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Consume token only when it matches a predicate? #1931

Answered by msujew
thejohnfreeman asked this question in Q&A
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@thejohnfreeman You can probably accomplish this using a structure like this:

$.OR([
  {
    GATE: () => predicate(),
    ALT: () => $.CONSUME(<token>)
  },
  {
    GATE: () => !predicate(),
    ALT: EMPTY_ALT
  }
]);

Note that for specific use cases such as "does the image match a predicate" you can probably also use custom token patterns. They're probably more efficient, but they operate on the lexer level, not the parser level.

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@msujew
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msujew Mar 15, 2023
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@thejohnfreeman
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@bd82
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bd82 Mar 16, 2023
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@thejohnfreeman
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@bd82
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bd82 Mar 17, 2023
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Answer selected by thejohnfreeman
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Converted from issue

This discussion was converted from issue #1930 on March 13, 2023 15:44.