net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/ast/DoStatement.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.ast;
  12
  13 import net.sourceforge.phpdt.internal.compiler.ASTVisitor;
  14 import net.sourceforge.phpdt.internal.compiler.codegen.Label;
  15 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  16 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  17 import net.sourceforge.phpdt.internal.compiler.flow.LoopingFlowContext;
  18 import net.sourceforge.phpdt.internal.compiler.impl.Constant;
  19 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  20 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  21
  22 public class DoStatement extends Statement {
  23
  24         public Expression condition;
  25         public Statement action;
  26
  27         private Label breakLabel, continueLabel;
  28
  29         // for local variables table attributes
  30         int mergedInitStateIndex = -1;
  31
  32         public DoStatement(Expression condition, Statement action, int s, int e) {
  33
  34                 this.sourceStart = s;
  35                 this.sourceEnd = e;
  36                 this.condition = condition;
  37                 this.action = action;
  38         }
  39
  40         public FlowInfo analyseCode(
  41                 BlockScope currentScope,
  42                 FlowContext flowContext,
  43                 FlowInfo flowInfo) {
  44
  45                 breakLabel = new Label();
  46                 continueLabel = new Label();
  47                 LoopingFlowContext loopingContext =
  48                         new LoopingFlowContext(
  49                                 flowContext,
  50                                 this,
  51                                 breakLabel,
  52                                 continueLabel,
  53                                 currentScope);
  54
  55                 Constant cst = condition.constant;
  56                 boolean isConditionTrue = cst != NotAConstant && cst.booleanValue() == true;
  57                 cst = condition.optimizedBooleanConstant();
  58                 boolean isConditionOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true;
  59                 boolean isConditionOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false;
  60
  61                 int previousMode = flowInfo.reachMode();
  62
  63                 if ((action != null) && !action.isEmptyBlock()) {
  64                         flowInfo = action.analyseCode(currentScope, loopingContext, flowInfo);
  65
  66                         // code generation can be optimized when no need to continue in the loop
  67                         if (!flowInfo.isReachable() && !loopingContext.initsOnContinue.isReachable()) {
  68                                 continueLabel = null;
  69                         }
  70                 }
  71                 /* Reset reach mode, to address following scenario.
  72                  *   final blank;
  73                  *   do { if (true) break; else blank = 0; } while(false);
  74                  *   blank = 1; // may be initialized already
  75                  */
  76                 flowInfo.setReachMode(previousMode);
  77
  78                 flowInfo =
  79                         condition.analyseCode(
  80                                 currentScope,
  81                                 loopingContext,
  82                                 (action == null
  83                                         ? flowInfo
  84                                         : (flowInfo.mergedWith(loopingContext.initsOnContinue))));
  85                 if (!isConditionOptimizedFalse && continueLabel != null) {
  86                         loopingContext.complainOnFinalAssignmentsInLoop(currentScope, flowInfo);
  87                 }
  88
  89                 // infinite loop
  90                 FlowInfo mergedInfo;
  91                 if (isConditionTrue) {
  92                         mergedInfo = loopingContext.initsOnBreak;
  93                         if (!mergedInfo.isReachable()) mergedInfo.addPotentialInitializationsFrom(flowInfo.initsWhenFalse());
  94                 } else {
  95                         // end of loop: either condition false or break
  96                         mergedInfo =
  97                                 flowInfo.initsWhenFalse().unconditionalInits().mergedWith(
  98                                         loopingContext.initsOnBreak);
  99                         if (isConditionOptimizedTrue && !loopingContext.initsOnBreak.isReachable()) {
 100                                 mergedInfo.setReachMode(FlowInfo.UNREACHABLE);
 101                         }
 102                 }
 103                 mergedInitStateIndex =
 104                         currentScope.methodScope().recordInitializationStates(mergedInfo);
 105                 return mergedInfo;
 106         }
 107
 108         /**
 109          * Do statement code generation
 110          *
 111          */
 112 //      public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 113 //
 114 //              if ((bits & IsReachableMASK) == 0) {
 115 //                      return;
 116 //              }
 117 //              int pc = codeStream.position;
 118 //
 119 //              // labels management
 120 //              Label actionLabel = new Label(codeStream);
 121 //              actionLabel.place();
 122 //              breakLabel.codeStream = codeStream;
 123 //              if (continueLabel != null) {
 124 //                      continueLabel.codeStream = codeStream;
 125 //              }
 126 //
 127 //              // generate action
 128 //              if (action != null) {
 129 //                      action.generateCode(currentScope, codeStream);
 130 //              }
 131 //              // generate condition
 132 //              if (continueLabel != null) {
 133 //                      continueLabel.place();
 134 //                      condition.generateOptimizedBoolean(
 135 //                              currentScope,
 136 //                              codeStream,
 137 //                              actionLabel,
 138 //                              null,
 139 //                              true);
 140 //              }
 141 //              breakLabel.place();
 142 //
 143 //              // May loose some local variable initializations : affecting the local variable attributes
 144 //              if (mergedInitStateIndex != -1) {
 145 //                      codeStream.removeNotDefinitelyAssignedVariables(
 146 //                              currentScope,
 147 //                              mergedInitStateIndex);
 148 //              }
 149 //              codeStream.recordPositionsFrom(pc, this.sourceStart);
 150 //
 151 //      }
 152
 153         public void resetStateForCodeGeneration() {
 154                 if (this.breakLabel != null) {
 155                         this.breakLabel.resetStateForCodeGeneration();
 156                 }
 157                 if (this.continueLabel != null) {
 158                         this.continueLabel.resetStateForCodeGeneration();
 159                 }
 160         }
 161
 162         public void resolve(BlockScope scope) {
 163
 164                 TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding);
 165                 condition.implicitWidening(type, type);
 166                 if (action != null)
 167                         action.resolve(scope);
 168         }
 169         public StringBuffer printStatement(int indent, StringBuffer output) {
 170
 171                 printIndent(indent, output).append("do"); //$NON-NLS-1$
 172                 if (action == null)
 173                         output.append(" ;\n"); //$NON-NLS-1$
 174                 else {
 175                         output.append('\n');
 176                         action.printStatement(indent + 1, output).append('\n');
 177                 }
 178                 output.append("while ("); //$NON-NLS-1$
 179                 return condition.printExpression(0, output).append(");"); //$NON-NLS-1$
 180         }
 181         public String toString(int tab) {
 182
 183                 String inFront, s = tabString(tab);
 184                 inFront = s;
 185                 s = s + "do"; //$NON-NLS-1$
 186                 if (action == null)
 187                         s = s + " {}\n"; //$NON-NLS-1$
 188                 else if (action instanceof Block)
 189                         s = s + "\n" + action.toString(tab + 1) + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
 190                 else
 191                         s = s + " {\n" + action.toString(tab + 1) + ";}\n"; //$NON-NLS-1$ //$NON-NLS-2$
 192                 s = s + inFront + "while (" + condition.toStringExpression() + ")"; //$NON-NLS-1$ //$NON-NLS-2$
 193                 return s;
 194         }
 195
 196         public void traverse(ASTVisitor visitor, BlockScope scope) {
 197
 198                 if (visitor.visit(this, scope)) {
 199                         if (action != null) {
 200                                 action.traverse(visitor, scope);
 201                         }
 202                         condition.traverse(visitor, scope);
 203                 }
 204                 visitor.endVisit(this, scope);
 205         }
 206 }