,
 168                    span_lo: &mut BytePos,
 169                    span_hi: BytePos,
 170                    context: &RewriteContext,
 171                    width: usize,
 172                    offset: Indent)
 173                    -> Option<String> {
 174     let ident_len = segment.identifier.to_string().len();
 175     let width = try_opt!(width.checked_sub(ident_len));
 176     let offset = offset + ident_len;
 177
 178     let params = match segment.parameters {
 179         ast::PathParameters::AngleBracketedParameters(ref data) if !data.lifetimes.is_empty() ||
 180                                                                    !data.types.is_empty() ||
 181                                                                    !data.bindings.is_empty() => {
 182             let param_list = data.lifetimes
 183                                  .iter()
 184                                  .map(SegmentParam::LifeTime)
 185                                  .chain(data.types.iter().map(|x| SegmentParam::Type(&*x)))
 186                                  .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
 187                                  .collect::<Vec<_>>();
 188
 189             let next_span_lo = param_list.last().unwrap().get_span().hi + BytePos(1);
 190             let list_lo = span_after(codemap::mk_sp(*span_lo, span_hi), "<", context.codemap);
 191             let separator = if expr_context {
 192                 "::"
 193             } else {
 194                 ""
 195             };
 196
 197             // 1 for <
 198             let extra_offset = 1 + separator.len();
 199             // 1 for >
 200             let list_width = try_opt!(width.checked_sub(extra_offset + 1));
 201
 202             let items = itemize_list(context.codemap,
 203                                      param_list.into_iter(),
 204                                      ">",
 205                                      |param| param.get_span().lo,
 206                                      |param| param.get_span().hi,
 207                                      |seg| seg.rewrite(context, list_width, offset + extra_offset),
 208                                      list_lo,
 209                                      span_hi);
 210             let list_str = try_opt!(format_item_list(items,
 211                                                      list_width,
 212                                                      offset + extra_offset,
 213                                                      context.config));
 214
 215             // Update position of last bracket.
 216             *span_lo = next_span_lo;
 217
 218             format!("{}<{}>", separator, list_str)
 219         }
 220         ast::PathParameters::ParenthesizedParameters(ref data) => {
 221             let output = match data.output {
 222                 Some(ref ty) => FunctionRetTy::Return(ty.clone()),
 223                 None => FunctionRetTy::DefaultReturn(codemap::DUMMY_SP),
 224             };
 225             try_opt!(format_function_type(data.inputs.iter().map(|x| &**x),
 226                                           &output,
 227                                           data.span,
 228                                           context,
 229                                           width,
 230                                           offset))
 231         }
 232         _ => String::new(),
 233     };
 234
 235     Some(format!("{}{}", segment.identifier, params))
 236 }
 237
 238 fn format_function_type<'a, I>(inputs: I,
 239                                output: &FunctionRetTy,
 240                                span: Span,
 241                                context: &RewriteContext,
 242                                width: usize,
 243                                offset: Indent)
 244                                -> Option<String>
 245     where I: ExactSizeIterator,
 246           <I as Iterator>::Item: Deref,
 247           <I::Item as Deref>::Target: Rewrite + Spanned + 'a
 248 {
 249     // 2 for ()
 250     let budget = try_opt!(width.checked_sub(2));
 251     // 1 for (
 252     let offset = offset + 1;
 253     let list_lo = span_after(span, "(", context.codemap);
 254     let items = itemize_list(context.codemap,
 255                              inputs,
 256                              ")",
 257                              |ty| ty.span().lo,
 258                              |ty| ty.span().hi,
 259                              |ty| ty.rewrite(context, budget, offset),
 260                              list_lo,
 261                              span.hi);
 262
 263     let list_str = try_opt!(format_fn_args(items, budget, offset, context.config));
 264
 265     let output = match *output {
 266         FunctionRetTy::Return(ref ty) => {
 267             let budget = try_opt!(width.checked_sub(4));
 268             let type_str = try_opt!(ty.rewrite(context, budget, offset + 4));
 269             format!(" -> {}", type_str)
 270         }
 271         FunctionRetTy::NoReturn(..) => " -> !".to_owned(),
 272         FunctionRetTy::DefaultReturn(..) => String::new(),
 273     };
 274
 275     let infix = if output.len() + list_str.len() > width {
 276         format!("\n{}", (offset - 1).to_string(context.config))
 277     } else {
 278         String::new()
 279     };
 280
 281     Some(format!("({}){}{}", list_str, infix, output))
 282 }
 283
 284 impl Rewrite for ast::WherePredicate {
 285     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 286         // TODO: dead spans?
