src/libsyntax_pos/lib.rs

   1 // Copyright 2012-2013 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 //! The source positions and related helper functions
  12 //!
  13 //! # Note
  14 //!
  15 //! This API is completely unstable and subject to change.
  16
  17 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  18       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  19       html_root_url = "https://doc.rust-lang.org/nightly/")]
  20
  21 #![feature(const_fn)]
  22 #![feature(crate_visibility_modifier)]
  23 #![feature(custom_attribute)]
  24 #![feature(nll)]
  25 #![feature(non_exhaustive)]
  26 #![feature(optin_builtin_traits)]
  27 #![feature(specialization)]
  28 #![cfg_attr(not(stage0), feature(stdsimd))]
  29
  30 use std::borrow::Cow;
  31 use std::cell::Cell;
  32 use std::cmp::{self, Ordering};
  33 use std::fmt;
  34 use std::hash::{Hasher, Hash};
  35 use std::ops::{Add, Sub};
  36 use std::path::PathBuf;
  37
  38 use rustc_data_structures::stable_hasher::StableHasher;
  39 use rustc_data_structures::sync::{Lrc, Lock};
  40
  41 extern crate arena;
  42 extern crate rustc_data_structures;
  43
  44 #[macro_use]
  45 extern crate scoped_tls;
  46
  47 use serialize::{Encodable, Decodable, Encoder, Decoder};
  48
  49 extern crate serialize;
  50 extern crate serialize as rustc_serialize; // used by deriving
  51
  52 #[macro_use]
  53 extern crate cfg_if;
  54
  55 extern crate unicode_width;
  56
  57 pub mod edition;
  58 pub mod hygiene;
  59 pub use hygiene::{Mark, SyntaxContext, ExpnInfo, ExpnFormat, CompilerDesugaringKind};
  60
  61 mod span_encoding;
  62 pub use span_encoding::{Span, DUMMY_SP};
  63
  64 pub mod symbol;
  65
  66 mod analyze_source_file;
  67
  68 pub struct Globals {
  69     symbol_interner: Lock<symbol::Interner>,
  70     span_interner: Lock<span_encoding::SpanInterner>,
  71     hygiene_data: Lock<hygiene::HygieneData>,
  72 }
  73
  74 impl Globals {
  75     pub fn new() -> Globals {
  76         Globals {
  77             symbol_interner: Lock::new(symbol::Interner::fresh()),
  78             span_interner: Lock::new(span_encoding::SpanInterner::default()),
  79             hygiene_data: Lock::new(hygiene::HygieneData::new()),
  80         }
  81     }
  82 }
  83
  84 scoped_thread_local!(pub static GLOBALS: Globals);
  85
  86 /// Differentiates between real files and common virtual files
  87 #[derive(Debug, Eq, PartialEq, Clone, Ord, PartialOrd, Hash, RustcDecodable, RustcEncodable)]
  88 pub enum FileName {
  89     Real(PathBuf),
  90     /// A macro.  This includes the full name of the macro, so that there are no clashes.
  91     Macros(String),
  92     /// call to `quote!`
  93     QuoteExpansion,
  94     /// Command line
  95     Anon,
  96     /// Hack in src/libsyntax/parse.rs
  97     /// FIXME(jseyfried)
  98     MacroExpansion,
  99     ProcMacroSourceCode,
 100     /// Strings provided as --cfg [cfgspec] stored in a crate_cfg
 101     CfgSpec,
 102     /// Strings provided as crate attributes in the CLI
 103     CliCrateAttr,
 104     /// Custom sources for explicit parser calls from plugins and drivers
 105     Custom(String),
 106 }
 107
 108 impl std::fmt::Display for FileName {
 109     fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
 110         use self::FileName::*;
 111         match *self {
 112             Real(ref path) => write!(fmt, "{}", path.display()),
 113             Macros(ref name) => write!(fmt, "<{} macros>", name),
 114             QuoteExpansion => write!(fmt, "<quote expansion>"),
 115             MacroExpansion => write!(fmt, "<macro expansion>"),
 116             Anon => write!(fmt, "<anon>"),
 117             ProcMacroSourceCode => write!(fmt, "<proc-macro source code>"),
 118             CfgSpec => write!(fmt, "cfgspec"),
 119             CliCrateAttr => write!(fmt, "<crate attribute>"),
 120             Custom(ref s) => write!(fmt, "<{}>", s),
 121         }
 122     }
 123 }
 124
 125 impl From<PathBuf> for FileName {
 126     fn from(p: PathBuf) -> Self {
 127         assert!(!p.to_string_lossy().ends_with('>'));
 128         FileName::Real(p)
 129     }
 130 }
 131
 132 impl FileName {
 133     pub fn is_real(&self) -> bool {
 134         use self::FileName::*;
 135         match *self {
 136             Real(_) => true,
 137             Macros(_) |
 138             Anon |
 139             MacroExpansion |
 140             ProcMacroSourceCode |
 141             CfgSpec |
 142             CliCrateAttr |
 143             Custom(_) |
 144             QuoteExpansion => false,
 145         }
 146     }
 147
 148     pub fn is_macros(&self) -> bool {
 149         use self::FileName::*;
 150         match *self {
 151             Real(_) |
 152             Anon |
 153             MacroExpansion |
 154             ProcMacroSourceCode |
 155             CfgSpec |
 156             CliCrateAttr |
 157             Custom(_) |
 158             QuoteExpansion => false,
 159             Macros(_) => true,
 160         }
 161     }
 162 }
 163
 164 /// Spans represent a region of code, used for error reporting. Positions in spans
 165 /// are *absolute* positions from the beginning of the source_map, not positions
 166 /// relative to SourceFiles. Methods on the SourceMap can be used to relate spans back
 167 /// to the original source.
 168 /// You must be careful if the span crosses more than one file - you will not be
 169 /// able to use many of the functions on spans in source_map and you cannot assume
 170 /// that the length of the span = hi - lo; there may be space in the BytePos
 171 /// range between files.
 172 ///
 173 /// `SpanData` is public because `Span` uses a thread-local interner and can't be
 174 /// sent to other threads, but some pieces of performance infra run in a separate thread.
 175 /// Using `Span` is generally preferred.
 176 #[derive(Clone, Copy, Hash, PartialEq, Eq, Ord, PartialOrd)]
 177 pub struct SpanData {
 178     pub lo: BytePos,
 179     pub hi: BytePos,
 180     /// Information about where the macro came from, if this piece of
 181     /// code was created by a macro expansion.
