Port and integrate the irregexp engine from V8

tests/language/regex/zero-length-alternatives_test.dart

+// Copyright (c) 2014, 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.
+
+import 'util.dart';
+import 'package:expect/expect.dart';
+
+void main() {
+  description(
+  'Test regular expression processing with alternatives that match consuming no characters'
+  );
+
+  var emptyStr = "";
+  var s1 = "xxxx";
+  var s2 = "aaaa";
+  var s3 = "aax";
+  var s4 = "abab";
+  var s5 = "ab";
+  var s6 = "xabx";
+  var s7 = "g0";
+
+  // Non-capturing empty first alternative greedy '*'
+  var re1 = new RegExp(r"(?:|a|z)*");
+  shouldBe(firstMatch(emptyStr, re1), [""]);
+  shouldBe(firstMatch(s1, re1), [""]);
+  shouldBe(firstMatch(s2, re1), ["aaaa"]);
+  shouldBe(firstMatch(s3, re1), ["aa"]);
+
+  // Non-capturing empty middle alternative greedy '*'
+  var re2 = new RegExp(r"(?:a||z)*");
+  shouldBe(firstMatch(emptyStr, re2), [""]);
+  shouldBe(firstMatch(s1, re2), [""]);
+  shouldBe(firstMatch(s2, re2), ["aaaa"]);
+  shouldBe(firstMatch(s3, re2), ["aa"]);
+
+  // Non-capturing empty last alternative greedy '*'
+  var re3 = new RegExp(r"(?:a|z|)*");
+  shouldBe(firstMatch(emptyStr, re3), [""]);
+  shouldBe(firstMatch(s1, re3), [""]);
+  shouldBe(firstMatch(s2, re3), ["aaaa"]);
+  shouldBe(firstMatch(s3, re3), ["aa"]);
+
+  // Capturing empty first alternative greedy '*'
+  var re4 = new RegExp(r"(|a|z)*");
+  shouldBe(firstMatch(emptyStr, re4), ["", null]);
+  shouldBe(firstMatch(s1, re4), ["", null]);
+  shouldBe(firstMatch(s2, re4), ["aaaa", "a"]);
+  shouldBe(firstMatch(s3, re4), ["aa", "a"]);
+
+  // Capturing empty middle alternative greedy '*'
+  var re5 = new RegExp(r"(a||z)*");
+  shouldBe(firstMatch(emptyStr, re5), ["", null]);
+  shouldBe(firstMatch(s1, re5), ["", null]);
+  shouldBe(firstMatch(s2, re5), ["aaaa", "a"]);
+  shouldBe(firstMatch(s3, re5), ["aa", "a"]);
+
+  // Capturing empty last alternative greedy '*'
+  var re6 = new RegExp(r"(a|z|)*");
+  shouldBe(firstMatch(emptyStr, re6), ["", null]);
+  shouldBe(firstMatch(s1, re6), ["", null]);
+  shouldBe(firstMatch(s2, re6), ["aaaa", "a"]);
+  shouldBe(firstMatch(s3, re6), ["aa", "a"]);
+
+  // Non-capturing empty first alternative fixed-count
+  var re7 = new RegExp(r"(?:|a|z){2,5}");
+  shouldBe(firstMatch(emptyStr, re7), [""]);
+  shouldBe(firstMatch(s1, re7), [""]);
+  shouldBe(firstMatch(s2, re7), ["aaa"]);
+  shouldBe(firstMatch(s3, re7), ["aa"]);
+
+  // Non-capturing empty middle alternative fixed-count
+  var re8 = new RegExp(r"(?:a||z){2,5}");
+  shouldBe(firstMatch(emptyStr, re8), [""]);
+  shouldBe(firstMatch(s1, re8), [""]);
+  shouldBe(firstMatch(s2, re8), ["aaaa"]);
+  shouldBe(firstMatch(s3, re8), ["aa"]);
+
+  // Non-capturing empty last alternative fixed-count
+  var re9 = new RegExp(r"(?:a|z|){2,5}");
+  shouldBe(firstMatch(emptyStr, re9), [""]);
+  shouldBe(firstMatch(s1, re9), [""]);
+  shouldBe(firstMatch(s2, re9), ["aaaa"]);
+  shouldBe(firstMatch(s3, re9), ["aa"]);
+
+  // Non-capturing empty first alternative non-greedy '*'
+  var re10 = new RegExp(r"(?:|a|z)*?");
+  shouldBe(firstMatch(emptyStr, re10), [""]);
+  shouldBe(firstMatch(s1, re10), [""]);
+  shouldBe(firstMatch(s2, re10), [""]);
+  shouldBe(firstMatch(s3, re10), [""]);
+
+  // Non-capturing empty middle alternative non-greedy '*'
