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   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v0.5
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v05.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  ******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.flow;
  12
  13 import java.util.ArrayList;
  14
  15 import net.sourceforge.phpdt.internal.compiler.ast.AstNode;
  16 import net.sourceforge.phpdt.internal.compiler.ast.TryStatement;
  17 import net.sourceforge.phpdt.internal.compiler.codegen.ObjectCache;
  18 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  19 import net.sourceforge.phpdt.internal.compiler.lookup.ReferenceBinding;
  20 import net.sourceforge.phpdt.internal.compiler.lookup.Scope;
  21 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  22
  23 /**
  24  * Reflects the context of code analysis, keeping track of enclosing
  25  *      try statements, exception handlers, etc...
  26  */
  27 public class ExceptionHandlingFlowContext extends FlowContext {
  28
  29         ReferenceBinding[] handledExceptions;
  30
  31         public final static int BitCacheSize = 32; // 32 bits per int
  32         int[] isReached;
  33         int[] isNeeded;
  34         UnconditionalFlowInfo[] initsOnExceptions;
  35         ObjectCache indexes = new ObjectCache();
  36         boolean isMethodContext;
  37
  38         public UnconditionalFlowInfo initsOnReturn;
  39
  40         // for dealing with anonymous constructor thrown exceptions
  41         public ArrayList extendedExceptions;
  42
  43         public ExceptionHandlingFlowContext(
  44                 FlowContext parent,
  45                 AstNode associatedNode,
  46                 ReferenceBinding[] handledExceptions,
  47                 BlockScope scope,
  48                 UnconditionalFlowInfo flowInfo) {
  49
  50                 super(parent, associatedNode);
  51                 isMethodContext = scope == scope.methodScope();
  52                 this.handledExceptions = handledExceptions;
  53                 int count = handledExceptions.length, cacheSize = (count / BitCacheSize) + 1;
  54                 this.isReached = new int[cacheSize]; // none is reached by default
  55                 this.isNeeded = new int[cacheSize]; // none is needed by default
  56                 this.initsOnExceptions = new UnconditionalFlowInfo[count];
  57                 for (int i = 0; i < count; i++) {
  58                         this.indexes.put(handledExceptions[i], i); // key type  -> value index
  59                         boolean isUnchecked =
  60                                 (scope.compareUncheckedException(handledExceptions[i]) != NotRelated);
  61                         int cacheIndex = i / BitCacheSize, bitMask = 1 << (i % BitCacheSize);
  62                         if (isUnchecked) {
  63                                 isReached[cacheIndex] |= bitMask;
  64                                 this.initsOnExceptions[i] = flowInfo.copy().unconditionalInits();
  65                         } else {
  66                                 this.initsOnExceptions[i] = FlowInfo.DeadEnd;
  67                         }
  68                 }
  69                 System.arraycopy(this.isReached, 0, this.isNeeded, 0, cacheSize);
  70                 this.initsOnReturn = FlowInfo.DeadEnd;
  71         }
  72
  73         public void complainIfUnusedExceptionHandlers(
  74                 AstNode[] exceptionHandlers,
  75                 BlockScope scope,
  76                 TryStatement tryStatement) {
  77                 // report errors for unreachable exception handlers
  78                 for (int i = 0, count = handledExceptions.length; i < count; i++) {
  79                         int index = indexes.get(handledExceptions[i]);
  80                         int cacheIndex = index / BitCacheSize;
  81                         int bitMask = 1 << (index % BitCacheSize);
  82                         if ((isReached[cacheIndex] & bitMask) == 0) {
  83                                 scope.problemReporter().unreachableExceptionHandler(
  84                                         handledExceptions[index],
  85                                         exceptionHandlers[index]);
  86                         } else {
  87                                 if ((isNeeded[cacheIndex] & bitMask) == 0) {
  88                                         scope.problemReporter().maskedExceptionHandler(
  89                                                 handledExceptions[index],
  90                                                 exceptionHandlers[index]);
  91                                 }
  92                         }
  93                 }
