Source/JavaScriptCore/runtime/JSModuleEnvironment.cpp

/*
 * Copyright (C) 2015-2017 Apple Inc. All rights reserved.
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#include "config.h"
#include "JSModuleEnvironment.h"

#include "AbstractModuleRecord.h"
#include "Interpreter.h"
#include "JSCInlines.h"
#include "JSFunction.h"

using namespace std;

namespace JSC {

const ClassInfo JSModuleEnvironment::s_info = { "JSModuleEnvironment", &Base::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(JSModuleEnvironment) };

JSModuleEnvironment* JSModuleEnvironment::create(
    VM& vm, Structure* structure, JSScope* currentScope, SymbolTable* symbolTable, JSValue initialValue, AbstractModuleRecord* moduleRecord)
{
    // JSLexicalEnvironment (precisely, JSEnvironmentRecord) has the storage to store the variable slots after the its class storage.
    // Because the offset of the variable slots are fixed in the JSEnvironmentRecord, inheritting these class and adding new member field is not allowed,
    // the new member will overlap the variable slots.
    // To keep the JSModuleEnvironment compatible to the JSLexicalEnvironment but add the new member to store the AbstractModuleRecord, we additionally allocate
    // the storage after the variable slots.
    //
    // JSLexicalEnvironment:
    //     [ JSLexicalEnvironment ][ variable slots ]
    //
    // JSModuleEnvironment:
    //     [ JSLexicalEnvironment ][ variable slots ][ additional slots for JSModuleEnvironment ]
    JSModuleEnvironment* result =
        new (
            NotNull,
            allocateCell<JSModuleEnvironment>(vm.heap, JSModuleEnvironment::allocationSize(symbolTable)))
        JSModuleEnvironment(vm, structure, currentScope, symbolTable);
    result->finishCreation(vm, initialValue, moduleRecord);
    return result;
}

void JSModuleEnvironment::finishCreation(VM& vm, JSValue initialValue, AbstractModuleRecord* moduleRecord)
{
    Base::finishCreation(vm, initialValue);
    this->moduleRecordSlot().set(vm, this, moduleRecord);
}

void JSModuleEnvironment::visitChildren(JSCell* cell, SlotVisitor& visitor)
{
    JSModuleEnvironment* thisObject = jsCast<JSModuleEnvironment*>(cell);
    Base::visitChildren(thisObject, visitor);
    visitor.appendValues(thisObject->variables(), thisObject->symbolTable()->scopeSize());
    visitor.append(thisObject->moduleRecordSlot());
}

bool JSModuleEnvironment::getOwnPropertySlot(JSObject* cell, ExecState* exec, PropertyName propertyName, PropertySlot& slot)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);
    JSModuleEnvironment* thisObject = jsCast<JSModuleEnvironment*>(cell);
    AbstractModuleRecord::Resolution resolution = thisObject->moduleRecord()->resolveImport(exec, Identifier::fromUid(exec, propertyName.uid()));
    if (resolution.type == AbstractModuleRecord::Resolution::Type::Resolved) {
        // When resolveImport resolves the resolution, the imported module environment must have the binding.
        JSModuleEnvironment* importedModuleEnvironment = resolution.moduleRecord->moduleEnvironment();
        PropertySlot redirectSlot(importedModuleEnvironment, PropertySlot::InternalMethodType::Get);
        bool result = importedModuleEnvironment->methodTable(vm)->getOwnPropertySlot(importedModuleEnvironment, exec, resolution.localName, redirectSlot);
        ASSERT_UNUSED(result, result);
        ASSERT(redirectSlot.isValue());
        JSValue value = redirectSlot.getValue(exec, resolution.localName);
        scope.assertNoException();
        slot.setValue(thisObject, redirectSlot.attributes(), value);
        return true;
    }
    return Base::getOwnPropertySlot(thisObject, exec, propertyName, slot);
}

void JSModuleEnvironment::getOwnNonIndexPropertyNames(JSObject* cell, ExecState* exec, PropertyNameArray& propertyNamesArray, EnumerationMode mode)
{
    JSModuleEnvironment* thisObject = jsCast<JSModuleEnvironment*>(cell);
    if (propertyNamesArray.includeStringProperties()) {
        for (const auto& pair : thisObject->moduleRecord()->importEntries()) {
            const AbstractModuleRecord::ImportEntry& importEntry = pair.value;
            if (!importEntry.isNamespace(exec->vm()))
                propertyNamesArray.add(importEntry.localName);
        }
    }
    return Base::getOwnNonIndexPropertyNames(thisObject, exec, propertyNamesArray, mode);
}

bool JSModuleEnvironment::put(JSCell* cell, ExecState* exec, PropertyName propertyName, JSValue value, PutPropertySlot& slot)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    JSModuleEnvironment* thisObject = jsCast<JSModuleEnvironment*>(cell);
    // All imported bindings are immutable.
    AbstractModuleRecord::Resolution resolution = thisObject->moduleRecord()->resolveImport(exec, Identifier::fromUid(exec, propertyName.uid()));
    if (resolution.type == AbstractModuleRecord::Resolution::Type::Resolved) {
        throwTypeError(exec, scope, ASCIILiteral(ReadonlyPropertyWriteError));
        return false;
    }
    return Base::put(thisObject, exec, propertyName, value, slot);
}

bool JSModuleEnvironment::deleteProperty(JSCell* cell, ExecState* exec, PropertyName propertyName)
{
    JSModuleEnvironment* thisObject = jsCast<JSModuleEnvironment*>(cell);
    // All imported bindings are immutable.
    AbstractModuleRecord::Resolution resolution = thisObject->moduleRecord()->resolveImport(exec, Identifier::fromUid(exec, propertyName.uid()));
    if (resolution.type == AbstractModuleRecord::Resolution::Type::Resolved)
        return false;
    return Base::deleteProperty(thisObject, exec, propertyName);
}

} // namespace JSC