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) => ty.rewrite(context, width, offset),
 141             SegmentParam::Binding(ref binding) => {
 142                 let mut result = format!("{} = ", binding.ident);
 143                 let budget = try_opt!(width.checked_sub(result.len()));
 144                 let rewrite = try_opt!(binding.ty.rewrite(context, budget, offset + result.len()));
 145                 result.push_str(&rewrite);
 146                 Some(result)
 147             }
 148         }
 149     }
 150 }
 151
 152 // Formats a path segment. There are some hacks involved to correctly determine
 153 // the segment's associated span since it's not part of the AST.
 154 //
 155 // The span_lo is assumed to be greater than the end of any previous segment's
 156 // parameters and lesser or equal than the start of current segment.
 157 //
 158 // span_hi is assumed equal to the end of the entire path.
 159 //
 160 // When the segment contains a positive number of parameters, we update span_lo
 161 // so that invariants described above will hold for the next segment.
 162 fn rewrite_segment(expr_context: bool,
 163                    segment: &ast::PathSegment,
 164                    span_lo: &mut BytePos,
 165                    span_hi: BytePos,
 166                    context: &RewriteContext,
 167                    width: usize,
 168                    offset: Indent)
 169                    -> Option<String> {
 170     let ident_len = segment.identifier.to_string().len();
 171     let width = try_opt!(width.checked_sub(ident_len));
 172     let offset = offset + ident_len;
 173
 174     let params = match segment.parameters {
 175         ast::PathParameters::AngleBracketedParameters(ref data) if !data.lifetimes.is_empty() ||
 176                                                                    !data.types.is_empty() ||
 177                                                                    !data.bindings.is_empty() => {
 178             let param_list = data.lifetimes
 179                                  .iter()
 180                                  .map(SegmentParam::LifeTime)
 181                                  .chain(data.types.iter().map(|x| SegmentParam::Type(&*x)))
 182                                  .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
 183                                  .collect::<Vec<_>>();
 184
 185             let next_span_lo = param_list.last().unwrap().get_span().hi + BytePos(1);
 186             let list_lo = span_after(codemap::mk_sp(*span_lo, span_hi), "<", context.codemap);
 187             let separator = if expr_context {
 188                 "::"
 189             } else {
 190                 ""
 191             };
 192
 193             // 1 for <
 194             let extra_offset = 1 + separator.len();
 195             // 1 for >
 196             let list_width = try_opt!(width.checked_sub(extra_offset + 1));
 197
 198             let items = itemize_list(context.codemap,
 199                                      param_list.into_iter(),
 200                                      ">",
 201                                      |param| param.get_span().lo,
 202                                      |param| param.get_span().hi,
 203                                      |seg| {
 204                                          seg.rewrite(context,
 205                                                      context.config.max_width,
 206                                                      offset + extra_offset)
 207                                      },
 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) => {
 223                     let type_str = try_opt!(ty.rewrite(context, width, offset));
 224                     format!(" -> {}", type_str)
 225                 }
 226                 None => String::new(),
 227             };
 228
 229             // 2 for ()
 230             let budget = try_opt!(width.checked_sub(output.len() + 2));
 231             // 1 for (
 232             let offset = offset + 1;
 233             let list_lo = span_after(data.span, "(", context.codemap);
 234             let items = itemize_list(context.codemap,
 235                                      data.inputs.iter(),
 236                                      ")",
 237                                      |ty| ty.span.lo,
 238                                      |ty| ty.span.hi,
 239                                      |ty| ty.rewrite(context, budget, offset),
 240                                      list_lo,
 241                                      span_hi);
 242             let list_str = try_opt!(format_fn_args(items, budget, offset, context.config));
 243
 244             format!("({}){}", list_str, output)
 245         }
 246         _ => String::new(),
 247     };
 248
 249     Some(format!("{}{}", segment.identifier, params))
 250 }
 251
 252 impl Rewrite for ast::WherePredicate {
 253     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 254         // TODO: dead spans?
