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