path: root/src/main/javassist/bytecode/ExceptionTable.java

/*
 * This file is part of the Javassist toolkit.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License.  You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Javassist.
 *
 * The Initial Developer of the Original Code is Shigeru Chiba.  Portions
 * created by Shigeru Chiba are Copyright (C) 1999-2003 Shigeru Chiba.
 * All Rights Reserved.
 *
 * Contributor(s):
 *
 * The development of this software is supported in part by the PRESTO
 * program (Sakigake Kenkyu 21) of Japan Science and Technology Corporation.
 */

package javassist.bytecode;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Map;

class ExceptionTableEntry {
    int startPc;
    int endPc;
    int handlerPc;
    int catchType;

    ExceptionTableEntry(int start, int end, int handle, int type) {
	startPc = start;
	endPc = end;
	handlerPc = handle;
	catchType = type;
    }
}

/**
 * <code>exception_table[]</code> of <code>Code_attribute</code>.
 */
public class ExceptionTable {
    private ConstPool constPool;
    private ArrayList entries;

    /**
     * Constructs an <code>exception_table[]</code>.
     *
     * @param cp	constant pool table.
     */
    public ExceptionTable(ConstPool cp) {
	constPool = cp;
	entries = new ArrayList();
    }

    ExceptionTable(ConstPool cp, DataInputStream in) throws IOException {
	constPool = cp;
	int length = in.readUnsignedShort();
	ArrayList list = new ArrayList(length);
	for (int i = 0; i < length; ++i) {
	    int start = in.readUnsignedShort();
	    int end = in.readUnsignedShort();
	    int handle = in.readUnsignedShort();
	    int type = in.readUnsignedShort();
	    list.add(new ExceptionTableEntry(start, end, handle, type));
	}

	entries = list;
    }

    /**
     * Returns <code>exception_table_length</code>, which is the number
     * of entries in the <code>exception_table[]</code>.
     */
    public int size() {
	return entries.size();
    }

    /**
     * Returns <code>startPc</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     */
    public int startPc(int nth) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	return e.startPc;
    }

    /**
     * Sets <code>startPc</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     * @param value		new value.
     */
    public void setStartPc(int nth, int value) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	e.startPc = value;
    }

    /**
     * Returns <code>endPc</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     */
    public int endPc(int nth) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	return e.endPc;
    }

    /**
     * Sets <code>endPc</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     * @param value		new value.
     */
    public void setEndPc(int nth, int value) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	e.endPc = value;
    }

    /**
     * Returns <code>handlerPc</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     */
    public int handlerPc(int nth) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	return e.handlerPc;
    }

    /**
     * Sets <code>handlerPc</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     * @param value		new value.
     */
    public void setHandlerPc(int nth, int value) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	e.handlerPc = value;
    }

    /**
     * Returns <code>catchType</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     */
    public int catchType(int nth) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	return e.catchType;
    }

    /**
     * Sets <code>catchType</code> of the <i>n</i>-th entry.
     *
     * @param nth		the <i>n</i>-th (&gt;= 0).
     * @param value		new value.
     */
    public void setCatchType(int nth, int value) {
	ExceptionTableEntry e = (ExceptionTableEntry)entries.get(nth);
	e.catchType = value;
    }

    /**
     * Copies the given exception table at the specified position
     * in the table.
     *
     * @param index	index (&gt;= 0) at which the entry is to be inserted.
     * @param offset	the offset added to the code position.
     */
    public void add(int index, ExceptionTable table, int offset) {
	int len = table.size();
	while (--len >= 0) {
	    ExceptionTableEntry e
		= (ExceptionTableEntry)table.entries.get(len);
	    add(index, e.startPc + offset, e.endPc + offset,
		e.handlerPc + offset, e.catchType);
	}
    }

    /**
     * Adds a new entry at the specified position in the table.
     *
     * @param index	index (&gt;= 0) at which the entry is to be inserted.
     * @param start	<code>startPc</code>
     * @param end	<code>endPc</code>
     * @param handler	<code>handlerPc</code>
     * @param type	<code>catchType</code>
     */
    public void add(int index, int start, int end, int handler, int type) {
	entries.add(index,
		    new ExceptionTableEntry(start, end, handler, type));
    }

    /**
     * Appends a new entry at the end of the table.
     *
     * @param start	<code>startPc</code>
     * @param end	<code>endPc</code>
     * @param handler	<code>handlerPc</code>
     * @param type	<code>catchType</code>
     */
    public void add(int start, int end, int handler, int type) {
	entries.add(new ExceptionTableEntry(start, end, handler, type));
    }

    /**
     * Removes the entry at the specified position in the table.
     *
     * @param index	the index of the removed entry.
     */
    public void remove(int index) {
	entries.remove(index);
    }

    /**
     * Makes a copy of this <code>exception_table[]</code>.
     * Class names are replaced according to the
     * given <code>Map</code> object.
     *
     * @param newCp	the constant pool table used by the new copy.
     * @param classnames	pairs of replaced and substituted
     *				class names.
     */
    public ExceptionTable copy(ConstPool newCp, Map classnames) {
	ExceptionTable et = new ExceptionTable(newCp);
	ConstPool srcCp = constPool;
	int len = size();
	for (int i = 0; i < len; ++i) {
	    ExceptionTableEntry e = (ExceptionTableEntry)entries.get(i);
	    int type = srcCp.copy(e.catchType, newCp, classnames);
	    et.add(e.startPc, e.endPc, e.handlerPc, type);
	}

	return et;
    }

    void shiftPc(int where, int gapLength, boolean exclusive) {
	int len = size();
	for (int i = 0; i < len; ++i) {
	    ExceptionTableEntry e = (ExceptionTableEntry)entries.get(i);
	    e.startPc = shiftPc(e.startPc, where, gapLength, exclusive);
	    e.endPc = shiftPc(e.endPc, where, gapLength, exclusive);
	    e.handlerPc = shiftPc(e.handlerPc, where, gapLength, exclusive);
	}
    }

    private static int shiftPc(int pc, int where, int gapLength,
			       boolean exclusive) {
	if (pc > where || (exclusive && pc == where))
	    pc += gapLength;

	return pc;
    }

    void write(DataOutputStream out) throws IOException {
	int len = size();
	out.writeShort(len);		// exception_table_length
	for (int i = 0; i < len; ++i) {
	    ExceptionTableEntry e = (ExceptionTableEntry)entries.get(i);
	    out.writeShort(e.startPc);
	    out.writeShort(e.endPc);
	    out.writeShort(e.handlerPc);
	    out.writeShort(e.catchType);
	}
    }
}