 182     pub ctxt: SyntaxContext,
 183 }
 184
 185 impl SpanData {
 186     #[inline]
 187     pub fn with_lo(&self, lo: BytePos) -> Span {
 188         Span::new(lo, self.hi, self.ctxt)
 189     }
 190     #[inline]
 191     pub fn with_hi(&self, hi: BytePos) -> Span {
 192         Span::new(self.lo, hi, self.ctxt)
 193     }
 194     #[inline]
 195     pub fn with_ctxt(&self, ctxt: SyntaxContext) -> Span {
 196         Span::new(self.lo, self.hi, ctxt)
 197     }
 198 }
 199
 200 // The interner is pointed to by a thread local value which is only set on the main thread
 201 // with parallelization is disabled. So we don't allow Span to transfer between threads
 202 // to avoid panics and other errors, even though it would be memory safe to do so.
 203 #[cfg(not(parallel_queries))]
 204 impl !Send for Span {}
 205 #[cfg(not(parallel_queries))]
 206 impl !Sync for Span {}
 207
 208 impl PartialOrd for Span {
 209     fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> {
 210         PartialOrd::partial_cmp(&self.data(), &rhs.data())
 211     }
 212 }
 213 impl Ord for Span {
 214     fn cmp(&self, rhs: &Self) -> Ordering {
 215         Ord::cmp(&self.data(), &rhs.data())
 216     }
 217 }
 218
 219 /// A collection of spans. Spans have two orthogonal attributes:
 220 ///
 221 /// - they can be *primary spans*. In this case they are the locus of
 222 ///   the error, and would be rendered with `^^^`.
 223 /// - they can have a *label*. In this case, the label is written next
 224 ///   to the mark in the snippet when we render.
 225 #[derive(Clone, Debug, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
 226 pub struct MultiSpan {
 227     primary_spans: Vec<Span>,
 228     span_labels: Vec<(Span, String)>,
 229 }
 230
 231 impl Span {
 232     #[inline]
 233     pub fn lo(self) -> BytePos {
 234         self.data().lo
 235     }
 236     #[inline]
 237     pub fn with_lo(self, lo: BytePos) -> Span {
 238         self.data().with_lo(lo)
 239     }
 240     #[inline]
 241     pub fn hi(self) -> BytePos {
 242         self.data().hi
 243     }
 244     #[inline]
 245     pub fn with_hi(self, hi: BytePos) -> Span {
 246         self.data().with_hi(hi)
 247     }
 248     #[inline]
 249     pub fn ctxt(self) -> SyntaxContext {
 250         self.data().ctxt
 251     }
 252     #[inline]
 253     pub fn with_ctxt(self, ctxt: SyntaxContext) -> Span {
 254         self.data().with_ctxt(ctxt)
 255     }
 256
 257     /// Returns `true` if this is a dummy span with any hygienic context.
 258     #[inline]
 259     pub fn is_dummy(self) -> bool {
 260         let span = self.data();
 261         span.lo.0 == 0 && span.hi.0 == 0
 262     }
 263
 264     /// Returns a new span representing an empty span at the beginning of this span
 265     #[inline]
 266     pub fn shrink_to_lo(self) -> Span {
 267         let span = self.data();
 268         span.with_hi(span.lo)
 269     }
 270     /// Returns a new span representing an empty span at the end of this span
 271     #[inline]
 272     pub fn shrink_to_hi(self) -> Span {
 273         let span = self.data();
 274         span.with_lo(span.hi)
 275     }
 276
 277     /// Returns `self` if `self` is not the dummy span, and `other` otherwise.
 278     pub fn substitute_dummy(self, other: Span) -> Span {
 279         if self.is_dummy() { other } else { self }
 280     }
 281
 282     /// Return true if `self` fully encloses `other`.
 283     pub fn contains(self, other: Span) -> bool {
 284         let span = self.data();
 285         let other = other.data();
 286         span.lo <= other.lo && other.hi <= span.hi
 287     }
 288
 289     /// Return true if the spans are equal with regards to the source text.
 290     ///
 291     /// Use this instead of `==` when either span could be generated code,
 292     /// and you only care that they point to the same bytes of source text.
 293     pub fn source_equal(&self, other: &Span) -> bool {
 294         let span = self.data();
 295         let other = other.data();
 296         span.lo == other.lo && span.hi == other.hi
 297     }
 298
 299     /// Returns `Some(span)`, where the start is trimmed by the end of `other`
 300     pub fn trim_start(self, other: Span) -> Option<Span> {
 301         let span = self.data();
 302         let other = other.data();
 303         if span.hi > other.hi {
 304             Some(span.with_lo(cmp::max(span.lo, other.hi)))
 305         } else {
 306             None
 307         }
 308     }
 309
 310     /// Return the source span - this is either the supplied span, or the span for
 311     /// the macro callsite that expanded to it.
 312     pub fn source_callsite(self) -> Span {
 313         self.ctxt().outer().expn_info().map(|info| info.call_site.source_callsite()).unwrap_or(self)
 314     }
 315
 316     /// The `Span` for the tokens in the previous macro expansion from which `self` was generated,
 317     /// if any
 318     pub fn parent(self) -> Option<Span> {
 319         self.ctxt().outer().expn_info().map(|i| i.call_site)
 320     }
 321
 322     /// Edition of the crate from which this span came.
 323     pub fn edition(self) -> edition::Edition {
 324         self.ctxt().outer().expn_info().map_or_else(|| hygiene::default_edition(),
 325                                                     |einfo| einfo.edition)
 326     }
 327
 328     #[inline]
 329     pub fn rust_2015(&self) -> bool {
 330         self.edition() == edition::Edition::Edition2015
 331     }
 332
 333     #[inline]
 334     pub fn rust_2018(&self) -> bool {
 335         self.edition() >= edition::Edition::Edition2018
 336     }
 337
 338     /// Return the source callee.
 339     ///
 340     /// Returns `None` if the supplied span has no expansion trace,
 341     /// else returns the `ExpnInfo` for the macro definition
 342     /// corresponding to the source callsite.
 343     pub fn source_callee(self) -> Option<ExpnInfo> {
 344         fn source_callee(info: ExpnInfo) -> ExpnInfo {
 345             match info.call_site.ctxt().outer().expn_info() {
 346                 Some(info) => source_callee(info),
 347                 None => info,
 348             }
 349         }
 350         self.ctxt().outer().expn_info().map(source_callee)
 351     }
 352
 353     /// Check if a span is "internal" to a macro in which #[unstable]
 354     /// items can be used (that is, a macro marked with
 355     /// `#[allow_internal_unstable]`).
