net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/flow/FlowInfo.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 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 net.sourceforge.phpdt.internal.compiler.flow;
  12
  13 import net.sourceforge.phpdt.internal.compiler.ast.Statement;
  14 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  15 import net.sourceforge.phpdt.internal.compiler.lookup.FieldBinding;
  16 import net.sourceforge.phpdt.internal.compiler.lookup.LocalVariableBinding;
  17
  18 public abstract class FlowInfo {
  19
  20         public final static int REACHABLE = 0;
  21
  22         public final static int UNREACHABLE = 1;
  23
  24         public static final UnconditionalFlowInfo DEAD_END; // Represents a dead
  25                                                                                                                 // branch status of
  26                                                                                                                 // initialization
  27         static {
  28                 DEAD_END = new UnconditionalFlowInfo();
  29                 DEAD_END.reachMode = UNREACHABLE;
  30         }
  31
  32         abstract public FlowInfo addInitializationsFrom(FlowInfo otherInits);
  33
  34         abstract public FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits);
  35
  36         public FlowInfo asNegatedCondition() {
  37
  38                 return this;
  39         }
  40
  41         public boolean complainIfUnreachable(Statement statement, BlockScope scope,
  42                         boolean didAlreadyComplain) {
  43
  44                 // Report an error if necessary
  45                 return false;
  46         }
  47
  48         public static FlowInfo conditional(FlowInfo initsWhenTrue,
  49                         FlowInfo initsWhenFalse) {
  50
  51                 // if (initsWhenTrue.equals(initsWhenFalse)) return initsWhenTrue; --
  52                 // could optimize if #equals is defined
  53                 return new ConditionalFlowInfo(initsWhenTrue, initsWhenFalse);
  54         }
  55
  56         abstract public FlowInfo copy();
  57
  58         public static UnconditionalFlowInfo initial(int maxFieldCount) {
  59                 UnconditionalFlowInfo info = new UnconditionalFlowInfo();
  60                 info.maxFieldCount = maxFieldCount;
  61                 return info;
  62         }
  63
  64         abstract public FlowInfo initsWhenFalse();
  65
  66         abstract public FlowInfo initsWhenTrue();
  67
  68         /**
  69          * Check status of definite assignment for a field.
  70          */
  71         abstract public boolean isDefinitelyAssigned(FieldBinding field);
  72
  73         /**
  74          * Check status of definite assignment for a local.
  75          */
  76         public abstract boolean isDefinitelyAssigned(LocalVariableBinding local);
  77
  78         // abstract public int reachMode();
  79
  80         /**
  81          * Check status of potential assignment for a field.
  82          */
  83         abstract public boolean isPotentiallyAssigned(FieldBinding field);
  84
  85         /**
  86          * Check status of potential assignment for a local variable.
  87          */
  88
  89         abstract public boolean isPotentiallyAssigned(LocalVariableBinding field);
  90
  91         abstract public boolean isReachable();
  92
  93         /**
  94          * Record a field got definitely assigned.
  95          */
  96         abstract public void markAsDefinitelyAssigned(FieldBinding field);
  97
  98         /**
  99          * Record a local got definitely assigned.
 100          */
 101         abstract public void markAsDefinitelyAssigned(LocalVariableBinding local);
 102
 103         /**
 104          * Clear the initialization info for a field
 105          */
 106         abstract public void markAsDefinitelyNotAssigned(FieldBinding field);
 107
 108         /**
 109          * Clear the initialization info for a local variable
 110          */
 111         abstract public void markAsDefinitelyNotAssigned(LocalVariableBinding local);
 112
 113         abstract public int reachMode();
 114
 115         abstract public FlowInfo setReachMode(int reachMode);
 116
 117         /**
 118          * Returns the receiver updated in the following way:
 119          * <ul>
 120          * <li> intersection of definitely assigned variables,
 121          * <li> union of potentially assigned variables.
 122          * </ul>
 123          */
 124         abstract public UnconditionalFlowInfo mergedWith(
 125                         UnconditionalFlowInfo otherInits);
 126
 127         public String toString() {
 128
 129                 if (this == DEAD_END) {
 130                         return "FlowInfo.DEAD_END"; //$NON-NLS-1$
 131                 }
 132                 return super.toString();
 133         }
 134
 135         abstract public UnconditionalFlowInfo unconditionalInits();
 136 }