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 #![crate_name = "syntax_pos"]
  18 #![crate_type = "dylib"]
  19 #![crate_type = "rlib"]
  20 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  21       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  22       html_root_url = "https://doc.rust-lang.org/nightly/")]
  23 #![deny(warnings)]
  24
  25 #![feature(const_fn)]
  26 #![feature(custom_attribute)]
  27 #![feature(optin_builtin_traits)]
  28 #![allow(unused_attributes)]
  29 #![feature(specialization)]
  30
  31 #![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
  32 #![cfg_attr(stage0, feature(rustc_private))]
  33 #![cfg_attr(stage0, feature(staged_api))]
  34
  35 use std::cell::{Cell, RefCell};
  36 use std::ops::{Add, Sub};
  37 use std::rc::Rc;
  38 use std::cmp;
  39
  40 use std::fmt;
  41
  42 use serialize::{Encodable, Decodable, Encoder, Decoder};
  43
  44 extern crate serialize;
  45 extern crate serialize as rustc_serialize; // used by deriving
  46
  47 pub mod hygiene;
  48 pub use hygiene::{SyntaxContext, ExpnInfo, ExpnFormat, NameAndSpan};
  49
  50 pub mod symbol;
  51
  52 pub type FileName = String;
  53
  54 /// Spans represent a region of code, used for error reporting. Positions in spans
  55 /// are *absolute* positions from the beginning of the codemap, not positions
  56 /// relative to FileMaps. Methods on the CodeMap can be used to relate spans back
  57 /// to the original source.
  58 /// You must be careful if the span crosses more than one file - you will not be
  59 /// able to use many of the functions on spans in codemap and you cannot assume
  60 /// that the length of the span = hi - lo; there may be space in the BytePos
  61 /// range between files.
  62 #[derive(Clone, Copy, Hash, PartialEq, Eq, Ord, PartialOrd)]
  63 pub struct Span {
  64     pub lo: BytePos,
  65     pub hi: BytePos,
  66     /// Information about where the macro came from, if this piece of
  67     /// code was created by a macro expansion.
  68     pub ctxt: SyntaxContext,
  69 }
  70
  71 /// A collection of spans. Spans have two orthogonal attributes:
  72 ///
  73 /// - they can be *primary spans*. In this case they are the locus of
  74 ///   the error, and would be rendered with `^^^`.
  75 /// - they can have a *label*. In this case, the label is written next
  76 ///   to the mark in the snippet when we render.
  77 #[derive(Clone, Debug, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
  78 pub struct MultiSpan {
  79     primary_spans: Vec<Span>,
  80     span_labels: Vec<(Span, String)>,
  81 }
  82
  83 impl Span {
  84     /// Returns a new span representing just the end-point of this span
  85     pub fn end_point(self) -> Span {
  86         let lo = cmp::max(self.hi.0 - 1, self.lo.0);
  87         Span { lo: BytePos(lo), ..self }
  88     }
  89
  90     /// Returns a new span representing the next character after the end-point of this span
  91     pub fn next_point(self) -> Span {
  92         let lo = cmp::max(self.hi.0, self.lo.0 + 1);
  93         Span { lo: BytePos(lo), hi: BytePos(lo), ..self }
  94     }
  95
  96     /// Returns `self` if `self` is not the dummy span, and `other` otherwise.
  97     pub fn substitute_dummy(self, other: Span) -> Span {
  98         if self.source_equal(&DUMMY_SP) { other } else { self }
  99     }
 100
 101     pub fn contains(self, other: Span) -> bool {
 102         self.lo <= other.lo && other.hi <= self.hi
 103     }
 104
 105     /// Return true if the spans are equal with regards to the source text.
 106     ///
 107     /// Use this instead of `==` when either span could be generated code,
 108     /// and you only care that they point to the same bytes of source text.
 109     pub fn source_equal(&self, other: &Span) -> bool {
 110         self.lo == other.lo && self.hi == other.hi
 111     }
 112
 113     /// Returns `Some(span)`, where the start is trimmed by the end of `other`
 114     pub fn trim_start(self, other: Span) -> Option<Span> {
 115         if self.hi > other.hi {
 116             Some(Span { lo: cmp::max(self.lo, other.hi), .. self })
 117         } else {
 118             None
 119         }
 120     }
 121
 122     /// Return the source span - this is either the supplied span, or the span for
 123     /// the macro callsite that expanded to it.
