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 * 017 */ 018package org.apache.bcel.verifier.structurals; 019 020 021 022/** 023 * This class represents a JVM execution frame; that means, 024 * a local variable array and an operand stack. 025 * 026 */ 027 028public class Frame{ 029 030 /** 031 * For instance initialization methods, it is important to remember 032 * which instance it is that is not initialized yet. It will be 033 * initialized invoking another constructor later. 034 * NULL means the instance already *is* initialized. 035 * @deprecated Use the getter/setter to access the field as it may 036 * be made private in a later release 037 */ 038 @Deprecated 039 protected static UninitializedObjectType _this; 040 041 /** 042 * 043 */ 044 private final LocalVariables locals; 045 046 /** 047 * 048 */ 049 private final OperandStack stack; 050 051 /** 052 * 053 */ 054 public Frame(final int maxLocals, final int maxStack) { 055 locals = new LocalVariables(maxLocals); 056 stack = new OperandStack(maxStack); 057 } 058 059 /** 060 * 061 */ 062 public Frame(final LocalVariables locals, final OperandStack stack) { 063 this.locals = locals; 064 this.stack = stack; 065 } 066 067 /** 068 * 069 */ 070 @Override 071 protected Object clone() { 072 final Frame f = new Frame(locals.getClone(), stack.getClone()); 073 return f; 074 } 075 076 /** 077 * 078 */ 079 public Frame getClone() { 080 return (Frame) clone(); 081 } 082 083 /** 084 * 085 */ 086 public LocalVariables getLocals() { 087 return locals; 088 } 089 090 /** 091 * 092 */ 093 public OperandStack getStack() { 094 return stack; 095 } 096 097 /** @return a hash code value for the object. 098 */ 099 @Override 100 public int hashCode() { return stack.hashCode() ^ locals.hashCode(); } 101 102 /** 103 * 104 */ 105 @Override 106 public boolean equals(final Object o) { 107 if (!(o instanceof Frame)) { 108 return false; // implies "null" is non-equal. 109 } 110 final Frame f = (Frame) o; 111 return this.stack.equals(f.stack) && this.locals.equals(f.locals); 112 } 113 114 /** 115 * Returns a String representation of the Frame instance. 116 */ 117 @Override 118 public String toString() { 119 String s="Local Variables:\n"; 120 s += locals; 121 s += "OperandStack:\n"; 122 s += stack; 123 return s; 124 } 125 126 /** 127 * @return the _this 128 * @since 6.0 129 */ 130 public static UninitializedObjectType getThis() { 131 return _this; 132 } 133 134 /** 135 * @param _this the _this to set 136 * @since 6.0 137 */ 138 public static void setThis(final UninitializedObjectType _this) { 139 Frame._this = _this; 140 } 141}