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.
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.
11 //! The source positions and related helper functions
15 //! This API is completely unstable and subject to change.
17 #![crate_name = "syntax_pos"]
18 #![unstable(feature = "rustc_private", issue = "27812")]
19 #![crate_type = "dylib"]
20 #![crate_type = "rlib"]
21 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
22 html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
23 html_root_url = "https://doc.rust-lang.org/nightly/")]
27 #![feature(custom_attribute)]
28 #![feature(optin_builtin_traits)]
29 #![allow(unused_attributes)]
30 #![feature(rustc_private)]
31 #![feature(staged_api)]
32 #![feature(specialization)]
34 use std::cell::{Cell, RefCell};
35 use std::ops::{Add, Sub};
41 use serialize::{Encodable, Decodable, Encoder, Decoder};
43 extern crate serialize;
44 extern crate serialize as rustc_serialize; // used by deriving
47 pub use hygiene::{SyntaxContext, ExpnInfo, ExpnFormat, NameAndSpan};
51 pub type FileName = String;
53 /// Spans represent a region of code, used for error reporting. Positions in spans
54 /// are *absolute* positions from the beginning of the codemap, not positions
55 /// relative to FileMaps. Methods on the CodeMap can be used to relate spans back
56 /// to the original source.
57 /// You must be careful if the span crosses more than one file - you will not be
58 /// able to use many of the functions on spans in codemap and you cannot assume
59 /// that the length of the span = hi - lo; there may be space in the BytePos
60 /// range between files.
61 #[derive(Clone, Copy, Hash, PartialEq, Eq, Ord, PartialOrd)]
65 /// Information about where the macro came from, if this piece of
66 /// code was created by a macro expansion.
67 pub ctxt: SyntaxContext,
70 /// A collection of spans. Spans have two orthogonal attributes:
72 /// - they can be *primary spans*. In this case they are the locus of
73 /// the error, and would be rendered with `^^^`.
74 /// - they can have a *label*. In this case, the label is written next
75 /// to the mark in the snippet when we render.
76 #[derive(Clone, Debug, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
77 pub struct MultiSpan {
78 primary_spans: Vec<Span>,
79 span_labels: Vec<(Span, String)>,
83 /// Returns a new span representing just the end-point of this span
84 pub fn end_point(self) -> Span {
85 let lo = cmp::max(self.hi.0 - 1, self.lo.0);
86 Span { lo: BytePos(lo), ..self }
89 /// Returns a new span representing the next character after the end-point of this span
90 pub fn next_point(self) -> Span {
91 let lo = cmp::max(self.hi.0, self.lo.0 + 1);
92 Span { lo: BytePos(lo), hi: BytePos(lo), ..self }
95 /// Returns `self` if `self` is not the dummy span, and `other` otherwise.
96 pub fn substitute_dummy(self, other: Span) -> Span {
97 if self.source_equal(&DUMMY_SP) { other } else { self }
100 pub fn contains(self, other: Span) -> bool {
101 self.lo <= other.lo && other.hi <= self.hi
104 /// Return true if the spans are equal with regards to the source text.
106 /// Use this instead of `==` when either span could be generated code,
107 /// and you only care that they point to the same bytes of source text.
108 pub fn source_equal(&self, other: &Span) -> bool {
109 self.lo == other.lo && self.hi == other.hi
112 /// Returns `Some(span)`, where the start is trimmed by the end of `other`
113 pub fn trim_start(self, other: Span) -> Option<Span> {
114 if self.hi > other.hi {
115 Some(Span { lo: cmp::max(self.lo, other.hi), .. self })
121 /// Return the source span - this is either the supplied span, or the span for
122 /// the macro callsite that expanded to it.
123 pub fn source_callsite(self) -> Span {
124 self.ctxt.outer().expn_info().map(|info| info.call_site.source_callsite()).unwrap_or(self)
127 /// Return the source callee.
