/* ConstantPool Copyright (C) 1998-1999 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 net.sf.jode.bytecode;
import java.io.DataInputStream;
import java.io.IOException;

import java.util.NoSuchElementException;
///#def COLLECTIONS java.util
import java.util.Iterator;
///#enddef
///#def COLLECTIONEXTRA java.lang
import java.lang.UnsupportedOperationException;
///#enddef

/**
 * This class represent the constant pool.  You normally don't need to
 * access this class, except if you want to add your own custom
 * attributes that use 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 count;
    int[] tags;
    int[] indices1, indices2;

    Object[] constants;

    public ConstantPool () {
    }

    public void read(DataInputStream stream) 
	throws IOException {
	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] = stream.readUTF().intern();
		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 (tags[i] != UTF8)
            throw new ClassFormatException("Tag mismatch");
        return (String)constants[i];
    }

    public Reference getRef(int i) throws ClassFormatException {
        if (tags[i] != FIELDREF
            && tags[i] != METHODREF && tags[i] != INTERFACEMETHODREF)
            throw new ClassFormatException("Tag mismatch");
	if (constants[i] == null) {
	    int classIndex = indices1[i];
	    int nameTypeIndex = indices2[i];
	    if (tags[nameTypeIndex] != NAMEANDTYPE)
		throw new ClassFormatException("Tag mismatch");
	    String type = getUTF8(indices2[nameTypeIndex]);
	    try {
		if (tags[i] == FIELDREF)
		    TypeSignature.checkTypeSig(type);
		else
		    TypeSignature.checkMethodTypeSig(type);
	    } catch (IllegalArgumentException ex) {
		throw new ClassFormatException(ex.getMessage());
	    }
	    String clName = getClassType(classIndex);
	    constants[i] = Reference.getReference
		(clName, getUTF8(indices1[nameTypeIndex]), type);
	}
	return (Reference) constants[i];
    }

    public Object getConstant(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];
        case ConstantPool.STRING: 
            return getUTF8(indices1[i]);
        }
        throw new ClassFormatException("Tag mismatch: "+tags[i]);
    }

    public String getClassType(int i) throws ClassFormatException {
        if (tags[i] != CLASS)
            throw new ClassFormatException("Tag mismatch");
	String clName = getUTF8(indices1[i]);
	if (clName.charAt(0) != '[') {
	    clName = ("L"+clName+';').intern();
	}
	try {
	    TypeSignature.checkTypeSig(clName);
	} catch (IllegalArgumentException ex) {
	    throw new ClassFormatException(ex.getMessage());
	}
        return clName;
    }

    public String getClassName(int i) throws ClassFormatException {
        if (tags[i] != CLASS)
            throw new ClassFormatException("Tag mismatch");
	String clName = getUTF8(indices1[i]);
	try {
	    TypeSignature.checkTypeSig("L"+clName+";");
	} catch (IllegalArgumentException ex) {
	    throw new ClassFormatException(ex.getMessage());
	}
        return clName.replace('/','.').intern();
    }

    /**
     * Iterates through all class entries in the class pool and returns
     * their (dot seperated) class name.
     */
    public Iterator iterateClassNames() {
	return new Iterator() 
	    {
		int entry = 1;
		public boolean hasNext() {
		    try {
			while (entry < count 
			       && (tags[entry] != CLASS
				   || getUTF8(indices1[entry])
				   .charAt(0) == '['))
			    entry++;
		    } catch (ClassFormatException ex) {
			throw new InternalError(ex.getMessage());
		    }
		    return entry < count;
		}

		public Object next() {
		    if (!hasNext())
			throw new NoSuchElementException();
		    try {
			return getClassName(entry++);
		    } catch (ClassFormatException ex) {
			throw new InternalError(ex.getMessage());
		    }
		}

		public void remove() {
		    throw new UnsupportedOperationException();
		}
	    };
    }

    public String toString(int i) {
	switch (tags[i]) {
        case CLASS:
            return "Class "+toString(indices1[i]);
        case STRING:
            return "String \""+toString(indices1[i])+"\"";
        case INTEGER:
            return "Int "+constants[i].toString();
        case FLOAT:
            return "Float "+constants[i].toString();
        case LONG:
            return "Long "+constants[i].toString();
        case DOUBLE:
            return "Double "+constants[i].toString();
        case UTF8:
            return constants[i].toString();
        case FIELDREF:
            return "Fieldref: "+toString(indices1[i])+"; "
                + toString(indices2[i]);
        case METHODREF:
            return "Methodref: "+toString(indices1[i])+"; "
                + toString(indices2[i]);
        case INTERFACEMETHODREF:
            return "Interfaceref: "+toString(indices1[i])+"; "
                + toString(indices2[i]);
        case NAMEANDTYPE:
            return "Name "+toString(indices1[i])
		+"; Type "+toString(indices2[i]);
        default:
            return "unknown tag: "+tags[i];
	}
    }

    public int size() {
	return count;
    }

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