repo/org.ibex.tool/src/org/eclipse/jdt/internal/compiler/flow/FlowInfo.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2004 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package org.eclipse.jdt.internal.compiler.flow;
  12
  13 import org.eclipse.jdt.internal.compiler.lookup.FieldBinding;
  14 import org.eclipse.jdt.internal.compiler.lookup.LocalVariableBinding;
  15
  16 public abstract class FlowInfo {
  17
  18         public final static int REACHABLE = 0;
  19         public final static int UNREACHABLE = 1;
  20
  21         public static final UnconditionalFlowInfo DEAD_END; // Represents a dead branch status of initialization
  22         static {
  23                 DEAD_END = new UnconditionalFlowInfo();
  24                 DEAD_END.reachMode = UNREACHABLE;
  25         }
  26         abstract public FlowInfo addInitializationsFrom(FlowInfo otherInits);
  27
  28         abstract public FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits);
  29
  30         public FlowInfo asNegatedCondition() {
  31
  32                 return this;
  33         }
  34
  35         public static FlowInfo conditional(FlowInfo initsWhenTrue, FlowInfo initsWhenFalse){
  36
  37                 // if (initsWhenTrue.equals(initsWhenFalse)) return initsWhenTrue; -- could optimize if #equals is defined
  38                 return new ConditionalFlowInfo(initsWhenTrue, initsWhenFalse);
  39         }
  40
  41         abstract public FlowInfo copy();
  42
  43         public static UnconditionalFlowInfo initial(int maxFieldCount) {
  44                 UnconditionalFlowInfo info = new UnconditionalFlowInfo();
  45                 info.maxFieldCount = maxFieldCount;
  46                 return info;
  47         }
  48
  49         abstract public FlowInfo initsWhenFalse();
  50
  51         abstract public FlowInfo initsWhenTrue();
  52
  53         /**
  54          * Check status of definite assignment for a field.
  55          */
  56          abstract public boolean isDefinitelyAssigned(FieldBinding field);
  57
  58         /**
  59          * Check status of definite assignment for a local.
  60          */
  61         public abstract boolean isDefinitelyAssigned(LocalVariableBinding local);
  62
  63         //abstract public int reachMode();
  64
  65         /**
  66          * Check status of potential assignment for a field.
  67          */
  68          abstract public boolean isPotentiallyAssigned(FieldBinding field);
  69
  70         /**
  71          * Check status of potential assignment for a local variable.
  72          */
  73
  74          abstract public boolean isPotentiallyAssigned(LocalVariableBinding field);
  75
  76         abstract public boolean isReachable();
  77
  78         /**
  79          * Record a field got definitely assigned.
  80          */
  81         abstract public void markAsDefinitelyAssigned(FieldBinding field);
  82
  83         /**
  84          * Record a local got definitely assigned.
  85          */
  86         abstract public void markAsDefinitelyAssigned(LocalVariableBinding local);
  87
  88         /**
  89          * Clear the initialization info for a field
  90          */
  91         abstract public void markAsDefinitelyNotAssigned(FieldBinding field);
  92
  93         /**
  94          * Clear the initialization info for a local variable
  95          */
  96         abstract public void markAsDefinitelyNotAssigned(LocalVariableBinding local);
  97
  98         /**
  99          * Merge branches using optimized boolean conditions
 100          */
 101         public static FlowInfo mergedOptimizedBranches(FlowInfo initsWhenTrue, boolean isOptimizedTrue, FlowInfo initsWhenFalse, boolean isOptimizedFalse, boolean allowFakeDeadBranch) {
 102                 FlowInfo mergedInfo;
 103                 if (isOptimizedTrue){
 104                         if (initsWhenTrue == FlowInfo.DEAD_END && allowFakeDeadBranch) {
 105                                 mergedInfo = initsWhenFalse.setReachMode(FlowInfo.UNREACHABLE);
 106                         } else {
 107                                 mergedInfo = initsWhenTrue.addPotentialInitializationsFrom(initsWhenFalse);
 108                         }
 109
 110                 } else if (isOptimizedFalse) {
 111                         if (initsWhenFalse == FlowInfo.DEAD_END && allowFakeDeadBranch) {
 112                                 mergedInfo = initsWhenTrue.setReachMode(FlowInfo.UNREACHABLE);
 113                         } else {
 114                                 mergedInfo = initsWhenFalse.addPotentialInitializationsFrom(initsWhenTrue);
 115                         }
 116
 117                 } else {
 118                         mergedInfo = initsWhenTrue.unconditionalInits().mergedWith(initsWhenFalse.unconditionalInits());
 119                 }
 120                 return mergedInfo;
 121         }
 122
 123         abstract public int reachMode();
 124
 125         abstract public FlowInfo setReachMode(int reachMode);
 126
 127         /**
 128          * Returns the receiver updated in the following way: <ul>
 129          * <li> intersection of definitely assigned variables,
 130          * <li> union of potentially assigned variables.
 131          * </ul>
 132          */
 133         abstract public UnconditionalFlowInfo mergedWith(UnconditionalFlowInfo otherInits);
 134
 135         public String toString(){
 136
 137                 if (this == DEAD_END){
 138                         return "FlowInfo.DEAD_END"; //$NON-NLS-1$
 139                 }
 140                 return super.toString();
 141         }
 142
 143         abstract public UnconditionalFlowInfo unconditionalInits();
 144 }