/*

 *  Copyright (C) 1999-2002 Harri Porten (porten@kde.org)

 *  Copyright (C) 2001 Peter Kelly (pmk@post.com)

 *  Copyright (C) 2004, 2007, 2008 Apple Inc. All rights reserved.

 *

 *  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.

 *

 */

#include "config.h"

#include "JSString.h"

#include "JSGlobalObject.h"

#include "JSObject.h"

#include "Operations.h"

#include "StringObject.h"

#include "StringPrototype.h"

namespace JSC {

// Overview: this methods converts a JSString from holding a string in rope form

// down to a simple UString representation.  It does so by building up the string

// backwards, since we want to avoid recursion, we expect that the tree structure

// representing the rope is likely imbalanced with more nodes down the left side

// (since appending to the string is likely more common) - and as such resolving

// in this fashion should minimize work queue size.  (If we built the queue forwards

// we would likely have to place all of the constituent UStringImpls into the

// Vector before performing any concatenation, but by working backwards we likely

// only fill the queue with the number of substrings at any given level in a

// rope-of-ropes.)

void JSString::resolveRope(ExecState* exec) const

{

    ASSERT(isRope());

    // Allocate the buffer to hold the final string, position initially points to the end.

    UChar* buffer;

    if (PassRefPtr<UStringImpl> newImpl = UStringImpl::tryCreateUninitialized(m_length, buffer))

        m_value = newImpl;

    else {

        for (unsigned i = 0; i < m_fiberCount; ++i) {

            RopeImpl::deref(m_other.m_fibers[i]);

            m_other.m_fibers[i] = 0;

        }

        m_fiberCount = 0;

        ASSERT(!isRope());

        ASSERT(m_value == UString());

        if (exec)

            throwOutOfMemoryError(exec);

        return;

    }

    UChar* position = buffer + m_length;

    // Start with the current RopeImpl.

    Vector<RopeImpl::Fiber, 32> workQueue;

    RopeImpl::Fiber currentFiber;

    for (unsigned i = 0; i < (m_fiberCount - 1); ++i)

        workQueue.append(m_other.m_fibers[i]);

    currentFiber = m_other.m_fibers[m_fiberCount - 1];

    while (true) {

        if (RopeImpl::isRope(currentFiber)) {

            RopeImpl* rope = static_cast<RopeImpl*>(currentFiber);

            // Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber'

            // (we will be working backwards over the rope).

            unsigned fiberCountMinusOne = rope->fiberCount() - 1;

            for (unsigned i = 0; i < fiberCountMinusOne; ++i)

                workQueue.append(rope->fibers()[i]);

            currentFiber = rope->fibers()[fiberCountMinusOne];

        } else {

            UStringImpl* string = static_cast<UStringImpl*>(currentFiber);

            unsigned length = string->length();

            position -= length;

            UStringImpl::copyChars(position, string->characters(), length);

            // Was this the last item in the work queue?

            if (workQueue.isEmpty()) {

                // Create a string from the UChar buffer, clear the rope RefPtr.

                ASSERT(buffer == position);

                for (unsigned i = 0; i < m_fiberCount; ++i) {

                    RopeImpl::deref(m_other.m_fibers[i]);

                    m_other.m_fibers[i] = 0;

                }

                m_fiberCount = 0;

                ASSERT(!isRope());

                return;

            }

            // No! - set the next item up to process.

            currentFiber = workQueue.last();

            workQueue.removeLast();

        }

    }

}

JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UString& replacement)

{

    if (!isRope()) {

        unsigned matchPosition = m_value.find(character);

        if (matchPosition == UString::NotFound)

            return JSValue(this);

        return jsString(exec, m_value.substr(0, matchPosition), replacement, m_value.substr(matchPosition + 1));

    }

    RopeIterator end;

    // Count total fibers and find matching string.

    size_t fiberCount = 0;

