294 lines
10 KiB
Rust
294 lines
10 KiB
Rust
use crate::source_map::SourceMap;
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use crate::{BytePos, SourceFile, SpanData};
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use rustc_data_structures::sync::Lrc;
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use std::ops::Range;
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#[derive(Clone)]
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struct CacheEntry {
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time_stamp: usize,
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line_number: usize,
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// The line's byte position range in the `SourceMap`. This range will fail to contain a valid
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// position in certain edge cases. Spans often start/end one past something, and when that
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// something is the last character of a file (this can happen when a file doesn't end in a
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// newline, for example), we'd still like for the position to be considered within the last
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// line. However, it isn't according to the exclusive upper bound of this range. We cannot
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// change the upper bound to be inclusive, because for most lines, the upper bound is the same
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// as the lower bound of the next line, so there would be an ambiguity.
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//
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// Since the containment aspect of this range is only used to see whether or not the cache
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// entry contains a position, the only ramification of the above is that we will get cache
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// misses for these rare positions. A line lookup for the position via `SourceMap::lookup_line`
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// after a cache miss will produce the last line number, as desired.
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line: Range<BytePos>,
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file: Lrc<SourceFile>,
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file_index: usize,
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}
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impl CacheEntry {
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#[inline]
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fn update(
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&mut self,
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new_file_and_idx: Option<(Lrc<SourceFile>, usize)>,
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pos: BytePos,
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time_stamp: usize,
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) {
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if let Some((file, file_idx)) = new_file_and_idx {
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self.file = file;
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self.file_index = file_idx;
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}
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let line_index = self.file.lookup_line(pos).unwrap();
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let line_bounds = self.file.line_bounds(line_index);
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self.line_number = line_index + 1;
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self.line = line_bounds;
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self.touch(time_stamp);
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}
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#[inline]
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fn touch(&mut self, time_stamp: usize) {
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self.time_stamp = time_stamp;
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}
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}
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#[derive(Clone)]
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pub struct CachingSourceMapView<'sm> {
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source_map: &'sm SourceMap,
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line_cache: [CacheEntry; 3],
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time_stamp: usize,
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}
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impl<'sm> CachingSourceMapView<'sm> {
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pub fn new(source_map: &'sm SourceMap) -> CachingSourceMapView<'sm> {
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let files = source_map.files();
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let first_file = files[0].clone();
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let entry = CacheEntry {
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time_stamp: 0,
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line_number: 0,
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line: BytePos(0)..BytePos(0),
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file: first_file,
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file_index: 0,
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};
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CachingSourceMapView {
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source_map,
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line_cache: [entry.clone(), entry.clone(), entry],
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time_stamp: 0,
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}
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}
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pub fn byte_pos_to_line_and_col(
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&mut self,
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pos: BytePos,
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) -> Option<(Lrc<SourceFile>, usize, BytePos)> {
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self.time_stamp += 1;
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// Check if the position is in one of the cached lines
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let cache_idx = self.cache_entry_index(pos);
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if cache_idx != -1 {
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let cache_entry = &mut self.line_cache[cache_idx as usize];
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cache_entry.touch(self.time_stamp);
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return Some((
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cache_entry.file.clone(),
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cache_entry.line_number,
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pos - cache_entry.line.start,
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));
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}
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// No cache hit ...
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let oldest = self.oldest_cache_entry_index();
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// If the entry doesn't point to the correct file, get the new file and index.
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let new_file_and_idx = if !file_contains(&self.line_cache[oldest].file, pos) {
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Some(self.file_for_position(pos)?)
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} else {
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None
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};
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let cache_entry = &mut self.line_cache[oldest];
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cache_entry.update(new_file_and_idx, pos, self.time_stamp);
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Some((cache_entry.file.clone(), cache_entry.line_number, pos - cache_entry.line.start))
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}
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pub fn span_data_to_lines_and_cols(
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&mut self,
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span_data: &SpanData,
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) -> Option<(Lrc<SourceFile>, usize, BytePos, usize, BytePos)> {
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self.time_stamp += 1;
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// Check if lo and hi are in the cached lines.
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let lo_cache_idx = self.cache_entry_index(span_data.lo);
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let hi_cache_idx = self.cache_entry_index(span_data.hi);
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if lo_cache_idx != -1 && hi_cache_idx != -1 {
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// Cache hit for span lo and hi. Check if they belong to the same file.
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let result = {
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let lo = &self.line_cache[lo_cache_idx as usize];
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let hi = &self.line_cache[hi_cache_idx as usize];
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if lo.file_index != hi.file_index {
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return None;
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}
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(
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lo.file.clone(),
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lo.line_number,
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span_data.lo - lo.line.start,
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hi.line_number,
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span_data.hi - hi.line.start,
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)
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};
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self.line_cache[lo_cache_idx as usize].touch(self.time_stamp);
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self.line_cache[hi_cache_idx as usize].touch(self.time_stamp);
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return Some(result);
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}
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// No cache hit or cache hit for only one of span lo and hi.
