LibTest/core/RegExp/Pattern_semantics/firstMatch_NonEmptyClassRanges_A01_t06.dart

// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// @dart = 2.9

/// @assertion 15.10.2.15: The production NonemptyClassRanges :: ClassAtom -
///            ClassAtom ClassRanges evaluates as follows:
///            <ol>
///            <li>Evaluate the first ClassAtom to obtain a CharSet A. </li>
///            <li>Evaluate the second ClassAtom to obtain a CharSet B.</li>
///            <li>Evaluate ClassRanges to obtain a CharSet C. </li>
///            <li>Call CharacterRange(A, B) and let D be the resulting CharSet.</li>
///            <li>Return the union of CharSets D and C.</li>
///            </ol>
///            <br/> The abstract operation CharacterRange takes two CharSet
///            parameters A and B and performs the following:
///            <ol>
///            <li>If A does not contain exactly one character or B does not
///            contain exactly one character then throw a SyntaxError exception.
///            </li>
///            <li>Let a be the one character in CharSet A. </li>
///            <li>Let b be the one character in CharSet B. </li>
///            <li>Let i be the code unit value of character a. </li>
///            <li>Let j be the code unit value of character b. </li>
///            <li>If i > j then throw a SyntaxError exception. </li>
///            <li>Return the set containing all characters numbered i through
///            j, inclusive.</li>
///            </ol>
///            <br/> 15.10.2.19: NOTE A ClassAtom can use any of the escape
///            sequences that are allowed in the rest of the regular expression
///            except for \b, \B, and backreferences. Inside a CharacterClass, \b
///            means the backspace character, while \B and backreferences raise
///            errors. Using a backreference inside a ClassAtom causes an error.
/// @description Checks that using backreferences inside a ClassAtom doesn't
/// cause an error.
/// @author rodionov
/// @note issue 1299

import "../../../../Utils/expect.dart";
 
main() {
  checkNeg(r"(a)[\1]*", "aa");
  checkNeg(r"(a)(b)[\1\2]*", "abab");
  checkNeg(r"(a)(b)[\1-\2]*", "abab");
  checkNeg(r"[\1]?", "a");
  checkNeg(r"(a)[\1]?", "aa");
  checkNeg(r"(a)(b)[\1-\2]", "aba");
}

void checkNeg(String pattern, [String testStr = ""]) {
  RegExp re = new RegExp(pattern);
  re.firstMatch(testStr);
}