 124     pub fn source_callsite(self) -> Span {
 125         self.ctxt.outer().expn_info().map(|info| info.call_site.source_callsite()).unwrap_or(self)
 126     }
 127
 128     /// Return the source callee.
 129     ///
 130     /// Returns None if the supplied span has no expansion trace,
 131     /// else returns the NameAndSpan for the macro definition
 132     /// corresponding to the source callsite.
 133     pub fn source_callee(self) -> Option<NameAndSpan> {
 134         fn source_callee(info: ExpnInfo) -> NameAndSpan {
 135             match info.call_site.ctxt.outer().expn_info() {
 136                 Some(info) => source_callee(info),
 137                 None => info.callee,
 138             }
 139         }
 140         self.ctxt.outer().expn_info().map(source_callee)
 141     }
 142
 143     /// Check if a span is "internal" to a macro in which #[unstable]
 144     /// items can be used (that is, a macro marked with
 145     /// `#[allow_internal_unstable]`).
 146     pub fn allows_unstable(&self) -> bool {
 147         match self.ctxt.outer().expn_info() {
 148             Some(info) => info.callee.allow_internal_unstable,
 149             None => false,
 150         }
 151     }
 152
 153     pub fn macro_backtrace(mut self) -> Vec<MacroBacktrace> {
 154         let mut prev_span = DUMMY_SP;
 155         let mut result = vec![];
 156         loop {
 157             let info = match self.ctxt.outer().expn_info() {
 158                 Some(info) => info,
 159                 None => break,
 160             };
 161
 162             let (pre, post) = match info.callee.format {
 163                 ExpnFormat::MacroAttribute(..) => ("#[", "]"),
 164                 ExpnFormat::MacroBang(..) => ("", "!"),
 165                 ExpnFormat::CompilerDesugaring(..) => ("desugaring of `", "`"),
 166             };
 167             let macro_decl_name = format!("{}{}{}", pre, info.callee.name(), post);
 168             let def_site_span = info.callee.span;
 169
 170             // Don't print recursive invocations
 171             if !info.call_site.source_equal(&prev_span) {
 172                 result.push(MacroBacktrace {
 173                     call_site: info.call_site,
 174                     macro_decl_name: macro_decl_name,
 175                     def_site_span: def_site_span,
 176                 });
 177             }
 178
 179             prev_span = self;
 180             self = info.call_site;
 181         }
 182         result
 183     }
 184
 185     pub fn to(self, end: Span) -> Span {
 186         // FIXME(jseyfried): self.ctxt should always equal end.ctxt here (c.f. issue #23480)
 187         if end.ctxt == SyntaxContext::empty() {
 188             Span { lo: self.lo, ..end }
 189         } else {
 190             Span { hi: end.hi, ..self }
 191         }
 192     }
 193
 194     pub fn between(self, end: Span) -> Span {
 195         Span {
 196             lo: self.hi,
 197             hi: end.lo,
 198             ctxt: if end.ctxt == SyntaxContext::empty() {
 199                 end.ctxt
 200             } else {
 201                 self.ctxt
 202             }
 203         }
 204     }
 205
 206     pub fn until(self, end: Span) -> Span {
 207         Span {
 208             lo: self.lo,
 209             hi: end.lo,
 210             ctxt: if end.ctxt == SyntaxContext::empty() {
 211                 end.ctxt
 212             } else {
 213                 self.ctxt
 214             }
 215         }
 216     }
 217 }
 218
 219 #[derive(Clone, Debug)]
 220 pub struct SpanLabel {
 221     /// The span we are going to include in the final snippet.
 222     pub span: Span,
 223
 224     /// Is this a primary span? This is the "locus" of the message,
 225     /// and is indicated with a `^^^^` underline, versus `----`.
 226     pub is_primary: bool,
 227
 228     /// What label should we attach to this span (if any)?
