ES6: Implement lexical scoping for function definitions in strict mode
https://bugs.webkit.org/show_bug.cgi?id=152844
Reviewed by Geoffrey Garen.
Source/JavaScriptCore:
This patch implements block scoping for function definitions
in strict mode. The implementation works as follows:
- If we're in sloppy mode, function declarations work exactly
as they did before this patch. I.e, function declarations are hoisted
and declared like "var" variables.
- If you're in strict mode and at the top of a function scope or program
scope, function declarations still work like they used to. They are defined
like "var" variables. This is necessary for backwards compatibility
because ES5 strict mode allowed duplicate function declarations at the
top-most scope of a program/function.
- If you're in strict mode and inside a block statement or a switch statement,
function declarations are now block scoped. All function declarations within
a block are hoisted to the beginning of the block. They are not hoisted out of the
block like they are in sloppy mode. This allows for the following types of
programs:
function bar() { return 20; }
{
function bar() { return 30; }
bar(); 30
}
bar(); 20
}
- bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::BytecodeGenerator):
(JSC::BytecodeGenerator::instantiateLexicalVariables):
(JSC::BytecodeGenerator::emitPrefillStackTDZVariables):
(JSC::BytecodeGenerator::pushLexicalScope):
(JSC::BytecodeGenerator::pushLexicalScopeInternal):
(JSC::BytecodeGenerator::initializeBlockScopedFunctions):
(JSC::BytecodeGenerator::popLexicalScope):
(JSC::BytecodeGenerator::liftTDZCheckIfPossible):
(JSC::BytecodeGenerator::pushTDZVariables):
(JSC::BytecodeGenerator::getVariablesUnderTDZ):
(JSC::BytecodeGenerator::emitNewRegExp):
(JSC::BytecodeGenerator::emitNewFunctionExpressionCommon):
(JSC::BytecodeGenerator::emitNewFunctionExpression):
(JSC::BytecodeGenerator::emitNewArrowFunctionExpression):
- bytecompiler/BytecodeGenerator.h:
- parser/ASTBuilder.h:
(JSC::ASTBuilder::createSourceElements):
(JSC::ASTBuilder::features):
(JSC::ASTBuilder::numConstants):
(JSC::ASTBuilder::createFuncDeclStatement):
(JSC::ASTBuilder::createClassDeclStatement):
(JSC::ASTBuilder::createBlockStatement):
(JSC::ASTBuilder::createTryStatement):
(JSC::ASTBuilder::createSwitchStatement):
(JSC::ASTBuilder::Scope::Scope):
(JSC::ASTBuilder::funcDeclarations): Deleted.
- parser/NodeConstructors.h:
(JSC::CaseBlockNode::CaseBlockNode):
(JSC::SwitchNode::SwitchNode):
(JSC::BlockNode::BlockNode):
(JSC::ScopeNode::ScopeNode):
(JSC::ScopeNode::singleStatement):
(JSC::ProgramNode::ProgramNode):
(JSC::ModuleProgramNode::ModuleProgramNode):
(JSC::EvalNode::EvalNode):
(JSC::FunctionNode::FunctionNode):
(JSC::VariableEnvironmentNode::VariableEnvironmentNode):
(JSC::VariableEnvironmentNode::VariableEnvironmentNode):
(JSC::VariableEnvironmentNode::lexicalVariables):
(JSC::VariableEnvironmentNode::functionStack):
(JSC::ScopeNode::captures):
(JSC::ScopeNode::varDeclarations):
(JSC::ScopeNode::neededConstants):
(JSC::ProgramNode::startColumn):
(JSC::ProgramNode::endColumn):
(JSC::EvalNode::startColumn):
(JSC::EvalNode::endColumn):
(JSC::ModuleProgramNode::startColumn):
(JSC::ModuleProgramNode::endColumn):
(JSC::ScopeNode::functionStack): Deleted.
(JSC::Parser<LexerType>::parseInner):
(JSC::Parser<LexerType>::didFinishParsing):
(JSC::Parser<LexerType>::parseStatementListItem):
(JSC::Parser<LexerType>::parseSwitchStatement):
(JSC::Parser<LexerType>::parseBlockStatement):
(JSC::Parser<LexerType>::parseStatement):
(JSC::Parser<LexerType>::parseFunctionInfo):
(JSC::getMetadata):
(JSC::Parser<LexerType>::parseFunctionDeclaration):
(JSC::Parser<LexerType>::parseExportDeclaration):
(JSC::Scope::declareVariable):
(JSC::Scope::declareFunction):
(JSC::Scope::appendFunction):
(JSC::Scope::takeFunctionDeclarations):
(JSC::Scope::declareLexicalVariable):
(JSC::Parser::currentVariableScope):
(JSC::Parser::currentLexicalDeclarationScope):
(JSC::Parser::currentFunctionScope):
(JSC::Parser::pushScope):
(JSC::Parser::popScopeInternal):
(JSC::Parser::declareVariable):
(JSC::Parser::declareFunction):
(JSC::Parser::hasDeclaredVariable):
(JSC::Parser::isFunctionMetadataNode):
(JSC::Parser<LexerType>::parse):
(JSC::SyntaxChecker::createFuncDeclStatement):
(JSC::SyntaxChecker::createClassDeclStatement):
(JSC::SyntaxChecker::createBlockStatement):
(JSC::SyntaxChecker::createExprStatement):
(JSC::SyntaxChecker::createIfStatement):
(JSC::SyntaxChecker::createContinueStatement):
(JSC::SyntaxChecker::createTryStatement):
(JSC::SyntaxChecker::createSwitchStatement):
(JSC::SyntaxChecker::createWhileStatement):
(JSC::SyntaxChecker::createWithStatement):
(JSC::SyntaxChecker::createDoWhileStatement):
- parser/VariableEnvironment.h:
(JSC::VariableEnvironmentEntry::isExported):
(JSC::VariableEnvironmentEntry::isImported):
(JSC::VariableEnvironmentEntry::isImportedNamespace):
(JSC::VariableEnvironmentEntry::isFunction):
(JSC::VariableEnvironmentEntry::setIsCaptured):
(JSC::VariableEnvironmentEntry::setIsConst):
(JSC::VariableEnvironmentEntry::setIsExported):
(JSC::VariableEnvironmentEntry::setIsImported):
(JSC::VariableEnvironmentEntry::setIsImportedNamespace):
(JSC::VariableEnvironmentEntry::setIsFunction):
(JSC::VariableEnvironmentEntry::clearIsVar):
(JSC::VariableEnvironment::VariableEnvironment):
(JSC::VariableEnvironment::begin):
(JSC::VariableEnvironment::end):
- tests/es6.yaml:
- tests/stress/block-scoped-function-declarations.js: Added.
(assert):
(test):
(f.foo.bar):
(f.foo.):
(f.foo):
(f):
(assert.foo.):
(assert.foo):
(assert.foo.foo):
(assert.foo.bar):
(assert.foo.switch.case.1):
(assert.foo.switch.case.2):
(assert.foo.switch.foo):
(assert.foo.switch.bar):
LayoutTests:
- js/let-syntax-expected.txt:
- js/parser-syntax-check-expected.txt:
- js/script-tests/parser-syntax-check.js:
(testFailed):
(runTest):
