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perf: inline getArg(source) in generatedPositionFor #73

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

perf: inline getArg(source) in generatedPositionFor #73

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11 changes: 9 additions & 2 deletions lib/source-map-consumer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1200,9 +1200,16 @@ BasicSourceMapConsumer.prototype.sourceContentFor =
*/
BasicSourceMapConsumer.prototype.generatedPositionFor =
function SourceMapConsumer_generatedPositionFor(aArgs) {
var source = util.getArg(aArgs, 'source');
source = this._findSourceIndex(source);
// Inline the `source` read — same megamorphic-call-site issue that hit
// the line/column reads in PR #72. The hot path is a single property
// access; the "is a required argument" throw is preserved but deferred
// to the slow path: if the lookup fails AND the key is absent, throw.
// Defined values (the hot path) never see the `in` check.
var source = this._findSourceIndex(aArgs.source);
if (source < 0) {
if (!('source' in aArgs)) {
throw new Error('"source" is a required argument.');
}
return {
line: null,
column: null,
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