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