Migrate language_2/reg_exp to NNBD.

Change-Id: I662add43926c09735f7ae3899567f5df085ff6a9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150465
Auto-Submit: Bob Nystrom <rnystrom@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>
Reviewed-by: Srujan Gaddam <srujzs@google.com>

tests/language/reg_exp/reg_exp2_test.dart

@@ -0,0 +1,34 @@
+// 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 test for testing regular expressions in Dart.
+
+import "package:expect/expect.dart";
+
+class RegExp2Test {
+  static String? findImageTag_(String text, String extensions) {
+    final re = new RegExp('src="(http://\\S+\\.(${extensions}))"');
+    print('REGEXP findImageTag_ $extensions text: \n$text');
+    final match = re.firstMatch(text);
+    print('REGEXP findImageTag_ $extensions SUCCESS');
+    if (match != null) {
+      return match[1];
+    } else {
+      return null;
+    }
+  }
+
+  static testMain() {
+    String text =
+        '''<img src="http://cdn.archinect.net/images/514x/c0/c0p3qo202oxp0e6z.jpg" width="514" height="616" border="0" title="" alt=""><em><p>My last entry was in December of 2009. I suppose I never was particularly good about updating this thing, but it seems a bit ridiculous that I couldn't be bothered to post once about the many, many things that have gone on since then. My apologies. I guess I could start by saying that the world looks like a very different place than it did back in second year.</p></em>
+
+''';
+    String extensions = 'jpg|jpeg|png';
+    String? tag = findImageTag_(text, extensions);
+    Expect.isNotNull(tag);
+  }
+}
+
+main() {
+  RegExp2Test.testMain();
+}

tests/language/reg_exp/reg_exp3_test.dart

@@ -0,0 +1,23 @@
+// 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 test for testing regular expressions in Dart.
+
+import "package:expect/expect.dart";
+
+class RegExp3Test {
+  static testMain() {
+    var i = 2000;
+    try {
+      RegExp exp = new RegExp("[");
+      i = 100; // Should not reach here.
+    } on FormatException catch (e) {
+      i = 0;
+    }
+    Expect.equals(0, i);
+  }
+}
+
+main() {
+  RegExp3Test.testMain();
+}

tests/language/reg_exp/reg_exp4_test.dart

@@ -0,0 +1,26 @@
+// 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 test for testing regular expressions in Dart.
+
+class RegEx2Test {
+  static void testMain() {
+    final helloPattern = new RegExp("with (hello)");
+    String s = "this is a string with hello somewhere";
+    Match? match = helloPattern.firstMatch(s);
+    if (match != null) {
+      print("got match");
+      int groupCount = match.groupCount;
+      print("groupCount is $groupCount");
+      print("group 0 is ${match.group(0)}");
+      print("group 1 is ${match.group(1)}");
+    } else {
+      print("match not round");
+    }
+    print("done");
+  }
+}
+
+main() {
+  RegEx2Test.testMain();
+}

tests/language/reg_exp/reg_exp_test.dart

@@ -0,0 +1,84 @@
+// 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 test for testing regular expressions in Dart.
+
+import "package:expect/expect.dart";
+
+void main() {
+  RegExp exp = new RegExp(r"(\w+)");
+  String str = "Parse my string";
+  List<Match> matches = exp.allMatches(str).toList();
+  Expect.equals(3, matches.length);
+  Expect.equals("Parse", matches[0].group(0));
+  Expect.equals("my", matches[1].group(0));
+  Expect.equals("string", matches[2].group(0));
+
+  // Check that allMatches progresses correctly for empty matches, and that
+  // it includes the empty match at the end position.
+  exp = new RegExp("a?");
+  str = "babba";
+  Expect.listEquals(["", "a", "", "", "a", ""],
+      exp.allMatches(str).map((x) => x[0]).toList());
+
+  // Check that allMatches works with optional start index.
+  exp = new RegExp("as{2}");
+  str = "assassin";
+  Expect.equals(2, exp.allMatches(str).length);
+  Expect.equals(2, exp.allMatches(str, 0).length);
+  Expect.equals(1, exp.allMatches(str, 1).length);
+  Expect.equals(0, exp.allMatches(str, 4).length);
+  Expect.equals(0, exp.allMatches(str, str.length).length);
+  Expect.throws(() => exp.allMatches(str, -1));
+  Expect.throws(() => exp.allMatches(str, str.length + 1));
+
+  exp = new RegExp(".*");
+  Expect.equals("", exp.allMatches(str, str.length).single[0]);
+
+  // The "^" must only match at the beginning of the string.
+  // Using a start-index doesn't change where the string starts.
+  exp = new RegExp("^ass");
+  Expect.equals(1, exp.allMatches(str, 0).length);
+  Expect.equals(0, exp.allMatches(str, 3).length);
+
+  // Regression test for http://dartbug.com/2980
+  exp = new RegExp("^", multiLine: true); // Any zero-length match will work.
+  str = "foo\nbar\nbaz";
+  Expect.equals(" foo\n bar\n baz", str.replaceAll(exp, " "));
+
+  exp = new RegExp(r"(\w+)");
+  Expect.isNull(exp.matchAsPrefix(" xyz ab"));
+  Expect.isNull(exp.matchAsPrefix(" xyz ab", 0));
+
+  var m = exp.matchAsPrefix(" xyz ab", 1)!;
+  Expect.equals("xyz", m[0]);
+  Expect.equals("xyz", m[1]);
+  Expect.equals(1, m.groupCount);
+
+  m = exp.matchAsPrefix(" xyz ab", 2)!;
+  Expect.equals("yz", m[0]);
+  Expect.equals("yz", m[1]);
+  Expect.equals(1, m.groupCount);
+
+  m = exp.matchAsPrefix(" xyz ab", 3)!;
+  Expect.equals("z", m[0]);
+  Expect.equals("z", m[1]);
+  Expect.equals(1, m.groupCount);
+
+  Expect.isNull(exp.matchAsPrefix(" xyz ab", 4));
+
+  m = exp.matchAsPrefix(" xyz ab", 5)!;
+  Expect.equals("ab", m[0]);
+  Expect.equals("ab", m[1]);
+  Expect.equals(1, m.groupCount);
+
+  m = exp.matchAsPrefix(" xyz ab", 6)!;
+  Expect.equals("b", m[0]);
+  Expect.equals("b", m[1]);
+  Expect.equals(1, m.groupCount);
+
+  Expect.isNull(exp.matchAsPrefix(" xyz ab", 7));
+
+  Expect.throws(() => exp.matchAsPrefix(" xyz ab", -1));
+  Expect.throws(() => exp.matchAsPrefix(" xyz ab", 8));
+}