 356     pub fn allows_unstable(&self) -> bool {
 357         match self.ctxt().outer().expn_info() {
 358             Some(info) => info.allow_internal_unstable,
 359             None => false,
 360         }
 361     }
 362
 363     /// Check if this span arises from a compiler desugaring of kind `kind`.
 364     pub fn is_compiler_desugaring(&self, kind: CompilerDesugaringKind) -> bool {
 365         match self.ctxt().outer().expn_info() {
 366             Some(info) => match info.format {
 367                 ExpnFormat::CompilerDesugaring(k) => k == kind,
 368                 _ => false,
 369             },
 370             None => false,
 371         }
 372     }
 373
 374     /// Return the compiler desugaring that created this span, or None
 375     /// if this span is not from a desugaring.
 376     pub fn compiler_desugaring_kind(&self) -> Option<CompilerDesugaringKind> {
 377         match self.ctxt().outer().expn_info() {
 378             Some(info) => match info.format {
 379                 ExpnFormat::CompilerDesugaring(k) => Some(k),
 380                 _ => None
 381             },
 382             None => None
 383         }
 384     }
 385
 386     /// Check if a span is "internal" to a macro in which `unsafe`
 387     /// can be used without triggering the `unsafe_code` lint
 388     //  (that is, a macro marked with `#[allow_internal_unsafe]`).
 389     pub fn allows_unsafe(&self) -> bool {
 390         match self.ctxt().outer().expn_info() {
 391             Some(info) => info.allow_internal_unsafe,
 392             None => false,
 393         }
 394     }
 395
 396     pub fn macro_backtrace(mut self) -> Vec<MacroBacktrace> {
 397         let mut prev_span = DUMMY_SP;
 398         let mut result = vec![];
 399         while let Some(info) = self.ctxt().outer().expn_info() {
 400             // Don't print recursive invocations
 401             if !info.call_site.source_equal(&prev_span) {
 402                 let (pre, post) = match info.format {
 403                     ExpnFormat::MacroAttribute(..) => ("#[", "]"),
 404                     ExpnFormat::MacroBang(..) => ("", "!"),
 405                     ExpnFormat::CompilerDesugaring(..) => ("desugaring of `", "`"),
 406                 };
 407                 result.push(MacroBacktrace {
 408                     call_site: info.call_site,
 409                     macro_decl_name: format!("{}{}{}", pre, info.format.name(), post),
 410                     def_site_span: info.def_site,
 411                 });
 412             }
 413
 414             prev_span = self;
 415             self = info.call_site;
 416         }
 417         result
 418     }
 419
 420     /// Return a `Span` that would enclose both `self` and `end`.
 421     pub fn to(self, end: Span) -> Span {
 422         let span_data = self.data();
 423         let end_data = end.data();
 424         // FIXME(jseyfried): self.ctxt should always equal end.ctxt here (c.f. issue #23480)
 425         // Return the macro span on its own to avoid weird diagnostic output. It is preferable to
 426         // have an incomplete span than a completely nonsensical one.
 427         if span_data.ctxt != end_data.ctxt {
 428             if span_data.ctxt == SyntaxContext::empty() {
 429                 return end;
 430             } else if end_data.ctxt == SyntaxContext::empty() {
 431                 return self;
 432             }
 433             // both span fall within a macro
 434             // FIXME(estebank) check if it is the *same* macro
 435         }
 436         Span::new(
 437             cmp::min(span_data.lo, end_data.lo),
 438             cmp::max(span_data.hi, end_data.hi),
 439             if span_data.ctxt == SyntaxContext::empty() { end_data.ctxt } else { span_data.ctxt },
 440         )
 441     }
 442
 443     /// Return a `Span` between the end of `self` to the beginning of `end`.
 444     pub fn between(self, end: Span) -> Span {
 445         let span = self.data();
 446         let end = end.data();
 447         Span::new(
 448             span.hi,
 449             end.lo,
 450             if end.ctxt == SyntaxContext::empty() { end.ctxt } else { span.ctxt },
 451         )
 452     }
 453
 454     /// Return a `Span` between the beginning of `self` to the beginning of `end`.
 455     pub fn until(self, end: Span) -> Span {
 456         let span = self.data();
 457         let end = end.data();
 458         Span::new(
 459             span.lo,
 460             end.lo,
 461             if end.ctxt == SyntaxContext::empty() { end.ctxt } else { span.ctxt },
 462         )
 463     }
 464
 465     pub fn from_inner_byte_pos(self, start: usize, end: usize) -> Span {
 466         let span = self.data();
 467         Span::new(span.lo + BytePos::from_usize(start),
 468                   span.lo + BytePos::from_usize(end),
 469                   span.ctxt)
 470     }
 471
 472     #[inline]
 473     pub fn apply_mark(self, mark: Mark) -> Span {
 474         let span = self.data();
 475         span.with_ctxt(span.ctxt.apply_mark(mark))
 476     }
 477
 478     #[inline]
 479     pub fn remove_mark(&mut self) -> Mark {
 480         let mut span = self.data();
 481         let mark = span.ctxt.remove_mark();
 482         *self = Span::new(span.lo, span.hi, span.ctxt);
 483         mark
 484     }
 485
 486     #[inline]
 487     pub fn adjust(&mut self, expansion: Mark) -> Option<Mark> {
 488         let mut span = self.data();
 489         let mark = span.ctxt.adjust(expansion);
 490         *self = Span::new(span.lo, span.hi, span.ctxt);
 491         mark
 492     }
 493
 494     #[inline]
 495     pub fn glob_adjust(&mut self, expansion: Mark, glob_ctxt: SyntaxContext)
 496                        -> Option<Option<Mark>> {
 497         let mut span = self.data();
 498         let mark = span.ctxt.glob_adjust(expansion, glob_ctxt);
 499         *self = Span::new(span.lo, span.hi, span.ctxt);
 500         mark
 501     }
 502
 503     #[inline]
 504     pub fn reverse_glob_adjust(&mut self, expansion: Mark, glob_ctxt: SyntaxContext)
 505                                -> Option<Option<Mark>> {
 506         let mut span = self.data();
 507         let mark = span.ctxt.reverse_glob_adjust(expansion, glob_ctxt);
 508         *self = Span::new(span.lo, span.hi, span.ctxt);
 509         mark
 510     }
 511
 512     #[inline]
 513     pub fn modern(self) -> Span {
 514         let span = self.data();
 515         span.with_ctxt(span.ctxt.modern())
 516     }
 517
 518     #[inline]
 519     pub fn modern_and_legacy(self) -> Span {
 520         let span = self.data();
 521         span.with_ctxt(span.ctxt.modern_and_legacy())
 522     }
 523 }
 524
 525 #[derive(Clone, Debug)]
 526 pub struct SpanLabel {
 527     /// The span we are going to include in the final snippet.
