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
9 * IBM Corporation - initial API and implementation
10 *******************************************************************************/
11 package org.eclipse.jdt.internal.compiler.flow;
13 import org.eclipse.jdt.internal.compiler.lookup.FieldBinding;
14 import org.eclipse.jdt.internal.compiler.lookup.LocalVariableBinding;
16 public abstract class FlowInfo {
18 public final static int REACHABLE = 0;
19 public final static int UNREACHABLE = 1;
21 public static final UnconditionalFlowInfo DEAD_END; // Represents a dead branch status of initialization
23 DEAD_END = new UnconditionalFlowInfo();
24 DEAD_END.reachMode = UNREACHABLE;
26 abstract public FlowInfo addInitializationsFrom(FlowInfo otherInits);
28 abstract public FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits);
30 public FlowInfo asNegatedCondition() {
35 public static FlowInfo conditional(FlowInfo initsWhenTrue, FlowInfo initsWhenFalse){
37 // if (initsWhenTrue.equals(initsWhenFalse)) return initsWhenTrue; -- could optimize if #equals is defined
38 return new ConditionalFlowInfo(initsWhenTrue, initsWhenFalse);
41 abstract public FlowInfo copy();
43 public static UnconditionalFlowInfo initial(int maxFieldCount) {
44 UnconditionalFlowInfo info = new UnconditionalFlowInfo();
45 info.maxFieldCount = maxFieldCount;
49 abstract public FlowInfo initsWhenFalse();
51 abstract public FlowInfo initsWhenTrue();
54 * Check status of definite assignment for a field.
56 abstract public boolean isDefinitelyAssigned(FieldBinding field);
59 * Check status of definite assignment for a local.
61 public abstract boolean isDefinitelyAssigned(LocalVariableBinding local);
63 //abstract public int reachMode();
66 * Check status of potential assignment for a field.
68 abstract public boolean isPotentiallyAssigned(FieldBinding field);
71 * Check status of potential assignment for a local variable.
74 abstract public boolean isPotentiallyAssigned(LocalVariableBinding field);
76 abstract public boolean isReachable();
79 * Record a field got definitely assigned.
81 abstract public void markAsDefinitelyAssigned(FieldBinding field);
84 * Record a local got definitely assigned.
86 abstract public void markAsDefinitelyAssigned(LocalVariableBinding local);
89 * Clear the initialization info for a field
91 abstract public void markAsDefinitelyNotAssigned(FieldBinding field);
94 * Clear the initialization info for a local variable
96 abstract public void markAsDefinitelyNotAssigned(LocalVariableBinding local);
99 * Merge branches using optimized boolean conditions
101 public static FlowInfo mergedOptimizedBranches(FlowInfo initsWhenTrue, boolean isOptimizedTrue, FlowInfo initsWhenFalse, boolean isOptimizedFalse, boolean allowFakeDeadBranch) {
103 if (isOptimizedTrue){
104 if (initsWhenTrue == FlowInfo.DEAD_END && allowFakeDeadBranch) {
105 mergedInfo = initsWhenFalse.setReachMode(FlowInfo.UNREACHABLE);
107 mergedInfo = initsWhenTrue.addPotentialInitializationsFrom(initsWhenFalse);
110 } else if (isOptimizedFalse) {
111 if (initsWhenFalse == FlowInfo.DEAD_END && allowFakeDeadBranch) {
112 mergedInfo = initsWhenTrue.setReachMode(FlowInfo.UNREACHABLE);
114 mergedInfo = initsWhenFalse.addPotentialInitializationsFrom(initsWhenTrue);
118 mergedInfo = initsWhenTrue.unconditionalInits().mergedWith(initsWhenFalse.unconditionalInits());
123 abstract public int reachMode();
125 abstract public FlowInfo setReachMode(int reachMode);
128 * Returns the receiver updated in the following way: <ul>
129 * <li> intersection of definitely assigned variables,
130 * <li> union of potentially assigned variables.
133 abstract public UnconditionalFlowInfo mergedWith(UnconditionalFlowInfo otherInits);
135 public String toString(){
137 if (this == DEAD_END){
138 return "FlowInfo.DEAD_END"; //$NON-NLS-1$
140 return super.toString();
143 abstract public UnconditionalFlowInfo unconditionalInits();