| /******************************************************************************* |
| * Copyright (c) 2000, 2004 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.jdt.internal.compiler.ast; |
| |
| import org.eclipse.jdt.internal.compiler.ASTVisitor; |
| import org.eclipse.jdt.internal.compiler.impl.*; |
| import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants; |
| import org.eclipse.jdt.internal.compiler.codegen.*; |
| import org.eclipse.jdt.internal.compiler.flow.*; |
| import org.eclipse.jdt.internal.compiler.lookup.*; |
| |
| public class WhileStatement extends Statement { |
| |
| public Expression condition; |
| public Statement action; |
| private Label breakLabel, continueLabel; |
| int preCondInitStateIndex = -1; |
| int condIfTrueInitStateIndex = -1; |
| int mergedInitStateIndex = -1; |
| |
| public WhileStatement(Expression condition, Statement action, int s, int e) { |
| |
| this.condition = condition; |
| this.action = action; |
| // remember useful empty statement |
| if (action instanceof EmptyStatement) action.bits |= IsUsefulEmptyStatementMASK; |
| sourceStart = s; |
| sourceEnd = e; |
| } |
| |
| public FlowInfo analyseCode( |
| BlockScope currentScope, |
| FlowContext flowContext, |
| FlowInfo flowInfo) { |
| |
| breakLabel = new Label(); |
| continueLabel = new Label(); |
| |
| Constant cst = this.condition.constant; |
| boolean isConditionTrue = cst != NotAConstant && cst.booleanValue() == true; |
| boolean isConditionFalse = cst != NotAConstant && cst.booleanValue() == false; |
| |
| cst = this.condition.optimizedBooleanConstant(); |
| boolean isConditionOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true; |
| boolean isConditionOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false; |
| |
| preCondInitStateIndex = |
| currentScope.methodScope().recordInitializationStates(flowInfo); |
| LoopingFlowContext condLoopContext; |
| FlowInfo condInfo = flowInfo.copy().unconditionalInits().discardNullRelatedInitializations(); |
| condInfo = this.condition.analyseCode( |
| currentScope, |
| (condLoopContext = |
| new LoopingFlowContext(flowContext, this, null, null, currentScope)), |
| condInfo); |
| |
| LoopingFlowContext loopingContext; |
| FlowInfo actionInfo; |
| FlowInfo exitBranch; |
| if (action == null |
| || (action.isEmptyBlock() && currentScope.compilerOptions().complianceLevel <= ClassFileConstants.JDK1_3)) { |
| condLoopContext.complainOnDeferredChecks(currentScope, condInfo); |
| if (isConditionTrue) { |
| return FlowInfo.DEAD_END; |
| } else { |
| FlowInfo mergedInfo = condInfo.initsWhenFalse().unconditionalInits(); |
| if (isConditionOptimizedTrue){ |
| mergedInfo.setReachMode(FlowInfo.UNREACHABLE); |
| } |
| mergedInitStateIndex = |
| currentScope.methodScope().recordInitializationStates(mergedInfo); |
| return mergedInfo; |
| } |
| } else { |
| // in case the condition was inlined to false, record the fact that there is no way to reach any |
| // statement inside the looping action |
| loopingContext = |
| new LoopingFlowContext( |
| flowContext, |
| this, |
| breakLabel, |
| continueLabel, |
| currentScope); |
| if (isConditionFalse) { |
| actionInfo = FlowInfo.DEAD_END; |
| } else { |
| actionInfo = condInfo.initsWhenTrue().copy(); |
| if (isConditionOptimizedFalse){ |
| actionInfo.setReachMode(FlowInfo.UNREACHABLE); |
| } |
| } |
| |
| // for computing local var attributes |
| condIfTrueInitStateIndex = |
| currentScope.methodScope().recordInitializationStates( |
| condInfo.initsWhenTrue()); |
| |
| if (!this.action.complainIfUnreachable(actionInfo, currentScope, false)) { |
| actionInfo = this.action.analyseCode(currentScope, loopingContext, actionInfo); |
| } |
| |
| // code generation can be optimized when no need to continue in the loop |
| exitBranch = condInfo.initsWhenFalse(); |
| exitBranch.addInitializationsFrom(flowInfo); // recover null inits from before condition analysis |
| if (!actionInfo.isReachable() && !loopingContext.initsOnContinue.isReachable()) { |
