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.statics; 019 020 021import java.util.Hashtable; 022 023import org.apache.bcel.generic.Type; 024import org.apache.bcel.verifier.exc.LocalVariableInfoInconsistentException; 025 026/** 027 * A utility class holding the information about 028 * the name and the type of a local variable in 029 * a given slot (== index). This information 030 * often changes in course of byte code offsets. 031 * 032 * @version $Id: LocalVariableInfo.java 1749600 2016-06-21 20:43:38Z ggregory $ 033 */ 034public class LocalVariableInfo{ 035 036 /** The types database. KEY: String representing the offset integer. */ 037 private final Hashtable<String, Type> types = new Hashtable<>(); 038 /** The names database. KEY: String representing the offset integer. */ 039 private final Hashtable<String, String> names = new Hashtable<>(); 040 041 /** 042 * Adds a name of a local variable and a certain slot to our 'names' 043 * (Hashtable) database. 044 */ 045 private void setName(final int offset, final String name) { 046 names.put(Integer.toString(offset), name); 047 } 048 /** 049 * Adds a type of a local variable and a certain slot to our 'types' 050 * (Hashtable) database. 051 */ 052 private void setType(final int offset, final Type t) { 053 types.put(Integer.toString(offset), t); 054 } 055 056 /** 057 * Returns the type of the local variable that uses this local 058 * variable slot at the given bytecode offset. 059 * Care for legal bytecode offsets yourself, otherwise the return value 060 * might be wrong. 061 * May return 'null' if nothing is known about the type of this local 062 * variable slot at the given bytecode offset. 063 */ 064 public Type getType(final int offset) { 065 return types.get(Integer.toString(offset)); 066 } 067 /** 068 * Returns the name of the local variable that uses this local 069 * variable slot at the given bytecode offset. 070 * Care for legal bytecode offsets yourself, otherwise the return value 071 * might be wrong. 072 * May return 'null' if nothing is known about the type of this local 073 * variable slot at the given bytecode offset. 074 */ 075 public String getName(final int offset) { 076 return names.get(Integer.toString(offset)); 077 } 078 /** 079 * Adds some information about this local variable (slot). 080 * @throws LocalVariableInfoInconsistentException if the new information conflicts 081 * with already gathered information. 082 */ 083 public void add(final String name, final int startpc, final int length, final Type t) throws LocalVariableInfoInconsistentException{ 084 for (int i=startpc; i<=startpc+length; i++) { // incl/incl-notation! 085 add(i,name,t); 086 } 087 } 088 089 /** 090 * Adds information about name and type for a given offset. 091 * @throws LocalVariableInfoInconsistentException if the new information conflicts 092 * with already gathered information. 093 */ 094 private void add(final int offset, final String name, final Type t) throws LocalVariableInfoInconsistentException{ 095 if (getName(offset) != null) { 096 if (! getName(offset).equals(name)) { 097 throw new LocalVariableInfoInconsistentException("At bytecode offset '"+offset+ 098 "' a local variable has two different names: '"+getName(offset)+"' and '"+name+"'."); 099 } 100 } 101 if (getType(offset) != null) { 102 if (! getType(offset).equals(t)) { 103 throw new LocalVariableInfoInconsistentException("At bytecode offset '"+offset+ 104 "' a local variable has two different types: '"+getType(offset)+"' and '"+t+"'."); 105 } 106 } 107 setName(offset, name); 108 setType(offset, t); 109 } 110}