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