C++ SymbolTableEntry类代码示例

inline bool JSActivation::symbolTablePut(JSGlobalData& globalData, const Identifier& propertyName, JSValue value)
{
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
    
    SymbolTableEntry entry = symbolTable().inlineGet(propertyName.impl());
    if (entry.isNull())
        return false;
    if (entry.isReadOnly())
        return true;
    if (entry.getIndex() >= m_numCapturedVars)
        return false;

    registerAt(entry.getIndex()).set(globalData, this, value);
    return true;
}

inline bool JSActivation::symbolTablePut(ExecState* exec, PropertyName propertyName, JSValue value, bool shouldThrow)
{
    JSGlobalData& globalData = exec->globalData();
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
    
    SymbolTableEntry entry = symbolTable().inlineGet(propertyName.impl());
    if (entry.isNull())
        return false;
    if (entry.isReadOnly()) {
        if (shouldThrow)
            throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
        return true;
    }
    if (m_isTornOff && entry.getIndex() >= m_numCapturedVars)
        return false;

    registerAt(entry.getIndex()).set(globalData, this, value);
    return true;
}

inline bool JSActivation::symbolTablePut(ExecState* exec, PropertyName propertyName, JSValue value, bool shouldThrow)
{
    VM& vm = exec->vm();
    ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
    
    SymbolTableEntry entry = symbolTable()->inlineGet(propertyName.publicName());
    if (entry.isNull())
        return false;
    if (entry.isReadOnly()) {
        if (shouldThrow)
            throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
        return true;
    }

    // Defend against the inspector asking for a var after it has been optimized out.
    if (isTornOff() && !isValid(entry))
        return false;

    registerAt(entry.getIndex()).set(vm, this, value);
    return true;
}

void JSModuleRecord::instantiateDeclarations(ExecState* exec, ModuleProgramExecutable* moduleProgramExecutable)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    // http://www.ecma-international.org/ecma-262/6.0/#sec-moduledeclarationinstantiation

    SymbolTable* symbolTable = moduleProgramExecutable->moduleEnvironmentSymbolTable();
    JSModuleEnvironment* moduleEnvironment = JSModuleEnvironment::create(vm, exec->lexicalGlobalObject(), exec->lexicalGlobalObject(), symbolTable, jsTDZValue(), this);

    // http://www.ecma-international.org/ecma-262/6.0/#sec-moduledeclarationinstantiation
    // section 15.2.1.16.4 step 9.
    // Ensure all the indirect exports are correctly resolved to unique bindings.
    // Even if we avoided duplicate exports in the parser, still ambiguous exports occur due to the star export (`export * from "mod"`).
    // When we see this type of ambiguity for the indirect exports here, throw a syntax error.
    for (const auto& pair : exportEntries()) {
        const ExportEntry& exportEntry = pair.value;
        if (exportEntry.type == JSModuleRecord::ExportEntry::Type::Indirect) {
            Resolution resolution = resolveExport(exec, exportEntry.exportName);
            switch (resolution.type) {
            case Resolution::Type::NotFound:
                throwSyntaxError(exec, scope, makeString("Indirectly exported binding name '", String(exportEntry.exportName.impl()), "' is not found."));
                return;

            case Resolution::Type::Ambiguous:
                throwSyntaxError(exec, scope, makeString("Indirectly exported binding name '", String(exportEntry.exportName.impl()), "' cannot be resolved due to ambiguous multiple bindings."));
                return;

            case Resolution::Type::Error:
                throwSyntaxError(exec, scope, makeString("Indirectly exported binding name 'default' cannot be resolved by star export entries."));
                return;

            case Resolution::Type::Resolved:
                break;
            }
        }
    }

    // http://www.ecma-international.org/ecma-262/6.0/#sec-moduledeclarationinstantiation
    // section 15.2.1.16.4 step 12.
    // Instantiate namespace objects and initialize the bindings with them if required.
    // And ensure that all the imports correctly resolved to unique bindings.
    for (const auto& pair : importEntries()) {
        const ImportEntry& importEntry = pair.value;
        AbstractModuleRecord* importedModule = hostResolveImportedModule(exec, importEntry.moduleRequest);
        if (importEntry.isNamespace(vm)) {
            JSModuleNamespaceObject* namespaceObject = importedModule->getModuleNamespace(exec);
            RETURN_IF_EXCEPTION(scope, void());
            bool putResult = false;
            symbolTablePutTouchWatchpointSet(moduleEnvironment, exec, importEntry.localName, namespaceObject, /* shouldThrowReadOnlyError */ false, /* ignoreReadOnlyErrors */ true, putResult);
        } else {
            Resolution resolution = importedModule->resolveExport(exec, importEntry.importName);
            switch (resolution.type) {
            case Resolution::Type::NotFound:
                throwSyntaxError(exec, scope, makeString("Importing binding name '", String(importEntry.importName.impl()), "' is not found."));
                return;