+  var re11 = new RegExp(r"(?:a||z)*?");
+  shouldBe(firstMatch(emptyStr, re11), [""]);
+  shouldBe(firstMatch(s1, re11), [""]);
+  shouldBe(firstMatch(s2, re11), [""]);
+  shouldBe(firstMatch(s3, re11), [""]);
+
+  // Non-capturing empty last alternative non-greedy '*'
+  var re12 = new RegExp(r"(?:a|z|)*?");
+  shouldBe(firstMatch(emptyStr, re12), [""]);
+  shouldBe(firstMatch(s1, re12), [""]);
+  shouldBe(firstMatch(s2, re12), [""]);
+  shouldBe(firstMatch(s3, re12), [""]);
+
+  // Capturing empty first alternative non-greedy '*'
+  var re13 = new RegExp(r"(|a|z)*?");
+  shouldBe(firstMatch(emptyStr, re13), ["", null]);
+  shouldBe(firstMatch(s1, re13), ["", null]);
+  shouldBe(firstMatch(s2, re13), ["", null]);
+  shouldBe(firstMatch(s3, re13), ["", null]);
+
+  // Capturing empty middle alternative non-greedy '*'
+  var re14 = new RegExp(r"(a||z)*?");
+  shouldBe(firstMatch(emptyStr, re14), ["", null]);
+  shouldBe(firstMatch(s1, re14), ["", null]);
+  shouldBe(firstMatch(s2, re14), ["", null]);
+  shouldBe(firstMatch(s3, re14), ["", null]);
+
+  // Capturing empty last alternative non-greedy '*'
+  var re15 = new RegExp(r"(a|z|)*?");
+  shouldBe(firstMatch(emptyStr, re15), ["", null]);
+  shouldBe(firstMatch(s1, re15), ["", null]);
+  shouldBe(firstMatch(s2, re15), ["", null]);
+  shouldBe(firstMatch(s3, re15), ["", null]);
+
+  // Non-capturing empty first alternative greedy '?'
+  var re16 = new RegExp(r"(?:|a|z)?");
+  shouldBe(firstMatch(emptyStr, re16), [""]);
+  shouldBe(firstMatch(s1, re16), [""]);
+  shouldBe(firstMatch(s2, re16), ["a"]);
+  shouldBe(firstMatch(s3, re16), ["a"]);
+
+  // Non-capturing empty middle alternative greedy '?'
+  var re17 = new RegExp(r"(?:a||z)?");
+  shouldBe(firstMatch(emptyStr, re17), [""]);
+  shouldBe(firstMatch(s1, re17), [""]);
+  shouldBe(firstMatch(s2, re17), ["a"]);
+  shouldBe(firstMatch(s3, re17), ["a"]);
+
+  // Non-capturing empty last alternative greedy '?'
+  var re18 = new RegExp(r"(?:a|z|)?");
+  shouldBe(firstMatch(emptyStr, re18), [""]);
+  shouldBe(firstMatch(s1, re18), [""]);
+  shouldBe(firstMatch(s2, re18), ["a"]);
+  shouldBe(firstMatch(s3, re18), ["a"]);
+
+  // Capturing empty first alternative greedy '?'
+  var re19 = new RegExp(r"(|a|z)?");
+  shouldBe(firstMatch(emptyStr, re19), ["", null]);
+  shouldBe(firstMatch(s1, re19), ["", null]);
+  shouldBe(firstMatch(s2, re19), ["a", "a"]);
+  shouldBe(firstMatch(s3, re19), ["a", "a"]);
+
+  // Capturing empty middle alternative greedy '?'
+  var re20 = new RegExp(r"(a||z)?");
+  shouldBe(firstMatch(emptyStr, re20), ["", null]);
+  shouldBe(firstMatch(s1, re20), ["", null]);
+  shouldBe(firstMatch(s2, re20), ["a", "a"]);
+  shouldBe(firstMatch(s3, re20), ["a", "a"]);
+
+  // Capturing empty last alternative greedy '?'
+  var re21 = new RegExp(r"(a|z|)?");
+  shouldBe(firstMatch(emptyStr, re21), ["", null]);
+  shouldBe(firstMatch(s1, re21), ["", null]);
+  shouldBe(firstMatch(s2, re21), ["a", "a"]);
+  shouldBe(firstMatch(s3, re21), ["a", "a"]);
+
+  // Non-capturing empty first alternative non-greedy '?'
+  var re22 = new RegExp(r"(?:|a|z)??");
+  shouldBe(firstMatch(emptyStr, re22), [""]);
+  shouldBe(firstMatch(s1, re22), [""]);
+  shouldBe(firstMatch(s2, re22), [""]);
+  shouldBe(firstMatch(s3, re22), [""]);
+
+  // Non-capturing empty middle alternative non-greedy '?'
