Introduce builtin for Array.slice function.

test/mjsunit/array-slice.js

+// Copyright 2010 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.
+
+// Check that slicing array of holes keeps it as array of holes
+(function() {
+  var array = new Array(10);
+  for (var i = 0; i < 7; i++) {
+    var sliced = array.slice();
+    assertEquals(array.length, sliced.length);
+    assertFalse(0 in sliced);
+  }
+})();
+
+
+// Check various forms of arguments omission.
+(function() {
+  var array = new Array(7);
+
+  for (var i = 0; i < 7; i++) {
+    assertEquals(array, array.slice());
+    assertEquals(array, array.slice(0));
+    assertEquals(array, array.slice(undefined));
+    assertEquals(array, array.slice("foobar"));
+    assertEquals(array, array.slice(undefined, undefined));
+  }
+})();
+
+
+// Check variants of negatives and positive indices.
+(function() {
+  var array = new Array(7);
+
+  for (var i = 0; i < 7; i++) {
+    assertEquals(7, array.slice(-100).length);
+    assertEquals(3, array.slice(-3).length);
+    assertEquals(3, array.slice(4).length);
+    assertEquals(1, array.slice(6).length);
+    assertEquals(0, array.slice(7).length);
+    assertEquals(0, array.slice(8).length);
+    assertEquals(0, array.slice(100).length);
+
+    assertEquals(0, array.slice(0, -100).length);
+    assertEquals(4, array.slice(0, -3).length);
+    assertEquals(4, array.slice(0, 4).length);
+    assertEquals(6, array.slice(0, 6).length);
+    assertEquals(7, array.slice(0, 7).length);
+    assertEquals(7, array.slice(0, 8).length);
+    assertEquals(7, array.slice(0, 100).length);
+
+    // Some exotic cases.
+
+    obj = { toString: function() { throw 'Exception'; } };
+
+    // More than 2 arguments:
+    assertEquals(7, array.slice(0, 7, obj, null, undefined).length);
+
+    // Custom conversion:
+    assertEquals(1, array.slice({valueOf: function() { return 1; }},
+                                {toString: function() { return 2; }}).length);
+
+    // Throwing an exception in conversion:
+    try {
+      assertEquals(7, array.slice(0, obj).length);
+      throw 'Should have thrown';
+    } catch (e) {
+      assertEquals('Exception', e);
+    }
+  }
+})();
+
+
+// Nasty: modify the array in ToInteger.
+(function() {
+  var array = [];
+  var expected = []
+  bad_guy = { valueOf: function() { array.push(array.length); return -1; } };
+
+  for (var i = 0; i < 13; i++) {
+    var sliced = array.slice(bad_guy);
+    expected.push(i);
+    assertEquals(expected, array);
+    // According to the spec (15.4.4.10), length is calculated before
+    // performing ToInteger on arguments.
+    if (i == 0) {
+      assertEquals([], sliced);  // Length was 0, nothing to get.
+    } else {
+      // Actually out of array [0..i] we get [i - 1] as length is i.
+      assertEquals([i - 1], sliced);
+    }
+  }
+})();
+
+
+// Now check the case with array of holes and some elements on prototype.
+(function() {
+  var len = 9;
+  var array = new Array(len);
+
+  var at3 = "@3";
+  var at7 = "@7";
+
+  for (var i = 0; i < 7; i++) {
+    Array.prototype[3] = at3;
+    Array.prototype[7] = at7;
+
+    assertEquals(len, array.length);
+    for (var i = 0; i < array.length; i++) {
+      assertEquals(array[i], Array.prototype[i]);
+    }
+
+    var sliced = array.slice();
+
+    assertEquals(len, sliced.length);
+
+    assertTrue(delete Array.prototype[3]);
+    assertTrue(delete Array.prototype[7]);
+
+    // Note that slice copies values from prototype into the array.
+    assertEquals(array[3], undefined);
+    assertFalse(array.hasOwnProperty(3));
+    assertEquals(sliced[3], at3);
+    assertTrue(sliced.hasOwnProperty(3));
+
+    assertEquals(array[7], undefined);
+    assertFalse(array.hasOwnProperty(7));
+    assertEquals(sliced[7], at7);
+    assertTrue(sliced.hasOwnProperty(7));
+
+    // ... but keeps the rest as holes:
+    Array.prototype[5] = "@5";
+    assertEquals(array[5], Array.prototype[5]);
+    assertFalse(array.hasOwnProperty(5));
+    assertEquals(sliced[5], Array.prototype[5]);
+    assertFalse(sliced.hasOwnProperty(5));
+
+    assertTrue(delete Array.prototype[5]);
+  }
+})();