129 /// Returns None if the supplied span has no expansion trace,
130 /// else returns the NameAndSpan for the macro definition
131 /// corresponding to the source callsite.
132 pub fn source_callee(self) -> Option<NameAndSpan> {
133 fn source_callee(info: ExpnInfo) -> NameAndSpan {
134 match info.call_site.ctxt.outer().expn_info() {
135 Some(info) => source_callee(info),
139 self.ctxt.outer().expn_info().map(source_callee)
142 /// Check if a span is "internal" to a macro in which #[unstable]
143 /// items can be used (that is, a macro marked with
144 /// `#[allow_internal_unstable]`).
145 pub fn allows_unstable(&self) -> bool {
146 match self.ctxt.outer().expn_info() {
147 Some(info) => info.callee.allow_internal_unstable,
152 pub fn macro_backtrace(mut self) -> Vec<MacroBacktrace> {
153 let mut prev_span = DUMMY_SP;
154 let mut result = vec![];
156 let info = match self.ctxt.outer().expn_info() {
161 let (pre, post) = match info.callee.format {
162 ExpnFormat::MacroAttribute(..) => ("#[", "]"),
163 ExpnFormat::MacroBang(..) => ("", "!"),
164 ExpnFormat::CompilerDesugaring(..) => ("desugaring of `", "`"),
166 let macro_decl_name = format!("{}{}{}", pre, info.callee.name(), post);
167 let def_site_span = info.callee.span;
169 // Don't print recursive invocations
170 if !info.call_site.source_equal(&prev_span) {
171 result.push(MacroBacktrace {
172 call_site: info.call_site,
173 macro_decl_name: macro_decl_name,
174 def_site_span: def_site_span,
179 self = info.call_site;
184 pub fn to(self, end: Span) -> Span {
185 // FIXME(jseyfried): self.ctxt should always equal end.ctxt here (c.f. issue #23480)
186 if end.ctxt == SyntaxContext::empty() {
187 Span { lo: self.lo, ..end }
189 Span { hi: end.hi, ..self }
193 pub fn between(self, end: Span) -> Span {
197 ctxt: if end.ctxt == SyntaxContext::empty() {
205 pub fn until(self, end: Span) -> Span {
209 ctxt: if end.ctxt == SyntaxContext::empty() {
218 #[derive(Clone, Debug)]
219 pub struct SpanLabel {
220 /// The span we are going to include in the final snippet.
223 /// Is this a primary span? This is the "locus" of the message,
224 /// and is indicated with a `^^^^` underline, versus `----`.
225 pub is_primary: bool,
227 /// What label should we attach to this span (if any)?
228 pub label: Option<String>,
231 impl serialize::UseSpecializedEncodable for Span {
232 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
233 s.emit_struct("Span", 2, |s| {
234 s.emit_struct_field("lo", 0, |s| {
238 s.emit_struct_field("hi", 1, |s| {
245 impl serialize::UseSpecializedDecodable for Span {
246 fn default_decode<D: Decoder>(d: &mut D) -> Result<Span, D::Error> {
247 d.read_struct("Span", 2, |d| {
248 let lo = d.read_struct_field("lo", 0, Decodable::decode)?;
249 let hi = d.read_struct_field("hi", 1, Decodable::decode)?;
250 Ok(Span { lo: lo, hi: hi, ctxt: NO_EXPANSION })
255 fn default_span_debug(span: Span, f: &mut fmt::Formatter) -> fmt::Result {
256 write!(f, "Span {{ lo: {:?}, hi: {:?}, ctxt: {:?} }}",
257 span.lo, span.hi, span.ctxt)
260 impl fmt::Debug for Span {
261 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
262 SPAN_DEBUG.with(|span_debug| span_debug.get()(*self, f))
266 pub const DUMMY_SP: Span = Span { lo: BytePos(0), hi: BytePos(0), ctxt: NO_EXPANSION };
269 pub fn new() -> MultiSpan {
271 primary_spans: vec![],
276 pub fn from_span(primary_span: Span) -> MultiSpan {
278 primary_spans: vec![primary_span],
283 pub fn from_spans(vec: Vec<Span>) -> MultiSpan {
290 pub fn push_span_label(&mut self, span: Span, label: String) {
291 self.span_labels.push((span, label));
294 /// Selects the first primary span (if any)
295 pub fn primary_span(&self) -> Option<Span> {
296 self.primary_spans.first().cloned()
299 /// Returns all primary spans.
