ASM: a very small and fast Java bytecode manipulation framework
Copyright (c) 2000-2011 INRIA, France Telecom
All rights reserved.
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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
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THE POSSIBILITY OF SUCH DAMAGE.
/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 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.optimizer;

import java.util.Arrays;

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Handle;

A constant pool item.
Author:
Eric Bruneton/**
 * A constant pool item.
 * 
 * @author Eric Bruneton
 */
class Constant {

    
Type of this constant pool item. A single class is used to represent all
constant pool item types, in order to minimize the bytecode size of this
package. The value of this field is I, J, F, D, S, s, C, T, G, M, N, y,
t, [h..p] (for Constant Integer, Long, Float, Double, STR, UTF8, Class,
NameType, Fieldref, Methodref, InterfaceMethodref, InvokeDynamic,
MethodType and MethodHandle constant pool items respectively).
The 9 variable of MethodHandle constants are stored between h and p.
/**
     * Type of this constant pool item. A single class is used to represent all
     * constant pool item types, in order to minimize the bytecode size of this
     * package. The value of this field is I, J, F, D, S, s, C, T, G, M, N, y,
     * t, [h..p] (for Constant Integer, Long, Float, Double, STR, UTF8, Class,
     * NameType, Fieldref, Methodref, InterfaceMethodref, InvokeDynamic,
     * MethodType and MethodHandle constant pool items respectively).
     * 
     * The 9 variable of MethodHandle constants are stored between h and p.
     */
    char type;

    
Value of this item, for an integer item.
/**
     * Value of this item, for an integer item.
     */
    int intVal;

    
Value of this item, for a long item.
/**
     * Value of this item, for a long item.
     */
    long longVal;

    
Value of this item, for a float item.
/**
     * Value of this item, for a float item.
     */
    float floatVal;

    
Value of this item, for a double item.
/**
     * Value of this item, for a double item.
     */
    double doubleVal;

    
First part of the value of this item, for items that do not hold a
primitive value.
/**
     * First part of the value of this item, for items that do not hold a
     * primitive value.
     */
    String strVal1;

    
Second part of the value of this item, for items that do not hold a
primitive value.
/**
     * Second part of the value of this item, for items that do not hold a
     * primitive value.
     */
    String strVal2;

    
Third part of the value of this item, for items that do not hold a
primitive value.
/**
     * Third part of the value of this item, for items that do not hold a
     * primitive value.
     */
    Object objVal3;

    
InvokeDynamic's constant values.
/**
     * InvokeDynamic's constant values.
     */
    Object[] objVals;

    
The hash code value of this constant pool item.
/**
     * The hash code value of this constant pool item.
     */
    int hashCode;

    Constant() {
    }

    Constant(final Constant i) {
        type = i.type;
        intVal = i.intVal;
        longVal = i.longVal;
        floatVal = i.floatVal;
        doubleVal = i.doubleVal;
        strVal1 = i.strVal1;
        strVal2 = i.strVal2;
        objVal3 = i.objVal3;
        objVals = i.objVals;
        hashCode = i.hashCode;
    }

    
Sets this item to an integer item.
Params:
intVal – 
           the value of this item./**
     * Sets this item to an integer item.
     * 
     * @param intVal
     *            the value of this item.
     */
    void set(final int intVal) {
        this.type = 'I';
        this.intVal = intVal;
        this.hashCode = 0x7FFFFFFF & (type + intVal);
    }

    
Sets this item to a long item.
Params:
longVal – 
           the value of this item./**
     * Sets this item to a long item.
     * 
     * @param longVal
     *            the value of this item.
     */
    void set(final long longVal) {
        this.type = 'J';
        this.longVal = longVal;
        this.hashCode = 0x7FFFFFFF & (type + (int) longVal);
    }

    
Sets this item to a float item.
Params:
floatVal – 
           the value of this item./**
     * Sets this item to a float item.
     * 
     * @param floatVal
     *            the value of this item.
     */
    void set(final float floatVal) {
        this.type = 'F';
        this.floatVal = floatVal;
        this.hashCode = 0x7FFFFFFF & (type + (int) floatVal);
    }

    
Sets this item to a double item.
Params:
doubleVal – 
           the value of this item./**
     * Sets this item to a double item.
     * 
     * @param doubleVal
     *            the value of this item.
     */
    void set(final double doubleVal) {
        this.type = 'D';
        this.doubleVal = doubleVal;
        this.hashCode = 0x7FFFFFFF & (type + (int) doubleVal);
    }