 528     pub span: Span,
 529
 530     /// Is this a primary span? This is the "locus" of the message,
 531     /// and is indicated with a `^^^^` underline, versus `----`.
 532     pub is_primary: bool,
 533
 534     /// What label should we attach to this span (if any)?
 535     pub label: Option<String>,
 536 }
 537
 538 impl Default for Span {
 539     fn default() -> Self {
 540         DUMMY_SP
 541     }
 542 }
 543
 544 impl serialize::UseSpecializedEncodable for Span {
 545     fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 546         let span = self.data();
 547         s.emit_struct("Span", 2, |s| {
 548             s.emit_struct_field("lo", 0, |s| {
 549                 span.lo.encode(s)
 550             })?;
 551
 552             s.emit_struct_field("hi", 1, |s| {
 553                 span.hi.encode(s)
 554             })
 555         })
 556     }
 557 }
 558
 559 impl serialize::UseSpecializedDecodable for Span {
 560     fn default_decode<D: Decoder>(d: &mut D) -> Result<Span, D::Error> {
 561         d.read_struct("Span", 2, |d| {
 562             let lo = d.read_struct_field("lo", 0, Decodable::decode)?;
 563             let hi = d.read_struct_field("hi", 1, Decodable::decode)?;
 564             Ok(Span::new(lo, hi, NO_EXPANSION))
 565         })
 566     }
 567 }
 568
 569 fn default_span_debug(span: Span, f: &mut fmt::Formatter) -> fmt::Result {
 570     f.debug_struct("Span")
 571         .field("lo", &span.lo())
 572         .field("hi", &span.hi())
 573         .field("ctxt", &span.ctxt())
 574         .finish()
 575 }
 576
 577 impl fmt::Debug for Span {
 578     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 579         SPAN_DEBUG.with(|span_debug| span_debug.get()(*self, f))
 580     }
 581 }
 582
 583 impl fmt::Debug for SpanData {
 584     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 585         SPAN_DEBUG.with(|span_debug| span_debug.get()(Span::new(self.lo, self.hi, self.ctxt), f))
 586     }
 587 }
 588
 589 impl MultiSpan {
 590     #[inline]
 591     pub fn new() -> MultiSpan {
 592         MultiSpan {
 593             primary_spans: vec![],
 594             span_labels: vec![]
 595         }
 596     }
 597
 598     pub fn from_span(primary_span: Span) -> MultiSpan {
 599         MultiSpan {
 600             primary_spans: vec![primary_span],
 601             span_labels: vec![]
 602         }
 603     }
 604
 605     pub fn from_spans(vec: Vec<Span>) -> MultiSpan {
 606         MultiSpan {
 607             primary_spans: vec,
 608             span_labels: vec![]
 609         }
 610     }
 611
 612     pub fn push_span_label(&mut self, span: Span, label: String) {
 613         self.span_labels.push((span, label));
 614     }
 615
 616     /// Selects the first primary span (if any)
 617     pub fn primary_span(&self) -> Option<Span> {
 618         self.primary_spans.first().cloned()
 619     }
 620
 621     /// Returns all primary spans.
 622     pub fn primary_spans(&self) -> &[Span] {
 623         &self.primary_spans
 624     }
 625
 626     /// Returns `true` if this contains only a dummy primary span with any hygienic context.
 627     pub fn is_dummy(&self) -> bool {
 628         let mut is_dummy = true;
 629         for span in &self.primary_spans {
 630             if !span.is_dummy() {
 631                 is_dummy = false;
 632             }
 633         }
 634         is_dummy
 635     }
 636
 637     /// Replaces all occurrences of one Span with another. Used to move Spans in areas that don't
 638     /// display well (like std macros). Returns true if replacements occurred.
 639     pub fn replace(&mut self, before: Span, after: Span) -> bool {
 640         let mut replacements_occurred = false;
 641         for primary_span in &mut self.primary_spans {
 642             if *primary_span == before {
 643                 *primary_span = after;
 644                 replacements_occurred = true;
 645             }
 646         }
 647         for span_label in &mut self.span_labels {
 648             if span_label.0 == before {
 649                 span_label.0 = after;
 650                 replacements_occurred = true;
 651             }
 652         }
 653         replacements_occurred
 654     }
 655
 656     /// Returns the strings to highlight. We always ensure that there
 657     /// is an entry for each of the primary spans -- for each primary
 658     /// span P, if there is at least one label with span P, we return
 659     /// those labels (marked as primary). But otherwise we return
 660     /// `SpanLabel` instances with empty labels.
