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Merged
luojiyin1987 merged 1 commit into from
Sep 7, 2026
Merged

perf(source-map): reuse resolved segments in range queries #108

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21 changes: 18 additions & 3 deletions scripts/bench-source-map.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -114,11 +114,11 @@ for (const kib of SIZES_KIB) {
[
'query full value range',
() => {
for (let r = 0; r < 1000; r++) sourceMap.getSourceRange(node, 0, len);
for (let r = 0; r < 10_000; r++) sourceMap.getSourceRange(node, 0, len);
},
],
[
'random queries',
'random single-unit queries',
() => {
let seed = 12345;
const rand = () => {
Expand All @@ -131,6 +131,21 @@ for (const kib of SIZES_KIB) {
}
},
],
[
'random range queries',
() => {
let seed = 12345;
const rand = () => {
seed = (seed * 1103515245 + 12345) & 0x7FFFFFFF;
return seed / 0x7FFFFFFF;
};
for (let r = 0; r < 10_000; r++) {
const a = Math.floor(rand() * len);
const b = Math.floor(rand() * (len - a)) + a + 1;
sourceMap.getSourceRange(node, a, Math.min(b, len));
}
},
],
[
'sequential span queries',
() => {
Expand All @@ -144,7 +159,7 @@ for (const kib of SIZES_KIB) {
const selectedPatterns = SMOKE ? [patterns[0]] : patterns;

for (const [label, fn] of selectedPatterns) {
const r = time(label, fn);
const r = timeMedian(label, fn);
console.log(` ${r.label.padEnd(28)} ${fmt(r.ms)}`);

if (SMOKE && r.ms > SMOKE_QUERY_BUDGET_MS) {
Expand Down
49 changes: 15 additions & 34 deletions src/source-map/build-source-map.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -424,25 +424,6 @@ function validateValueRange(
};
}

function sourceOffsetAt(
segments: MarkdownSourceMapSegment[],
valueLength: number,
valueIndex: number,
pastUnit: boolean,
incompleteMessage: string,
): number {
const segment = findSegmentAt(segments, valueIndex);
if (!segment) {
if (valueIndex === valueLength && segments.length > 0)
return segments[segments.length - 1].sourceEnd;
throw new RangeError(incompleteMessage);
}
if (segment.kind !== 'literal')
return pastUnit ? segment.sourceEnd : segment.sourceStart;
const units = (pastUnit ? valueIndex + 1 : valueIndex) - segment.valueStart;
return segment.sourceStart + units;
}

function resolveEmptyRange(
options: SegmentRangeOptions,
): number {
Expand Down Expand Up @@ -473,7 +454,6 @@ function resolveEmptyRange(
function resolveSegmentRange(options: SegmentRangeOptions): ParsedPosition {
const {
segments,
valueLength,
valueStart,
valueEnd,
sourceGapPrefix,
Expand Down Expand Up @@ -506,20 +486,21 @@ function resolveSegmentRange(options: SegmentRangeOptions): ParsedPosition {
throw new RangeError(messages.nonContiguous);
}

const startOffset = sourceOffsetAt(
segments,
valueLength,
valueStart,
false,
messages.incomplete,
);
const endOffset = sourceOffsetAt(
segments,
valueLength,
valueEnd - 1,
true,
messages.incomplete,
);
const startSegment = segments[startSegmentIndex];
const endSegment = segments[endSegmentIndex];

let startOffset: number;
if (startSegment.kind !== 'literal')
startOffset = startSegment.sourceStart;
else
startOffset = startSegment.sourceStart + valueStart - startSegment.valueStart;

let endOffset: number;
if (endSegment.kind !== 'literal')
endOffset = endSegment.sourceEnd;
else
endOffset = endSegment.sourceStart + (valueEnd - 1) + 1 - endSegment.valueStart;

return {
start: pointAtOffset(lineStarts, source, startOffset),
end: pointAtOffset(lineStarts, source, endOffset),
Expand Down