 287         let result = match *self {
 288             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate { ref bound_lifetimes,
 289                                                                            ref bounded_ty,
 290                                                                            ref bounds,
 291                                                                            .. }) => {
 292                 let type_str = try_opt!(bounded_ty.rewrite(context, width, offset));
 293
 294                 if !bound_lifetimes.is_empty() {
 295                     let lifetime_str = try_opt!(bound_lifetimes.iter()
 296                                                                .map(|lt| {
 297                                                                    lt.rewrite(context,
 298                                                                               width,
 299                                                                               offset)
 300                                                                })
 301                                                                .collect::<Option<Vec<_>>>())
 302                                            .join(", ");
 303                     // 8 = "for<> : ".len()
 304                     let used_width = lifetime_str.len() + type_str.len() + 8;
 305                     let budget = try_opt!(width.checked_sub(used_width));
 306                     let bounds_str = try_opt!(bounds.iter()
 307                                                     .map(|ty_bound| {
 308                                                         ty_bound.rewrite(context,
 309                                                                          budget,
 310                                                                          offset + used_width)
 311                                                     })
 312                                                     .collect::<Option<Vec<_>>>())
 313                                          .join(" + ");
 314
 315                     format!("for<{}> {}: {}", lifetime_str, type_str, bounds_str)
 316                 } else {
 317                     // 2 = ": ".len()
 318                     let used_width = type_str.len() + 2;
 319                     let budget = try_opt!(width.checked_sub(used_width));
 320                     let bounds_str = try_opt!(bounds.iter()
 321                                                     .map(|ty_bound| {
 322                                                         ty_bound.rewrite(context,
 323                                                                          budget,
 324                                                                          offset + used_width)
 325                                                     })
 326                                                     .collect::<Option<Vec<_>>>())
 327                                          .join(" + ");
 328
 329                     format!("{}: {}", type_str, bounds_str)
 330                 }
 331             }
 332             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate { ref lifetime,
 333                                                                              ref bounds,
 334                                                                              .. }) => {
 335                 format!("{}: {}",
 336                         pprust::lifetime_to_string(lifetime),
 337                         bounds.iter()
 338                               .map(pprust::lifetime_to_string)
 339                               .collect::<Vec<_>>()
 340                               .join(" + "))
 341             }
 342             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate { ref path, ref ty, .. }) => {
 343                 let ty_str = try_opt!(ty.rewrite(context, width, offset));
 344                 // 3 = " = ".len()
 345                 let used_width = 3 + ty_str.len();
 346                 let budget = try_opt!(width.checked_sub(used_width));
 347                 let path_str = try_opt!(rewrite_path(context,
 348                                                      false,
 349                                                      None,
 350                                                      path,
 351                                                      budget,
 352                                                      offset + used_width));
 353                 format!("{} = {}", path_str, ty_str)
 354             }
 355         };
 356
 357         wrap_str(result, context.config.max_width, width, offset)
 358     }
 359 }
 360
 361 impl Rewrite for ast::LifetimeDef {