 661     pub fn span_labels(&self) -> Vec<SpanLabel> {
 662         let is_primary = |span| self.primary_spans.contains(&span);
 663
 664         let mut span_labels = self.span_labels.iter().map(|&(span, ref label)|
 665             SpanLabel {
 666                 span,
 667                 is_primary: is_primary(span),
 668                 label: Some(label.clone())
 669             }
 670         ).collect::<Vec<_>>();
 671
 672         for &span in &self.primary_spans {
 673             if !span_labels.iter().any(|sl| sl.span == span) {
 674                 span_labels.push(SpanLabel {
 675                     span,
 676                     is_primary: true,
 677                     label: None
 678                 });
 679             }
 680         }
 681
 682         span_labels
 683     }
 684 }
 685
 686 impl From<Span> for MultiSpan {
 687     fn from(span: Span) -> MultiSpan {
 688         MultiSpan::from_span(span)
 689     }
 690 }
 691
 692 impl From<Vec<Span>> for MultiSpan {
 693     fn from(spans: Vec<Span>) -> MultiSpan {
 694         MultiSpan::from_spans(spans)
 695     }
 696 }
 697
 698 pub const NO_EXPANSION: SyntaxContext = SyntaxContext::empty();
 699
 700 /// Identifies an offset of a multi-byte character in a SourceFile
 701 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Eq, PartialEq, Debug)]
 702 pub struct MultiByteChar {
 703     /// The absolute offset of the character in the SourceMap
 704     pub pos: BytePos,
 705     /// The number of bytes, >=2
 706     pub bytes: u8,
 707 }
 708
 709 /// Identifies an offset of a non-narrow character in a SourceFile
 710 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Eq, PartialEq, Debug)]
 711 pub enum NonNarrowChar {
 712     /// Represents a zero-width character
 713     ZeroWidth(BytePos),
 714     /// Represents a wide (fullwidth) character
 715     Wide(BytePos),
 716     /// Represents a tab character, represented visually with a width of 4 characters
 717     Tab(BytePos),
 718 }
 719
 720 impl NonNarrowChar {
 721     fn new(pos: BytePos, width: usize) -> Self {
 722         match width {
 723             0 => NonNarrowChar::ZeroWidth(pos),
 724             2 => NonNarrowChar::Wide(pos),
 725             4 => NonNarrowChar::Tab(pos),
 726             _ => panic!("width {} given for non-narrow character", width),
 727         }
 728     }
 729
 730     /// Returns the absolute offset of the character in the SourceMap
 731     pub fn pos(&self) -> BytePos {
 732         match *self {
 733             NonNarrowChar::ZeroWidth(p) |
 734             NonNarrowChar::Wide(p) |
 735             NonNarrowChar::Tab(p) => p,
 736         }
 737     }
 738
 739     /// Returns the width of the character, 0 (zero-width) or 2 (wide)
 740     pub fn width(&self) -> usize {
 741         match *self {
 742             NonNarrowChar::ZeroWidth(_) => 0,
 743             NonNarrowChar::Wide(_) => 2,
 744             NonNarrowChar::Tab(_) => 4,
 745         }
 746     }
 747 }
 748
 749 impl Add<BytePos> for NonNarrowChar {
 750     type Output = Self;
 751
 752     fn add(self, rhs: BytePos) -> Self {
 753         match self {
 754             NonNarrowChar::ZeroWidth(pos) => NonNarrowChar::ZeroWidth(pos + rhs),
 755             NonNarrowChar::Wide(pos) => NonNarrowChar::Wide(pos + rhs),
 756             NonNarrowChar::Tab(pos) => NonNarrowChar::Tab(pos + rhs),
 757         }
 758     }
 759 }
 760
 761 impl Sub<BytePos> for NonNarrowChar {
 762     type Output = Self;
 763
 764     fn sub(self, rhs: BytePos) -> Self {
 765         match self {
 766             NonNarrowChar::ZeroWidth(pos) => NonNarrowChar::ZeroWidth(pos - rhs),
 767             NonNarrowChar::Wide(pos) => NonNarrowChar::Wide(pos - rhs),
 768             NonNarrowChar::Tab(pos) => NonNarrowChar::Tab(pos - rhs),
 769         }
 770     }
 771 }
 772
 773 /// The state of the lazy external source loading mechanism of a SourceFile.
 774 #[derive(PartialEq, Eq, Clone)]
 775 pub enum ExternalSource {
 776     /// The external source has been loaded already.
 777     Present(String),
 778     /// No attempt has been made to load the external source.
 779     AbsentOk,
 780     /// A failed attempt has been made to load the external source.
 781     AbsentErr,
 782     /// No external source has to be loaded, since the SourceFile represents a local crate.
 783     Unneeded,
 784 }
 785
 786 impl ExternalSource {
 787     pub fn is_absent(&self) -> bool {
 788         match *self {
 789             ExternalSource::Present(_) => false,
 790             _ => true,
 791         }
 792     }
 793
 794     pub fn get_source(&self) -> Option<&str> {
 795         match *self {
 796             ExternalSource::Present(ref src) => Some(src),
 797             _ => None,
 798         }
 799     }
 800 }
 801
 802 /// A single source in the SourceMap.
 803 #[derive(Clone)]
 804 pub struct SourceFile {
 805     /// The name of the file that the source came from, source that doesn't
 806     /// originate from files has names between angle brackets by convention,
 807     /// e.g. `<anon>`
 808     pub name: FileName,
 809     /// True if the `name` field above has been modified by --remap-path-prefix
 810     pub name_was_remapped: bool,
 811     /// The unmapped path of the file that the source came from.
 812     /// Set to `None` if the SourceFile was imported from an external crate.
 813     pub unmapped_path: Option<FileName>,
 814     /// Indicates which crate this SourceFile was imported from.
 815     pub crate_of_origin: u32,
 816     /// The complete source code
 817     pub src: Option<Lrc<String>>,
 818     /// The source code's hash
 819     pub src_hash: u128,
 820     /// The external source code (used for external crates, which will have a `None`
 821     /// value as `self.src`.
 822     pub external_src: Lock<ExternalSource>,
 823     /// The start position of this source in the SourceMap
 824     pub start_pos: BytePos,
 825     /// The end position of this source in the SourceMap
 826     pub end_pos: BytePos,
 827     /// Locations of lines beginnings in the source code
 828     pub lines: Vec<BytePos>,
 829     /// Locations of multi-byte characters in the source code
 830     pub multibyte_chars: Vec<MultiByteChar>,
 831     /// Width of characters that are not narrow in the source code
 832     pub non_narrow_chars: Vec<NonNarrowChar>,
 833     /// A hash of the filename, used for speeding up the incr. comp. hashing.
 834     pub name_hash: u128,
 835 }
 836
 837 impl Encodable for SourceFile {
 838     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 839         s.emit_struct("SourceFile", 8, |s| {
 840             s.emit_struct_field("name", 0, |s| self.name.encode(s))?;
 841             s.emit_struct_field("name_was_remapped", 1, |s| self.name_was_remapped.encode(s))?;
 842             s.emit_struct_field("src_hash", 2, |s| self.src_hash.encode(s))?;
 843             s.emit_struct_field("start_pos", 4, |s| self.start_pos.encode(s))?;
 844             s.emit_struct_field("end_pos", 5, |s| self.end_pos.encode(s))?;
 845             s.emit_struct_field("lines", 6, |s| {
 846                 let lines = &self.lines[..];
 847                 // store the length
 848                 s.emit_u32(lines.len() as u32)?;
 849
 850                 if !lines.is_empty() {
 851                     // In order to preserve some space, we exploit the fact that
 852                     // the lines list is sorted and individual lines are
 853                     // probably not that long. Because of that we can store lines
 854                     // as a difference list, using as little space as possible
 855                     // for the differences.
