/*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 *
 * 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 Label_h
#define Label_h

#include "CodeBlock.h"
#include "Instruction.h"
#include <wtf/Assertions.h>
#include <wtf/Vector.h>
#include <limits.h>

namespace JSC {

class BytecodeGenerator;

class Label {
public:
	Label()
		: m_refCount(0)
		, m_location(invalidLocation)
		, m_bound(false)
	{
	}

    void setLocation(BytecodeGenerator&, unsigned);

	int bind(int opcode, int offset) const
	{
        m_bound = true;
		if (m_location == invalidLocation) {
			m_unresolvedJumps.append(std::make_pair(opcode, offset));
			return 0;
		}
		return m_location - opcode;
	}

	void ref() { ++m_refCount; }
	void deref()
	{
		--m_refCount;
		ASSERT(m_refCount >= 0);
	}
	int refCount() const { return m_refCount; }
    bool hasOneRef() const { return m_refCount == 1; }

	bool isForward() const { return m_location == invalidLocation; }

	int bind()
	{
		ASSERT(!isForward());
		return bind(0, 0);
	}

    bool isBound() const { return m_bound; }

private:
	typedef Vector<std::pair<int, int>, 8> JumpVector;

	static const unsigned invalidLocation = UINT_MAX;

	int m_refCount;
	unsigned m_location;
	mutable bool m_bound;
	mutable JumpVector m_unresolvedJumps;
};

} // namespace JSC

#endif // Label_h
