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 // Flags: --harmony-generators 29 30 // Test basic generator syntax. 31 32 // Yield statements. 33 function* g() { yield 3; yield 4; } 34 35 // Yield expressions. 36 function* g() { (yield 3) + (yield 4); } 37 38 // You can have a generator in strict mode. 39 function* g() { "use strict"; yield 3; yield 4; } 40 41 // Generators can have return statements also, which internally parse to a kind 42 // of yield expression. 43 function* g() { yield 1; return; } 44 function* g() { yield 1; return 2; } 45 function* g() { yield 1; return 2; yield "dead"; } 46 47 // Generator expression. 48 (function* () { yield 3; }); 49 50 // Named generator expression. 51 (function* g() { yield 3; }); 52 53 // A generator without a yield is specified as causing an early error. This 54 // behavior is currently unimplemented. See 55 // https://bugs.ecmascript.org/show_bug.cgi?id=1283. 56 function* g() { } 57 58 // A YieldExpression in the RHS of a YieldExpression is currently specified as 59 // causing an early error. This behavior is currently unimplemented. See 60 // https://bugs.ecmascript.org/show_bug.cgi?id=1283. 61 function* g() { yield yield 1; } 62 function* g() { yield 3 + (yield 4); } 63 64 // Generator definitions with a name of "yield" are not specifically ruled out 65 // by the spec, as the `yield' name is outside the generator itself. However, 66 // in strict-mode, "yield" is an invalid identifier. 67 function* yield() { (yield 3) + (yield 4); } 68 assertThrows("function* yield() { \"use strict\"; (yield 3) + (yield 4); }", 69 SyntaxError); 70 71 // In classic mode, yield is a normal identifier, outside of generators. 72 function yield(yield) { yield: yield (yield + yield (0)); } 73 74 // Yield is always valid as a key in an object literal. 75 ({ yield: 1 }); 76 function* g() { yield ({ yield: 1 }) } 77 function* g() { yield ({ get yield() { return 1; }}) } 78 79 // Checks that yield is a valid label in classic mode, but not valid in a strict 80 // mode or in generators. 81 function f() { yield: 1 } 82 assertThrows("function f() { \"use strict\"; yield: 1 }", SyntaxError) 83 assertThrows("function* g() { yield: 1 }", SyntaxError) 84 85 // Yield is only a keyword in the body of the generator, not in nested 86 // functions. 87 function* g() { function f() { yield (yield + yield (0)); } } 88 89 // Yield needs a RHS. 90 assertThrows("function* g() { yield; }", SyntaxError); 91 92 // Yield in a generator is not an identifier. 93 assertThrows("function* g() { yield = 10; }", SyntaxError); 94 95 // Yield binds very loosely, so this parses as "yield (3 + yield 4)", which is 96 // invalid. 97 assertThrows("function* g() { yield 3 + yield 4; }", SyntaxError); 98 99 // Yield is still a future-reserved-word in strict mode 100 assertThrows("function f() { \"use strict\"; var yield = 13; }", SyntaxError); 101 102 // The name of the NFE is let-bound in G, so is invalid. 103 assertThrows("function* g() { yield (function yield() {}); }", SyntaxError); 104 105 // In generators, yield is invalid as a formal argument name. 106 assertThrows("function* g(yield) { yield (10); }", SyntaxError); 107