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let oldest = if lo_cache_idx != -1 || hi_cache_idx != -1 {
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let avoid_idx = if lo_cache_idx != -1 { lo_cache_idx } else { hi_cache_idx };
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self.oldest_cache_entry_index_avoid(avoid_idx as usize)
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} else {
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self.oldest_cache_entry_index()
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};
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// If the entry doesn't point to the correct file, get the new file and index.
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// Return early if the file containing beginning of span doesn't contain end of span.
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let new_file_and_idx = if !file_contains(&self.line_cache[oldest].file, span_data.lo) {
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let new_file_and_idx = self.file_for_position(span_data.lo)?;
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if !file_contains(&new_file_and_idx.0, span_data.hi) {
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return None;
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}
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Some(new_file_and_idx)
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} else {
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let file = &self.line_cache[oldest].file;
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if !file_contains(file, span_data.hi) {
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return None;
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}
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None
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};
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// Update the cache entries.
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let (lo_idx, hi_idx) = match (lo_cache_idx, hi_cache_idx) {
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// Oldest cache entry is for span_data.lo line.
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(-1, -1) => {
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let lo = &mut self.line_cache[oldest];
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lo.update(new_file_and_idx, span_data.lo, self.time_stamp);
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if !lo.line.contains(&span_data.hi) {
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let new_file_and_idx = Some((lo.file.clone(), lo.file_index));
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let next_oldest = self.oldest_cache_entry_index_avoid(oldest);
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let hi = &mut self.line_cache[next_oldest];
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hi.update(new_file_and_idx, span_data.hi, self.time_stamp);
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(oldest, next_oldest)
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} else {
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(oldest, oldest)
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}
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}
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// Oldest cache entry is for span_data.lo line.
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(-1, _) => {
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let lo = &mut self.line_cache[oldest];
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lo.update(new_file_and_idx, span_data.lo, self.time_stamp);
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let hi = &mut self.line_cache[hi_cache_idx as usize];
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hi.touch(self.time_stamp);
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(oldest, hi_cache_idx as usize)
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}
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// Oldest cache entry is for span_data.hi line.
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(_, -1) => {
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let hi = &mut self.line_cache[oldest];
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hi.update(new_file_and_idx, span_data.hi, self.time_stamp);
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let lo = &mut self.line_cache[lo_cache_idx as usize];
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lo.touch(self.time_stamp);
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(lo_cache_idx as usize, oldest)
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}
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_ => {
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panic!();
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}
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};
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let lo = &self.line_cache[lo_idx];
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let hi = &self.line_cache[hi_idx];
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// Span lo and hi may equal line end when last line doesn't
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// end in newline, hence the inclusive upper bounds below.
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assert!(span_data.lo >= lo.line.start);
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assert!(span_data.lo <= lo.line.end);
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assert!(span_data.hi >= hi.line.start);
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assert!(span_data.hi <= hi.line.end);
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assert!(lo.file.contains(span_data.lo));
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assert!(lo.file.contains(span_data.hi));
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assert_eq!(lo.file_index, hi.file_index);
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Some((
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lo.file.clone(),
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lo.line_number,
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span_data.lo - lo.line.start,
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hi.line_number,
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span_data.hi - hi.line.start,
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))
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}
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fn cache_entry_index(&self, pos: BytePos) -> isize {
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for (idx, cache_entry) in self.line_cache.iter().enumerate() {
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if cache_entry.line.contains(&pos) {
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return idx as isize;
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}
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}
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-1
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}
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fn oldest_cache_entry_index(&self) -> usize {
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let mut oldest = 0;
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for idx in 1..self.line_cache.len() {
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if self.line_cache[idx].time_stamp < self.line_cache[oldest].time_stamp {
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oldest = idx;
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}
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}
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oldest
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}
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fn oldest_cache_entry_index_avoid(&self, avoid_idx: usize) -> usize {
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let mut oldest = if avoid_idx != 0 { 0 } else { 1 };
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for idx in 0..self.line_cache.len() {
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if idx != avoid_idx
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&& self.line_cache[idx].time_stamp < self.line_cache[oldest].time_stamp
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{
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oldest = idx;
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}
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}
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oldest
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}
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fn file_for_position(&self, pos: BytePos) -> Option<(Lrc<SourceFile>, usize)> {
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if !self.source_map.files().is_empty() {
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let file_idx = self.source_map.lookup_source_file_idx(pos);
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let file = &self.source_map.files()[file_idx];
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if file_contains(file, pos) {
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return Some((file.clone(), file_idx));
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}
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}
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None
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}
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}
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#[inline]
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fn file_contains(file: &SourceFile, pos: BytePos) -> bool {
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// `SourceMap::lookup_source_file_idx` and `SourceFile::contains` both consider the position
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// one past the end of a file to belong to it. Normally, that's what we want. But for the
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// purposes of converting a byte position to a line and column number, we can't come up with a
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// line and column number if the file is empty, because an empty file doesn't contain any
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// lines. So for our purposes, we don't consider empty files to contain any byte position.
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file.contains(pos) && !file.is_empty()
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}
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