path: root/asm4/src/org/objectweb/asm/optimizer/Constant.java

/***
 * 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
 */
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.
     */
    char type;

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

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

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

    /**
     * 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.
     */
    String strVal1;

    /**
     * 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.
     */
    Object objVal3;

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

    /**
     * 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.
     * 
     * @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.
     * 
     * @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.
     * 
     * @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.
     * 
     * @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.
     * 
     * @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.
     * 
     * @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;
    }
}