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}