    UStringImpl* matchString = 0;

    int matchPosition = -1;

    for (RopeIterator it(m_other.m_fibers.data(), m_fiberCount); it != end; ++it) {

        ++fiberCount;

        if (matchString)

            continue;

        UStringImpl* string = *it;

        matchPosition = string->find(character);

        if (matchPosition == -1)

            continue;

        matchString = string;

    }

    if (!matchString)

        return this;

    RopeBuilder builder(replacement.size() ? fiberCount + 2 : fiberCount + 1);

    if (UNLIKELY(builder.isOutOfMemory()))

        return throwOutOfMemoryError(exec);

    for (RopeIterator it(m_other.m_fibers.data(), m_fiberCount); it != end; ++it) {

        UStringImpl* string = *it;

        if (string != matchString) {

            builder.append(UString(string));

            continue;

        }

        builder.append(UString(string).substr(0, matchPosition));

        if (replacement.size())

            builder.append(replacement);

        builder.append(UString(string).substr(matchPosition + 1));

        matchString = 0;

    }

    JSGlobalData* globalData = &exec->globalData();

    return JSValue(new (globalData) JSString(globalData, builder.release()));

}

JSString* JSString::getIndexSlowCase(ExecState* exec, unsigned i)

{

    ASSERT(isRope());

    resolveRope(exec);

    // Return a safe no-value result, this should never be used, since the excetion will be thrown.

    if (exec->exception())

        return jsString(exec, "");

    ASSERT(!isRope());

    ASSERT(i < m_value.size());

    return jsSingleCharacterSubstring(exec, m_value, i);

}

JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const

{

    return const_cast<JSString*>(this);

}

bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)

{

    result = this;

    number = value(exec).toDouble();

    return false;

}

bool JSString::toBoolean(ExecState*) const

{

    return m_length;

}

double JSString::toNumber(ExecState* exec) const

{

    return value(exec).toDouble();

}

UString JSString::toString(ExecState* exec) const

{

    return value(exec);

}

inline StringObject* StringObject::create(ExecState* exec, JSString* string)

{

    return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string);

}

JSObject* JSString::toObject(ExecState* exec) const

{

    return StringObject::create(exec, const_cast<JSString*>(this));

}

JSObject* JSString::toThisObject(ExecState* exec) const

{

    return StringObject::create(exec, const_cast<JSString*>(this));

}

bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)

{

    // The semantics here are really getPropertySlot, not getOwnPropertySlot.

    // This function should only be called by JSValue::get.

    if (getStringPropertySlot(exec, propertyName, slot))

        return true;

    if (propertyName == exec->propertyNames().underscoreProto) {

        slot.setValue(exec->lexicalGlobalObject()->stringPrototype());

        return true;

    }

    slot.setBase(this);

    JSObject* object;

    for (JSValue prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) {

        object = asObject(prototype);

        if (object->getOwnPropertySlot(exec, propertyName, slot))

            return true;

    }

    slot.setUndefined();

    return true;

}

bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)

{

    if (propertyName == exec->propertyNames().length) {

        descriptor.setDescriptor(jsNumber(exec, m_length), DontEnum | DontDelete | ReadOnly);

        return true;

    }

    bool isStrictUInt32;

    unsigned i = propertyName.toStrictUInt32(&isStrictUInt32);

    if (isStrictUInt32 && i < m_length) {

        descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly);

        return true;

    }

    return false;

}

bool JSString::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)

{

    if (getStringPropertyDescriptor(exec, propertyName, descriptor))

        return true;

    if (propertyName != exec->propertyNames().underscoreProto)

        return false;

    descriptor.setDescriptor(exec->lexicalGlobalObject()->stringPrototype(), DontEnum);

    return true;

}

bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)

{

    // The semantics here are really getPropertySlot, not getOwnPropertySlot.

    // This function should only be called by JSValue::get.

    if (getStringPropertySlot(exec, propertyName, slot))

        return true;

    return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);

}

} // namespace JSC