 229     pub label: Option<String>,
 230 }
 231
 232 impl serialize::UseSpecializedEncodable for Span {
 233     fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 234         s.emit_struct("Span", 2, |s| {
 235             s.emit_struct_field("lo", 0, |s| {
 236                 self.lo.encode(s)
 237             })?;
 238
 239             s.emit_struct_field("hi", 1, |s| {
 240                 self.hi.encode(s)
 241             })
 242         })
 243     }
 244 }
 245
 246 impl serialize::UseSpecializedDecodable for Span {
 247     fn default_decode<D: Decoder>(d: &mut D) -> Result<Span, D::Error> {
 248         d.read_struct("Span", 2, |d| {
 249             let lo = d.read_struct_field("lo", 0, Decodable::decode)?;
 250             let hi = d.read_struct_field("hi", 1, Decodable::decode)?;
 251             Ok(Span { lo: lo, hi: hi, ctxt: NO_EXPANSION })
 252         })
 253     }
 254 }
 255
 256 fn default_span_debug(span: Span, f: &mut fmt::Formatter) -> fmt::Result {
 257     write!(f, "Span {{ lo: {:?}, hi: {:?}, ctxt: {:?} }}",
 258            span.lo, span.hi, span.ctxt)
 259 }
 260
 261 impl fmt::Debug for Span {
 262     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 263         SPAN_DEBUG.with(|span_debug| span_debug.get()(*self, f))
 264     }
 265 }
 266
 267 pub const DUMMY_SP: Span = Span { lo: BytePos(0), hi: BytePos(0), ctxt: NO_EXPANSION };
 268
 269 impl MultiSpan {
 270     pub fn new() -> MultiSpan {
 271         MultiSpan {
 272             primary_spans: vec![],
 273             span_labels: vec![]
 274         }
 275     }
 276
 277     pub fn from_span(primary_span: Span) -> MultiSpan {
 278         MultiSpan {
 279             primary_spans: vec![primary_span],
 280             span_labels: vec![]
 281         }
 282     }
 283
 284     pub fn from_spans(vec: Vec<Span>) -> MultiSpan {
 285         MultiSpan {
 286             primary_spans: vec,
 287             span_labels: vec![]
 288         }
 289     }
 290
 291     pub fn push_span_label(&mut self, span: Span, label: String) {
 292         self.span_labels.push((span, label));
 293     }
 294
 295     /// Selects the first primary span (if any)
 296     pub fn primary_span(&self) -> Option<Span> {
 297         self.primary_spans.first().cloned()
 298     }
 299
 300     /// Returns all primary spans.
 301     pub fn primary_spans(&self) -> &[Span] {
 302         &self.primary_spans
 303     }
 304
 305     /// Replaces all occurances of one Span with another. Used to move Spans in areas that don't
 306     /// display well (like std macros). Returns true if replacements occurred.
 307     pub fn replace(&mut self, before: Span, after: Span) -> bool {
 308         let mut replacements_occurred = false;
 309         for primary_span in &mut self.primary_spans {
 310             if *primary_span == before {
 311                 *primary_span = after;
 312                 replacements_occurred = true;
 313             }
 314         }
 315         for span_label in &mut self.span_labels {
 316             if span_label.0 == before {
 317                 span_label.0 = after;
 318                 replacements_occurred = true;
 319             }
 320         }
 321         replacements_occurred
 322     }
 323
 324     /// Returns the strings to highlight. We always ensure that there
 325     /// is an entry for each of the primary spans -- for each primary
 326     /// span P, if there is at least one label with span P, we return
 327     /// those labels (marked as primary). But otherwise we return
 328     /// `SpanLabel` instances with empty labels.
 329     pub fn span_labels(&self) -> Vec<SpanLabel> {
 330         let is_primary = |span| self.primary_spans.contains(&span);
 331         let mut span_labels = vec![];
 332
 333         for &(span, ref label) in &self.span_labels {
 334             span_labels.push(SpanLabel {
 335                 span: span,
 336                 is_primary: is_primary(span),
 337                 label: Some(label.clone())
 338             });
 339         }
 340
 341         for &span in &self.primary_spans {
 342             if !span_labels.iter().any(|sl| sl.span == span) {
 343                 span_labels.push(SpanLabel {
 344                     span: span,
 345                     is_primary: true,
 346                     label: None
 347                 });
 348             }
 349         }
 350
 351         span_labels
 352     }
 353 }
 354
 355 impl From<Span> for MultiSpan {
 356     fn from(span: Span) -> MultiSpan {
 357         MultiSpan::from_span(span)
 358     }
 359 }
 360
 361 pub const NO_EXPANSION: SyntaxContext = SyntaxContext::empty();
 362
 363 /// Identifies an offset of a multi-byte character in a FileMap
 364 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Eq, PartialEq)]
 365 pub struct MultiByteChar {
 366     /// The absolute offset of the character in the CodeMap
 367     pub pos: BytePos,
 368     /// The number of bytes, >=2
 369     pub bytes: usize,
 370 }
 371
 372 /// A single source in the CodeMap.