+  var re23 = new RegExp(r"(?:a||z)??");
+  shouldBe(firstMatch(emptyStr, re23), [""]);
+  shouldBe(firstMatch(s1, re23), [""]);
+  shouldBe(firstMatch(s2, re23), [""]);
+  shouldBe(firstMatch(s3, re23), [""]);
+
+  // Non-capturing empty last alternative non-greedy '?'
+  var re24 = new RegExp(r"(?:a|z|)??");
+  shouldBe(firstMatch(emptyStr, re24), [""]);
+  shouldBe(firstMatch(s1, re24), [""]);
+  shouldBe(firstMatch(s2, re24), [""]);
+  shouldBe(firstMatch(s3, re24), [""]);
+
+  // Capturing empty first alternative non-greedy '?'
+  var re25 = new RegExp(r"(|a|z)??");
+  shouldBe(firstMatch(emptyStr, re25), ["", null]);
+  shouldBe(firstMatch(s1, re25), ["", null]);
+  shouldBe(firstMatch(s2, re25), ["", null]);
+  shouldBe(firstMatch(s3, re25), ["", null]);
+
+  // Capturing empty middle alternative non-greedy '?'
+  var re26 = new RegExp(r"(a||z)??");
+  shouldBe(firstMatch(emptyStr, re26), ["", null]);
+  shouldBe(firstMatch(s1, re26), ["", null]);
+  shouldBe(firstMatch(s2, re26), ["", null]);
+  shouldBe(firstMatch(s3, re26), ["", null]);
+
+  // Capturing empty last alternative non-greedy '?'
+  var re27 = new RegExp(r"(a|z|)??");
+  shouldBe(firstMatch(emptyStr, re27), ["", null]);
+  shouldBe(firstMatch(s1, re27), ["", null]);
+  shouldBe(firstMatch(s2, re27), ["", null]);
+  shouldBe(firstMatch(s3, re27), ["", null]);
+
+  // Non-capturing empty first alternative greedy '*' non-terminal
+  var re28 = new RegExp(r"(?:|a|z)*x");
+  shouldBe(firstMatch(emptyStr, re28), null);
+  shouldBe(firstMatch(s1, re28), ["x"]);
+  shouldBe(firstMatch(s2, re28), null);
+  shouldBe(firstMatch(s3, re28), ["aax"]);
+
+  // Non-capturing empty middle alternative greedy '*' non-terminal
+  var re29 = new RegExp(r"(?:a||z)*x");
+  shouldBe(firstMatch(emptyStr, re29), null);
+  shouldBe(firstMatch(s1, re29), ["x"]);
+  shouldBe(firstMatch(s2, re29), null);
+  shouldBe(firstMatch(s3, re29), ["aax"]);
+
+  // Non-capturing empty last alternative greedy '*' non-terminal
+  var re30 = new RegExp(r"(?:a|z|)*x");
+  shouldBe(firstMatch(emptyStr, re30), null);
+  shouldBe(firstMatch(s1, re30), ["x"]);
+  shouldBe(firstMatch(s2, re30), null);
+  shouldBe(firstMatch(s3, re30), ["aax"]);
+
+  // Non-capturing two possibly empty alternatives greedy '*'
+  var re31 = new RegExp(r"(?:a*|b*)*");
+  shouldBe(firstMatch(emptyStr, re31), [""]);
+  shouldBe(firstMatch(s1, re31), [""]);
+  shouldBe(firstMatch(s3, re31), ["aa"]);
+  shouldBe(firstMatch(s4, re31), ["abab"]);
+
+  // Non-capturing two possibly empty non-greedy alternatives non-greedy '*'
+  var re32 = new RegExp(r"(?:a*?|b*?)*");
+  shouldBe(firstMatch(emptyStr, re32), [""]);
+  shouldBe(firstMatch(s1, re32), [""]);
+  shouldBe(firstMatch(s2, re32), ["aaaa"]);
+  shouldBe(firstMatch(s4, re32), ["abab"]);
+  shouldBe(firstMatch(s5, re32), ["ab"]);
+  shouldBe(firstMatch(s6, re32), [""]);
+
+  // Three possibly empty alternatives with greedy +
+  var re33 = new RegExp(r"(?:(?:(?!))|g?|0*\*?)+");
+  shouldBe(firstMatch(emptyStr, re33), [""]);
+  shouldBe(firstMatch(s1, re33), [""]);
+  shouldBe(firstMatch(s7, re33), ["g0"]);
+
+  // first alternative zero length fixed count
+  var re34 = new RegExp(r"(?:|a)");
+  shouldBe(firstMatch(emptyStr, re34), [""]);
+  shouldBe(firstMatch(s1, re34), [""]);
+  shouldBe(firstMatch(s2, re34), [""]);
+  shouldBe(firstMatch(s3, re34), [""]);
+}