src/kjs/JSVariableObject.h

/*
 * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
 *           (C) 2008 Maksim Orlovich <maksim@kde.org>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 *
 * Portions of this code that are (C) 2007, 2008 Apple Inc. were
 * originally distributed under the following terms
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *   are met:
 *
 *   1.  Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *   2.  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.
 *   3.  Neither the name of Apple Computer, Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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.
 */

#ifndef JSVariableObject_h
#define JSVariableObject_h

#include "LocalStorage.h"
#include "SymbolTable.h"
#include "object.h"

#include <wtf/Vector.h>

namespace KJS
{
class Interpreter;

class JSVariableObject : public JSObject
{
public:
    using KJS::JSObject::deleteProperty;
    bool deleteProperty(ExecState *, const Identifier &) override;

    void getOwnPropertyNames(ExecState *, PropertyNameArray &, PropertyMap::PropertyMode mode) override;

    void mark() override;

    enum {
        LengthSlot,
        TearOffNeeded, // Set when a tearoff is requested;
        // the actual tearoff will only happen once the function
        // stops running, though
        ScopeLink,
        NumVarObjectSlots = 3
    };

    int32_t &lengthSlot()
    {
        return localStorage[LengthSlot].val.int32Val;
    }
    const int32_t &lengthSlot() const
    {
        return localStorage[LengthSlot].val.int32Val;
    }

    bool &tearOffNeededSlot()
    {
        return localStorage[TearOffNeeded].val.boolVal;
    }

    ScopeChainLink &scopeLink()
    {
        return localStorage[ScopeLink].val.scopeVal;
    }
protected:
    JSVariableObject(): localStorage(nullptr), symbolTable(nullptr) { }
    ~JSVariableObject() override;

    bool symbolTableGet(const Identifier &, PropertySlot &);
    bool symbolTablePut(const Identifier &, JSValue *, bool checkReadOnly);

public:
    LocalStorageEntry *localStorage; // Storage for variables in the symbol table.
    SymbolTable       *symbolTable; // Maps name -> index in localStorage.
};

inline bool JSVariableObject::symbolTableGet(const Identifier &propertyName, PropertySlot &slot)
{
    size_t index = symbolTable->get(propertyName.ustring().rep());
    if (index != missingSymbolMarker()) {
        slot.setValueSlot(this, &localStorage[index].val.valueVal);
        return true;
    }
    return false;
}

inline bool JSVariableObject::symbolTablePut(const Identifier &propertyName, JSValue *value, bool checkReadOnly)
{
    size_t index = symbolTable->get(propertyName.ustring().rep());
    if (index == missingSymbolMarker()) {
        return false;
    }
    LocalStorageEntry &entry = localStorage[index];
    if (checkReadOnly && (entry.attributes & ReadOnly)) {
        return true;
    }
    entry.val.valueVal = value;
    return true;
}

inline JSVariableObject::~JSVariableObject()
{
    if (localStorage) {
        scopeLink().deref();
        if (tearOffNeededSlot()) {
            delete[] localStorage;
        }
    }
}

inline JSObject *ScopeChainLink::object() const
{
    if (isToScopeChainNode()) {
        return asScopeChainNode()->object;
    } else {
        return asVariableObject();
    }
}

inline ScopeChainLink ScopeChainLink::next() const
{
    if (isToScopeChainNode()) {
        return asScopeChainNode()->next;
    } else {
        return asVariableObject()->scopeLink();
    }
}

inline void ScopeChain::mark()
{
    for (ScopeChainLink n = m_top; n.ptr; n = n.next()) {
        JSObject *o = n.object();
        if (!o->marked()) {
            o->mark();
        }
    }
}

inline void ScopeChain::pushVariableObject(JSVariableObject *act)
{
    // note: this assumes the new variable object is not in any
    // scope chain in the moment.

    // Set the item's next pointer to the current top.
    // there is no refcount ops since it's transferring a reference
    act->scopeLink() = m_top;

    // new top!
    m_top.set(act);
}

class KJS_EXPORT JSGlobalObject :  public JSObject // ### TODO: should inherit off JSVariableObject
{
public:
    JSGlobalObject(): m_interpreter(nullptr) {}
    JSGlobalObject(JSValue *proto): JSObject(proto), m_interpreter(nullptr) {}
    bool isGlobalObject() const override
    {
        return true;
    }

    void setInterpreter(Interpreter *intp)
    {
        m_interpreter = intp;
    }
    Interpreter *interpreter() const
    {
        return m_interpreter;
    }
private:
    Interpreter *m_interpreter;
};
} // namespace KJS

#endif // JSVariableObject_h