 373 #[derive(Clone)]
 374 pub struct FileMap {
 375     /// The name of the file that the source came from, source that doesn't
 376     /// originate from files has names between angle brackets by convention,
 377     /// e.g. `<anon>`
 378     pub name: FileName,
 379     /// True if the `name` field above has been modified by -Zremap-path-prefix
 380     pub name_was_remapped: bool,
 381     /// Indicates which crate this FileMap was imported from.
 382     pub crate_of_origin: u32,
 383     /// The complete source code
 384     pub src: Option<Rc<String>>,
 385     /// The start position of this source in the CodeMap
 386     pub start_pos: BytePos,
 387     /// The end position of this source in the CodeMap
 388     pub end_pos: BytePos,
 389     /// Locations of lines beginnings in the source code
 390     pub lines: RefCell<Vec<BytePos>>,
 391     /// Locations of multi-byte characters in the source code
 392     pub multibyte_chars: RefCell<Vec<MultiByteChar>>,
 393 }
 394
 395 impl Encodable for FileMap {
 396     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 397         s.emit_struct("FileMap", 6, |s| {
 398             s.emit_struct_field("name", 0, |s| self.name.encode(s))?;
 399             s.emit_struct_field("name_was_remapped", 1, |s| self.name_was_remapped.encode(s))?;
 400             s.emit_struct_field("start_pos", 2, |s| self.start_pos.encode(s))?;
 401             s.emit_struct_field("end_pos", 3, |s| self.end_pos.encode(s))?;
 402             s.emit_struct_field("lines", 4, |s| {
 403                 let lines = self.lines.borrow();
 404                 // store the length
 405                 s.emit_u32(lines.len() as u32)?;
 406
 407                 if !lines.is_empty() {
 408                     // In order to preserve some space, we exploit the fact that
 409                     // the lines list is sorted and individual lines are
 410                     // probably not that long. Because of that we can store lines
 411                     // as a difference list, using as little space as possible
 412                     // for the differences.
 413                     let max_line_length = if lines.len() == 1 {
 414                         0
 415                     } else {
 416                         lines.windows(2)
 417                              .map(|w| w[1] - w[0])
 418                              .map(|bp| bp.to_usize())
 419                              .max()
 420                              .unwrap()
 421                     };
 422
 423                     let bytes_per_diff: u8 = match max_line_length {
 424                         0 ... 0xFF => 1,
 425                         0x100 ... 0xFFFF => 2,
 426                         _ => 4
 427                     };
 428
 429                     // Encode the number of bytes used per diff.
 430                     bytes_per_diff.encode(s)?;
 431
 432                     // Encode the first element.
 433                     lines[0].encode(s)?;
 434
 435                     let diff_iter = (&lines[..]).windows(2)
 436                                                 .map(|w| (w[1] - w[0]));
 437
 438                     match bytes_per_diff {
 439                         1 => for diff in diff_iter { (diff.0 as u8).encode(s)? },
 440                         2 => for diff in diff_iter { (diff.0 as u16).encode(s)? },
 441                         4 => for diff in diff_iter { diff.0.encode(s)? },
 442                         _ => unreachable!()
 443                     }
 444                 }
 445
 446                 Ok(())
 447             })?;
 448             s.emit_struct_field("multibyte_chars", 5, |s| {
 449                 (*self.multibyte_chars.borrow()).encode(s)
 450             })
 451         })
 452     }
 453 }
 454
 455 impl Decodable for FileMap {
 456     fn decode<D: Decoder>(d: &mut D) -> Result<FileMap, D::Error> {
 457
 458         d.read_struct("FileMap", 6, |d| {
 459             let name: String = d.read_struct_field("name", 0, |d| Decodable::decode(d))?;
 460             let name_was_remapped: bool =
 461                 d.read_struct_field("name_was_remapped", 1, |d| Decodable::decode(d))?;
 462             let start_pos: BytePos = d.read_struct_field("start_pos", 2, |d| Decodable::decode(d))?;
 463             let end_pos: BytePos = d.read_struct_field("end_pos", 3, |d| Decodable::decode(d))?;
 464             let lines: Vec<BytePos> = d.read_struct_field("lines", 4, |d| {
 465                 let num_lines: u32 = Decodable::decode(d)?;
 466                 let mut lines = Vec::with_capacity(num_lines as usize);
 467
 468                 if num_lines > 0 {
 469                     // Read the number of bytes used per diff.