 856                     let max_line_length = if lines.len() == 1 {
 857                         0
 858                     } else {
 859                         lines.windows(2)
 860                              .map(|w| w[1] - w[0])
 861                              .map(|bp| bp.to_usize())
 862                              .max()
 863                              .unwrap()
 864                     };
 865
 866                     let bytes_per_diff: u8 = match max_line_length {
 867                         0 ..= 0xFF => 1,
 868                         0x100 ..= 0xFFFF => 2,
 869                         _ => 4
 870                     };
 871
 872                     // Encode the number of bytes used per diff.
 873                     bytes_per_diff.encode(s)?;
 874
 875                     // Encode the first element.
 876                     lines[0].encode(s)?;
 877
 878                     let diff_iter = (&lines[..]).windows(2)
 879                                                 .map(|w| (w[1] - w[0]));
 880
 881                     match bytes_per_diff {
 882                         1 => for diff in diff_iter { (diff.0 as u8).encode(s)? },
 883                         2 => for diff in diff_iter { (diff.0 as u16).encode(s)? },
 884                         4 => for diff in diff_iter { diff.0.encode(s)? },
 885                         _ => unreachable!()
 886                     }
 887                 }
 888
 889                 Ok(())
 890             })?;
 891             s.emit_struct_field("multibyte_chars", 7, |s| {
 892                 self.multibyte_chars.encode(s)
 893             })?;
 894             s.emit_struct_field("non_narrow_chars", 8, |s| {
 895                 self.non_narrow_chars.encode(s)
 896             })?;
 897             s.emit_struct_field("name_hash", 9, |s| {
 898                 self.name_hash.encode(s)
 899             })
 900         })
 901     }
 902 }
 903
 904 impl Decodable for SourceFile {
 905     fn decode<D: Decoder>(d: &mut D) -> Result<SourceFile, D::Error> {
 906
 907         d.read_struct("SourceFile", 8, |d| {
 908             let name: FileName = d.read_struct_field("name", 0, |d| Decodable::decode(d))?;
 909             let name_was_remapped: bool =
 910                 d.read_struct_field("name_was_remapped", 1, |d| Decodable::decode(d))?;
 911             let src_hash: u128 =
 912                 d.read_struct_field("src_hash", 2, |d| Decodable::decode(d))?;
 913             let start_pos: BytePos =
 914                 d.read_struct_field("start_pos", 4, |d| Decodable::decode(d))?;
 915             let end_pos: BytePos = d.read_struct_field("end_pos", 5, |d| Decodable::decode(d))?;
 916             let lines: Vec<BytePos> = d.read_struct_field("lines", 6, |d| {
 917                 let num_lines: u32 = Decodable::decode(d)?;
 918                 let mut lines = Vec::with_capacity(num_lines as usize);
 919
 920                 if num_lines > 0 {
 921                     // Read the number of bytes used per diff.
 922                     let bytes_per_diff: u8 = Decodable::decode(d)?;
 923
 924                     // Read the first element.
 925                     let mut line_start: BytePos = Decodable::decode(d)?;
 926                     lines.push(line_start);
 927
 928                     for _ in 1..num_lines {
 929                         let diff = match bytes_per_diff {
 930                             1 => d.read_u8()? as u32,
 931                             2 => d.read_u16()? as u32,
 932                             4 => d.read_u32()?,
 933                             _ => unreachable!()
 934                         };
 935
 936                         line_start = line_start + BytePos(diff);
 937
 938                         lines.push(line_start);
 939                     }
 940                 }
 941
 942                 Ok(lines)
 943             })?;
 944             let multibyte_chars: Vec<MultiByteChar> =
 945                 d.read_struct_field("multibyte_chars", 7, |d| Decodable::decode(d))?;
 946             let non_narrow_chars: Vec<NonNarrowChar> =
 947                 d.read_struct_field("non_narrow_chars", 8, |d| Decodable::decode(d))?;
 948             let name_hash: u128 =
 949                 d.read_struct_field("name_hash", 9, |d| Decodable::decode(d))?;
 950             Ok(SourceFile {
 951                 name,
 952                 name_was_remapped,
 953                 unmapped_path: None,
 954                 // `crate_of_origin` has to be set by the importer.
 955                 // This value matches up with rustc::hir::def_id::INVALID_CRATE.
 956                 // That constant is not available here unfortunately :(
 957                 crate_of_origin: ::std::u32::MAX - 1,
 958                 start_pos,
 959                 end_pos,
 960                 src: None,
 961                 src_hash,
 962                 external_src: Lock::new(ExternalSource::AbsentOk),
 963                 lines,
 964                 multibyte_chars,
 965                 non_narrow_chars,
 966                 name_hash,
 967             })
 968         })
 969     }
 970 }
 971
 972 impl fmt::Debug for SourceFile {
 973     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
 974         write!(fmt, "SourceFile({})", self.name)
 975     }
 976 }
 977
 978 impl SourceFile {
 979     pub fn new(name: FileName,
 980                name_was_remapped: bool,
 981                unmapped_path: FileName,
 982                mut src: String,
 983                start_pos: BytePos) -> SourceFile {
 984         remove_bom(&mut src);
 985
 986         let src_hash = {
 987             let mut hasher: StableHasher<u128> = StableHasher::new();
 988             hasher.write(src.as_bytes());
 989             hasher.finish()
 990         };
 991         let name_hash = {
 992             let mut hasher: StableHasher<u128> = StableHasher::new();
 993             name.hash(&mut hasher);
 994             hasher.finish()
 995         };
 996         let end_pos = start_pos.to_usize() + src.len();
 997
 998         let (lines, multibyte_chars, non_narrow_chars) =
 999             analyze_source_file::analyze_source_file(&src[..], start_pos);
1000
1001         SourceFile {
1002             name,
1003             name_was_remapped,
1004             unmapped_path: Some(unmapped_path),
1005             crate_of_origin: 0,
1006             src: Some(Lrc::new(src)),
1007             src_hash,
1008             external_src: Lock::new(ExternalSource::Unneeded),
1009             start_pos,
1010             end_pos: Pos::from_usize(end_pos),
1011             lines,
1012             multibyte_chars,
1013             non_narrow_chars,
1014             name_hash,
1015         }
1016     }
1017
1018     /// Return the BytePos of the beginning of the current line.
