recursive_regex 1.0.0 icon indicating copy to clipboard operation
recursive_regex: ^1.0.0 copied to clipboard

An implementation of RegExp that isolates delimited blocks of text and applies the pattern to each block separately.

recursive_regex #

pub package

An implementation of Dart's RegExp class that isolates delimited blocks of text and applies the delimited pattern to each block separately.

The [RecursiveRegex] class implements Dart's [RegExp] class. As such, it has all of the same methods as [RegExp] and can be used interchangeably with [RegExp]s.

Usage #

import 'package:recursive_regex/recursive_regex.dart';

[RecursiveRegex] has 2 required parameters, [startDelimiter] and [endDelimiter]. Both accept a [RegExp], must not be null, and must not have identical patterns.

final regex = RecursiveRegex(
  startDelimiter: RegExp(r'<'),
  endDelimiter: RegExp(r'>'),
);

This [RecursiveRegex], if applied to a string, would capture every block of text delimited by the < and > characters.

final input = 'a<b<c<d><e>f>g>h';
regex.allMatches(input); // ['<b<c<d><e>f>g>']

By default, only top-level blocks of delimited text are matched. To match every block of delimited text, nested or not, [global] can be flagged true.

final input = '<a<b<c><d>>>';

final regex = RecursiveRegex(
  startDelimiter: RegExp(r'<'),
  endDelimiter: RegExp(r'>'),
  global: true,
);

regex.allMatches(input); // ['<c>', '<d>', '<b<c><d>>', '<a<b<c><d>>>']

Delimited blocks of text are matched in the order that they're closed.

Note: [RecursiveRegex] is not optimized for parsing strings that do not contain nested blocks of delimited text, [RegExp] would be more efficient if you know the string doesn't contain any nested delimiters.

[prepended] & [appended] Patterns #

[Pattern]s can be provided to [RecursiveRegex]'s [prepended] and [appended] parameters to disqualify any matched set of delimiters that aren't lead and/or followed by the provided [Pattern].

final input = '0<a<b<1<c>2>3<d>>>';

final prepended = RecursiveRegex(
  startDelimiter: RegExp(r'<'),
  endDelimiter: RegExp(r'>'),
  prepended: RegExp(r'[0-9]'),
  global: true,
);

prepended.allMatches(input); // ['1<c>', '3<d>', '0<a<b<1<c>2>3<d>>>']

final appended = RecursiveRegex(
  startDelimiter: RegExp(r'<'),
  endDelimiter: RegExp(r'>'),
  appended: RegExp(r'[0-9]'),
  global: true,
);

appended.allMatches(input); // ['<c>2', '<1<c>2>3']

final both = RecursiveRegex(
  startDelimiter: RegExp(r'<'),
  endDelimiter: RegExp(r'>'),
  prepended: RegExp(r'[0-9]'),
  appended: RegExp(r'[0-9]'),
  global: true,
);

both.allMatches(input); // ['0<a<b<1<c>2>3']

inverseMatch #

A [Pattern] can be provided to the [inverseMatch] parameter to define a pattern that should be matched, but only if it's not delimited.

Note: [global] has no affect on the matches if an [inverseMatch] pattern is provided, as all lower-level matches are delimited.

final input = 'a<b<c<d><e>f>g>h';

final regex = RecursiveRegex(
  startDelimiter: RegExp(r'<'),
  endDelimiter: RegExp(r'>'),
  inverseMatch: RegExp(r'[a-z]'),
  global: true,
);

regex.allMatches(input); // ['a', 'h']

Capture Groups #

The block of text captured between the delimiters can be captured in a named group by providing [RecursiveRegex] with a [captureGroupName].

final input = '<!ELEMENT [ some markup ]>';

final regex = RecursiveRegex(
  startDelimiter: RegExp(r'<!(?<type>\w*)\s*\['),
  endDelimiter: RegExp(r']>'),
  captureGroupName: 'value',
);

print(regex.firstMatch(input).namedGroup('value')); // ' some markup '

// Groups named within the delimiters can also be called.
print(regex.firstMatch(input).namedGroup('type')); // 'ELEMENT'
6
likes
130
pub points
77%
popularity

Publisher

verified publisher iconjamesalex.dev

An implementation of RegExp that isolates delimited blocks of text and applies the pattern to each block separately.

Homepage

Documentation

API reference

License

Icon for licenses.BSD-2-Clause (LICENSE)

Dependencies

meta

More

Packages that depend on recursive_regex