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perf: inline getArg(line/column) in originalPositionFor and generatedPositionFor #72

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Merged
7rulnik merged 1 commit into from
May 10, 2026
Merged

perf: inline getArg(line/column) in originalPositionFor and generatedPositionFor #72

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29 changes: 22 additions & 7 deletions lib/source-map-consumer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -966,14 +966,22 @@ BasicSourceMapConsumer.prototype.computeColumnSpans =
*/
BasicSourceMapConsumer.prototype.originalPositionFor =
function SourceMapConsumer_originalPositionFor(aArgs) {
var needleLine = util.getArg(aArgs, 'line');
var needleColumn = util.getArg(aArgs, 'column');
// The legacy code path went through `_findMapping` which validated
// line/column at the entry. Slab-direct lookups bypass that, so
// we have to validate explicitly to keep the documented errors.
// Inline the optional read for required args — every trace call paid
// for a `getArg` function call plus an `'in' in aArgs` check. Combining
// the value validation with a `typeof !== 'number'` guard preserves the
// documented "is a required argument" error for missing/undefined args
// while skipping the function-call overhead.
var needleLine = aArgs.line;
var needleColumn = aArgs.column;
if (typeof needleLine !== 'number') {
throw new Error('"line" is a required argument.');
}
if (needleLine <= 0) {
throw new TypeError('Line must be greater than or equal to 1, got ' + needleLine);
}
if (typeof needleColumn !== 'number') {
throw new Error('"column" is a required argument.');
}
if (needleColumn < 0) {
throw new TypeError('Column must be greater than or equal to 0, got ' + needleColumn);
}
Expand Down Expand Up @@ -1202,11 +1210,18 @@ BasicSourceMapConsumer.prototype.generatedPositionFor =
};
}

var needleLine = util.getArg(aArgs, 'line');
var needleColumn = util.getArg(aArgs, 'column');
// Inline the required-arg reads — same pattern as originalPositionFor.
var needleLine = aArgs.line;
var needleColumn = aArgs.column;
if (typeof needleLine !== 'number') {
throw new Error('"line" is a required argument.');
}
if (needleLine <= 0) {
throw new TypeError('Line must be greater than or equal to 1, got ' + needleLine);
}
if (typeof needleColumn !== 'number') {
throw new Error('"column" is a required argument.');
}
if (needleColumn < 0) {
throw new TypeError('Column must be greater than or equal to 0, got ' + needleColumn);
}
Expand Down
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