1019     pub fn line_begin_pos(&self, pos: BytePos) -> BytePos {
1020         let line_index = self.lookup_line(pos).unwrap();
1021         self.lines[line_index]
1022     }
1023
1024     /// Add externally loaded source.
1025     /// If the hash of the input doesn't match or no input is supplied via None,
1026     /// it is interpreted as an error and the corresponding enum variant is set.
1027     /// The return value signifies whether some kind of source is present.
1028     pub fn add_external_src<F>(&self, get_src: F) -> bool
1029         where F: FnOnce() -> Option<String>
1030     {
1031         if *self.external_src.borrow() == ExternalSource::AbsentOk {
1032             let src = get_src();
1033             let mut external_src = self.external_src.borrow_mut();
1034             // Check that no-one else have provided the source while we were getting it
1035             if *external_src == ExternalSource::AbsentOk {
1036                 if let Some(src) = src {
1037                     let mut hasher: StableHasher<u128> = StableHasher::new();
1038                     hasher.write(src.as_bytes());
1039
1040                     if hasher.finish() == self.src_hash {
1041                         *external_src = ExternalSource::Present(src);
1042                         return true;
1043                     }
1044                 } else {
1045                     *external_src = ExternalSource::AbsentErr;
1046                 }
1047
1048                 false
1049             } else {
1050                 self.src.is_some() || external_src.get_source().is_some()
1051             }
1052         } else {
1053             self.src.is_some() || self.external_src.borrow().get_source().is_some()
1054         }
1055     }
1056
1057     /// Get a line from the list of pre-computed line-beginnings.
1058     /// The line number here is 0-based.
1059     pub fn get_line(&self, line_number: usize) -> Option<Cow<str>> {
1060         fn get_until_newline(src: &str, begin: usize) -> &str {
1061             // We can't use `lines.get(line_number+1)` because we might
1062             // be parsing when we call this function and thus the current
1063             // line is the last one we have line info for.
1064             let slice = &src[begin..];
1065             match slice.find('\n') {
1066                 Some(e) => &slice[..e],
1067                 None => slice
1068             }
1069         }
1070
1071         let begin = {
1072             let line = if let Some(line) = self.lines.get(line_number) {
1073                 line
1074             } else {
1075                 return None;
1076             };
1077             let begin: BytePos = *line - self.start_pos;
1078             begin.to_usize()
1079         };
1080
1081         if let Some(ref src) = self.src {
1082             Some(Cow::from(get_until_newline(src, begin)))
1083         } else if let Some(src) = self.external_src.borrow().get_source() {
1084             Some(Cow::Owned(String::from(get_until_newline(src, begin))))
1085         } else {
1086             None
1087         }
1088     }
1089
1090     pub fn is_real_file(&self) -> bool {
1091         self.name.is_real()
1092     }
1093
1094     pub fn is_imported(&self) -> bool {
1095         self.src.is_none()
1096     }
1097
1098     pub fn byte_length(&self) -> u32 {
1099         self.end_pos.0 - self.start_pos.0
1100     }
1101     pub fn count_lines(&self) -> usize {
1102         self.lines.len()
1103     }
1104
1105     /// Find the line containing the given position. The return value is the
1106     /// index into the `lines` array of this SourceFile, not the 1-based line
1107     /// number. If the source_file is empty or the position is located before the
1108     /// first line, None is returned.
1109     pub fn lookup_line(&self, pos: BytePos) -> Option<usize> {
1110         if self.lines.len() == 0 {
1111             return None;
1112         }
1113
1114         let line_index = lookup_line(&self.lines[..], pos);
1115         assert!(line_index < self.lines.len() as isize);
1116         if line_index >= 0 {
1117             Some(line_index as usize)
1118         } else {
1119             None
1120         }
1121     }
1122
1123     pub fn line_bounds(&self, line_index: usize) -> (BytePos, BytePos) {
1124         if self.start_pos == self.end_pos {
1125             return (self.start_pos, self.end_pos);
1126         }
1127
1128         assert!(line_index < self.lines.len());
1129         if line_index == (self.lines.len() - 1) {
1130             (self.lines[line_index], self.end_pos)
1131         } else {
1132             (self.lines[line_index], self.lines[line_index + 1])
1133         }
1134     }
1135
1136     #[inline]
1137     pub fn contains(&self, byte_pos: BytePos) -> bool {
1138         byte_pos >= self.start_pos && byte_pos <= self.end_pos
1139     }
1140 }
1141
1142 /// Remove utf-8 BOM if any.
1143 fn remove_bom(src: &mut String) {
1144     if src.starts_with("\u{feff}") {
1145         src.drain(..3);
1146     }
1147 }
1148
1149 // _____________________________________________________________________________
1150 // Pos, BytePos, CharPos
1151 //
1152
1153 pub trait Pos {
1154     fn from_usize(n: usize) -> Self;
1155     fn to_usize(&self) -> usize;
1156     fn from_u32(n: u32) -> Self;
1157     fn to_u32(&self) -> u32;
1158 }
1159
1160 /// A byte offset. Keep this small (currently 32-bits), as AST contains
1161 /// a lot of them.
1162 #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
1163 pub struct BytePos(pub u32);
1164
1165 /// A character offset. Because of multibyte utf8 characters, a byte offset
1166 /// is not equivalent to a character offset. The SourceMap will convert BytePos
1167 /// values to CharPos values as necessary.
1168 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
1169 pub struct CharPos(pub usize);
1170
1171 // FIXME: Lots of boilerplate in these impls, but so far my attempts to fix
1172 // have been unsuccessful
1173
1174 impl Pos for BytePos {
1175     #[inline(always)]
1176     fn from_usize(n: usize) -> BytePos { BytePos(n as u32) }
1177
1178     #[inline(always)]
1179     fn to_usize(&self) -> usize { self.0 as usize }
1180
1181     #[inline(always)]
1182     fn from_u32(n: u32) -> BytePos { BytePos(n) }
1183
1184     #[inline(always)]
1185     fn to_u32(&self) -> u32 { self.0 }
1186 }
1187
1188 impl Add for BytePos {
1189     type Output = BytePos;
1190
1191     #[inline(always)]
1192     fn add(self, rhs: BytePos) -> BytePos {
1193         BytePos((self.to_usize() + rhs.to_usize()) as u32)
1194     }
1195 }
1196
1197 impl Sub for BytePos {
1198     type Output = BytePos;
1199
1200     #[inline(always)]
1201     fn sub(self, rhs: BytePos) -> BytePos {
1202         BytePos((self.to_usize() - rhs.to_usize()) as u32)
1203     }
1204 }
1205
1206 impl Encodable for BytePos {
1207     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1208         s.emit_u32(self.0)
