/*******************************************************************************
 * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v0.5 
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v05.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/
package net.sourceforge.phpdt.internal.compiler.ast;

import net.sourceforge.phpdt.internal.compiler.IAbstractSyntaxTreeVisitor;
import net.sourceforge.phpdt.internal.compiler.codegen.CodeStream;
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.LabelFlowContext;
import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;

public class LabeledStatement extends Statement {
	
	public Statement statement;
	public char[] label;
	public Label targetLabel;

	// for local variables table attributes
	int mergedInitStateIndex = -1;
	
	/**
	 * LabeledStatement constructor comment.
	 */
	public LabeledStatement(char[] l, Statement st, int s, int e) {
		
		this.statement = st;
		this.label = l;
		this.sourceStart = s;
		this.sourceEnd = e;
	}
	
	public FlowInfo analyseCode(
		BlockScope currentScope,
		FlowContext flowContext,
		FlowInfo flowInfo) {

		// need to stack a context to store explicit label, answer inits in case of normal completion merged
		// with those relative to the exit path from break statement occurring inside the labeled statement.
		if (statement == null) {
			return flowInfo;
		} else {
			LabelFlowContext labelContext;
			FlowInfo mergedInfo =
				statement
					.analyseCode(
						currentScope,
						(labelContext =
							new LabelFlowContext(
								flowContext,
								this,
								label,
								(targetLabel = new Label()),
								currentScope)),
						flowInfo)
					.mergedWith(labelContext.initsOnBreak);
			mergedInitStateIndex =
				currentScope.methodScope().recordInitializationStates(mergedInfo);
			return mergedInfo;
		}
	}
	
	public AstNode concreteStatement() {
		
		return statement.concreteStatement();
	}
	
	/**
	 * Code generation for labeled statement
	 *
	 * may not need actual source positions recording
	 *
	 * @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) {
		
		int pc = codeStream.position;
		if (targetLabel != null) {
			targetLabel.codeStream = codeStream;
			if (statement != null) {
				statement.generateCode(currentScope, codeStream);
			}
			targetLabel.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 resolve(BlockScope scope) {
		
		statement.resolve(scope);
	}
	
	public String toString(int tab) {

		String s = tabString(tab);
		s += new String(label) + ": " + statement.toString(0); //$NON-NLS-1$
		return s;
	}

	public void traverse(
		IAbstractSyntaxTreeVisitor visitor,
		BlockScope blockScope) {

		if (visitor.visit(this, blockScope)) {
			statement.traverse(visitor, blockScope);
		}
		visitor.endVisit(this, blockScope);
	}

	public void resetStateForCodeGeneration() {

		this.targetLabel.resetStateForCodeGeneration();
	}
}