 362     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 363         let result = if self.bounds.is_empty() {
 364             pprust::lifetime_to_string(&self.lifetime)
 365         } else {
 366             format!("{}: {}",
 367                     pprust::lifetime_to_string(&self.lifetime),
 368                     self.bounds
 369                         .iter()
 370                         .map(pprust::lifetime_to_string)
 371                         .collect::<Vec<_>>()
 372                         .join(" + "))
 373         };
 374
 375         wrap_str(result, context.config.max_width, width, offset)
 376     }
 377 }
 378
 379 impl Rewrite for ast::TyParamBound {
 380     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 381         match *self {
 382             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::None) => {
 383                 tref.rewrite(context, width, offset)
 384             }
 385             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::Maybe) => {
 386                 let budget = try_opt!(width.checked_sub(1));
 387                 Some(format!("?{}", try_opt!(tref.rewrite(context, budget, offset + 1))))
 388             }
 389             ast::TyParamBound::RegionTyParamBound(ref l) => {
 390                 wrap_str(pprust::lifetime_to_string(l),
 391                          context.config.max_width,
 392                          width,
 393                          offset)
 394             }
 395         }
 396     }
 397 }
 398
 399 impl Rewrite for ast::TyParamBounds {
 400     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 401         let strs: Vec<_> = try_opt!(self.iter()
 402                                         .map(|b| b.rewrite(context, width, offset))
 403                                         .collect());
 404         wrap_str(strs.join(" + "), context.config.max_width, width, offset)
 405     }
 406 }
 407
 408 impl Rewrite for ast::TyParam {
 409     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 410         let mut result = String::with_capacity(128);
 411         result.push_str(&self.ident.to_string());
 412         if !self.bounds.is_empty() {
 413             result.push_str(": ");
 414
 415             let bounds = try_opt!(self.bounds
 416                                       .iter()
 417                                       .map(|ty_bound| ty_bound.rewrite(context, width, offset))
 418                                       .collect::<Option<Vec<_>>>())
 419                              .join(" + ");
 420
 421             result.push_str(&bounds);
 422         }
 423         if let Some(ref def) = self.default {
 424             result.push_str(" = ");
 425             let budget = try_opt!(width.checked_sub(result.len()));
 426             let rewrite = try_opt!(def.rewrite(context, budget, offset + result.len()));
 427             result.push_str(&rewrite);
 428         }
 429
 430         wrap_str(result, context.config.max_width, width, offset)
 431     }
 432 }
 433
 434 impl Rewrite for ast::PolyTraitRef {
 435     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 436         if !self.bound_lifetimes.is_empty() {
 437             let lifetime_str = try_opt!(self.bound_lifetimes
 438                                             .iter()
 439                                             .map(|lt| lt.rewrite(context, width, offset))
 440                                             .collect::<Option<Vec<_>>>())
 441                                    .join(", ");
 442             // 6 is "for<> ".len()
 443             let extra_offset = lifetime_str.len() + 6;
 444             let max_path_width = try_opt!(width.checked_sub(extra_offset));
 445             let path_str = try_opt!(self.trait_ref
 446                                         .rewrite(context, max_path_width, offset + extra_offset));
 447
 448             Some(format!("for<{}> {}", lifetime_str, path_str))
 449         } else {
 450             self.trait_ref.rewrite(context, width, offset)
 451         }
 452     }
 453 }
 454
 455 impl Rewrite for ast::TraitRef {
 456     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 457         rewrite_path(context, false, None, &self.path, width, offset)
 458     }
 459 }
 460
 461 impl Rewrite for ast::Ty {
 462     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 463         match self.node {
 464             ast::TyObjectSum(ref ty, ref bounds) => {
 465                 let ty_str = try_opt!(ty.rewrite(context, width, offset));
 466                 let overhead = ty_str.len() + 3;
 467                 Some(format!("{} + {}",
 468                              ty_str,
 469                              try_opt!(bounds.rewrite(context,