 470                     let bytes_per_diff: u8 = Decodable::decode(d)?;
 471
 472                     // Read the first element.
 473                     let mut line_start: BytePos = Decodable::decode(d)?;
 474                     lines.push(line_start);
 475
 476                     for _ in 1..num_lines {
 477                         let diff = match bytes_per_diff {
 478                             1 => d.read_u8()? as u32,
 479                             2 => d.read_u16()? as u32,
 480                             4 => d.read_u32()?,
 481                             _ => unreachable!()
 482                         };
 483
 484                         line_start = line_start + BytePos(diff);
 485
 486                         lines.push(line_start);
 487                     }
 488                 }
 489
 490                 Ok(lines)
 491             })?;
 492             let multibyte_chars: Vec<MultiByteChar> =
 493                 d.read_struct_field("multibyte_chars", 5, |d| Decodable::decode(d))?;
 494             Ok(FileMap {
 495                 name: name,
 496                 name_was_remapped: name_was_remapped,
 497                 // `crate_of_origin` has to be set by the importer.
 498                 // This value matches up with rustc::hir::def_id::INVALID_CRATE.
 499                 // That constant is not available here unfortunately :(
 500                 crate_of_origin: ::std::u32::MAX - 1,
 501                 start_pos: start_pos,
 502                 end_pos: end_pos,
 503                 src: None,
 504                 lines: RefCell::new(lines),
 505                 multibyte_chars: RefCell::new(multibyte_chars)
 506             })
 507         })
 508     }
 509 }
 510
 511 impl fmt::Debug for FileMap {
 512     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
 513         write!(fmt, "FileMap({})", self.name)
 514     }
 515 }
 516
 517 impl FileMap {
 518     /// EFFECT: register a start-of-line offset in the
 519     /// table of line-beginnings.
 520     /// UNCHECKED INVARIANT: these offsets must be added in the right
 521     /// order and must be in the right places; there is shared knowledge
 522     /// about what ends a line between this file and parse.rs
 523     /// WARNING: pos param here is the offset relative to start of CodeMap,
 524     /// and CodeMap will append a newline when adding a filemap without a newline at the end,
 525     /// so the safe way to call this is with value calculated as
 526     /// filemap.start_pos + newline_offset_relative_to_the_start_of_filemap.
 527     pub fn next_line(&self, pos: BytePos) {
 528         // the new charpos must be > the last one (or it's the first one).
 529         let mut lines = self.lines.borrow_mut();
 530         let line_len = lines.len();
 531         assert!(line_len == 0 || ((*lines)[line_len - 1] < pos));
 532         lines.push(pos);
 533     }
 534
 535     /// get a line from the list of pre-computed line-beginnings.
 536     /// line-number here is 0-based.
 537     pub fn get_line(&self, line_number: usize) -> Option<&str> {
 538         match self.src {
 539             Some(ref src) => {
 540                 let lines = self.lines.borrow();
 541                 lines.get(line_number).map(|&line| {
 542                     let begin: BytePos = line - self.start_pos;
 543                     let begin = begin.to_usize();
 544                     // We can't use `lines.get(line_number+1)` because we might
 545                     // be parsing when we call this function and thus the current
 546                     // line is the last one we have line info for.
 547                     let slice = &src[begin..];
 548                     match slice.find('\n') {
 549                         Some(e) => &slice[..e],
 550                         None => slice
 551                     }
 552                 })
 553             }
 554             None => None
 555         }
 556     }
 557
 558     pub fn record_multibyte_char(&self, pos: BytePos, bytes: usize) {
 559         assert!(bytes >=2 && bytes <= 4);
 560         let mbc = MultiByteChar {
 561             pos: pos,
 562             bytes: bytes,
 563         };
 564         self.multibyte_chars.borrow_mut().push(mbc);
 565     }
 566
 567     pub fn is_real_file(&self) -> bool {
 568         !(self.name.starts_with("<") &&
 569           self.name.ends_with(">"))
 570     }
 571
 572     pub fn is_imported(&self) -> bool {
 573         self.src.is_none()
 574     }
 575
 576     pub fn byte_length(&self) -> u32 {
 577         self.end_pos.0 - self.start_pos.0
 578     }
 579     pub fn count_lines(&self) -> usize {
 580         self.lines.borrow().len()
 581     }
 582
 583     /// Find the line containing the given position. The return value is the
 584     /// index into the `lines` array of this FileMap, not the 1-based line
 585     /// number. If the filemap is empty or the position is located before the
 586     /// first line, None is returned.