300 pub fn primary_spans(&self) -> &[Span] {
304 /// Replaces all occurances of one Span with another. Used to move Spans in areas that don't
305 /// display well (like std macros). Returns true if replacements occurred.
306 pub fn replace(&mut self, before: Span, after: Span) -> bool {
307 let mut replacements_occurred = false;
308 for primary_span in &mut self.primary_spans {
309 if *primary_span == before {
310 *primary_span = after;
311 replacements_occurred = true;
314 for span_label in &mut self.span_labels {
315 if span_label.0 == before {
316 span_label.0 = after;
317 replacements_occurred = true;
320 replacements_occurred
323 /// Returns the strings to highlight. We always ensure that there
324 /// is an entry for each of the primary spans -- for each primary
325 /// span P, if there is at least one label with span P, we return
326 /// those labels (marked as primary). But otherwise we return
327 /// `SpanLabel` instances with empty labels.
328 pub fn span_labels(&self) -> Vec<SpanLabel> {
329 let is_primary = |span| self.primary_spans.contains(&span);
330 let mut span_labels = vec![];
332 for &(span, ref label) in &self.span_labels {
333 span_labels.push(SpanLabel {
335 is_primary: is_primary(span),
336 label: Some(label.clone())
340 for &span in &self.primary_spans {
341 if !span_labels.iter().any(|sl| sl.span == span) {
342 span_labels.push(SpanLabel {
354 impl From<Span> for MultiSpan {
355 fn from(span: Span) -> MultiSpan {
356 MultiSpan::from_span(span)
360 pub const NO_EXPANSION: SyntaxContext = SyntaxContext::empty();
362 /// Identifies an offset of a multi-byte character in a FileMap
363 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Eq, PartialEq)]
364 pub struct MultiByteChar {
365 /// The absolute offset of the character in the CodeMap
367 /// The number of bytes, >=2
371 /// A single source in the CodeMap.
374 /// The name of the file that the source came from, source that doesn't
375 /// originate from files has names between angle brackets by convention,
378 /// True if the `name` field above has been modified by -Zremap-path-prefix
379 pub name_was_remapped: bool,
380 /// The complete source code
381 pub src: Option<Rc<String>>,
382 /// The start position of this source in the CodeMap
383 pub start_pos: BytePos,
384 /// The end position of this source in the CodeMap
385 pub end_pos: BytePos,
386 /// Locations of lines beginnings in the source code
387 pub lines: RefCell<Vec<BytePos>>,
388 /// Locations of multi-byte characters in the source code
389 pub multibyte_chars: RefCell<Vec<MultiByteChar>>,
392 impl Encodable for FileMap {
393 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
394 s.emit_struct("FileMap", 6, |s| {
395 s.emit_struct_field("name", 0, |s| self.name.encode(s))?;
396 s.emit_struct_field("name_was_remapped", 1, |s| self.name_was_remapped.encode(s))?;
397 s.emit_struct_field("start_pos", 2, |s| self.start_pos.encode(s))?;
398 s.emit_struct_field("end_pos", 3, |s| self.end_pos.encode(s))?;
399 s.emit_struct_field("lines", 4, |s| {
400 let lines = self.lines.borrow();
402 s.emit_u32(lines.len() as u32)?;
404 if !lines.is_empty() {
405 // In order to preserve some space, we exploit the fact that
406 // the lines list is sorted and individual lines are
407 // probably not that long. Because of that we can store lines
408 // as a difference list, using as little space as possible
409 // for the differences.