1209     }
1210 }
1211
1212 impl Decodable for BytePos {
1213     fn decode<D: Decoder>(d: &mut D) -> Result<BytePos, D::Error> {
1214         Ok(BytePos(d.read_u32()?))
1215     }
1216 }
1217
1218 impl Pos for CharPos {
1219     #[inline(always)]
1220     fn from_usize(n: usize) -> CharPos { CharPos(n) }
1221
1222     #[inline(always)]
1223     fn to_usize(&self) -> usize { self.0 }
1224
1225     #[inline(always)]
1226     fn from_u32(n: u32) -> CharPos { CharPos(n as usize) }
1227
1228     #[inline(always)]
1229     fn to_u32(&self) -> u32 { self.0 as u32}
1230 }
1231
1232 impl Add for CharPos {
1233     type Output = CharPos;
1234
1235     #[inline(always)]
1236     fn add(self, rhs: CharPos) -> CharPos {
1237         CharPos(self.to_usize() + rhs.to_usize())
1238     }
1239 }
1240
1241 impl Sub for CharPos {
1242     type Output = CharPos;
1243
1244     #[inline(always)]
1245     fn sub(self, rhs: CharPos) -> CharPos {
1246         CharPos(self.to_usize() - rhs.to_usize())
1247     }
1248 }
1249
1250 // _____________________________________________________________________________
1251 // Loc, LocWithOpt, SourceFileAndLine, SourceFileAndBytePos
1252 //
1253
1254 /// A source code location used for error reporting
1255 #[derive(Debug, Clone)]
1256 pub struct Loc {
1257     /// Information about the original source
1258     pub file: Lrc<SourceFile>,
1259     /// The (1-based) line number
1260     pub line: usize,
1261     /// The (0-based) column offset
1262     pub col: CharPos,
1263     /// The (0-based) column offset when displayed
1264     pub col_display: usize,
1265 }
1266
1267 /// A source code location used as the result of lookup_char_pos_adj
1268 // Actually, *none* of the clients use the filename *or* file field;
1269 // perhaps they should just be removed.
1270 #[derive(Debug)]
1271 pub struct LocWithOpt {
1272     pub filename: FileName,
1273     pub line: usize,
1274     pub col: CharPos,
1275     pub file: Option<Lrc<SourceFile>>,
1276 }
1277
1278 // used to be structural records. Better names, anyone?
1279 #[derive(Debug)]
1280 pub struct SourceFileAndLine { pub sf: Lrc<SourceFile>, pub line: usize }
1281 #[derive(Debug)]
1282 pub struct SourceFileAndBytePos { pub sf: Lrc<SourceFile>, pub pos: BytePos }
1283
1284 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
1285 pub struct LineInfo {
1286     /// Index of line, starting from 0.
1287     pub line_index: usize,
1288
1289     /// Column in line where span begins, starting from 0.
1290     pub start_col: CharPos,
1291
1292     /// Column in line where span ends, starting from 0, exclusive.
1293     pub end_col: CharPos,
1294 }
1295
1296 pub struct FileLines {
1297     pub file: Lrc<SourceFile>,
1298     pub lines: Vec<LineInfo>
1299 }
1300
1301 thread_local!(pub static SPAN_DEBUG: Cell<fn(Span, &mut fmt::Formatter) -> fmt::Result> =
1302                 Cell::new(default_span_debug));
1303
1304 #[derive(Debug)]
1305 pub struct MacroBacktrace {
1306     /// span where macro was applied to generate this code
1307     pub call_site: Span,
1308
1309     /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
1310     pub macro_decl_name: String,
1311
1312     /// span where macro was defined (if known)
1313     pub def_site_span: Option<Span>,
1314 }
1315
1316 // _____________________________________________________________________________
1317 // SpanLinesError, SpanSnippetError, DistinctSources, MalformedSourceMapPositions
1318 //
1319
1320 pub type FileLinesResult = Result<FileLines, SpanLinesError>;
1321
1322 #[derive(Clone, PartialEq, Eq, Debug)]
1323 pub enum SpanLinesError {
1324     IllFormedSpan(Span),
1325     DistinctSources(DistinctSources),
1326 }
1327
1328 #[derive(Clone, PartialEq, Eq, Debug)]
1329 pub enum SpanSnippetError {
1330     IllFormedSpan(Span),
1331     DistinctSources(DistinctSources),
1332     MalformedForSourcemap(MalformedSourceMapPositions),
1333     SourceNotAvailable { filename: FileName }
1334 }
1335
1336 #[derive(Clone, PartialEq, Eq, Debug)]
1337 pub struct DistinctSources {
1338     pub begin: (FileName, BytePos),
1339     pub end: (FileName, BytePos)
1340 }
1341
1342 #[derive(Clone, PartialEq, Eq, Debug)]
1343 pub struct MalformedSourceMapPositions {
1344     pub name: FileName,
1345     pub source_len: usize,
1346     pub begin_pos: BytePos,
1347     pub end_pos: BytePos
1348 }
1349
1350 // Given a slice of line start positions and a position, returns the index of
1351 // the line the position is on. Returns -1 if the position is located before
1352 // the first line.
1353 fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
1354     match lines.binary_search(&pos) {
1355         Ok(line) => line as isize,
1356         Err(line) => line as isize - 1
1357     }
1358 }
1359
1360 #[cfg(test)]
1361 mod tests {
1362     use super::{lookup_line, BytePos};
1363
1364     #[test]
1365     fn test_lookup_line() {
1366
1367         let lines = &[BytePos(3), BytePos(17), BytePos(28)];
1368
1369         assert_eq!(lookup_line(lines, BytePos(0)), -1);
1370         assert_eq!(lookup_line(lines, BytePos(3)),  0);
1371         assert_eq!(lookup_line(lines, BytePos(4)),  0);
1372
1373         assert_eq!(lookup_line(lines, BytePos(16)), 0);
1374         assert_eq!(lookup_line(lines, BytePos(17)), 1);
1375         assert_eq!(lookup_line(lines, BytePos(18)), 1);
1376
1377         assert_eq!(lookup_line(lines, BytePos(28)), 2);
1378         assert_eq!(lookup_line(lines, BytePos(29)), 2);
1379     }
1380 }