Revision: 9658
Author: [email protected]
Date: Mon Oct 17 05:19:06 2011
Log: Let bound iteration variables in for-loops
TEST=mjsunit/harmony/block-for.js
Review URL: http://codereview.chromium.org/7837028
http://code.google.com/p/v8/source/detail?r=9658
Added:
/branches/bleeding_edge/test/mjsunit/harmony/block-for.js
Modified:
/branches/bleeding_edge/src/parser.cc
/branches/bleeding_edge/src/parser.h
/branches/bleeding_edge/src/preparser.cc
/branches/bleeding_edge/src/preparser.h
/branches/bleeding_edge/test/mjsunit/harmony/debug-blockscopes.js
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/harmony/block-for.js Mon Oct 17
05:19:06 2011
@@ -0,0 +1,142 @@
+// Copyright 2011 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-scoping
+
+function props(x) {
+ var array = [];
+ for (let p in x) array.push(p);
+ return array.sort();
+}
+
+assertEquals(0, props({}).length);
+assertEquals(1, props({x:1}).length);
+assertEquals(2, props({x:1, y:2}).length);
+
+assertArrayEquals(["x"], props({x:1}));
+assertArrayEquals(["x", "y"], props({x:1, y:2}));
+assertArrayEquals(["x", "y", "zoom"], props({x:1, y:2, zoom:3}));
+
+assertEquals(0, props([]).length);
+assertEquals(1, props([1]).length);
+assertEquals(2, props([1,2]).length);
+
+assertArrayEquals(["0"], props([1]));
+assertArrayEquals(["0", "1"], props([1,2]));
+assertArrayEquals(["0", "1", "2"], props([1,2,3]));
+
+var o = {};
+var a = [];
+let i = "outer_i";
+let s = "outer_s";
+for (let i = 0x0020; i < 0x01ff; i+=2) {
+ let s = 'char:' + String.fromCharCode(i);
+ a.push(s);
+ o[s] = i;
+}
+assertArrayEquals(a, props(o));
+assertEquals(i, "outer_i");
+assertEquals(s, "outer_s");
+
+var a = [];
+assertEquals(0, props(a).length);
+a[Math.pow(2,30)-1] = 0;
+assertEquals(1, props(a).length);
+a[Math.pow(2,31)-1] = 0;
+assertEquals(2, props(a).length);
+a[1] = 0;
+assertEquals(3, props(a).length);
+
+var result = '';
+for (let p in {a : [0], b : 1}) { result += p; }
+assertEquals('ab', result);
+
+var result = '';
+for (let p in {a : {v:1}, b : 1}) { result += p; }
+assertEquals('ab', result);
+
+var result = '';
+for (let p in { get a() {}, b : 1}) { result += p; }
+assertEquals('ab', result);
+
+var result = '';
+for (let p in { get a() {}, set a(x) {}, b : 1}) { result += p; }
+assertEquals('ab', result);
+
+
+// Check that there is exactly one variable without initializer
+// in a for-in statement with let variables.
+assertThrows("function foo() { for (let in {}) { } }", SyntaxError);
+assertThrows("function foo() { for (let x = 3 in {}) { } }", SyntaxError);
+assertThrows("function foo() { for (let x, y in {}) { } }", SyntaxError);
+assertThrows("function foo() { for (let x = 3, y in {}) { } }",
SyntaxError);
+assertThrows("function foo() { for (let x, y = 4 in {}) { } }",
SyntaxError);
+assertThrows("function foo() { for (let x = 3, y = 4 in {}) { } }",
SyntaxError);
+
+
+// In a normal for statement the iteration variable is not
+// freshly allocated for each iteration.
+function closures1() {
+ let a = [];
+ for (let i = 0; i < 5; ++i) {
+ a.push(function () { return i; });
+ }
+ for (let j = 0; j < 5; ++j) {
+ assertEquals(5, a[j]());
+ }
+}
+closures1();
+
+
+function closures2() {
+ let a = [], b = [];
+ for (let i = 0, j = 10; i < 5; ++i, ++j) {
+ a.push(function () { return i; });
+ b.push(function () { return j; });
+ }
+ for (let k = 0; k < 5; ++k) {
+ assertEquals(5, a[k]());
+ assertEquals(15, b[k]());
+ }
+}
+closures2();
+
+
+// In a for-in statement the iteration variable is fresh
+// for earch iteration.
