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/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
 *
 * 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.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later,
 * or the Apache License Version 2.0.
 *
 * 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.
 */

package com.feilong.lib.javassist.bytecode;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
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;
    }
}

/**
 * exception_table[] of Code_attribute.
 */
public class ExceptionTable implements Cloneable{

    private ConstPool                 constPool;

    private List entries;

    /**
     * Constructs an exception_table[].
     *
     * @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();
        List 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;
    }

    /**
     * Creates and returns a copy of this object.
     * The constant pool object is shared between this object
     * and the cloned object.
     */
    @Override
    public Object clone() throws CloneNotSupportedException{
        ExceptionTable r = (ExceptionTable) super.clone();
        r.entries = new ArrayList<>(entries);
        return r;
    }

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

    /**
     * Returns startPc of the n-th entry.
     *
     * @param nth
     *            the n-th (>= 0).
     */
    public int startPc(int nth){
        return entries.get(nth).startPc;
    }

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

    /**
     * Returns endPc of the n-th entry.
     *
     * @param nth
     *            the n-th (>= 0).
     */
    public int endPc(int nth){
        return entries.get(nth).endPc;
    }

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

    /**
     * Returns handlerPc of the n-th entry.
     *
     * @param nth
     *            the n-th (>= 0).
     */
    public int handlerPc(int nth){
        return entries.get(nth).handlerPc;
    }

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

    /**
     * Returns catchType of the n-th entry.
     *
     * @param nth
     *            the n-th (>= 0).
     * @return an index into the constant_pool table,
     *         or zero if this exception handler is for all exceptions.
     */
    public int catchType(int nth){
        return entries.get(nth).catchType;
    }

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

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

    /**
     * Appends a new entry at the end of the table.
     *
     * @param start
     *            startPc
     * @param end
     *            endPc
     * @param handler
     *            handlerPc
     * @param type
     *            catchType
     */
    public void add(int start,int end,int handler,int type){
        if (start < end){
            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 exception_table[].
     * Class names are replaced according to the
     * given Map 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;
        for (ExceptionTableEntry e : entries){
            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){
        for (ExceptionTableEntry e : entries){
            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{
        out.writeShort(size()); // exception_table_length
        for (ExceptionTableEntry e : entries){
            out.writeShort(e.startPc);
            out.writeShort(e.endPc);
            out.writeShort(e.handlerPc);
            out.writeShort(e.catchType);
        }
    }
}




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