 255         let result = match *self {
 256             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate { ref bound_lifetimes,
 257                                                                            ref bounded_ty,
 258                                                                            ref bounds,
 259                                                                            .. }) => {
 260                 let type_str = try_opt!(bounded_ty.rewrite(context, width, offset));
 261
 262                 if !bound_lifetimes.is_empty() {
 263                     let lifetime_str = try_opt!(bound_lifetimes.iter()
 264                                                                .map(|lt| {
 265                                                                    lt.rewrite(context,
 266                                                                               width,
 267                                                                               offset)
 268                                                                })
 269                                                                .collect::<Option<Vec<_>>>())
 270                                            .join(", ");
 271                     // 8 = "for<> : ".len()
 272                     let used_width = lifetime_str.len() + type_str.len() + 8;
 273                     let budget = try_opt!(width.checked_sub(used_width));
 274                     let bounds_str = try_opt!(bounds.iter()
 275                                                     .map(|ty_bound| {
 276                                                         ty_bound.rewrite(context,
 277                                                                          budget,
 278                                                                          offset + used_width)
 279                                                     })
 280                                                     .collect::<Option<Vec<_>>>())
 281                                          .join(" + ");
 282
 283                     format!("for<{}> {}: {}", lifetime_str, type_str, bounds_str)
 284                 } else {
 285                     // 2 = ": ".len()
 286                     let used_width = type_str.len() + 2;
 287                     let budget = try_opt!(width.checked_sub(used_width));
 288                     let bounds_str = try_opt!(bounds.iter()
 289                                                     .map(|ty_bound| {
 290                                                         ty_bound.rewrite(context,
 291                                                                          budget,
 292                                                                          offset + used_width)
 293                                                     })
 294                                                     .collect::<Option<Vec<_>>>())
 295                                          .join(" + ");
 296
 297                     format!("{}: {}", type_str, bounds_str)
 298                 }
 299             }
 300             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate { ref lifetime,
 301                                                                              ref bounds,
 302                                                                              .. }) => {
 303                 format!("{}: {}",
 304                         pprust::lifetime_to_string(lifetime),
 305                         bounds.iter()
 306                               .map(pprust::lifetime_to_string)
 307                               .collect::<Vec<_>>()
 308                               .join(" + "))
 309             }
 310             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate { ref path, ref ty, .. }) => {
 311                 let ty_str = try_opt!(ty.rewrite(context, width, offset));
 312                 // 3 = " = ".len()
 313                 let used_width = 3 + ty_str.len();
 314                 let budget = try_opt!(width.checked_sub(used_width));
 315                 let path_str = try_opt!(rewrite_path(context,
 316                                                      false,
 317                                                      None,
 318                                                      path,
 319                                                      budget,
 320                                                      offset + used_width));
 321                 format!("{} = {}", path_str, ty_str)
 322             }
 323         };
 324
 325         wrap_str(result, context.config.max_width, width, offset)
 326     }
 327 }
 328
 329 impl Rewrite for ast::LifetimeDef {
 330     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 331         let result = if self.bounds.is_empty() {
 332             pprust::lifetime_to_string(&self.lifetime)
 333         } else {
 334             format!("{}: {}",
 335                     pprust::lifetime_to_string(&self.lifetime),
 336                     self.bounds
 337                         .iter()
 338                         .map(pprust::lifetime_to_string)
 339                         .collect::<Vec<_>>()
 340                         .join(" + "))
 341         };
 342
 343         wrap_str(result, context.config.max_width, width, offset)
 344     }
 345 }
 346
 347 impl Rewrite for ast::TyParamBound {
 348     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 349         match *self {
 350             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::None) => {
 351                 tref.rewrite(context, width, offset)
 352             }
 353             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::Maybe) => {
 354                 let budget = try_opt!(width.checked_sub(1));
 355                 Some(format!("?{}", try_opt!(tref.rewrite(context, budget, offset + 1))))
 356             }
 357             ast::TyParamBound::RegionTyParamBound(ref l) => {
 358                 wrap_str(pprust::lifetime_to_string(l),
 359                          context.config.max_width,
 360                          width,
 361                          offset)
 362             }
 363         }
 364     }
 365 }
 366
 367 impl Rewrite for ast::TyParamBounds {
 368     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 369         let strs: Vec<_> = try_opt!(self.iter()
 370                                         .map(|b| b.rewrite(context, width, offset))
 371                                         .collect());
