21 lines
432 B
Markdown
21 lines
432 B
Markdown
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### Backtracking
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Unlike in regular expressions, there is no backtracking in PEG.js expressions.
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For example, using the input "hi!":
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```pegjs
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// This will fail
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HI = "hi" / "hi!"
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// This will pass
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HI = "hi!" / "hi"
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// This will also pass
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HI = w:"hi" !"!" { return w } / "hi!"
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```
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For more information on backtracking in PEG.js, [checkout this excellent answer on Stack Overflow](https://stackoverflow.com/a/24809596/1518408).
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