            case Resolution::Type::Ambiguous:
                throwSyntaxError(exec, scope, makeString("Importing binding name '", String(importEntry.importName.impl()), "' cannot be resolved due to ambiguous multiple bindings."));
                return;

            case Resolution::Type::Error:
                throwSyntaxError(exec, scope, makeString("Importing binding name 'default' cannot be resolved by star export entries."));
                return;

            case Resolution::Type::Resolved:
                break;
            }
        }
    }

    // http://www.ecma-international.org/ecma-262/6.0/#sec-moduledeclarationinstantiation
    // section 15.2.1.16.4 step 14.
    // Module environment contains the heap allocated "var", "function", "let", "const", and "class".
    // When creating the environment, we initialized all the slots with empty, it's ok for lexical values.
    // But for "var" and "function", we should initialize it with undefined. They are contained in the declared variables.
    for (const auto& variable : declaredVariables()) {
        SymbolTableEntry entry = symbolTable->get(variable.key.get());
        VarOffset offset = entry.varOffset();
        if (!offset.isStack()) {
            bool putResult = false;
            symbolTablePutTouchWatchpointSet(moduleEnvironment, exec, Identifier::fromUid(exec, variable.key.get()), jsUndefined(), /* shouldThrowReadOnlyError */ false, /* ignoreReadOnlyErrors */ true, putResult);
        }
    }

    // http://www.ecma-international.org/ecma-262/6.0/#sec-moduledeclarationinstantiation
    // section 15.2.1.16.4 step 16-a-iv.
    // Initialize heap allocated function declarations.
    // They can be called before the body of the module is executed under circular dependencies.
    UnlinkedModuleProgramCodeBlock* unlinkedCodeBlock = moduleProgramExecutable->unlinkedModuleProgramCodeBlock();
    for (size_t i = 0, numberOfFunctions = unlinkedCodeBlock->numberOfFunctionDecls(); i < numberOfFunctions; ++i) {
        UnlinkedFunctionExecutable* unlinkedFunctionExecutable = unlinkedCodeBlock->functionDecl(i);
        SymbolTableEntry entry = symbolTable->get(unlinkedFunctionExecutable->name().impl());
        VarOffset offset = entry.varOffset();
        if (!offset.isStack()) {
            ASSERT(!unlinkedFunctionExecutable->name().isEmpty());
            if (vm.typeProfiler() || vm.controlFlowProfiler()) {
                vm.functionHasExecutedCache()->insertUnexecutedRange(moduleProgramExecutable->sourceID(),
                    unlinkedFunctionExecutable->typeProfilingStartOffset(),
                    unlinkedFunctionExecutable->typeProfilingEndOffset());
//.........这里部分代码省略.........

// Returns true if we found enough information to terminate optimization.
static inline bool abstractAccess(ExecState* exec, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, size_t depth, bool& needsVarInjectionChecks, ResolveOp& op)
{
    if (JSActivation* activation = jsDynamicCast<JSActivation*>(scope)) {
        if (ident == exec->propertyNames().arguments) {
            // We know the property will be at this activation scope, but we don't know how to cache it.
            op = ResolveOp(Dynamic, 0, 0, 0, 0);
            return true;
        }

        SymbolTableEntry entry = activation->symbolTable()->get(ident.impl());
        if (entry.isReadOnly() && getOrPut == Put) {
            // We know the property will be at this activation scope, but we don't know how to cache it.
            op = ResolveOp(Dynamic, 0, 0, 0, 0);
            return true;
        }

        if (!entry.isNull()) {
            op = ResolveOp(makeType(ClosureVar, needsVarInjectionChecks), depth, activation->structure(), 0, entry.getIndex());
            return true;
        }

        if (activation->symbolTable()->usesNonStrictEval())
            needsVarInjectionChecks = true;
        return false;
    }

    if (JSGlobalObject* globalObject = jsDynamicCast<JSGlobalObject*>(scope)) {
        SymbolTableEntry entry = globalObject->symbolTable()->get(ident.impl());
        if (!entry.isNull()) {
            if (getOrPut == Put) {
                if (entry.isReadOnly()) {
                    // We know the property will be at global scope, but we don't know how to cache it.
                    op = ResolveOp(Dynamic, 0, 0, 0, 0);
                    return true;
                }