410 let max_line_length = if lines.len() == 1 {
414 .map(|w| w[1] - w[0])
415 .map(|bp| bp.to_usize())
420 let bytes_per_diff: u8 = match max_line_length {
422 0x100 ... 0xFFFF => 2,
426 // Encode the number of bytes used per diff.
427 bytes_per_diff.encode(s)?;
429 // Encode the first element.
432 let diff_iter = (&lines[..]).windows(2)
433 .map(|w| (w[1] - w[0]));
435 match bytes_per_diff {
436 1 => for diff in diff_iter { (diff.0 as u8).encode(s)? },
437 2 => for diff in diff_iter { (diff.0 as u16).encode(s)? },
438 4 => for diff in diff_iter { diff.0.encode(s)? },
445 s.emit_struct_field("multibyte_chars", 5, |s| {
446 (*self.multibyte_chars.borrow()).encode(s)
452 impl Decodable for FileMap {
453 fn decode<D: Decoder>(d: &mut D) -> Result<FileMap, D::Error> {
455 d.read_struct("FileMap", 6, |d| {
456 let name: String = d.read_struct_field("name", 0, |d| Decodable::decode(d))?;
457 let name_was_remapped: bool =
458 d.read_struct_field("name_was_remapped", 1, |d| Decodable::decode(d))?;
459 let start_pos: BytePos = d.read_struct_field("start_pos", 2, |d| Decodable::decode(d))?;
460 let end_pos: BytePos = d.read_struct_field("end_pos", 3, |d| Decodable::decode(d))?;
461 let lines: Vec<BytePos> = d.read_struct_field("lines", 4, |d| {
462 let num_lines: u32 = Decodable::decode(d)?;
463 let mut lines = Vec::with_capacity(num_lines as usize);
466 // Read the number of bytes used per diff.
467 let bytes_per_diff: u8 = Decodable::decode(d)?;
469 // Read the first element.
470 let mut line_start: BytePos = Decodable::decode(d)?;
471 lines.push(line_start);
473 for _ in 1..num_lines {
474 let diff = match bytes_per_diff {
475 1 => d.read_u8()? as u32,
476 2 => d.read_u16()? as u32,
481 line_start = line_start + BytePos(diff);
483 lines.push(line_start);
489 let multibyte_chars: Vec<MultiByteChar> =
490 d.read_struct_field("multibyte_chars", 5, |d| Decodable::decode(d))?;
493 name_was_remapped: name_was_remapped,
494 start_pos: start_pos,
497 lines: RefCell::new(lines),
498 multibyte_chars: RefCell::new(multibyte_chars)
504 impl fmt::Debug for FileMap {
505 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
506 write!(fmt, "FileMap({})", self.name)
511 /// EFFECT: register a start-of-line offset in the
512 /// table of line-beginnings.
513 /// UNCHECKED INVARIANT: these offsets must be added in the right
514 /// order and must be in the right places; there is shared knowledge
515 /// about what ends a line between this file and parse.rs
516 /// WARNING: pos param here is the offset relative to start of CodeMap,
517 /// and CodeMap will append a newline when adding a filemap without a newline at the end,
518 /// so the safe way to call this is with value calculated as
519 /// filemap.start_pos + newline_offset_relative_to_the_start_of_filemap.
520 pub fn next_line(&self, pos: BytePos) {
521 // the new charpos must be > the last one (or it's the first one).
522 let mut lines = self.lines.borrow_mut();
523 let line_len = lines.len();
524 assert!(line_len == 0 || ((*lines)[line_len - 1] < pos));
528 /// get a line from the list of pre-computed line-beginnings.
529 /// line-number here is 0-based.
