BackReference class

A reference to an existing Captured Group.

Given an expression that already includes a Captured Group somewhere within the expression, and it's not using a name, and not flagged as non-capturing, it is possible to "remember" it, and "echo" it once again elsewhere in the expression body, just like a variable.

Example:

import 'package:fancy_regex/fancy_regex.dart';

// Simple HTML-like tag matcher
RegExp exp = FancyRegex(
  expression: const SerialExpressions(
    [
      RawExpression("<",),
      CaptureGroup(
        MatchOneOrMore(
          CharacterGroup(
            [
              CharacterGroupRange.lowerCased(),
            ],
          ),
        ),
      ),
      RawExpression(">",),
      MatchZeroOrMore(
        CharacterClass.any(),
      ),
      RawExpression("<",),
      CharacterClass.literal("/",),
      BackReference(1,),
      RawExpression(">",),
    ],
  ),
);
// produces <([a-z]+)>.*<\/\1>
exp.hasMatch("<html>Hello Za Warudo</html>",);
Implemented types
Available Extensions

Constructors

BackReference(int groupReference)
Creates an expression that indicates a groupReference by index where the number indicates the index number of created Capturing Group.
const

Properties

groupReference → int
final
hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
override

Operators

operator ==(Object other) → bool
The equality operator.
inherited