net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/ast/DoStatement.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v0.5
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v05.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  ******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.ast;
  12
  13 import net.sourceforge.phpdt.internal.compiler.IAbstractSyntaxTreeVisitor;
  14 import net.sourceforge.phpdt.internal.compiler.codegen.CodeStream;
  15 import net.sourceforge.phpdt.internal.compiler.codegen.Label;
  16 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  17 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  18 import net.sourceforge.phpdt.internal.compiler.flow.LoopingFlowContext;
  19 import net.sourceforge.phpdt.internal.compiler.impl.Constant;
  20 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  21 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  22
  23 public class DoStatement extends Statement {
  24
  25         public Expression condition;
  26         public Statement action;
  27
  28         private Label breakLabel, continueLabel;
  29
  30         // for local variables table attributes
  31         int mergedInitStateIndex = -1;
  32
  33         public DoStatement(Expression condition, Statement action, int s, int e) {
  34
  35                 this.sourceStart = s;
  36                 this.sourceEnd = e;
  37                 this.condition = condition;
  38                 this.action = action;
  39         }
  40
  41         public FlowInfo analyseCode(
  42                 BlockScope currentScope,
  43                 FlowContext flowContext,
  44                 FlowInfo flowInfo) {
  45
  46                 breakLabel = new Label();
  47                 continueLabel = new Label();
  48                 LoopingFlowContext loopingContext =
  49                         new LoopingFlowContext(
  50                                 flowContext,
  51                                 this,
  52                                 breakLabel,
  53                                 continueLabel,
  54                                 currentScope);
  55
  56                 Constant conditionConstant = condition.constant;
  57                 Constant conditionalConstant = condition.conditionalConstant();
  58                 boolean isFalseCondition =
  59                         ((conditionConstant != NotAConstant)
  60                                 && (conditionConstant.booleanValue() == false))
  61                                 || ((conditionalConstant != NotAConstant)
  62                                         && (conditionalConstant.booleanValue() == false));
  63
  64                 if ((action != null) && !action.isEmptyBlock()) {
  65                         flowInfo = action.analyseCode(currentScope, loopingContext, flowInfo.copy());
  66
  67                         // code generation can be optimized when no need to continue in the loop
  68                         if ((flowInfo == FlowInfo.DeadEnd) || flowInfo.isFakeReachable()) {
  69                                 if ((loopingContext.initsOnContinue == FlowInfo.DeadEnd)
  70                                         || loopingContext.initsOnContinue.isFakeReachable()) {
  71                                         continueLabel = null;
  72                                 } else {
  73                                         flowInfo = loopingContext.initsOnContinue; // for condition
  74                                         if (isFalseCondition) {
  75                                                 //      continueLabel = null; - cannot nil the label since may be targeted already by 'continue' statements
  76                                         } else {
  77                                                 loopingContext.complainOnFinalAssignmentsInLoop(currentScope, flowInfo);
  78                                         }
  79                                 }
  80                         } else {
  81                                 if (isFalseCondition) {
  82                                         //      continueLabel = null; - cannot nil the label since may be targeted already by 'continue' statements
  83                                 } else {
  84                                         loopingContext.complainOnFinalAssignmentsInLoop(currentScope, flowInfo);
  85                                 }
  86                         }
  87                 }
  88                 LoopingFlowContext condLoopContext;
  89                 flowInfo =
  90                         condition.analyseCode(
  91                                 currentScope,
  92                                 (condLoopContext =
  93                                         new LoopingFlowContext(flowContext, this, null, null, currentScope)),
  94                                 (action == null
  95                                         ? flowInfo
  96                                         : (flowInfo.mergedWith(loopingContext.initsOnContinue))));
  97                 condLoopContext.complainOnFinalAssignmentsInLoop(currentScope, flowInfo);
  98
  99                 // infinite loop
 100                 FlowInfo mergedInfo;
 101                 if ((condition.constant != NotAConstant)
 102                         && (condition.constant.booleanValue() == true)) {
 103                         mergedInfo = loopingContext.initsOnBreak;
 104                         mergedInitStateIndex =
 105                                 currentScope.methodScope().recordInitializationStates(mergedInfo);
 106                         return mergedInfo;
 107                 }
 108
 109                 // end of loop: either condition false or break
 110                 mergedInfo =
 111                         flowInfo.initsWhenFalse().unconditionalInits().mergedWith(
 112                                 loopingContext.initsOnBreak);
 113                 mergedInitStateIndex =
 114                         currentScope.methodScope().recordInitializationStates(mergedInfo);
 115                 return mergedInfo;
 116         }
 117
 118         /**
 119          * Do statement code generation
 120          *
 121          */
 122         public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 123
 124                 if ((bits & IsReachableMASK) == 0) {
 125                         return;
 126                 }
 127                 int pc = codeStream.position;
 128
 129                 // labels management
 130                 Label actionLabel = new Label(codeStream);
 131                 actionLabel.place();
 132                 breakLabel.codeStream = codeStream;
 133                 if (continueLabel != null) {
 134                         continueLabel.codeStream = codeStream;
 135                 }
 136
 137                 // generate action
 138                 if (action != null) {
 139                         action.generateCode(currentScope, codeStream);
 140                 }
 141                 // generate condition
 142                 if (continueLabel != null) {
 143                         continueLabel.place();
 144                         condition.generateOptimizedBoolean(
 145                                 currentScope,
 146                                 codeStream,
 147                                 actionLabel,
 148                                 null,
 149                                 true);
 150                 }
 151                 breakLabel.place();
 152
 153                 // May loose some local variable initializations : affecting the local variable attributes
 154                 if (mergedInitStateIndex != -1) {
 155                         codeStream.removeNotDefinitelyAssignedVariables(
 156                                 currentScope,
 157                                 mergedInitStateIndex);
 158                 }
 159                 codeStream.recordPositionsFrom(pc, this.sourceStart);
 160
 161         }
 162
 163         public void resetStateForCodeGeneration() {
 164
 165                 this.breakLabel.resetStateForCodeGeneration();
 166                 this.continueLabel.resetStateForCodeGeneration();
 167         }
 168
 169         public void resolve(BlockScope scope) {
 170
 171                 TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding);
 172                 condition.implicitWidening(type, type);
 173                 if (action != null)
 174                         action.resolve(scope);
 175         }
 176
 177         public String toString(int tab) {
 178
 179                 String inFront, s = tabString(tab);
 180                 inFront = s;
 181                 s = s + "do"; //$NON-NLS-1$
 182                 if (action == null)
 183                         s = s + " {}\n"; //$NON-NLS-1$
 184                 else if (action instanceof Block)
 185                         s = s + "\n" + action.toString(tab + 1) + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
 186                 else
 187                         s = s + " {\n" + action.toString(tab + 1) + ";}\n"; //$NON-NLS-1$ //$NON-NLS-2$
 188                 s = s + inFront + "while (" + condition.toStringExpression() + ")"; //$NON-NLS-1$ //$NON-NLS-2$
 189                 return s;
 190         }
 191
 192         public void traverse(IAbstractSyntaxTreeVisitor visitor, BlockScope scope) {
 193
 194                 if (visitor.visit(this, scope)) {
 195                         if (action != null) {
 196                                 action.traverse(visitor, scope);
 197                         }
 198                         condition.traverse(visitor, scope);
 199                 }
 200                 visitor.endVisit(this, scope);
 201         }
 202 }