 470                                                      try_opt!(width.checked_sub(overhead)),
 471                                                      offset + overhead))))
 472             }
 473             ast::TyPtr(ref mt) => {
 474                 let prefix = match mt.mutbl {
 475                     Mutability::MutMutable => "*mut ",
 476                     Mutability::MutImmutable => "*const ",
 477                 };
 478
 479                 rewrite_unary_prefix(context, prefix, &*mt.ty, width, offset)
 480             }
 481             ast::TyRptr(ref lifetime, ref mt) => {
 482                 let mut_str = format_mutability(mt.mutbl);
 483                 let mut_len = mut_str.len();
 484                 Some(match *lifetime {
 485                     Some(ref lifetime) => {
 486                         let lt_str = pprust::lifetime_to_string(lifetime);
 487                         let lt_len = lt_str.len();
 488                         let budget = try_opt!(width.checked_sub(2 + mut_len + lt_len));
 489                         format!("&{} {}{}",
 490                                 lt_str,
 491                                 mut_str,
 492                                 try_opt!(mt.ty.rewrite(context,
 493                                                        budget,
 494                                                        offset + 2 + mut_len + lt_len)))
 495                     }
 496                     None => {
 497                         let budget = try_opt!(width.checked_sub(1 + mut_len));
 498                         format!("&{}{}",
 499                                 mut_str,
 500                                 try_opt!(mt.ty.rewrite(context, budget, offset + 1 + mut_len)))
 501                     }
 502                 })
 503             }
 504             // FIXME: we drop any comments here, even though it's a silly place to put
 505             // comments.
 506             ast::TyParen(ref ty) => {
 507                 let budget = try_opt!(width.checked_sub(2));
 508                 ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("({})", ty_str))
 509             }
 510             ast::TyVec(ref ty) => {
 511                 let budget = try_opt!(width.checked_sub(2));
 512                 ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("[{}]", ty_str))
 513             }
 514             ast::TyTup(ref items) => {
 515                 rewrite_tuple(context,
 516                               items.iter().map(|x| &**x),
 517                               self.span,
 518                               width,
 519                               offset)
 520             }
 521             ast::TyPolyTraitRef(ref trait_ref) => trait_ref.rewrite(context, width, offset),
 522             ast::TyPath(ref q_self, ref path) => {
 523                 rewrite_path(context, false, q_self.as_ref(), path, width, offset)
 524             }
 525             ast::TyFixedLengthVec(ref ty, ref repeats) => {
 526                 rewrite_pair(&**ty, &**repeats, "[", "; ", "]", context, width, offset)
 527             }
 528             ast::TyInfer => {
 529                 if width >= 1 {
 530                     Some("_".to_owned())
 531                 } else {
 532                     None
 533                 }
 534             }
 535             ast::TyBareFn(ref bare_fn) => {
 536                 rewrite_bare_fn(bare_fn, self.span, context, width, offset)
 537             }
 538             ast::TyMac(..) | ast::TyTypeof(..) => unreachable!(),
 539         }
 540     }
 541 }
 542
 543 fn rewrite_bare_fn(bare_fn: &ast::BareFnTy,
 544                    span: Span,
 545                    context: &RewriteContext,
 546                    width: usize,
 547                    offset: Indent)
 548                    -> Option<String> {
 549     let mut result = String::with_capacity(128);
 550
 551     result.push_str(&::utils::format_unsafety(bare_fn.unsafety));
 552
 553     if bare_fn.abi != abi::Rust {
 554         result.push_str(&::utils::format_abi(bare_fn.abi));
 555     }
 556
 557     result.push_str("fn");
 558
 559     let budget = try_opt!(width.checked_sub(result.len()));
 560     let indent = offset + result.len();
 561
 562     let rewrite = try_opt!(format_function_type(bare_fn.decl.inputs.iter(),
 563                                                 &bare_fn.decl.output,
 564                                                 span,
 565                                                 context,
 566                                                 budget,
 567                                                 indent));
 568
 569     result.push_str(&rewrite);
 570
 571     Some(result)
 572 }