2816f19680
This patchset begins by adding support for "yield", which is unlike other tokens in JS. In a generator, whether strict or classic, it is a syntactic keyword. In classic mode it is an identifier. In strict mode it is reserved. This patch adds YIELD as a token to the scanner, and adapts the preparser and parser appropriately. It also parses "function*", indicating that a function is actually a generator, for both eagerly and lazily parsed functions. Currently "yield" just compiles as "return". BUG=v8:2355 TEST=mjsunit/harmony/generators-parsing Review URL: https://codereview.chromium.org/12646003 Patch from Andy Wingo <wingo@igalia.com>. git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14116 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
101 lines
4.2 KiB
JavaScript
101 lines
4.2 KiB
JavaScript
// Copyright 2013 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Flags: --harmony-generators
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// Test basic generator syntax.
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// Yield statements.
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function* g() { yield 3; yield 4; }
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// Yield expressions.
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function* g() { (yield 3) + (yield 4); }
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// You can have a generator in strict mode.
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function* g() { "use strict"; yield 3; yield 4; }
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// Generator expression.
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(function* () { yield 3; });
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// Named generator expression.
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(function* g() { yield 3; });
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// A generator without a yield is specified as causing an early error. This
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// behavior is currently unimplemented. See
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// https://bugs.ecmascript.org/show_bug.cgi?id=1283.
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function* g() { }
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// A YieldExpression in the RHS of a YieldExpression is currently specified as
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// causing an early error. This behavior is currently unimplemented. See
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// https://bugs.ecmascript.org/show_bug.cgi?id=1283.
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function* g() { yield yield 1; }
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function* g() { yield 3 + (yield 4); }
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// Generator definitions with a name of "yield" are not specifically ruled out
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// by the spec, as the `yield' name is outside the generator itself. However,
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// in strict-mode, "yield" is an invalid identifier.
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function* yield() { (yield 3) + (yield 4); }
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assertThrows("function* yield() { \"use strict\"; (yield 3) + (yield 4); }",
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SyntaxError);
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// In classic mode, yield is a normal identifier, outside of generators.
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function yield(yield) { yield: yield (yield + yield (0)); }
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// Yield is always valid as a key in an object literal.
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({ yield: 1 });
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function* g() { yield ({ yield: 1 }) }
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function* g() { yield ({ get yield() { return 1; }}) }
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// Checks that yield is a valid label in classic mode, but not valid in a strict
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// mode or in generators.
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function f() { yield: 1 }
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assertThrows("function f() { \"use strict\"; yield: 1 }", SyntaxError)
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assertThrows("function f*() { yield: 1 }", SyntaxError)
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// Yield is only a keyword in the body of the generator, not in nested
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// functions.
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function* g() { function f() { yield (yield + yield (0)); } }
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// Yield needs a RHS.
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assertThrows("function* g() { yield; }", SyntaxError);
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// Yield in a generator is not an identifier.
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assertThrows("function* g() { yield = 10; }", SyntaxError);
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// Yield binds very loosely, so this parses as "yield (3 + yield 4)", which is
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// invalid.
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assertThrows("function* g() { yield 3 + yield 4; }", SyntaxError);
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// Yield is still a future-reserved-word in strict mode
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assertThrows("function f() { \"use strict\"; var yield = 13; }", SyntaxError);
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// The name of the NFE is let-bound in G, so is invalid.
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assertThrows("function* g() { yield (function yield() {}); }", SyntaxError);
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// In generators, yield is invalid as a formal argument name.
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assertThrows("function* g(yield) { yield (10); }", SyntaxError);
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