                // It's likely that we'll write to this var, so notify now and avoid the overhead of doing so at runtime.
                entry.notifyWrite();
            }

            op = ResolveOp(
                     makeType(GlobalVar, needsVarInjectionChecks), depth, 0, entry.watchpointSet(),
                     reinterpret_cast<uintptr_t>(globalObject->registerAt(entry.getIndex()).slot()));
            return true;
        }

        PropertySlot slot(globalObject);
        if (!globalObject->getOwnPropertySlot(globalObject, exec, ident, slot)
                || !slot.isCacheableValue()
                || !globalObject->structure()->propertyAccessesAreCacheable()
                || (globalObject->structure()->hasReadOnlyOrGetterSetterPropertiesExcludingProto() && getOrPut == Put)) {
            // We know the property will be at global scope, but we don't know how to cache it.
            ASSERT(!scope->next());
            op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, 0, 0, 0);
            return true;
        }

        op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, globalObject->structure(), 0, slot.cachedOffset());
        return true;
    }

    op = ResolveOp(Dynamic, 0, 0, 0, 0);
    return true;
}

// Returns true if we found enough information to terminate optimization.
static inline bool abstractAccess(ExecState* exec, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, size_t depth, bool& needsVarInjectionChecks, ResolveOp& op)
{
    if (JSActivation* activation = jsDynamicCast<JSActivation*>(scope)) {
        if (ident == exec->propertyNames().arguments) {
            // We know the property will be at this activation scope, but we don't know how to cache it.
            op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
            return true;
        }

        SymbolTableEntry entry = activation->symbolTable()->get(ident.impl());
        if (entry.isReadOnly() && getOrPut == Put) {
            // We know the property will be at this activation scope, but we don't know how to cache it.
            op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
            return true;
        }

        if (!entry.isNull()) {
            op = ResolveOp(makeType(ClosureVar, needsVarInjectionChecks), depth, 0, activation, entry.watchpointSet(), entry.getIndex());
            return true;
        }

        if (activation->symbolTable()->usesNonStrictEval())
            needsVarInjectionChecks = true;
        return false;
    }

    if (JSGlobalObject* globalObject = jsDynamicCast<JSGlobalObject*>(scope)) {
        SymbolTableEntry entry = globalObject->symbolTable()->get(ident.impl());
        if (!entry.isNull()) {
            if (getOrPut == Put && entry.isReadOnly()) {
                // We know the property will be at global scope, but we don't know how to cache it.
                op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
                return true;
            }

            op = ResolveOp(
                makeType(GlobalVar, needsVarInjectionChecks), depth, 0, 0, entry.watchpointSet(),
                reinterpret_cast<uintptr_t>(globalObject->registerAt(entry.getIndex()).slot()));
            return true;
        }

        PropertySlot slot(globalObject);
        if (!globalObject->getOwnPropertySlot(globalObject, exec, ident, slot)
            || !slot.isCacheableValue()
            || !globalObject->structure()->propertyAccessesAreCacheable()
            || (globalObject->structure()->hasReadOnlyOrGetterSetterPropertiesExcludingProto() && getOrPut == Put)) {
            // We know the property will be at global scope, but we don't know how to cache it.
            ASSERT(!scope->next());
            op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, 0, 0, 0, 0);
            return true;
        }
        
        WatchpointState state = globalObject->structure()->ensurePropertyReplacementWatchpointSet(exec->vm(), slot.cachedOffset())->state();
        if (state == IsWatched && getOrPut == Put) {
            // The field exists, but because the replacement watchpoint is still intact. This is
            // kind of dangerous. We have two options:
            // 1) Invalidate the watchpoint set. That would work, but it's possible that this code
            //    path never executes - in which case this would be unwise.
            // 2) Have the invalidation happen at run-time. All we have to do is leave the code
            //    uncached. The only downside is slightly more work when this does execute.
            // We go with option (2) here because it seems less evil.
            op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, 0, 0, 0, 0);
        } else
            op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, globalObject->structure(), 0, 0, slot.cachedOffset());
        return true;
    }

    op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
    return true;
}

// Returns true if we found enough information to terminate optimization.
static inline bool abstractAccess(ExecState* exec, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, size_t depth, bool& needsVarInjectionChecks, ResolveOp& op, InitializationMode initializationMode)
{
    if (scope->isJSLexicalEnvironment()) {
        JSLexicalEnvironment* lexicalEnvironment = jsCast<JSLexicalEnvironment*>(scope);
        if (ident == exec->propertyNames().arguments) {
            // We know the property will be at this lexical environment scope, but we don't know how to cache it.
            op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
            return true;
        }

