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use rustc_data_structures::sync::Lrc;
use syntax::source_map::SourceMap;
use syntax_pos::{BytePos, SourceFile};
#[derive(Clone)]
struct CacheEntry {
time_stamp: usize,
line_number: usize,
line_start: BytePos,
line_end: BytePos,
file: Lrc<SourceFile>,
file_index: usize,
}
#[derive(Clone)]
pub struct CachingSourceMapView<'cm> {
source_map: &'cm SourceMap,
line_cache: [CacheEntry; 3],
time_stamp: usize,
}
impl<'cm> CachingSourceMapView<'cm> {
pub fn new(source_map: &'cm SourceMap) -> CachingSourceMapView<'cm> {
let files = source_map.files();
let first_file = files[0].clone();
let entry = CacheEntry {
time_stamp: 0,
line_number: 0,
line_start: BytePos(0),
line_end: BytePos(0),
file: first_file,
file_index: 0,
};
CachingSourceMapView {
source_map,
line_cache: [entry.clone(), entry.clone(), entry],
time_stamp: 0,
}
}
pub fn byte_pos_to_line_and_col(&mut self,
pos: BytePos)
-> Option<(Lrc<SourceFile>, usize, BytePos)> {
self.time_stamp += 1;
// Check if the position is in one of the cached lines
for cache_entry in self.line_cache.iter_mut() {
if pos >= cache_entry.line_start && pos < cache_entry.line_end {
cache_entry.time_stamp = self.time_stamp;
return Some((cache_entry.file.clone(),
cache_entry.line_number,
pos - cache_entry.line_start));
}
}
// No cache hit ...
let mut oldest = 0;
for index in 1 .. self.line_cache.len() {
if self.line_cache[index].time_stamp < self.line_cache[oldest].time_stamp {
oldest = index;
}
}
let cache_entry = &mut self.line_cache[oldest];
// If the entry doesn't point to the correct file, fix it up
if pos < cache_entry.file.start_pos || pos >= cache_entry.file.end_pos {
let file_valid;
if self.source_map.files().len() > 0 {
let file_index = self.source_map.lookup_source_file_idx(pos);
let file = self.source_map.files()[file_index].clone();
if pos >= file.start_pos && pos < file.end_pos {
cache_entry.file = file;
cache_entry.file_index = file_index;
file_valid = true;
} else {
file_valid = false;
}
} else {
file_valid = false;
}
if !file_valid {
return None;
}
}
let line_index = cache_entry.file.lookup_line(pos).unwrap();
let line_bounds = cache_entry.file.line_bounds(line_index);
cache_entry.line_number = line_index + 1;
cache_entry.line_start = line_bounds.0;
cache_entry.line_end = line_bounds.1;
cache_entry.time_stamp = self.time_stamp;
return Some((cache_entry.file.clone(),
cache_entry.line_number,
pos - cache_entry.line_start));
}
}
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