+function closures3(x) {
+ let a = [];
+ for (let p in x) {
+ a.push(function () { return p; });
+ }
+ let k = 0;
+ for (let q in x) {
+ assertEquals(q, a[k]());
+ ++k;
+ }
+}
+closures3({a : [0], b : 1, c : {v : 1}, get d() {}, set e(x) {}});
=======================================
--- /branches/bleeding_edge/src/parser.cc Mon Oct 17 04:59:08 2011
+++ /branches/bleeding_edge/src/parser.cc Mon Oct 17 05:19:06 2011
@@ -1631,6 +1631,7 @@
Handle<String> ignore;
Block* result = ParseVariableDeclarations(var_context,
+ NULL,
&ignore,
CHECK_OK);
ExpectSemicolon(CHECK_OK);
@@ -1649,9 +1650,11 @@
// *var is untouched; in particular, it is the caller's responsibility
// to initialize it properly. This mechanism is used for the parsing
// of 'for-in' loops.
-Block* Parser::ParseVariableDeclarations(VariableDeclarationContext
var_context,
- Handle<String>* out,
- bool* ok) {
+Block* Parser::ParseVariableDeclarations(
+ VariableDeclarationContext var_context,
+ VariableDeclarationProperties* decl_props,
+ Handle<String>* out,
+ bool* ok) {
// VariableDeclarations ::
// ('var' | 'const') (Identifier ('=' AssignmentExpression)?)+[',']
@@ -1789,6 +1792,7 @@
} else {
fni_->RemoveLastFunction();
}
+ if (decl_props != NULL) *decl_props = kHasInitializers;
}
// Make sure that 'const x' and 'let x' initialize 'x' to undefined.
@@ -2369,13 +2373,21 @@
Statement* init = NULL;
+ // Create an in-between scope for let-bound iteration variables.
+ Scope* saved_scope = top_scope_;
+ Scope* for_scope = NewScope(top_scope_, Scope::BLOCK_SCOPE);
+ if (top_scope_->is_strict_mode()) {
+ for_scope->EnableStrictMode();
+ }
+ top_scope_ = for_scope;
+
Expect(Token::FOR, CHECK_OK);
Expect(Token::LPAREN, CHECK_OK);
if (peek() != Token::SEMICOLON) {
if (peek() == Token::VAR || peek() == Token::CONST) {
Handle<String> name;
Block* variable_statement =
- ParseVariableDeclarations(kForStatement, &name, CHECK_OK);
+ ParseVariableDeclarations(kForStatement, NULL, &name, CHECK_OK);
if (peek() == Token::IN && !name.is_null()) {
VariableProxy* each = top_scope_->NewUnresolved(name);
@@ -2391,12 +2403,71 @@
Block* result = new(zone()) Block(isolate(), NULL, 2, false);
result->AddStatement(variable_statement);
result->AddStatement(loop);
+ top_scope_ = saved_scope;
+ for_scope = for_scope->FinalizeBlockScope();
+ ASSERT(for_scope == NULL);
// Parsed for-in loop w/ variable/const declaration.
return result;
} else {
init = variable_statement;
}
-
+ } else if (peek() == Token::LET) {
+ Handle<String> name;
+ VariableDeclarationProperties decl_props = kHasNoInitializers;
+ Block* variable_statement =
+ ParseVariableDeclarations(kForStatement,
+ &decl_props,
+ &name,
+ CHECK_OK);
+ bool accept_IN = !name.is_null() && decl_props != kHasInitializers;
+ if (peek() == Token::IN && accept_IN) {
+ // Rewrite a for-in statement of the form
+ //
+ // for (let x in e) b
+ //
+ // into
+ //
+ // <let x' be a temporary variable>
+ // for (x' in e) {
+ // let x;
+ // x = x';
+ // b;
+ // }
+
+ // TODO(keuchel): Move the temporary variable to the block scope,
after
+ // implementing stack allocated block scoped variables.
+ Variable* temp =
top_scope_->DeclarationScope()->NewTemporary(name);
+ VariableProxy* temp_proxy = new(zone()) VariableProxy(isolate(),
temp);
+ VariableProxy* each = top_scope_->NewUnresolved(name,
inside_with());
+ ForInStatement* loop = new(zone()) ForInStatement(isolate(),
labels);
+ Target target(&this->target_stack_, loop);
+
+ Expect(Token::IN, CHECK_OK);
+ Expression* enumerable = ParseExpression(true, CHECK_OK);
+ Expect(Token::RPAREN, CHECK_OK);
+
+ Statement* body = ParseStatement(NULL, CHECK_OK);
+ Block* body_block = new(zone()) Block(isolate(), NULL, 3, false);
+ Assignment* assignment = new(zone()) Assignment(isolate(),
+ Token::ASSIGN,
+ each,
+ temp_proxy,
+
RelocInfo::kNoPosition);
+ Statement* assignment_statement =
+ new(zone()) ExpressionStatement(assignment);
+ body_block->AddStatement(variable_statement);
+ body_block->AddStatement(assignment_statement);
+ body_block->AddStatement(body);
+ loop->Initialize(temp_proxy, enumerable, body_block);
+ top_scope_ = saved_scope;
+ for_scope = for_scope->FinalizeBlockScope();
+ body_block->set_block_scope(for_scope);
+ // Parsed for-in loop w/ let declaration.