 587     pub fn lookup_line(&self, pos: BytePos) -> Option<usize> {
 588         let lines = self.lines.borrow();
 589         if lines.len() == 0 {
 590             return None;
 591         }
 592
 593         let line_index = lookup_line(&lines[..], pos);
 594         assert!(line_index < lines.len() as isize);
 595         if line_index >= 0 {
 596             Some(line_index as usize)
 597         } else {
 598             None
 599         }
 600     }
 601
 602     pub fn line_bounds(&self, line_index: usize) -> (BytePos, BytePos) {
 603         if self.start_pos == self.end_pos {
 604             return (self.start_pos, self.end_pos);
 605         }
 606
 607         let lines = self.lines.borrow();
 608         assert!(line_index < lines.len());
 609         if line_index == (lines.len() - 1) {
 610             (lines[line_index], self.end_pos)
 611         } else {
 612             (lines[line_index], lines[line_index + 1])
 613         }
 614     }
 615 }
 616
 617 // _____________________________________________________________________________
 618 // Pos, BytePos, CharPos
 619 //
 620
 621 pub trait Pos {
 622     fn from_usize(n: usize) -> Self;
 623     fn to_usize(&self) -> usize;
 624 }
 625
 626 /// A byte offset. Keep this small (currently 32-bits), as AST contains
 627 /// a lot of them.
 628 #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
 629 pub struct BytePos(pub u32);
 630
 631 /// A character offset. Because of multibyte utf8 characters, a byte offset
 632 /// is not equivalent to a character offset. The CodeMap will convert BytePos
 633 /// values to CharPos values as necessary.
 634 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
 635 pub struct CharPos(pub usize);
 636
 637 // FIXME: Lots of boilerplate in these impls, but so far my attempts to fix
 638 // have been unsuccessful
 639
 640 impl Pos for BytePos {
 641     fn from_usize(n: usize) -> BytePos { BytePos(n as u32) }
 642     fn to_usize(&self) -> usize { let BytePos(n) = *self; n as usize }
 643 }
 644
 645 impl Add for BytePos {
 646     type Output = BytePos;
 647
 648     fn add(self, rhs: BytePos) -> BytePos {
 649         BytePos((self.to_usize() + rhs.to_usize()) as u32)
 650     }
 651 }
 652
 653 impl Sub for BytePos {
 654     type Output = BytePos;
 655
 656     fn sub(self, rhs: BytePos) -> BytePos {
 657         BytePos((self.to_usize() - rhs.to_usize()) as u32)
 658     }
 659 }
 660
 661 impl Encodable for BytePos {
 662     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 663         s.emit_u32(self.0)
 664     }
 665 }
 666
 667 impl Decodable for BytePos {
 668     fn decode<D: Decoder>(d: &mut D) -> Result<BytePos, D::Error> {
 669         Ok(BytePos(d.read_u32()?))
 670     }
 671 }
 672
 673 impl Pos for CharPos {
 674     fn from_usize(n: usize) -> CharPos { CharPos(n) }
 675     fn to_usize(&self) -> usize { let CharPos(n) = *self; n }
 676 }
 677
 678 impl Add for CharPos {
 679     type Output = CharPos;
 680
 681     fn add(self, rhs: CharPos) -> CharPos {
 682         CharPos(self.to_usize() + rhs.to_usize())
 683     }
 684 }
 685
 686 impl Sub for CharPos {
 687     type Output = CharPos;
 688
 689     fn sub(self, rhs: CharPos) -> CharPos {
 690         CharPos(self.to_usize() - rhs.to_usize())
 691     }
 692 }
 693
 694 // _____________________________________________________________________________
 695 // Loc, LocWithOpt, FileMapAndLine, FileMapAndBytePos
 696 //
 697
 698 /// A source code location used for error reporting
 699 #[derive(Debug, Clone)]
 700 pub struct Loc {
 701     /// Information about the original source
 702     pub file: Rc<FileMap>,
 703     /// The (1-based) line number
 704     pub line: usize,
 705     /// The (0-based) column offset
 706     pub col: CharPos
 707 }
 708
 709 /// A source code location used as the result of lookup_char_pos_adj
 710 // Actually, *none* of the clients use the filename *or* file field;
 711 // perhaps they should just be removed.