530 pub fn get_line(&self, line_number: usize) -> Option<&str> {
533 let lines = self.lines.borrow();
534 lines.get(line_number).map(|&line| {
535 let begin: BytePos = line - self.start_pos;
536 let begin = begin.to_usize();
537 // We can't use `lines.get(line_number+1)` because we might
538 // be parsing when we call this function and thus the current
539 // line is the last one we have line info for.
540 let slice = &src[begin..];
541 match slice.find('\n') {
542 Some(e) => &slice[..e],
551 pub fn record_multibyte_char(&self, pos: BytePos, bytes: usize) {
552 assert!(bytes >=2 && bytes <= 4);
553 let mbc = MultiByteChar {
557 self.multibyte_chars.borrow_mut().push(mbc);
560 pub fn is_real_file(&self) -> bool {
561 !(self.name.starts_with("<") &&
562 self.name.ends_with(">"))
565 pub fn is_imported(&self) -> bool {
569 pub fn byte_length(&self) -> u32 {
570 self.end_pos.0 - self.start_pos.0
572 pub fn count_lines(&self) -> usize {
573 self.lines.borrow().len()
576 /// Find the line containing the given position. The return value is the
577 /// index into the `lines` array of this FileMap, not the 1-based line
578 /// number. If the filemap is empty or the position is located before the
579 /// first line, None is returned.
580 pub fn lookup_line(&self, pos: BytePos) -> Option<usize> {
581 let lines = self.lines.borrow();
582 if lines.len() == 0 {
586 let line_index = lookup_line(&lines[..], pos);
587 assert!(line_index < lines.len() as isize);
589 Some(line_index as usize)
595 pub fn line_bounds(&self, line_index: usize) -> (BytePos, BytePos) {
596 if self.start_pos == self.end_pos {
597 return (self.start_pos, self.end_pos);
600 let lines = self.lines.borrow();
601 assert!(line_index < lines.len());
602 if line_index == (lines.len() - 1) {
603 (lines[line_index], self.end_pos)
605 (lines[line_index], lines[line_index + 1])
610 // _____________________________________________________________________________
611 // Pos, BytePos, CharPos
615 fn from_usize(n: usize) -> Self;
616 fn to_usize(&self) -> usize;
619 /// A byte offset. Keep this small (currently 32-bits), as AST contains
621 #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
622 pub struct BytePos(pub u32);
624 /// A character offset. Because of multibyte utf8 characters, a byte offset
625 /// is not equivalent to a character offset. The CodeMap will convert BytePos
626 /// values to CharPos values as necessary.
627 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
628 pub struct CharPos(pub usize);
630 // FIXME: Lots of boilerplate in these impls, but so far my attempts to fix
631 // have been unsuccessful
633 impl Pos for BytePos {
634 fn from_usize(n: usize) -> BytePos { BytePos(n as u32) }
635 fn to_usize(&self) -> usize { let BytePos(n) = *self; n as usize }
638 impl Add for BytePos {
639 type Output = BytePos;
641 fn add(self, rhs: BytePos) -> BytePos {
642 BytePos((self.to_usize() + rhs.to_usize()) as u32)
646 impl Sub for BytePos {
647 type Output = BytePos;