+ return loop;
+
+ } else {
+ init = variable_statement;
+ }
} else {
Expression* expression = ParseExpression(false, CHECK_OK);
if (peek() == Token::IN) {
@@ -2418,6 +2489,9 @@
Statement* body = ParseStatement(NULL, CHECK_OK);
if (loop) loop->Initialize(expression, enumerable, body);
+ top_scope_ = saved_scope;
+ for_scope = for_scope->FinalizeBlockScope();
+ ASSERT(for_scope == NULL);
// Parsed for-in loop.
return loop;
@@ -2448,8 +2522,30 @@
Expect(Token::RPAREN, CHECK_OK);
Statement* body = ParseStatement(NULL, CHECK_OK);
- if (loop) loop->Initialize(init, cond, next, body);
- return loop;
+ top_scope_ = saved_scope;
+ for_scope = for_scope->FinalizeBlockScope();
+ if (for_scope != NULL) {
+ // Rewrite a for statement of the form
+ //
+ // for (let x = i; c; n) b
+ //
+ // into
+ //
+ // {
+ // let x = i;
+ // for (; c; n) b
+ // }
+ ASSERT(init != NULL);
+ Block* result = new(zone()) Block(isolate(), NULL, 2, false);
+ result->AddStatement(init);
+ result->AddStatement(loop);
+ result->set_block_scope(for_scope);
+ if (loop) loop->Initialize(NULL, cond, next, body);
+ return result;
+ } else {
+ if (loop) loop->Initialize(init, cond, next, body);
+ return loop;
+ }
}
=======================================
--- /branches/bleeding_edge/src/parser.h Mon Oct 17 02:29:37 2011
+++ /branches/bleeding_edge/src/parser.h Mon Oct 17 05:19:06 2011
@@ -460,6 +460,12 @@
kForStatement
};
+ // If a list of variable declarations includes any initializers.
+ enum VariableDeclarationProperties {
+ kHasInitializers,
+ kHasNoInitializers
+ };
+
Isolate* isolate() { return isolate_; }
Zone* zone() { return isolate_->zone(); }
@@ -497,6 +503,7 @@
Block* ParseVariableStatement(VariableDeclarationContext var_context,
bool* ok);
Block* ParseVariableDeclarations(VariableDeclarationContext var_context,
+ VariableDeclarationProperties*
decl_props,
Handle<String>* out,
bool* ok);
Statement* ParseExpressionOrLabelledStatement(ZoneStringList* labels,
=======================================
--- /branches/bleeding_edge/src/preparser.cc Mon Oct 17 04:59:08 2011
+++ /branches/bleeding_edge/src/preparser.cc Mon Oct 17 05:19:06 2011
@@ -312,6 +312,7 @@
Statement result = ParseVariableDeclarations(var_context,
NULL,
+ NULL,
CHECK_OK);
ExpectSemicolon(CHECK_OK);
return result;
@@ -325,6 +326,7 @@
// of 'for-in' loops.
PreParser::Statement PreParser::ParseVariableDeclarations(
VariableDeclarationContext var_context,
+ VariableDeclarationProperties* decl_props,
int* num_decl,
bool* ok) {
// VariableDeclarations ::
@@ -375,6 +377,7 @@
if (peek() == i::Token::ASSIGN) {
Expect(i::Token::ASSIGN, CHECK_OK);
ParseAssignmentExpression(var_context != kForStatement, CHECK_OK);
+ if (decl_props != NULL) *decl_props = kHasInitializers;
}
} while (peek() == i::Token::COMMA);
@@ -569,9 +572,14 @@
if (peek() != i::Token::SEMICOLON) {
if (peek() == i::Token::VAR || peek() == i::Token::CONST ||
peek() == i::Token::LET) {
+ bool is_let = peek() == i::Token::LET;
int decl_count;
- ParseVariableDeclarations(kForStatement, &decl_count, CHECK_OK);
- if (peek() == i::Token::IN && decl_count == 1) {
+ VariableDeclarationProperties decl_props = kHasNoInitializers;
+ ParseVariableDeclarations(
+ kForStatement, &decl_props, &decl_count, CHECK_OK);
+ bool accept_IN = decl_count == 1 &&
+ !(is_let && decl_props == kHasInitializers);
+ if (peek() == i::Token::IN && accept_IN) {
Expect(i::Token::IN, CHECK_OK);
ParseExpression(true, CHECK_OK);
Expect(i::Token::RPAREN, CHECK_OK);
=======================================
--- /branches/bleeding_edge/src/preparser.h Wed Oct 12 05:23:06 2011
+++ /branches/bleeding_edge/src/preparser.h Mon Oct 17 05:19:06 2011
@@ -179,6 +179,12 @@
kForStatement
};
+ // If a list of variable declarations includes any initializers.