 712 #[derive(Debug)]
 713 pub struct LocWithOpt {
 714     pub filename: FileName,
 715     pub line: usize,
 716     pub col: CharPos,
 717     pub file: Option<Rc<FileMap>>,
 718 }
 719
 720 // used to be structural records. Better names, anyone?
 721 #[derive(Debug)]
 722 pub struct FileMapAndLine { pub fm: Rc<FileMap>, pub line: usize }
 723 #[derive(Debug)]
 724 pub struct FileMapAndBytePos { pub fm: Rc<FileMap>, pub pos: BytePos }
 725
 726 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 727 pub struct LineInfo {
 728     /// Index of line, starting from 0.
 729     pub line_index: usize,
 730
 731     /// Column in line where span begins, starting from 0.
 732     pub start_col: CharPos,
 733
 734     /// Column in line where span ends, starting from 0, exclusive.
 735     pub end_col: CharPos,
 736 }
 737
 738 pub struct FileLines {
 739     pub file: Rc<FileMap>,
 740     pub lines: Vec<LineInfo>
 741 }
 742
 743 thread_local!(pub static SPAN_DEBUG: Cell<fn(Span, &mut fmt::Formatter) -> fmt::Result> =
 744                 Cell::new(default_span_debug));
 745
 746 pub struct MacroBacktrace {
 747     /// span where macro was applied to generate this code
 748     pub call_site: Span,
 749
 750     /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
 751     pub macro_decl_name: String,
 752
 753     /// span where macro was defined (if known)
 754     pub def_site_span: Option<Span>,
 755 }
 756
 757 // _____________________________________________________________________________
 758 // SpanLinesError, SpanSnippetError, DistinctSources, MalformedCodemapPositions
 759 //
 760
 761 pub type FileLinesResult = Result<FileLines, SpanLinesError>;
 762
 763 #[derive(Clone, PartialEq, Eq, Debug)]
 764 pub enum SpanLinesError {
 765     IllFormedSpan(Span),
 766     DistinctSources(DistinctSources),
 767 }
 768
 769 #[derive(Clone, PartialEq, Eq, Debug)]
 770 pub enum SpanSnippetError {
 771     IllFormedSpan(Span),
 772     DistinctSources(DistinctSources),
 773     MalformedForCodemap(MalformedCodemapPositions),
 774     SourceNotAvailable { filename: String }
 775 }
 776
 777 #[derive(Clone, PartialEq, Eq, Debug)]
 778 pub struct DistinctSources {
 779     pub begin: (String, BytePos),
 780     pub end: (String, BytePos)
 781 }
 782
 783 #[derive(Clone, PartialEq, Eq, Debug)]
 784 pub struct MalformedCodemapPositions {
 785     pub name: String,
 786     pub source_len: usize,
 787     pub begin_pos: BytePos,
 788     pub end_pos: BytePos
 789 }
 790
 791 // Given a slice of line start positions and a position, returns the index of
 792 // the line the position is on. Returns -1 if the position is located before
 793 // the first line.
 794 fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
 795     match lines.binary_search(&pos) {
 796         Ok(line) => line as isize,
 797         Err(line) => line as isize - 1
 798     }
 799 }
 800
 801 #[cfg(test)]
 802 mod tests {
 803     use super::{lookup_line, BytePos};
 804
 805     #[test]
 806     fn test_lookup_line() {
 807
 808         let lines = &[BytePos(3), BytePos(17), BytePos(28)];
 809
 810         assert_eq!(lookup_line(lines, BytePos(0)), -1);
 811         assert_eq!(lookup_line(lines, BytePos(3)),  0);
 812         assert_eq!(lookup_line(lines, BytePos(4)),  0);
 813
 814         assert_eq!(lookup_line(lines, BytePos(16)), 0);
 815         assert_eq!(lookup_line(lines, BytePos(17)), 1);
 816         assert_eq!(lookup_line(lines, BytePos(18)), 1);
 817
 818         assert_eq!(lookup_line(lines, BytePos(28)), 2);
 819         assert_eq!(lookup_line(lines, BytePos(29)), 2);
 820     }
 821 }