| continueLabel = null; |
| } else { |
| condLoopContext.complainOnDeferredChecks(currentScope, condInfo); |
| actionInfo = actionInfo.mergedWith(loopingContext.initsOnContinue.unconditionalInits()); |
| loopingContext.complainOnDeferredChecks(currentScope, actionInfo); |
| exitBranch.addPotentialInitializationsFrom(actionInfo.unconditionalInits()); |
| } |
| } |
| |
| // end of loop |
| FlowInfo mergedInfo = FlowInfo.mergedOptimizedBranches( |
| loopingContext.initsOnBreak, |
| isConditionOptimizedTrue, |
| exitBranch, |
| isConditionOptimizedFalse, |
| !isConditionTrue /*while(true); unreachable(); */); |
| mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo); |
| return mergedInfo; |
| } |
| |
| /** |
| * While code generation |
| * |
| * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope |
| * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream |
| */ |
| public void generateCode(BlockScope currentScope, CodeStream codeStream) { |
| |
| if ((bits & IsReachableMASK) == 0) { |
| return; |
| } |
| int pc = codeStream.position; |
| breakLabel.initialize(codeStream); |
| |
| // generate condition |
| if (continueLabel == null) { |
| // no need to reverse condition |
| if (condition.constant == NotAConstant) { |
| condition.generateOptimizedBoolean( |
| currentScope, |
| codeStream, |
| null, |
| breakLabel, |
| true); |
| } |
| } else { |
| continueLabel.initialize(codeStream); |
| if (!(((condition.constant != NotAConstant) |
| && (condition.constant.booleanValue() == true)) |
| || (action == null) |
| || action.isEmptyBlock())) { |
| int jumpPC = codeStream.position; |
| codeStream.goto_(continueLabel); |
| codeStream.recordPositionsFrom(jumpPC, condition.sourceStart); |
| } |
| } |
| // generate the action |
| Label actionLabel; |
| (actionLabel = new Label(codeStream)).place(); |
| if (action != null) { |
| // Required to fix 1PR0XVS: LFRE:WINNT - Compiler: variable table for method appears incorrect |
| if (condIfTrueInitStateIndex != -1) { |
| // insert all locals initialized inside the condition into the action generated prior to the condition |
| codeStream.addDefinitelyAssignedVariables( |
| currentScope, |
| condIfTrueInitStateIndex); |
| } |
| action.generateCode(currentScope, codeStream); |
| // May loose some local variable initializations : affecting the local variable attributes |
| if (preCondInitStateIndex != -1) { |
| codeStream.removeNotDefinitelyAssignedVariables(currentScope, preCondInitStateIndex); |
| } |
| |
| } |
| // output condition and branch back to the beginning of the repeated action |
| if (continueLabel != null) { |
| continueLabel.place(); |
| condition.generateOptimizedBoolean( |
| currentScope, |
| codeStream, |
| actionLabel, |
| null, |
| true); |
| } |
| breakLabel.place(); |
| |
| // May loose some local variable initializations : affecting the local variable attributes |
| if (mergedInitStateIndex != -1) { |
| codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex); |
| codeStream.addDefinitelyAssignedVariables(currentScope, mergedInitStateIndex); |
| } |
| codeStream.recordPositionsFrom(pc, this.sourceStart); |
| } |
| |
| public void resolve(BlockScope scope) { |
| |
| TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding); |
| condition.computeConversion(scope, type, type); |
| if (action != null) |
| action.resolve(scope); |
| } |
| |
| public StringBuffer printStatement(int tab, StringBuffer output) { |
| |
| printIndent(tab, output).append("while ("); //$NON-NLS-1$ |
| condition.printExpression(0, output).append(')'); |
| if (action == null) |
| output.append(';'); |
| else |
| action.printStatement(tab + 1, output); |
| return output; |
| } |
| |
| public void traverse( |
| ASTVisitor visitor, |
| BlockScope blockScope) { |
| |
| if (visitor.visit(this, blockScope)) { |
| condition.traverse(visitor, blockScope); |
| if (action != null) |
| action.traverse(visitor, blockScope); |
| } |
| visitor.endVisit(this, blockScope); |
| } |
| } |