649 fn sub(self, rhs: BytePos) -> BytePos {
650 BytePos((self.to_usize() - rhs.to_usize()) as u32)
654 impl Encodable for BytePos {
655 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
660 impl Decodable for BytePos {
661 fn decode<D: Decoder>(d: &mut D) -> Result<BytePos, D::Error> {
662 Ok(BytePos(d.read_u32()?))
666 impl Pos for CharPos {
667 fn from_usize(n: usize) -> CharPos { CharPos(n) }
668 fn to_usize(&self) -> usize { let CharPos(n) = *self; n }
671 impl Add for CharPos {
672 type Output = CharPos;
674 fn add(self, rhs: CharPos) -> CharPos {
675 CharPos(self.to_usize() + rhs.to_usize())
679 impl Sub for CharPos {
680 type Output = CharPos;
682 fn sub(self, rhs: CharPos) -> CharPos {
683 CharPos(self.to_usize() - rhs.to_usize())
687 // _____________________________________________________________________________
688 // Loc, LocWithOpt, FileMapAndLine, FileMapAndBytePos
691 /// A source code location used for error reporting
692 #[derive(Debug, Clone)]
694 /// Information about the original source
695 pub file: Rc<FileMap>,
696 /// The (1-based) line number
698 /// The (0-based) column offset
702 /// A source code location used as the result of lookup_char_pos_adj
703 // Actually, *none* of the clients use the filename *or* file field;
704 // perhaps they should just be removed.
706 pub struct LocWithOpt {
707 pub filename: FileName,
710 pub file: Option<Rc<FileMap>>,
713 // used to be structural records. Better names, anyone?
715 pub struct FileMapAndLine { pub fm: Rc<FileMap>, pub line: usize }
717 pub struct FileMapAndBytePos { pub fm: Rc<FileMap>, pub pos: BytePos }
719 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
720 pub struct LineInfo {
721 /// Index of line, starting from 0.
722 pub line_index: usize,
724 /// Column in line where span begins, starting from 0.
725 pub start_col: CharPos,
727 /// Column in line where span ends, starting from 0, exclusive.
728 pub end_col: CharPos,
731 pub struct FileLines {
732 pub file: Rc<FileMap>,
733 pub lines: Vec<LineInfo>
736 thread_local!(pub static SPAN_DEBUG: Cell<fn(Span, &mut fmt::Formatter) -> fmt::Result> =
737 Cell::new(default_span_debug));
739 pub struct MacroBacktrace {
740 /// span where macro was applied to generate this code
743 /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
744 pub macro_decl_name: String,
746 /// span where macro was defined (if known)
747 pub def_site_span: Option<Span>,
750 // _____________________________________________________________________________
751 // SpanLinesError, SpanSnippetError, DistinctSources, MalformedCodemapPositions
754 pub type FileLinesResult = Result<FileLines, SpanLinesError>;
756 #[derive(Clone, PartialEq, Eq, Debug)]
757 pub enum SpanLinesError {
759 DistinctSources(DistinctSources),
762 #[derive(Clone, PartialEq, Eq, Debug)]
763 pub enum SpanSnippetError {
765 DistinctSources(DistinctSources),
766 MalformedForCodemap(MalformedCodemapPositions),
767 SourceNotAvailable { filename: String }
770 #[derive(Clone, PartialEq, Eq, Debug)]
771 pub struct DistinctSources {
772 pub begin: (String, BytePos),
773 pub end: (String, BytePos)
776 #[derive(Clone, PartialEq, Eq, Debug)]
777 pub struct MalformedCodemapPositions {
779 pub source_len: usize,
780 pub begin_pos: BytePos,
784 // Given a slice of line start positions and a position, returns the index of
785 // the line the position is on. Returns -1 if the position is located before
787 fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
788 match lines.binary_search(&pos) {
789 Ok(line) => line as isize,
790 Err(line) => line as isize - 1
796 use super::{lookup_line, BytePos};
799 fn test_lookup_line() {
801 let lines = &[BytePos(3), BytePos(17), BytePos(28)];
803 assert_eq!(lookup_line(lines, BytePos(0)), -1);
804 assert_eq!(lookup_line(lines, BytePos(3)), 0);
805 assert_eq!(lookup_line(lines, BytePos(4)), 0);
807 assert_eq!(lookup_line(lines, BytePos(16)), 0);
808 assert_eq!(lookup_line(lines, BytePos(17)), 1);
809 assert_eq!(lookup_line(lines, BytePos(18)), 1);
811 assert_eq!(lookup_line(lines, BytePos(28)), 2);
812 assert_eq!(lookup_line(lines, BytePos(29)), 2);