jode/jode/jode/bytecode/ConstantPool.java

/* jode.bytecode.ConstantPool Copyright (C) 1998 Jochen Hoenicke.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id$
 */
package jode.bytecode;
import java.io.*;
import jode.Type;

/**
 * This class represent the constant pool.
 *
 * @author Jochen Hoenicke
 */
public class ConstantPool {
    public final static int CLASS              =  7;
    public final static int FIELDREF           =  9;
    public final static int METHODREF          = 10;
    public final static int INTERFACEMETHODREF = 11;
    public final static int STRING             =  8;
    public final static int INTEGER            =  3;
    public final static int FLOAT              =  4;
    public final static int LONG               =  5;
    public final static int DOUBLE             =  6;
    public final static int NAMEANDTYPE        = 12;
    public final static int UTF8               =  1;

    int[] tags;
    int[] indices1, indices2;

    Object[] constants;

    public ConstantPool () {
    }

    public void read(DataInputStream stream) 
	throws IOException {
	int count = stream.readUnsignedShort();
        tags = new int[count];
        indices1 = new int[count];
        indices2 = new int[count];
        constants = new Object[count];

	for (int i=1; i< count; i++) {
            int tag = stream.readUnsignedByte();
            tags[i] = tag;
            switch (tag) {
	    case CLASS:
		indices1[i] = stream.readUnsignedShort();
		break;
	    case FIELDREF:
	    case METHODREF:
	    case INTERFACEMETHODREF:
		indices1[i] = stream.readUnsignedShort();
		indices2[i] = stream.readUnsignedShort();
		break;
	    case STRING:
		indices1[i] = stream.readUnsignedShort();
		break;
	    case INTEGER:
		constants[i] = new Integer(stream.readInt());
		break;
	    case FLOAT:
		constants[i] = new Float(stream.readFloat());
		break;
	    case LONG:
		constants[i] = new Long(stream.readLong());
                tags[++i] = -LONG;
		break;
	    case DOUBLE:
		constants[i] = new Double(stream.readDouble());
                tags[++i] = -DOUBLE;
		break;
	    case NAMEANDTYPE:
		indices1[i] = stream.readUnsignedShort();
		indices2[i] = stream.readUnsignedShort();
		break;
	    case UTF8:
		constants[i] = new String(stream.readUTF());
		break;
	    default:
		throw new ClassFormatException("unknown constant tag");
            }
	}
    }

    public int getTag(int i) throws ClassFormatException {
        if (i == 0)
            throw new ClassFormatException("null tag");
        return tags[i];
    }

    public String getUTF8(int i) throws ClassFormatException {
        if (i == 0)
            return null;
        if (tags[i] != UTF8)
            throw new ClassFormatException("Tag mismatch");
        return (String)constants[i];
    }

    public String[] getRef(int i) throws ClassFormatException {
        if (i == 0)
            return null;
        if (tags[i] != FIELDREF
            && tags[i] != METHODREF && tags[i] != INTERFACEMETHODREF)
            throw new ClassFormatException("Tag mismatch");
        int classIndex = indices1[i];
        int nameTypeIndex = indices2[i];
        if (tags[nameTypeIndex] != NAMEANDTYPE)
            throw new ClassFormatException("Tag mismatch");
        return new String[] {
            getClassName(classIndex), 
            getUTF8(indices1[nameTypeIndex]), getUTF8(indices2[nameTypeIndex])
        };
    }

    public Type getConstantType(int i) throws ClassFormatException
    {
        if (i == 0)
            throw new ClassFormatException("null constant");
        switch(tags[i]) {
        case INTEGER: {
            int value = ((Integer)constants[i]).intValue();
            return ((value < Short.MIN_VALUE || value > Character.MAX_VALUE) 
                    ? Type.tInt
                    : (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) 
                    ? Type.tRange(Type.tInt, Type.tChar)
                    : (value == 0 || value == 1)
		    ? Type.tBoolInt
		    : Type.tUInt);
        }
        case FLOAT  : return Type.tFloat ;
        case LONG   : return Type.tLong  ;
        case DOUBLE : return Type.tDouble;
        case STRING : return Type.tString;
        default:
            throw new ClassFormatException
                ("invalid constant tag: " + tags[i]);
        }
    }

    private static String quoted(String str) {
        StringBuffer result = new StringBuffer("\"");
        for (int i=0; i< str.length(); i++) {
            char c;
            switch (c = str.charAt(i)) {
            case '\0':
                result.append("\\0");
                break;
            case '\t':
                result.append("\\t");
                break;
            case '\n':
                result.append("\\n");
                break;
            case '\r':
                result.append("\\r");
                break;
            case '\\':
                result.append("\\\\");
                break;
            case '\"':
                result.append("\\\"");
                break;
            default:
                if (c < 32) {
                    String oct = Integer.toOctalString(c);
                    result.append("\\000".substring(0, 4-oct.length()))
                        .append(oct);
                } else if (c >= 32 && c < 127)
                    result.append(str.charAt(i));
                else {
                    String hex = Integer.toHexString(c);
                    result.append("\\u0000".substring(0, 6-hex.length()))
                        .append(hex);
                }
            }
        }
        return result.append("\"").toString();
    }

    public String getConstantString(int i) throws ClassFormatException {
        if (i == 0)
            throw new ClassFormatException("null constant");
        switch (tags[i]) {
        case ConstantPool.INTEGER: 
        case ConstantPool.FLOAT:
        case ConstantPool.LONG:
        case ConstantPool.DOUBLE:
            return constants[i].toString();
        case ConstantPool.STRING: 
            return quoted(getUTF8(indices1[i]));
        }
        throw new ClassFormatException("unknown constant tag");
    }

    public String getClassName(int i) throws ClassFormatException {
        if (i == 0)
            return null;
        if (tags[i] != CLASS)
            throw new ClassFormatException("Tag mismatch");
        return getUTF8(indices1[i]);
    }

    public String toString(int i) {
	switch (tags[i]) {
        case CLASS:
            return "class "+toString(indices1[i]);
        case STRING:
            return "\""+toString(indices1[i])+"\"";
        case INTEGER:
        case FLOAT:
        case LONG:
        case DOUBLE:
        case UTF8:
            return constants[i].toString();
        case FIELDREF:
        case METHODREF:
        case INTERFACEMETHODREF:
            return "Ref: "+toString(indices1[i])+": "
                + toString(indices2[i]);
        case NAMEANDTYPE:
            return toString(indices1[i])+" "+toString(indices2[i]);
        default:
            return "unknown tag: "+tags[i];
	}
    }

    public String toString() {
        StringBuffer result = new StringBuffer("[ null");
        for (int i=1; i< tags.length; i++) {
            result.append(", ").append(toString(i));
        }
        result.append(" ]");
        return result.toString();
    }            
}