+ enum VariableDeclarationProperties {
+ kHasInitializers,
+ kHasNoInitializers
+ };
+
class Expression;
class Identifier {
@@ -493,6 +499,7 @@
Statement ParseVariableStatement(VariableDeclarationContext var_context,
bool* ok);
Statement ParseVariableDeclarations(VariableDeclarationContext
var_context,
+ VariableDeclarationProperties*
decl_props,
int* num_decl,
bool* ok);
Statement ParseExpressionOrLabelledStatement(bool* ok);
=======================================
--- /branches/bleeding_edge/test/mjsunit/harmony/debug-blockscopes.js Wed
Oct 12 05:23:06 2011
+++ /branches/bleeding_edge/test/mjsunit/harmony/debug-blockscopes.js Mon
Oct 17 05:19:06 2011
@@ -464,3 +464,112 @@
};
closure_1(1)();
EndTest();
+
+
+// Simple for-in loop over the keys of an object.
+BeginTest("For loop 1");
+
+function for_loop_1() {
+ for (let x in {y:undefined}) {
+ debugger;
+ }
+}
+
+listener_delegate = function(exec_state) {
+ CheckScopeChain([debug.ScopeType.Block,
+ debug.ScopeType.Local,
+ debug.ScopeType.Global], exec_state);
+ CheckScopeContent({x:'y'}, 0, exec_state);
+ // The function scope contains a temporary iteration variable.
+ CheckScopeContent({x:'y'}, 1, exec_state);
+};
+for_loop_1();
+EndTest();
+
+
+// For-in loop over the keys of an object with a block scoped let variable
+// shadowing the iteration variable.
+BeginTest("For loop 2");
+
+function for_loop_2() {
+ for (let x in {y:undefined}) {
+ let x = 3;
+ debugger;
+ }
+}
+
+listener_delegate = function(exec_state) {
+ CheckScopeChain([debug.ScopeType.Block,
+ debug.ScopeType.Block,
+ debug.ScopeType.Local,
+ debug.ScopeType.Global], exec_state);
+ CheckScopeContent({x:3}, 0, exec_state);
+ CheckScopeContent({x:'y'}, 1, exec_state);
+ // The function scope contains a temporary iteration variable.
+ CheckScopeContent({x:'y'}, 2, exec_state);
+};
+for_loop_2();
+EndTest();
+
+
+// Simple for loop.
+BeginTest("For loop 3");
+
+function for_loop_3() {
+ for (let x = 3; x < 4; ++x) {
+ debugger;
+ }
+}
+
+listener_delegate = function(exec_state) {
+ CheckScopeChain([debug.ScopeType.Block,
+ debug.ScopeType.Local,
+ debug.ScopeType.Global], exec_state);
+ CheckScopeContent({x:3}, 0, exec_state);
+ CheckScopeContent({}, 1, exec_state);
+};
+for_loop_3();
+EndTest();
+
+
+// For loop with a block scoped let variable shadowing the iteration
variable.
+BeginTest("For loop 4");
+
+function for_loop_4() {
+ for (let x = 3; x < 4; ++x) {
+ let x = 5;
+ debugger;
+ }
+}
+
+listener_delegate = function(exec_state) {
+ CheckScopeChain([debug.ScopeType.Block,
+ debug.ScopeType.Block,
+ debug.ScopeType.Local,
+ debug.ScopeType.Global], exec_state);
+ CheckScopeContent({x:5}, 0, exec_state);
+ CheckScopeContent({x:3}, 1, exec_state);
+ CheckScopeContent({}, 2, exec_state);
+};
+for_loop_4();
+EndTest();
+
+
+// For loop with two variable declarations.
+BeginTest("For loop 5");
+
+function for_loop_5() {
+ for (let x = 3, y = 5; x < 4; ++x) {
+ debugger;
+ }
+}
+
+listener_delegate = function(exec_state) {
+ CheckScopeChain([debug.ScopeType.Block,
+ debug.ScopeType.Local,
+ debug.ScopeType.Global], exec_state);
+ CheckScopeContent({x:3,y:5}, 0, exec_state);
+ CheckScopeContent({}, 1, exec_state);
+};
+for_loop_5();
+EndTest();
--
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