        SymbolTableEntry entry = lexicalEnvironment->symbolTable()->get(ident.impl());
        if (entry.isReadOnly() && getOrPut == Put) {
            // We know the property will be at this lexical environment scope, but we don't know how to cache it.
            op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
            return true;
        }

        if (!entry.isNull()) {
            op = ResolveOp(makeType(ClosureVar, needsVarInjectionChecks), depth, 0, lexicalEnvironment, entry.watchpointSet(), entry.scopeOffset().offset());
            return true;
        }

        if (scope->type() == ModuleEnvironmentType) {
            JSModuleEnvironment* moduleEnvironment = jsCast<JSModuleEnvironment*>(scope);
            JSModuleRecord* moduleRecord = moduleEnvironment->moduleRecord();
            JSModuleRecord::Resolution resolution = moduleRecord->resolveImport(exec, ident);
            if (resolution.type == JSModuleRecord::Resolution::Type::Resolved) {
                JSModuleRecord* importedRecord = resolution.moduleRecord;
                JSModuleEnvironment* importedEnvironment = importedRecord->moduleEnvironment();
                SymbolTableEntry entry = importedEnvironment->symbolTable()->get(resolution.localName.impl());
                ASSERT(!entry.isNull());
                op = ResolveOp(makeType(ModuleVar, needsVarInjectionChecks), depth, 0, importedEnvironment, entry.watchpointSet(), entry.scopeOffset().offset(), resolution.localName.impl());
                return true;
            }
        }

        if (lexicalEnvironment->symbolTable()->usesNonStrictEval())
            needsVarInjectionChecks = true;
        return false;
    }

    if (scope->isGlobalLexicalEnvironment()) {
        JSGlobalLexicalEnvironment* globalLexicalEnvironment = jsCast<JSGlobalLexicalEnvironment*>(scope);
        SymbolTableEntry entry = globalLexicalEnvironment->symbolTable()->get(ident.impl());
        if (!entry.isNull()) {
            if (getOrPut == Put && entry.isReadOnly() && initializationMode != Initialization) {
                // We know the property will be at global lexical environment, but we don't know how to cache it.
                op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
                return true;
            }

            // We can try to force const Initialization to always go down the fast path. It is provably impossible to construct
            // a program that needs a var injection check here. You can convince yourself of this as follows:
            // Any other let/const/class would be a duplicate of this in the global scope, so we would never get here in that situation.
            // Also, if we had an eval in the global scope that defined a const, it would also be a duplicate of this const, and so it would
            // also throw an error. Therefore, we're *the only* thing that can assign to this "const" slot for the first (and only) time. Also, 
            // we will never have a Dynamic ResolveType here because if we were inside a "with" statement, that would mean the "const" definition 
            // isn't a global, it would be a local to the "with" block. 
            // We still need to make the slow path correct for when we need to fire a watchpoint.
            ResolveType resolveType = initializationMode == Initialization ? GlobalLexicalVar : makeType(GlobalLexicalVar, needsVarInjectionChecks);
            op = ResolveOp(
                resolveType, depth, 0, 0, entry.watchpointSet(),
                reinterpret_cast<uintptr_t>(globalLexicalEnvironment->variableAt(entry.scopeOffset()).slot()));
            return true;
        }

        return false;
    }

    if (scope->isGlobalObject()) {
        JSGlobalObject* globalObject = jsCast<JSGlobalObject*>(scope);
        SymbolTableEntry entry = globalObject->symbolTable()->get(ident.impl());
        if (!entry.isNull()) {
            if (getOrPut == Put && entry.isReadOnly()) {
                // We know the property will be at global scope, but we don't know how to cache it.
                op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
                return true;
            }

            op = ResolveOp(
                makeType(GlobalVar, needsVarInjectionChecks), depth, 0, 0, entry.watchpointSet(),
                reinterpret_cast<uintptr_t>(globalObject->variableAt(entry.scopeOffset()).slot()));
            return true;
        }

        PropertySlot slot(globalObject, PropertySlot::InternalMethodType::VMInquiry);
        bool hasOwnProperty = globalObject->getOwnPropertySlot(globalObject, exec, ident, slot);
        if (!hasOwnProperty) {
            op = ResolveOp(makeType(UnresolvedProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0);
            return true;
        }

        if (!slot.isCacheableValue()
            || !globalObject->structure()->propertyAccessesAreCacheable()
            || (globalObject->structure()->hasReadOnlyOrGetterSetterPropertiesExcludingProto() && getOrPut == Put)) {
            // We know the property will be at global scope, but we don't know how to cache it.
            ASSERT(!scope->next());
            op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0);
            return true;
//.........这里部分代码省略.........

 // 환경 제거
 void pop() { envs.pop_back(); }

 // 특정 환경 얹기
 void push(Env& e) { envs.push_back(e); }