1 use crate::source_map::SourceMap;
2 use crate::{BytePos, SourceFile};
3 use rustc_data_structures::sync::Lrc;
10 // The line's byte position range in the `SourceMap`. This range will fail to contain a valid
11 // position in certain edge cases. Spans often start/end one past something, and when that
12 // something is the last character of a file (this can happen when a file doesn't end in a
13 // newline, for example), we'd still like for the position to be considered within the last
14 // line. However, it isn't according to the exclusive upper bound of this range. We cannot
15 // change the upper bound to be inclusive, because for most lines, the upper bound is the same
16 // as the lower bound of the next line, so there would be an ambiguity.
18 // Since the containment aspect of this range is only used to see whether or not the cache
19 // entry contains a position, the only ramification of the above is that we will get cache
20 // misses for these rare positions. A line lookup for the position via `SourceMap::lookup_line`
21 // after a cache miss will produce the last line number, as desired.
23 file: Lrc<SourceFile>,
28 pub struct CachingSourceMapView<'sm> {
29 source_map: &'sm SourceMap,
30 line_cache: [CacheEntry; 3],
34 impl<'sm> CachingSourceMapView<'sm> {
35 pub fn new(source_map: &'sm SourceMap) -> CachingSourceMapView<'sm> {
36 let files = source_map.files();
37 let first_file = files[0].clone();
38 let entry = CacheEntry {
41 line: BytePos(0)..BytePos(0),
46 CachingSourceMapView {
48 line_cache: [entry.clone(), entry.clone(), entry],
53 pub fn byte_pos_to_line_and_col(
56 ) -> Option<(Lrc<SourceFile>, usize, BytePos)> {
59 // Check if the position is in one of the cached lines
60 for cache_entry in self.line_cache.iter_mut() {
61 if cache_entry.line.contains(&pos) {
62 cache_entry.time_stamp = self.time_stamp;
65 cache_entry.file.clone(),
66 cache_entry.line_number,
67 pos - cache_entry.line.start,
74 for index in 1..self.line_cache.len() {
75 if self.line_cache[index].time_stamp < self.line_cache[oldest].time_stamp {
80 let cache_entry = &mut self.line_cache[oldest];
82 // If the entry doesn't point to the correct file, fix it up
83 if !file_contains(&cache_entry.file, pos) {
85 if self.source_map.files().len() > 0 {
86 let file_index = self.source_map.lookup_source_file_idx(pos);
87 let file = self.source_map.files()[file_index].clone();
89 if file_contains(&file, pos) {
90 cache_entry.file = file;
91 cache_entry.file_index = file_index;
105 let line_index = cache_entry.file.lookup_line(pos).unwrap();
106 let line_bounds = cache_entry.file.line_bounds(line_index);
108 cache_entry.line_number = line_index + 1;
109 cache_entry.line = line_bounds;
110 cache_entry.time_stamp = self.time_stamp;
112 Some((cache_entry.file.clone(), cache_entry.line_number, pos - cache_entry.line.start))
117 fn file_contains(file: &SourceFile, pos: BytePos) -> bool {
118 // `SourceMap::lookup_source_file_idx` and `SourceFile::contains` both consider the position
119 // one past the end of a file to belong to it. Normally, that's what we want. But for the
120 // purposes of converting a byte position to a line and column number, we can't come up with a
121 // line and column number if the file is empty, because an empty file doesn't contain any
122 // lines. So for our purposes, we don't consider empty files to contain any byte position.
123 file.contains(pos) && !file.is_empty()