Function within

within is a funny combinator. It finds zero or more instances of parser within the input. It always succeeds and returns an array of results, each one being a matched or unmatched string. You could think of "within" as a glorified search. For example, you can use it to look for quoted text or multiline comments within an input.

Example:

  const multilineComments = seq(
  [str("/*"), manyWithJoin(noneOf(`*/`)), str("*/")],
  (results: string[]) => results.join("")
);
  const parser = within(multilineComments);
  const input = `code before /* this is a comment */ code after /* another comment */ end`;

  const result = parser(input);
  console.log(JSON.stringify(result, null, 2));
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Result:

{
"success": true,
"result": [
  {
    "type": "unmatched",
    "value": "code before "
  },
  {
    "type": "matched",
    "value": "/* this is a comment */"
  },
  {
    "type": "unmatched",
    "value": " code after "
  },
  {
    "type": "matched",
    "value": "/* another comment */"
  },
  {
    "type": "unmatched",
    "value": " end"
  }
],
"rest": ""
}
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This parser is somewhat expensive, as it will go down the input string one character at a time, applying the given parser each time.