    
Sets this item to an item that do not hold a primitive value.
Params:
type – 
           the type of this item.
strVal1 – 
           first part of the value of this item.
strVal2 – 
           second part of the value of this item.
strVal3 – 
           third part of the value of this item./**
     * Sets this item to an item that do not hold a primitive value.
     * 
     * @param type
     *            the type of this item.
     * @param strVal1
     *            first part of the value of this item.
     * @param strVal2
     *            second part of the value of this item.
     * @param strVal3
     *            third part of the value of this item.
     */
    void set(final char type, final String strVal1, final String strVal2,
            final String strVal3) {
        this.type = type;
        this.strVal1 = strVal1;
        this.strVal2 = strVal2;
        this.objVal3 = strVal3;
        switch (type) {
        case 's':
        case 'S':
        case 'C':
        case 't':
            hashCode = 0x7FFFFFFF & (type + strVal1.hashCode());
            return;
        case 'T':
            hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
                    * strVal2.hashCode());
            return;
            // case 'G':
            // case 'M':
            // case 'N':
            // case 'h' ... 'p':
        default:
            hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
                    * strVal2.hashCode() * strVal3.hashCode());
        }
    }

    
Set this item to an InvokeDynamic item.
Params:
name – 
           invokedynamic's name.
desc – 
           invokedynamic's descriptor.
bsm – 
           bootstrap method.
bsmArgs – 
           bootstrap method constant arguments./**
     * Set this item to an InvokeDynamic item.
     * 
     * @param name
     *            invokedynamic's name.
     * @param desc
     *            invokedynamic's descriptor.
     * @param bsm
     *            bootstrap method.
     * @param bsmArgs
     *            bootstrap method constant arguments.
     */
    void set(final String name, final String desc, final Handle bsm,
            final Object[] bsmArgs) {
        this.type = 'y';
        this.strVal1 = name;
        this.strVal2 = desc;
        this.objVal3 = bsm;
        this.objVals = bsmArgs;

        int hashCode = 'y' + name.hashCode() * desc.hashCode() * bsm.hashCode();
        for (int i = 0; i < bsmArgs.length; i++) {
            hashCode *= bsmArgs[i].hashCode();
        }
        this.hashCode = 0x7FFFFFFF & hashCode;
    }

    void write(final ClassWriter cw) {
        switch (type) {
        case 'I':
            cw.newConst(new Integer(intVal));
            break;
        case 'J':
            cw.newConst(new Long(longVal));
            break;
        case 'F':
            cw.newConst(new Float(floatVal));
            break;
        case 'D':
            cw.newConst(new Double(doubleVal));
            break;
        case 'S':
            cw.newConst(strVal1);
            break;
        case 's':
            cw.newUTF8(strVal1);
            break;
        case 'C':
            cw.newClass(strVal1);
            break;
        case 'T':
            cw.newNameType(strVal1, strVal2);
            break;
        case 'G':
            cw.newField(strVal1, strVal2, (String) objVal3);
            break;
        case 'M':
            cw.newMethod(strVal1, strVal2, (String) objVal3, false);
            break;
        case 'N':
            cw.newMethod(strVal1, strVal2, (String) objVal3, true);
            break;
        case 'y':
            cw.newInvokeDynamic(strVal1, strVal2, (Handle) objVal3, objVals);
            break;
        case 't':
            cw.newMethodType(strVal1);
            break;
        default: // 'h' ... 'p': handle
            cw.newHandle(type - 'h' + 1, strVal1, strVal2, (String) objVal3);
        }
    }

    @Override
    public boolean equals(final Object o) {
        if (!(o instanceof Constant)) {
            return false;
        }
        Constant c = (Constant) o;
        if (c.type == type) {
            switch (type) {
            case 'I':
                return c.intVal == intVal;
            case 'J':
                return c.longVal == longVal;
            case 'F':
                return Float.compare(c.floatVal, floatVal) == 0;
            case 'D':
                return Double.compare(c.doubleVal, doubleVal) == 0;
            case 's':
            case 'S':
            case 'C':
            case 't':
                return c.strVal1.equals(strVal1);
            case 'T':
                return c.strVal1.equals(strVal1) && c.strVal2.equals(strVal2);
            case 'y':
                return c.strVal1.equals(strVal1) && c.strVal2.equals(strVal2)
                        && c.objVal3.equals(objVal3)
                        && Arrays.equals(c.objVals, objVals);
                // case 'G':
                // case 'M':
                // case 'N':
                // case 'h' ... 'p':
            default:
                return c.strVal1.equals(strVal1) && c.strVal2.equals(strVal2)
                        && c.objVal3.equals(objVal3);
            }
        }
        return false;
    }

    @Override
    public int hashCode() {
        return hashCode;
    }
}