Add parser support for generators.

test/mjsunit/harmony/generators-parsing.js

+// Copyright 2012 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.
+
+// Flags: --harmony-generators
+
+// Test basic generator syntax.
+
+// Yield statements.
+function* g() { yield 3; yield 4; }
+
+// Yield expressions.
+function* g() { (yield 3) + (yield 4); }
+
+// You can have a generator in strict mode.
+function* g() { "use strict"; yield 3; yield 4; }
+
+// Generator expression.
+(function* () { yield 3; });
+
+// Named generator expression.
+(function* g() { yield 3; });
+
+// A generator without a yield is specified as causing an early error.  This
+// behavior is currently unimplemented.  See
+// https://bugs.ecmascript.org/show_bug.cgi?id=1283.
+function* g() { }
+
+// A YieldExpression in the RHS of a YieldExpression is currently specified as
+// causing an early error.  This behavior is currently unimplemented.  See
+// https://bugs.ecmascript.org/show_bug.cgi?id=1283.
+function* g() { yield yield 1; }
+function* g() { yield 3 + (yield 4); }
+
+// Generator definitions with a name of "yield" are not specifically ruled out
+// by the spec, as the `yield' name is outside the generator itself.  However,
+// in strict-mode, "yield" is an invalid identifier.
+function* yield() { (yield 3) + (yield 4); }
+assertThrows("function* yield() { \"use strict\"; (yield 3) + (yield 4); }",
+             SyntaxError);
+
+// In classic mode, yield is a normal identifier, outside of generators.
+function yield(yield) { yield: yield (yield + yield (0)); }
+
+// Yield is always valid as a key in an object literal.
+({ yield: 1 });
+function* g() { yield ({ yield: 1 }) }
+function* g() { yield ({ get yield() { return 1; }}) }
+
+// Yield is only a keyword in the body of the generator, not in nested
+// functions.
+function* g() { function f() { yield (yield + yield (0)); } }
+
+// Yield needs a RHS.
+assertThrows("function* g() { yield; }", SyntaxError);
+
+// Yield in a generator is not an identifier.
+assertThrows("function* g() { yield = 10; }", SyntaxError);
+
+// Yield binds very loosely, so this parses as "yield (3 + yield 4)", which is
+// invalid.
+assertThrows("function* g() { yield 3 + yield 4; }", SyntaxError);
+
+// Yield is still a future-reserved-word in strict mode
+assertThrows("function f() { \"use strict\"; var yield = 13; }", SyntaxError);
+
+// The name of the NFE is let-bound in G, so is invalid.
+assertThrows("function* g() { yield (function yield() {}); }", SyntaxError);
+
+// In generators, yield is invalid as a formal argument name.
+assertThrows("function* g(yield) { yield (10); }", SyntaxError);