vmcp.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 214 行

/**
 * $Id: VmCP.java,v 1.3 2004/02/24 08:04:15 epr Exp $
 **/

package org.jnode.vm.classmgr;

import org.jnode.vm.VmSystemObject;

/**
 * A VmCP is the runtime representation of a constant pool
 * 
 * @author Ewout Prangsma ([e-mail])
 */
public final class VmCP extends VmSystemObject {

    public static final int TYPE_UTF8 = 1;

    public static final int TYPE_INT = 3;

    public static final int TYPE_FLOAT = 4;

    public static final int TYPE_LONG = 5;

    public static final int TYPE_DOUBLE = 6;

    public static final int TYPE_CLASSREF = 7;

    public static final int TYPE_STRING = 8;

    public static final int TYPE_FIELDREF = 9;

    public static final int TYPE_METHODREF = 10;

    public static final int TYPE_IMETHODREF = 11;

    public static final int TYPE_NAMEANDTYPE = 12;

    private Object[] cp;

    private int used;

    /**
     * Construct a new VmCP with a given number of entries
     * 
     * @param count
     */
    protected VmCP(int count) {
        this.cp = new Object[ count];
        this.used = count;
    }

    /**
     * Gets the number of enntries in this CP
     * 
     * @return int
     */
    public int getLength() {
        return cp.length;
    }

    /**
     * Read an int out of this CP
     * 
     * @param index
     *            The index where to read
     * @return int
     */
    public int getInt(int index) {
        if (index == 0)
            return 0;
        else
            return ((Integer) get(index)).intValue();
    }

    /**
     * Write an int into this CP
     * 
     * @param index
     *            The index where to read
     * @param data
     *            The int to write
     */
    protected void setInt(int index, int data) {
        set(index, new Integer(data));
    }

    /**
     * Read a long out of this CP
     * 
     * @param index
     *            The index where to read
     * @return long
     */
    public long getLong(int index) {
        return ((Long) get(index)).longValue();
    }

    /**
     * Write a long into this CP
     * 
     * @param index
     *            The index where to read
     * @param data
     *            The long to write
     */
    protected void setLong(int index, long data) {
        set(index, new Long(data));
    }

    protected String getUTF8(int index) {
        return (String) get(index);
    }

    protected void setUTF8(int index, String value) {
        set(index, value.intern());
    }

    public VmConstString getString(int index) {
        return (VmConstString) get(index);
    }

    protected void setString(int index, VmConstString value) {
        set(index, value);
    }

    public VmConstClass getConstClass(int index) {
        return (VmConstClass) get(index);
    }

    protected void setConstClass(int index, VmConstClass value) {
        set(index, value);
    }

    public VmConstFieldRef getConstFieldRef(int index) {
        return (VmConstFieldRef) get(index);
    }

    protected void setConstFieldRef(int index, VmConstFieldRef value) {
        set(index, value);
    }

    public VmConstMethodRef getConstMethodRef(int index) {
        return (VmConstMethodRef) get(index);
    }

    protected void setConstMethodRef(int index, VmConstMethodRef value) {
        set(index, value);
    }

    public VmConstIMethodRef getConstIMethodRef(int index) {
        return (VmConstIMethodRef) get(index);
    }

    protected void setConstIMethodRef(int index, VmConstIMethodRef value) {
        set(index, value);
    }

    public VmConstNameAndType getConstNameAndType(int index) {
        return (VmConstNameAndType) get(index);
    }

    protected void setConstNameAndType(int index, VmConstNameAndType value) {
        set(index, value);
    }

    public Object getAny(int index) {
        return get(index);
    }

    /**
     * Gets the index of a constant in this CP, or -1 if not found.
     * 
     * @param object
     * @return int
     */
    public int indexOf(Object object) {
        for (int i = 0; i < used; i++) {
            final Object o = cp[ i];
            if ((o != null) && (o.equals(object))) { return i; }
        }
        return -1;
    }

    /**
     * Read an Object out of this CP
     * 
     * @param index
     *            The index where to read
     * @return Object
     */
    private Object get(int index) {
        Object result = cp[ index];
        /*
         * if (result == null) { System.err.println("Warning: cp[" + index + "]
         * (tag " + tags[index] + ") returns null");
         */
        return result;
    }

    /**
     * Write an Object into this CP
     * 
     * @param index
     *            The index where to read
     * @param data
     *            The Object to write
     */
    private void set(int index, Object data) {
        if (data == null) { throw new NullPointerException(
                "Cannot set a null data"); }
        cp[ index] = data;
    }
}