path: root/src/declarative/qml/v8/qjsvalueiterator.cpp

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**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtScript module of the Qt Toolkit.
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** $QT_BEGIN_LICENSE:LGPL-ONLY$
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#include "qjsvalueiterator.h"

#include "qscriptisolate_p.h"
#include "qjsvalue_p.h"
#include "qv8engine_p.h"
#include "qscript_impl_p.h"

QT_BEGIN_NAMESPACE

/*!
    \class QJSValueIterator

    \brief The QJSValueIterator class provides a Java-style iterator for QJSValue.

    \ingroup script


    The QJSValueIterator constructor takes a QJSValue as
    argument.  After construction, the iterator is located at the very
    beginning of the sequence of properties. Here's how to iterate over
    all the properties of a QJSValue:

    \snippet doc/src/snippets/code/src_script_QJSValueIterator.cpp 0

    The next() advances the iterator. The name(), value() and flags()
    functions return the name, value and flags of the last item that was
    jumped over.

    If you want to remove properties as you iterate over the
    QJSValue, use remove(). If you want to modify the value of a
    property, use setValue().

    Note that QJSValueIterator only iterates over the QJSValue's
    own properties; i.e. it does not follow the prototype chain. You can
    use a loop like this to follow the prototype chain:

    \snippet doc/src/snippets/code/src_script_QJSValueIterator.cpp 1

    Note that QJSValueIterator will not automatically skip over
    properties that have the QJSValue::SkipInEnumeration flag set;
    that flag only affects iteration in script code.  If you want, you
    can skip over such properties with code like the following:

    \snippet doc/src/snippets/code/src_script_QJSValueIterator.cpp 2

    \sa QJSValue::property()
*/

using v8::Persistent;
using v8::Local;
using v8::Array;
using v8::String;
using v8::Handle;
using v8::Object;
using v8::Value;

// FIXME (Qt5) This class should be refactored. It should use the common Iterator interface.
// FIXME it could be faster!
class QJSValueIteratorPrivate {
public:
    inline QJSValueIteratorPrivate(const QJSValuePrivate* value);
    inline ~QJSValueIteratorPrivate();

    inline bool hasNext() const;
    inline bool next();

    inline QString name() const;

    inline QScriptPassPointer<QJSValuePrivate> value() const;

    inline bool isValid() const;
    inline QV8Engine* engine() const;
private:
    Q_DISABLE_COPY(QJSValueIteratorPrivate)
    //void dump(QString) const;

    QScriptSharedDataPointer<QJSValuePrivate> m_object;
    QList<v8::Persistent<v8::String> > m_names;
    QMutableListIterator<v8::Persistent<v8::String> > m_iterator;
};

inline QJSValueIteratorPrivate::QJSValueIteratorPrivate(const QJSValuePrivate* value)
    : m_object(const_cast<QJSValuePrivate*>(value))
    , m_iterator(m_names)
{
    Q_ASSERT(value);
    QV8Engine *engine = m_object->engine();
    QScriptIsolate api(engine);
    if (!m_object->isObject())
        m_object = 0;
    else {
        v8::HandleScope scope;
        Handle<Value> tmp = *value;
        Handle<Object> obj = Handle<Object>::Cast(tmp);
        Local<Array> names;

        // FIXME we need newer V8!
        //names = obj->GetOwnPropertyNames();
        names = engine->getOwnPropertyNames(obj);

        // it is suboptimal, it would be better to write iterator instead
        uint32_t count = names->Length();
        Local<String> name;
        m_names.reserve(count); // The count is the maximal count of values.
        for (uint32_t i = count - 1; i < count; --i) {
            name = names->Get(i)->ToString();
            m_names.append(v8::Persistent<v8::String>::New(name));
        }

