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 } addInitializationsFrom(FlowInfo otherInits)26 abstract public FlowInfo addInitializationsFrom(FlowInfo otherInits); 27 addPotentialInitializationsFrom(FlowInfo otherInits)28 abstract public FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits); 29 asNegatedCondition()30 public FlowInfo asNegatedCondition() { 31 32 return this; 33 } 34 conditional(FlowInfo initsWhenTrue, FlowInfo initsWhenFalse)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 copy()41 abstract public FlowInfo copy(); 42 initial(int maxFieldCount)43 public static UnconditionalFlowInfo initial(int maxFieldCount) { 44 UnconditionalFlowInfo info = new UnconditionalFlowInfo(); 45 info.maxFieldCount = maxFieldCount; 46 return info; 47 } 48 initsWhenFalse()49 abstract public FlowInfo initsWhenFalse(); 50 initsWhenTrue()51 abstract public FlowInfo initsWhenTrue(); 52 53 /** 54 * Check status of definite assignment for a field. 55 */ isDefinitelyAssigned(FieldBinding field)56 abstract public boolean isDefinitelyAssigned(FieldBinding field); 57 58 /** 59 * Check status of definite assignment for a local. 60 */ isDefinitelyAssigned(LocalVariableBinding local)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 */ isPotentiallyAssigned(FieldBinding field)68 abstract public boolean isPotentiallyAssigned(FieldBinding field); 69 70 /** 71 * Check status of potential assignment for a local variable. 72 */ 73 isPotentiallyAssigned(LocalVariableBinding field)74 abstract public boolean isPotentiallyAssigned(LocalVariableBinding field); 75 isReachable()76 abstract public boolean isReachable(); 77 78 /** 79 * Record a field got definitely assigned. 80 */ markAsDefinitelyAssigned(FieldBinding field)81 abstract public void markAsDefinitelyAssigned(FieldBinding field); 82 83 /** 84 * Record a local got definitely assigned. 85 */ markAsDefinitelyAssigned(LocalVariableBinding local)86 abstract public void markAsDefinitelyAssigned(LocalVariableBinding local); 87 88 /** 89 * Clear the initialization info for a field 90 */ markAsDefinitelyNotAssigned(FieldBinding field)91 abstract public void markAsDefinitelyNotAssigned(FieldBinding field); 92 93 /** 94 * Clear the initialization info for a local variable 95 */ markAsDefinitelyNotAssigned(LocalVariableBinding local)96 abstract public void markAsDefinitelyNotAssigned(LocalVariableBinding local); 97 98 /** 99 * Merge branches using optimized boolean conditions 100 */ mergedOptimizedBranches(FlowInfo initsWhenTrue, boolean isOptimizedTrue, FlowInfo initsWhenFalse, boolean isOptimizedFalse, boolean allowFakeDeadBranch)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 reachMode()123 abstract public int reachMode(); 124 setReachMode(int reachMode)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 */ mergedWith(UnconditionalFlowInfo otherInits)133 abstract public UnconditionalFlowInfo mergedWith(UnconditionalFlowInfo otherInits); 134 toString()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 unconditionalInits()143 abstract public UnconditionalFlowInfo unconditionalInits(); 144 } 145