| // 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. |
| |
| /// @assertion 15.10.2.8: The form (?= Disjunction ) specifies a zero-width |
| /// positive lookahead. In order for it to succeed, the pattern inside |
| /// Disjunction must match at the current position, but the current position is |
| /// not advanced before matching the sequel. If Disjunction can match at the |
| /// current position in several ways, only the first one is tried. Unlike other |
| /// regular expression operators, there is no backtracking into a (?= form (this |
| /// unusual behaviour is inherited from Perl). This only matters when the |
| /// Disjunction contains capturing parentheses and the sequel of the pattern |
| /// contains backreferences to those captures. |
| /// @description Checks that this syntax works as specified. |
| /// @3rdparty sputnik-v1:S15.10.2.8_A1_T1.js-S15.10.2.8_A1_T5.js |
| /// @author rodionov |
| |
| import "../../../../Utils/expect.dart"; |
| |
| |
| main() { |
| check(r"(?=(a+))", "baaabac", 1, ["", "aaa"]); |
| check(r"(?=(a+))a*b\1", "baaabac", 3, ["aba", "a"]); |
| check(r"[Jj]ava([Ss]cript)?(?=\:)", "just Javascript: the way 0f jedi", 5, |
| ["Javascript", "script"]); |
| check(r"[Jj]ava([Ss]cript)?(?=\:)", "taste of java: the cookbook", 9, |
| ["java", null]); |
| checkNeg(r"[Jj]ava([Ss]cript)?(?=\:)", "rhino is JavaScript engine"); |
| checkNeg(r"a(?=b)a", "aba"); |
| checkNeg(r"(?=a)b\1", "aabb"); |
| } |
| |
| void check(String pattern, String str, int matchPos, |
| List<String?> expectedGroups) { |
| RegExp re = new RegExp(pattern); |
| Expect.isNotNull(re.firstMatch(str), "\"$pattern\" !~ \"$str\""); |
| Match fm = re.firstMatch(str) as Match; |
| if(matchPos >= 0) { |
| Expect.equals(matchPos, fm.start); |
| } |
| if(null != expectedGroups) { |
| Expect.equals(expectedGroups.length, fm.groupCount + 1); |
| |
| for(int i = 0; i <= fm.groupCount; i++) { |
| String? expGr = expectedGroups[i]; |
| String? actGr = fm.group(i); |
| Expect.equals(expGr, actGr, |
| "Mismatch at group $i: \"$expGr\" expected instead of \"$actGr\""); |
| } |
| } |
| } |
| |
| void checkNeg(String pattern, String str) { |
| RegExp re = new RegExp(pattern); |
| if(null != re.firstMatch(str)) { |
| Expect.fail("\"$pattern\" ~ \"$str\""); |
| } |
| } |
| |
| void checkEx(String pattern, String str) { |
| bool fail = false; |
| try { |
| RegExp re = new RegExp(pattern); |
| re.firstMatch(str); |
| fail = true; |
| } catch(ok) {} |
| if(fail == true) { |
| Expect.fail("An error expected"); |
| } |
| } |