        // Reinitialize the iterator.
        m_iterator = m_names;
    }
}

inline QJSValueIteratorPrivate::~QJSValueIteratorPrivate()
{
    QMutableListIterator<v8::Persistent<v8::String> > it = m_names;
    //FIXME: we need register this QJSVAlueIterator
    if (engine()) {
        while (it.hasNext()) {
            it.next().Dispose();
        }
    } else {
        // FIXME leak ?
    }
}

inline bool QJSValueIteratorPrivate::hasNext() const
{
    //dump("hasNext()");
    return isValid()
            ? m_iterator.hasNext() : false;
}

inline bool QJSValueIteratorPrivate::next()
{
    //dump("next();");
    if (m_iterator.hasNext()) {
        m_iterator.next();
        return true;
    }
    return false;
}

inline QString QJSValueIteratorPrivate::name() const
{
    //dump("name");
    if (!isValid())
        return QString();

    return QJSConverter::toString(m_iterator.value());
}

inline QScriptPassPointer<QJSValuePrivate> QJSValueIteratorPrivate::value() const
{
    //dump("value()");
    if (!isValid())
        return InvalidValue();

    return m_object->property(m_iterator.value());
}

inline bool QJSValueIteratorPrivate::isValid() const
{
    bool result = m_object ? m_object->isValid() : false;
    // We know that if this object is still valid then it is an object
    // if this assumption is not correct then some other logic in this class
    // have to be changed too.
    Q_ASSERT(!result || m_object->isObject());
    return result;
}

inline QV8Engine* QJSValueIteratorPrivate::engine() const
{
    return m_object ? m_object->engine() : 0;
}

//void QJSValueIteratorPrivate::dump(QString fname) const
//{
//    qDebug() << "    *** " << fname << " ***";
//    foreach (Persistent<String> name, m_names) {
//        qDebug() << "        - " << QJSConverter::toString(name);
//    }
//}

/*!
    Constructs an iterator for traversing \a object. The iterator is
    set to be at the front of the sequence of properties (before the
    first property).
*/
QJSValueIterator::QJSValueIterator(const QJSValue& object)
    : d_ptr(new QJSValueIteratorPrivate(QJSValuePrivate::get(object)))
{}

/*!
    Destroys the iterator.
*/
QJSValueIterator::~QJSValueIterator()
{}

/*!
    Returns true if there is at least one item ahead of the iterator
    (i.e. the iterator is \e not at the back of the property sequence);
    otherwise returns false.

    \sa next(), hasPrevious()
*/
bool QJSValueIterator::hasNext() const
{
    Q_D(const QJSValueIterator);
    QScriptIsolate api(d->engine());
    return d->hasNext();
}

/*!
    Advances the iterator by one position.

    Calling this function on an iterator located at the back of the
    container leads to undefined results.

    \sa hasNext(), previous(), name()
*/
bool QJSValueIterator::next()
{
    Q_D(QJSValueIterator);
    QScriptIsolate api(d->engine());
    return d->next();
}

/*!
    Returns the name of the last property that was jumped over using
    next() or previous().

    \sa value(), flags()
*/
QString QJSValueIterator::name() const
{
    Q_D(const QJSValueIterator);
    QScriptIsolate api(d->engine());
    return d_ptr->name();
}


/*!
    Returns the value of the last property that was jumped over using
    next() or previous().

    \sa setValue(), name()
*/
QJSValue QJSValueIterator::value() const
{
    Q_D(const QJSValueIterator);
    QScriptIsolate api(d->engine());
    return QJSValuePrivate::get(d->value());
}


/*!
    Makes the iterator operate on \a object. The iterator is set to be
    at the front of the sequence of properties (before the first
    property).
*/
QJSValueIterator& QJSValueIterator::operator=(QJSValue& object)
{
    Q_D(QJSValueIterator);
    QScriptIsolate api(d->engine());
    d_ptr.reset(new QJSValueIteratorPrivate(QJSValuePrivate::get(object)));
    return *this;
}

QT_END_NAMESPACE