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/***

 * ASM: a very small and fast Java bytecode manipulation framework

 * Copyright (c) 2000-2005 INRIA, France Telecom

 * 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 the copyright holders 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT OWNER OR 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.

 */

package org.objectweb.asm.tree.analysis;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

import org.objectweb.asm.Opcodes;

import org.objectweb.asm.Type;

import org.objectweb.asm.tree.AbstractInsnNode;

import org.objectweb.asm.tree.FieldInsnNode;

import org.objectweb.asm.tree.LdcInsnNode;

import org.objectweb.asm.tree.MethodInsnNode;

/**

 * An {@link Interpreter} for {@link DataflowValue} values.

 *

 * @author Eric Bruneton

 */

public class DataflowInterpreter implements Opcodes, Interpreter {

    public Value newValue(final Type type) {

        return new DataflowValue(type == null ? 1 : type.getSize());

    }

    public Value newOperation(final AbstractInsnNode insn) {

        int size;

        switch (insn.getOpcode()) {

            case LCONST_0:

            case LCONST_1:

            case DCONST_0:

            case DCONST_1:

                size = 2;

                break;

            case LDC:

                Object cst = ((LdcInsnNode) insn).cst;

                size = cst instanceof Long || cst instanceof Double ? 2 : 1;

                break;

            case GETSTATIC:

                size = Type.getType(((FieldInsnNode) insn).desc).getSize();

                break;

            default:

                size = 1;

        }

        return new DataflowValue(size, insn);

    }

    public Value copyOperation(final AbstractInsnNode insn, final Value value) {

        return new DataflowValue(value.getSize(), insn);

    }

    public Value unaryOperation(final AbstractInsnNode insn, final Value value)

    {

        int size;

        switch (insn.getOpcode()) {

            case LNEG:

            case DNEG:

            case I2L:

            case I2D:

            case L2D:

            case F2L:

            case F2D:

            case D2L:

                size = 2;

                break;

            case GETFIELD:

                size = Type.getType(((FieldInsnNode) insn).desc).getSize();

                break;

            default:

                size = 1;

        }

        return new DataflowValue(size, insn);

    }

    public Value binaryOperation(

        final AbstractInsnNode insn,

        final Value value1,

        final Value value2)

    {

        int size;

        switch (insn.getOpcode()) {

            case LALOAD:

            case DALOAD:

            case LADD:

            case DADD:

            case LSUB:

            case DSUB:

            case LMUL:

            case DMUL:

            case LDIV:

            case DDIV:

            case LREM:

            case DREM:

            case LSHL:

            case LSHR:

            case LUSHR:

            case LAND:

            case LOR:

            case LXOR:

                size = 2;

                break;

            default:

                size = 1;

        }

        return new DataflowValue(size, insn);

    }

    public Value ternaryOperation(

        final AbstractInsnNode insn,

        final Value value1,

        final Value value2,

        final Value value3)

    {

        return new DataflowValue(1, insn);

    }

    public Value naryOperation(final AbstractInsnNode insn, final List values) {

        int size;

        if (insn.getOpcode() == MULTIANEWARRAY) {

            size = 1;

        } else {

            size = Type.getReturnType(((MethodInsnNode) insn).desc).getSize();

        }

        return new DataflowValue(size, insn);

    }

    public Value merge(final Value v, final Value w) {

        DataflowValue dv = (DataflowValue) v;

        DataflowValue dw = (DataflowValue) w;

        if (dv.insns instanceof SmallSet && dw.insns instanceof SmallSet) {

            Set s = ((SmallSet) dv.insns).union((SmallSet) dw.insns);

            if (s == dv.insns && dv.size == dw.size) {

                return v;

            } else {

                return new DataflowValue(Math.min(dv.size, dw.size), s);

            }

        }

        if (dv.size != dw.size || !dv.insns.containsAll(dw.insns)) {

            Set s = new HashSet();

            s.addAll(dv.insns);

            s.addAll(dw.insns);

            return new DataflowValue(Math.min(dv.size, dw.size), s);

        }

        return v;

    }

}