 372         wrap_str(strs.join(" + "), context.config.max_width, width, offset)
 373     }
 374 }
 375
 376 impl Rewrite for ast::TyParam {
 377     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 378         let mut result = String::with_capacity(128);
 379         result.push_str(&self.ident.to_string());
 380         if !self.bounds.is_empty() {
 381             result.push_str(": ");
 382
 383             let bounds = try_opt!(self.bounds
 384                                       .iter()
 385                                       .map(|ty_bound| ty_bound.rewrite(context, width, offset))
 386                                       .collect::<Option<Vec<_>>>())
 387                              .join(" + ");
 388
 389             result.push_str(&bounds);
 390         }
 391         if let Some(ref def) = self.default {
 392             result.push_str(" = ");
 393             let budget = try_opt!(width.checked_sub(result.len()));
 394             let rewrite = try_opt!(def.rewrite(context, budget, offset + result.len()));
 395             result.push_str(&rewrite);
 396         }
 397
 398         wrap_str(result, context.config.max_width, width, offset)
 399     }
 400 }
 401
 402 impl Rewrite for ast::PolyTraitRef {
 403     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 404         if !self.bound_lifetimes.is_empty() {
 405             let lifetime_str = try_opt!(self.bound_lifetimes
 406                                             .iter()
 407                                             .map(|lt| lt.rewrite(context, width, offset))
 408                                             .collect::<Option<Vec<_>>>())
 409                                    .join(", ");
 410             // 6 is "for<> ".len()
 411             let extra_offset = lifetime_str.len() + 6;
 412             let max_path_width = try_opt!(width.checked_sub(extra_offset));
 413             let path_str = try_opt!(rewrite_path(context,
 414                                                  false,
 415                                                  None,
 416                                                  &self.trait_ref.path,
 417                                                  max_path_width,
 418                                                  offset + extra_offset));
 419
 420             Some(format!("for<{}> {}", lifetime_str, path_str))
 421         } else {
 422             rewrite_path(context, false, None, &self.trait_ref.path, width, offset)
 423         }
 424     }
 425 }
 426
 427 impl Rewrite for ast::Ty {
 428     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 429         match self.node {
 430             ast::TyObjectSum(ref ty, ref bounds) => {
 431                 let ty_str = try_opt!(ty.rewrite(context, width, offset));
 432                 let overhead = ty_str.len() + 3;
 433                 Some(format!("{} + {}",
 434                              ty_str,
 435                              try_opt!(bounds.rewrite(context,
 436                                                      try_opt!(width.checked_sub(overhead)),
 437                                                      offset + overhead))))
 438             }
 439             ast::TyPtr(ref mt) => {
 440                 let prefix = match mt.mutbl {
 441                     Mutability::MutMutable => "*mut ",
 442                     Mutability::MutImmutable => "*const ",
 443                 };
 444
 445                 rewrite_unary_prefix(context, prefix, &*mt.ty, width, offset)
 446             }
 447             ast::TyRptr(ref lifetime, ref mt) => {
 448                 let mut_str = format_mutability(mt.mutbl);
 449                 let mut_len = mut_str.len();
 450                 Some(match *lifetime {
 451                     Some(ref lifetime) => {
 452                         let lt_str = pprust::lifetime_to_string(lifetime);
 453                         let lt_len = lt_str.len();
 454                         let budget = try_opt!(width.checked_sub(2 + mut_len + lt_len));
 455                         format!("&{} {}{}",
 456                                 lt_str,
 457                                 mut_str,
 458                                 try_opt!(mt.ty.rewrite(context,
 459                                                        budget,
 460                                                        offset + 2 + mut_len + lt_len)))
 461                     }
 462                     None => {
 463                         let budget = try_opt!(width.checked_sub(1 + mut_len));
 464                         format!("&{}{}",
 465                                 mut_str,
 466                                 try_opt!(mt.ty.rewrite(context, budget, offset + 1 + mut_len)))
 467                     }
 468                 })
 469             }
 470             // FIXME: we drop any comments here, even though it's a silly place to put
 471             // comments.
 472             ast::TyParen(ref ty) => {
 473                 let budget = try_opt!(width.checked_sub(2));
 474                 ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("({})", ty_str))
 475             }
 476             ast::TyVec(ref ty) => {
 477                 let budget = try_opt!(width.checked_sub(2));
 478                 ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("[{}]", ty_str))
 479             }
 480             ast::TyTup(ref items) => rewrite_tuple(context, items, self.span, width, offset),
 481             ast::TyPolyTraitRef(ref trait_ref) => trait_ref.rewrite(context, width, offset),
 482             ast::TyPath(ref q_self, ref path) => {
 483                 rewrite_path(context, false, q_self.as_ref(), path, width, offset)
 484             }
 485             ast::TyFixedLengthVec(ref ty, ref repeats) => {
 486                 rewrite_pair(&**ty, &**repeats, "[", "; ", "]", context, width, offset)
 487             }
 488             ast::TyInfer => {
 489                 if width >= 1 {
 490                     Some("_".to_owned())
 491                 } else {
 492                     None
 493                 }
 494             }
 495             ast::TyBareFn(..) => {
 496                 wrap_str(pprust::ty_to_string(self),
 497                          context.config.max_width,
 498                          width,
 499                          offset)
 500             }
 501             ast::TyMac(..) | ast::TyTypeof(..) => unreachable!(),
 502         }
 503     }
 504 }