Reviewers: marja, rossberg,
Description:
Allow yield expressions without a RHS.
[email protected], [email protected]
BUG=
Please review this at https://codereview.chromium.org/348893007/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+56, -14 lines):
M src/ast.h
M src/preparser.h
M test/mjsunit/harmony/generators-parsing.js
Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index
23f9eef477a9a318769ad67256b650e23ca11372..702eabd9263703711e6853ce9fc597bdb07f71f2
100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -3375,6 +3375,7 @@ class AstNodeFactory V8_FINAL BASE_EMBEDDED {
Expression* expression,
Yield::Kind yield_kind,
int pos) {
+ if (!expression) expression = NewUndefinedLiteral(pos);
Yield* yield = new(zone_) Yield(
zone_, generator_object, expression, yield_kind, pos);
VISIT_AND_RETURN(Yield, yield)
Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index
499240e63acc6b43bdcefd74edc183113600f432..c64c8de95b69efa2bb46f53ae933e9a3b8a4f249
100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -1792,15 +1792,29 @@ template <class Traits>
typename ParserBase<Traits>::ExpressionT
ParserBase<Traits>::ParseYieldExpression(bool* ok) {
// YieldExpression ::
- // 'yield' '*'? AssignmentExpression
+ // 'yield' ([no line terminator] '*'? AssignmentExpression)?
int pos = peek_position();
Expect(Token::YIELD, CHECK_OK);
- Yield::Kind kind =
- Check(Token::MUL) ? Yield::DELEGATING : Yield::SUSPEND;
ExpressionT generator_object =
factory()->NewVariableProxy(function_state_->generator_object_variable());
- ExpressionT expression =
- ParseAssignmentExpression(false, CHECK_OK);
+ ExpressionT expression = Traits::EmptyExpression();
+ Yield::Kind kind = Yield::SUSPEND;
+ if (!scanner()->HasAnyLineTerminatorBeforeNext()) {
+ if (Check(Token::MUL)) kind = Yield::DELEGATING;
+ switch (peek()) {
+ case Token::EOS:
+ case Token::SEMICOLON:
+ case Token::RBRACE:
+ case Token::RBRACK:
+ case Token::RPAREN:
+ case Token::COLON:
+ case Token::COMMA:
+ break;
+ default:
+ expression = ParseAssignmentExpression(false, CHECK_OK);
+ break;
+ }
+ }
typename Traits::Type::YieldExpression yield =
factory()->NewYield(generator_object, expression, kind, pos);
if (kind == Yield::DELEGATING) {
Index: test/mjsunit/harmony/generators-parsing.js
diff --git a/test/mjsunit/harmony/generators-parsing.js
b/test/mjsunit/harmony/generators-parsing.js
index
2a4a68c37cd3f71089c280d8b52dbe507b0f6fda..21790b0e1383b0a67dac5774a605b4c8d9916fab
100644
--- a/test/mjsunit/harmony/generators-parsing.js
+++ b/test/mjsunit/harmony/generators-parsing.js
@@ -35,6 +35,40 @@ function* g() { yield 3; yield 4; }
// Yield expressions.
function* g() { (yield 3) + (yield 4); }
+// Yield without a RHS.
+function* g() { yield; }
+function* g() { yield }
+function* g() {
+ yield
+}
+function* g() { (yield) }
+function* g() { [yield] }
+function* g() { {yield} }
+function* g() { yield, yield }
+function* g() { yield; yield }
+function* g() { (yield) ? yield : yield }
+function* g() {
+ (yield)
+ ? yield
+ : yield
+}
+
+// If yield has a RHS, it needs to start on the same line. The * in a
+// yield* counts as starting the RHS.
+function* g() {
+ yield *
+ foo
+}
+assertThrows("function* g() { yield\n* foo }", SyntaxError);
+assertEquals(undefined,
+ (function*(){
+ yield
+ 3
+ })().next().value);
+
+// A YieldExpression is not a LogicalORExpression.
+assertThrows("function* g() { yield ? yield : yield }", SyntaxError);
+
// You can have a generator in strict mode.
function* g() { "use strict"; yield 3; yield 4; }
@@ -50,14 +84,10 @@ function* g() { yield 1; return 2; yield "dead"; }
// 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.
+// You can have a generator without a yield.
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.
+// A YieldExpression is valid as the RHS of a YieldExpression.
function* g() { yield yield 1; }
function* g() { yield 3 + (yield 4); }
@@ -86,9 +116,6 @@ assertThrows("function* g() { yield: 1 }", SyntaxError)
// 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);
--
--
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