src/third_party/mozjs-45/js/src/vm/StringObject.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef vm_StringObject_h
#define vm_StringObject_h

#include "jsobj.h"
#include "jsstr.h"

#include "vm/Shape.h"

namespace js {

class StringObject : public NativeObject
{
    static const unsigned PRIMITIVE_VALUE_SLOT = 0;
    static const unsigned LENGTH_SLOT = 1;

  public:
    static const unsigned RESERVED_SLOTS = 2;

    static const Class class_;

    /*
     * Creates a new String object boxing the given string.  The object's
     * [[Prototype]] is determined from context.
     */
    static inline StringObject* create(JSContext* cx, HandleString str,
                                       HandleObject proto = nullptr,
                                       NewObjectKind newKind = GenericObject);

    /*
     * Compute the initial shape to associate with fresh String objects, which
     * encodes the initial length property. Return the shape after changing
     * |obj|'s last property to it.
     */
    static Shape*
    assignInitialShape(ExclusiveContext* cx, Handle<StringObject*> obj);

    JSString* unbox() const {
        return getFixedSlot(PRIMITIVE_VALUE_SLOT).toString();
    }

    inline size_t length() const {
        return size_t(getFixedSlot(LENGTH_SLOT).toInt32());
    }

    static size_t offsetOfPrimitiveValue() {
        return getFixedSlotOffset(PRIMITIVE_VALUE_SLOT);
    }
    static size_t offsetOfLength() {
        return getFixedSlotOffset(LENGTH_SLOT);
    }

  private:
    inline bool init(JSContext* cx, HandleString str);

    void setStringThis(JSString* str) {
        MOZ_ASSERT(getReservedSlot(PRIMITIVE_VALUE_SLOT).isUndefined());
        setFixedSlot(PRIMITIVE_VALUE_SLOT, StringValue(str));
        setFixedSlot(LENGTH_SLOT, Int32Value(int32_t(str->length())));
    }

    /* For access to init, as String.prototype is special. */
    friend JSObject*
    js::InitStringClass(JSContext* cx, HandleObject global);
};

} // namespace js

#endif /* vm_StringObject_h */