    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 */
    017package org.apache.bcel.verifier.structurals;
    018
    019/**
    020 * This class represents a JVM execution frame; that means, a local variable array and an operand stack.
    021 */
    022
    023public class Frame {
    024
    025    /**
    026     * For instance initialization methods, it is important to remember which instance it is that is not initialized yet. It
    027     * will be initialized invoking another constructor later. NULL means the instance already *is* initialized.
    028     *
    029     * @deprecated Use the getter/setter to access the field as it may be made private in a later release
    030     */
    031    @Deprecated
    032    protected static UninitializedObjectType _this;
    033
    034    /**
    035     * @return the _this
    036     * @since 6.0
    037     */
    038    public static UninitializedObjectType getThis() {
    039        return _this;
    040    }
    041
    042    /**
    043     * @param _this the _this to set
    044     * @since 6.0
    045     */
    046    public static void setThis(final UninitializedObjectType _this) {
    047        Frame._this = _this;
    048    }
    049
    050    /**
    051     *
    052     */
    053    private final LocalVariables locals;
    054
    055    /**
    056     *
    057     */
    058    private final OperandStack stack;
    059
    060    /**
    061     *
    062     */
    063    public Frame(final int maxLocals, final int maxStack) {
    064        locals = new LocalVariables(maxLocals);
    065        stack = new OperandStack(maxStack);
    066    }
    067
    068    /**
    069     *
    070     */
    071    public Frame(final LocalVariables locals, final OperandStack stack) {
    072        this.locals = locals;
    073        this.stack = stack;
    074    }
    075
    076    /**
    077     *
    078     */
    079    @Override
    080    protected Object clone() {
    081        return new Frame(locals.getClone(), stack.getClone());
    082    }
    083
    084    /**
    085     *
    086     */
    087    @Override
    088    public boolean equals(final Object o) {
    089        if (!(o instanceof Frame)) {
    090            return false; // implies "null" is non-equal.
    091        }
    092        final Frame f = (Frame) o;
    093        return this.stack.equals(f.stack) && this.locals.equals(f.locals);
    094    }
    095
    096    /**
    097     *
    098     */
    099    public Frame getClone() {
    100        return (Frame) clone();
    101    }
    102
    103    /**
    104     *
    105     */
    106    public LocalVariables getLocals() {
    107        return locals;
    108    }
    109
    110    /**
    111     *
    112     */
    113    public OperandStack getStack() {
    114        return stack;
    115    }
    116
    117    /**
    118     * @return a hash code value for the object.
    119     */
    120    @Override
    121    public int hashCode() {
    122        return stack.hashCode() ^ locals.hashCode();
    123    }
    124
    125    /**
    126     * Returns a String representation of the Frame instance.
    127     */
    128    @Override
    129    public String toString() {
    130        String s = "Local Variables:\n";
    131        s += locals;
    132        s += "OperandStack:\n";
    133        s += stack;
    134        return s;
    135    }
    136}