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Switch to binary search in codemap.lookup_pos

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Patrick observed excessive slowness when looking up positions
in rustc. This might help.
This commit is contained in:
Marijn Haverbeke 2011-04-22 12:11:00 +02:00
parent d3eb3b42aa
commit 2361b65526
1 changed files with 15 additions and 19 deletions
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34
src/comp/front/codemap.rs
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@ -28,26 +28,22 @@ fn next_line(filemap file, uint pos) {
}
fn lookup_pos(codemap map, uint pos) -> loc {
auto i = _vec.len[filemap](map.files);
while (i > 0u) {
i -= 1u;
auto f = map.files.(i);
if (f.start_pos <= pos) {
// FIXME this can be a binary search if we need to be faster
auto line = _vec.len[uint](f.lines);
while (line > 0u) {
line -= 1u;
auto line_start = f.lines.(line);
if (line_start <= pos) {
ret rec(filename=f.name,
line=line + 1u,
col=pos-line_start);
}
}
}
auto a = 0u; auto b = _vec.len[filemap](map.files);
while (b - a > 1u) {
auto m = (a + b) / 2u;
if (map.files.(m).start_pos > pos) { b = m; }
else { a = m; }
}
log_err #fmt("Failed to find a location for character %u", pos);
fail;
auto f = map.files.(a);
a = 0u; b = _vec.len[uint](f.lines);
while (b - a > 1u) {
auto m = (a + b) / 2u;
if (f.lines.(m) > pos) { b = m; }
else { a = m; }
}
ret rec(filename=f.name,
line=a + 1u,
col=pos - f.lines.(a));
}
//