  94                 // will optimized out unnecessary catch block during code gen
  95                 tryStatement.preserveExceptionHandler = isNeeded;
  96         }
  97
  98         public String individualToString() {
  99
 100                 StringBuffer buffer = new StringBuffer("Exception flow context"); //$NON-NLS-1$
 101                 int length = handledExceptions.length;
 102                 for (int i = 0; i < length; i++) {
 103                         int cacheIndex = i / BitCacheSize;
 104                         int bitMask = 1 << (i % BitCacheSize);
 105                         buffer.append('[').append(handledExceptions[i].readableName());
 106                         if ((isReached[cacheIndex] & bitMask) != 0) {
 107                                 if ((isNeeded[cacheIndex] & bitMask) == 0) {
 108                                         buffer.append("-masked"); //$NON-NLS-1$
 109                                 } else {
 110                                         buffer.append("-reached"); //$NON-NLS-1$
 111                                 }
 112                         } else {
 113                                 buffer.append("-not reached"); //$NON-NLS-1$
 114                         }
 115                         buffer.append('-').append(initsOnExceptions[i].toString()).append(']');
 116                 }
 117                 return buffer.toString();
 118         }
 119
 120         public UnconditionalFlowInfo initsOnException(ReferenceBinding exceptionType) {
 121
 122                 int index;
 123                 if ((index = indexes.get(exceptionType)) < 0) {
 124                         return FlowInfo.DeadEnd;
 125                 }
 126                 return initsOnExceptions[index];
 127         }
 128
 129         public void recordHandlingException(
 130                 ReferenceBinding exceptionType,
 131                 UnconditionalFlowInfo flowInfo,
 132                 TypeBinding raisedException,
 133                 AstNode invocationSite,
 134                 boolean wasAlreadyDefinitelyCaught) {
 135
 136                 int index = indexes.get(exceptionType);
 137                 // if already flagged as being reached (unchecked exception handler)
 138                 int cacheIndex = index / BitCacheSize;
 139                 int bitMask = 1 << (index % BitCacheSize);
 140                 if (!wasAlreadyDefinitelyCaught) {
 141                         this.isNeeded[cacheIndex] |= bitMask;
 142                 }
 143                 this.isReached[cacheIndex] |= bitMask;
 144                 initsOnExceptions[index] =
 145                         initsOnExceptions[index] == FlowInfo.DeadEnd
 146                                 ? flowInfo.copy().unconditionalInits()
 147                                 : initsOnExceptions[index].mergedWith(flowInfo);
 148         }
 149
 150         public void recordReturnFrom(UnconditionalFlowInfo flowInfo) {
 151
 152                 // record initializations which were performed at the return point
 153                 initsOnReturn = initsOnReturn.mergedWith(flowInfo);
 154         }
 155
 156         /*
 157          * Compute a merged list of unhandled exception types (keeping only the most generic ones).
 158          * This is necessary to add synthetic thrown exceptions for anonymous type constructors (JLS 8.6).
 159          */
 160         public void mergeUnhandledException(TypeBinding newException){
 161
 162                 if (this.extendedExceptions == null){
 163                         this.extendedExceptions = new ArrayList(5);
 164                         for (int i = 0; i < this.handledExceptions.length; i++){
 165                                 this.extendedExceptions.add(this.handledExceptions[i]);
 166                         }
 167                 }
 168
 169                 boolean isRedundant = false;
 170
 171                 for(int i = this.extendedExceptions.size()-1; i >= 0; i--){
 172                         switch(Scope.compareTypes(newException, (TypeBinding)this.extendedExceptions.get(i))){
 173                                 case MoreGeneric :
 174                                         this.extendedExceptions.remove(i);
 175                                         break;
 176                                 case EqualOrMoreSpecific :
 177                                         isRedundant = true;
 178                                         break;
 179                                 case NotRelated :
 180                                         break;
 181                         }
 182                 }
 183                 if (!isRedundant){
 184                         this.extendedExceptions.add(newException);
 185                 }
 186         }
 187 }