1 // Copyright 2013 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 // Test aspects of the generator runtime. 29 30 // See: 31 // http://people.mozilla.org/~jorendorff/es6-draft.html#sec-generatorfunction-objects 32 33 function f() { } 34 function* g() { yield 1; } 35 var GeneratorFunctionPrototype = Object.getPrototypeOf(g); 36 var GeneratorFunction = GeneratorFunctionPrototype.constructor; 37 var GeneratorObjectPrototype = GeneratorFunctionPrototype.prototype; 38 39 // A generator function should have the same set of properties as any 40 // other function. 41 function TestGeneratorFunctionInstance() { 42 var f_own_property_names = Object.getOwnPropertyNames(f); 43 var g_own_property_names = Object.getOwnPropertyNames(g); 44 45 f_own_property_names.sort(); 46 g_own_property_names.sort(); 47 48 assertArrayEquals(f_own_property_names, g_own_property_names); 49 var i; 50 for (i = 0; i < f_own_property_names.length; i++) { 51 var prop = f_own_property_names[i]; 52 var f_desc = Object.getOwnPropertyDescriptor(f, prop); 53 var g_desc = Object.getOwnPropertyDescriptor(g, prop); 54 assertEquals(f_desc.configurable, g_desc.configurable, prop); 55 if (prop === 'arguments' || prop === 'caller') { 56 // Unlike sloppy functions, which have read-only data arguments and caller 57 // properties, sloppy generators have a poison pill implemented via 58 // accessors 59 assertFalse('writable' in g_desc, prop); 60 assertTrue(g_desc.get instanceof Function, prop); 61 assertEquals(g_desc.get, g_desc.set, prop); 62 } else { 63 assertEquals(f_desc.writable, g_desc.writable, prop); 64 } 65 assertEquals(f_desc.enumerable, g_desc.enumerable, prop); 66 } 67 } 68 TestGeneratorFunctionInstance(); 69 70 71 // Generators have an additional object interposed in the chain between 72 // themselves and Function.prototype. 73 function TestGeneratorFunctionPrototype() { 74 // Sanity check. 75 assertSame(Object.getPrototypeOf(f), Function.prototype); 76 assertFalse(GeneratorFunctionPrototype === Function.prototype); 77 assertSame(Function.prototype, 78 Object.getPrototypeOf(GeneratorFunctionPrototype)); 79 assertSame(GeneratorFunctionPrototype, 80 Object.getPrototypeOf(function* () {})); 81 } 82 TestGeneratorFunctionPrototype(); 83 84 85 // Functions that we associate with generator objects are actually defined by 86 // a common prototype. 87 function TestGeneratorObjectPrototype() { 88 assertSame(Object.prototype, 89 Object.getPrototypeOf(GeneratorObjectPrototype)); 90 assertSame(GeneratorObjectPrototype, 91 Object.getPrototypeOf((function*(){yield 1}).prototype)); 92 93 var expected_property_names = ["next", "throw", "constructor"]; 94 var found_property_names = 95 Object.getOwnPropertyNames(GeneratorObjectPrototype); 96 97 expected_property_names.sort(); 98 found_property_names.sort(); 99 100 assertArrayEquals(expected_property_names, found_property_names); 101 102 iterator_desc = Object.getOwnPropertyDescriptor(GeneratorObjectPrototype, 103 Symbol.iterator); 104 assertTrue(iterator_desc !== undefined); 105 assertFalse(iterator_desc.writable); 106 assertFalse(iterator_desc.enumerable); 107 assertFalse(iterator_desc.configurable); 108 109 // The generator object's "iterator" function is just the identity. 110 assertSame(iterator_desc.value.call(42), 42); 111 } 112 TestGeneratorObjectPrototype(); 113 114 115 // This tests the object that would be called "GeneratorFunction", if it were 116 // like "Function". 117 function TestGeneratorFunction() { 118 assertSame(GeneratorFunctionPrototype, GeneratorFunction.prototype); 119 assertTrue(g instanceof GeneratorFunction); 120 121 assertSame(Function, Object.getPrototypeOf(GeneratorFunction)); 122 assertTrue(g instanceof Function); 123 124 assertEquals("function* g() { yield 1; }", g.toString()); 125 126 // Not all functions are generators. 127 assertTrue(f instanceof Function); // Sanity check. 128 assertTrue(!(f instanceof GeneratorFunction)); 129 130 assertTrue((new GeneratorFunction()) instanceof GeneratorFunction); 131 assertTrue(GeneratorFunction() instanceof GeneratorFunction); 132 } 133 TestGeneratorFunction(); 134 135 136 function TestPerGeneratorPrototype() { 137 assertTrue((function*(){}).prototype !== (function*(){}).prototype); 138 assertTrue((function*(){}).prototype !== g.prototype); 139 assertTrue(g.prototype instanceof GeneratorFunctionPrototype); 140 assertSame(GeneratorObjectPrototype, Object.getPrototypeOf(g.prototype)); 141 assertTrue(!(g.prototype instanceof Function)); 142 assertSame(typeof (g.prototype), "object"); 143 144 assertArrayEquals([], Object.getOwnPropertyNames(g.prototype)); 145 } 146 TestPerGeneratorPrototype(); 147