#include "Operations.h"

// 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) {

            m_other.m_fibers[i]->deref();

            m_other.m_fibers[i] = 0;

        }

        m_fiberCount = 0;

        ASSERT(!isRope());

        ASSERT(m_value == UString());

        throwOutOfMemoryError(exec);

        return;

    }

    UChar* position = buffer + m_length;

    // Start with the current Rope.

    Vector<Rope::Fiber, 32> workQueue;

    Rope::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 (currentFiber->isRope()) {

            Rope* rope = static_cast<URopeImpl*>(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) {

                    m_other.m_fibers[i]->deref();

                    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();

        }

    }

}

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);

}

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

    result = this;

    number = value(exec).toDouble();

    return m_length;

double JSString::toNumber(ExecState* exec) const

    return value(exec).toDouble();

UString JSString::toString(ExecState* exec) const

    return value(exec);

UString JSString::toThisString(ExecState* exec) const

    return value(exec);

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

    if (isStrictUInt32 && i < m_length) {

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