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fix: prevent infinite loop on empty input #302

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Merged
antfu merged 1 commit into from
Aug 22, 2025
Merged

fix: prevent infinite loop on empty input #302

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6 changes: 6 additions & 0 deletions src/MagicString.js
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Original file line number Diff line number Diff line change
Expand Up @@ -660,12 +660,18 @@ export default class MagicString {
if (DEBUG) this.stats.time('_split');

let chunk = this.lastSearchedChunk;
let previousChunk = chunk;
const searchForward = index > chunk.end;

while (chunk) {
if (chunk.contains(index)) return this._splitChunk(chunk, index);

chunk = searchForward ? this.byStart[chunk.end] : this.byEnd[chunk.start];

// Prevent infinite loop (e.g. via empty chunks, where start === end)
if (chunk === previousChunk) return;

previousChunk = chunk;
}
}

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20 changes: 20 additions & 0 deletions test/MagicString.test.js
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Expand Up @@ -98,6 +98,26 @@ describe('MagicString', () => {

assert.equal(s.toString(), 'x4213');
});

it('should append/prepend at end of string when index is out of upper bound', () => {
const s = new MagicString('x');
s.prependLeft(6, 'A');
s.appendLeft(6, 'B');
s.prependRight(6, 'C');
s.appendRight(6, 'D');

assert.equal(s.toString(), 'ABxCD');
});

it('should append/prepend on empty string when index is out of upper bound', () => {
const s = new MagicString('');
s.prependLeft(6, 'A');
s.appendLeft(6, 'B');
s.prependRight(6, 'C');
s.appendRight(6, 'D');

assert.equal(s.toString(), 'ABCD');
});
});

describe('appendLeft', () => {
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