/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpdt.internal.compiler.ast;

import net.sourceforge.phpdt.internal.compiler.ASTVisitor;
import net.sourceforge.phpdt.internal.compiler.codegen.Label;
import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
import net.sourceforge.phpdt.internal.compiler.flow.LoopingFlowContext;
import net.sourceforge.phpdt.internal.compiler.impl.Constant;
import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;

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;
		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 postCondInfo = this.condition.analyseCode(currentScope,
				(condLoopContext = new LoopingFlowContext(flowContext, this,
						null, null, currentScope)), flowInfo);

		LoopingFlowContext loopingContext;
		FlowInfo actionInfo;
		// if (action == null
		// || (action.isEmptyBlock() &&
		// currentScope.environment().options.complianceLevel <=
		// CompilerOptions.JDK1_3)) {
		// condLoopContext.complainOnFinalAssignmentsInLoop(currentScope,
		// postCondInfo);
		// if (isConditionTrue) {
		// return FlowInfo.DEAD_END;
		// } else {
		// FlowInfo mergedInfo =
		// postCondInfo.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 = postCondInfo.initsWhenTrue().copy();
			if (isConditionOptimizedFalse) {
				actionInfo.setReachMode(FlowInfo.UNREACHABLE);
			}
		}

		// for computing local var attributes
		condIfTrueInitStateIndex = currentScope.methodScope()
				.recordInitializationStates(postCondInfo.initsWhenTrue());

		if (!actionInfo.complainIfUnreachable(action, currentScope, false)) {
			actionInfo = action.analyseCode(currentScope, loopingContext,
					actionInfo);
		}

		// code generation can be optimized when no need to continue in the loop
		if (!actionInfo.isReachable()
				&& !loopingContext.initsOnContinue.isReachable()) {
			continueLabel = null;
		} else {
			// TODO: (philippe) should simplify in one Loop context
			condLoopContext.complainOnFinalAssignmentsInLoop(currentScope,
					postCondInfo);
			loopingContext.complainOnFinalAssignmentsInLoop(currentScope,
					actionInfo);
		}
		// }

		// infinite loop
		FlowInfo mergedInfo;
		if (isConditionOptimizedTrue) {
			mergedInitStateIndex = currentScope.methodScope()
					.recordInitializationStates(
							mergedInfo = loopingContext.initsOnBreak);
			return mergedInfo;
		}

		// end of loop: either condition false or break
		mergedInfo = postCondInfo.initsWhenFalse().unconditionalInits()
				.mergedWith(loopingContext.initsOnBreak);
		if (isConditionOptimizedTrue && continueLabel == null) {
			mergedInfo.setReachMode(FlowInfo.UNREACHABLE);
		}
		mergedInitStateIndex = currentScope.methodScope()
				.recordInitializationStates(mergedInfo);
		return mergedInfo;
	}

	/**
	 * While code generation
	 * 
	 * @param currentScope
	 *            net.sourceforge.phpdt.internal.compiler.lookup.BlockScope
	 * @param codeStream
	 *            net.sourceforge.phpdt.internal.compiler.codegen.CodeStream
	 */
	// public void generateCode(BlockScope currentScope, CodeStream codeStream)
	// {
	//
	// if ((bits & IsReachableMASK) == 0) {
	// return;
	// }
	// int pc = codeStream.position;
	// breakLabel.codeStream = codeStream;
	//
	// // generate condition
	// if (continueLabel == null) {
	// // no need to reverse condition
	// if (condition.constant == NotAConstant) {
	// condition.generateOptimizedBoolean(
	// currentScope,
	// codeStream,
	// null,
	// breakLabel,
	// true);
	// }
	// } else {
	// continueLabel.codeStream = 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.recordPositionsFrom(pc, this.sourceStart);
	// }
	public void resetStateForCodeGeneration() {
		if (this.breakLabel != null) {
			this.breakLabel.resetStateForCodeGeneration();
		}
		if (this.continueLabel != null) {
			this.continueLabel.resetStateForCodeGeneration();
		}
	}

	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 resolve(BlockScope scope) {

		TypeBinding type = condition
				.resolveTypeExpecting(scope, BooleanBinding);
		condition.implicitWidening(type, type);
		if (action != null)
			action.resolve(scope);
	}

	public String toString(int tab) {

		String s = tabString(tab);
		s = s + "while (" + condition.toStringExpression() + ")"; //$NON-NLS-1$ //$NON-NLS-2$
		if (action == null)
			s = s + " {} ;"; //$NON-NLS-1$ 
		else if (action instanceof Block)
			s = s + "\n" + action.toString(tab + 1); //$NON-NLS-1$
		else
			s = s + " {\n" + action.toString(tab + 1) + "}"; //$NON-NLS-2$ //$NON-NLS-1$
		return s;
	}

	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);
	}
}