* Irregexp: Handle backtrack past look-ahead.

test/mjsunit/regexp-lookahead.js

+// Copyright 2009 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Tests captures in positive and negative look-ahead in regular expressions.
+
+function stringEscape(string) {
+  // Converts string to source literal.
+  return '"' + string.replace(/["\\]/g, "\\$1") + '"';
+}
+
+function testRE(re, input, expected_result) {
+  var testName = re + ".test(" + stringEscape(input) +")";
+  if (expected_result) {
+    assertTrue(re.test(input), testName);
+  } else {
+    assertFalse(re.test(input), testName);
+  }
+}
+
+function execRE(re, input, expected_result) {
+  var testName = re + ".exec('" + stringEscape(input) +"')";
+  assertEquals(expected_result, re.exec(input), testName);
+}
+
+// Test of simple positive lookahead.
+
+var re = /^(?=a)/;
+testRE(re, "a", true);
+testRE(re, "b", false);
+execRE(re, "a", [""]);
+
+re = /^(?=\woo)f\w/;
+testRE(re, "foo", true);
+testRE(re, "boo", false);
+testRE(re, "fao", false);
+testRE(re, "foa", false);
+execRE(re, "foo", ["fo"]);
+
+re = /(?=\w).(?=\W)/;
+testRE(re, ".a! ", true);
+testRE(re, ".! ", false);
+testRE(re, ".ab! ", true);
+execRE(re, ".ab! ", ["b"]);
+
+re = /(?=f(?=[^f]o))../;
+testRE(re, ", foo!", true);
+testRE(re, ", fo!", false);
+testRE(re, ", ffo", false);
+execRE(re, ", foo!", ["fo"]);
+
+// Positive lookahead with captures.
+re = /^[^\'\"]*(?=([\'\"])).*\1(\w+)\1/;
+testRE(re, "  'foo' ", true);
+testRE(re, '  "foo" ', true);
+testRE(re, " \" 'foo' ", false);
+testRE(re, " ' \"foo\" ", false);
+testRE(re, "  'foo\" ", false);
+testRE(re, "  \"foo' ", false);
+execRE(re, "  'foo' ", ["  'foo'", "'", "foo"]);
+execRE(re, '  "foo" ', ['  "foo"', '"', 'foo']);
+
+// Captures are cleared on backtrack past the look-ahead.
+re = /^(?:(?=(.))a|b)\1$/;
+testRE(re, "aa", true);
+testRE(re, "b", true);
+testRE(re, "bb", false);
+testRE(re, "a", false);
+execRE(re, "aa", ["aa", "a"]);
+execRE(re, "b", ["b", undefined]);
+
+re = /^(?=(.)(?=(.)\1\2)\2\1)\1\2/;
+testRE(re, "abab", true);
+testRE(re, "ababxxxxxxxx", true);
+testRE(re, "aba", false);
+execRE(re, "abab", ["ab", "a", "b"]);
+
+re = /^(?:(?=(.))a|b|c)$/;
+testRE(re, "a", true);
+testRE(re, "b", true);
+testRE(re, "c", true);
+testRE(re, "d", false);
+execRE(re, "a", ["a", "a"]);
+execRE(re, "b", ["b", undefined]);
+execRE(re, "c", ["c", undefined]);
+
+execRE(/^(?=(b))b/, "b", ["b", "b"]);
+execRE(/^(?:(?=(b))|a)b/, "ab", ["ab", undefined]);
+execRE(/^(?:(?=(b)(?:(?=(c))|d))|)bd/, "bd", ["bd", "b", undefined]);
+
+
+
+// Test of Negative Look-Ahead.
+
+re = /(?!x)./;
+testRE(re, "y", true);
+testRE(re, "x", false);
+execRE(re, "y", ["y"]);
+
+re = /(?!(\d))|\d/;
+testRE(re, "4", true);
+execRE(re, "4", ["4", undefined]);
+execRE(re, "x", ["", undefined]);
+
+
+// Test mixed nested look-ahead with captures.
+
+re = /^(?=(x)(?=(y)))/;
+testRE(re, "xy", true);
+testRE(re, "xz", false);
+execRE(re, "xy", ["", "x", "y"]);
+
+re = /^(?!(x)(?!(y)))/;
+testRE(re, "xy", true);
+testRE(re, "xz", false);
+execRE(re, "xy", ["", undefined, undefined]);
+
+re = /^(?=(x)(?!(y)))/;
+testRE(re, "xz", true);
+testRE(re, "xy", false)
+execRE(re, "xz", ["", "x", undefined]);
+
+re = /^(?!(x)(?=(y)))/;
+testRE(re, "xz", true);
+testRE(re, "xy", false);
+execRE(re, "xz", ["", undefined, undefined]);
+
+re = /^(?=(x)(?!(y)(?=(z))))/;
+testRE(re, "xaz", true);
+testRE(re, "xya", true);
+testRE(re, "xyz", false);
+testRE(re, "a", false);
+execRE(re, "xaz", ["", "x", undefined, undefined]);
+execRE(re, "xya", ["", "x", undefined, undefined]);
+
+re = /^(?!(x)(?=(y)(?!(z))))/;
+testRE(re, "a", true);
+testRE(re, "xa", true);
+testRE(re, "xyz", true);
+testRE(re, "xya", false);
+execRE(re, "a", ["", undefined, undefined, undefined]);
+execRE(re, "xa", ["", undefined, undefined, undefined]);
+execRE(re, "xyz", ["", undefined, undefined, undefined]);