/*
 * <copyright>
 *
 * Copyright (c) 2005-2006 Sven Efftinge 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:
 *     Sven Efftinge - Initial API and implementation
 *
 * </copyright>
 */
package org.eclipse.gmf.internal.xpand.ast;

import org.eclipse.gmf.internal.xpand.eval.EvaluationListener;
import org.eclipse.gmf.internal.xpand.expression.ast.SyntaxElement;
import org.eclipse.gmf.internal.xpand.model.XpandExecutionContext;

public abstract class Statement extends SyntaxElement implements XpandAnalyzable, XpandEvaluatable {
    public Statement(final int start, final int end, final int line, final int startOffset, final int endOffset) {
        super(start, end, line, startOffset, endOffset);
    }

    public final void evaluate(final XpandExecutionContext ctx) {
        try {
        	notifyEnter(ctx);
            ctx.getOutput().enterStatement(this);
        	evaluateInternal(ctx);
            ctx.getOutput().exitStatement(null);
        } finally {
        	notifyLeave(ctx);
        }
    }

    protected abstract void evaluateInternal(XpandExecutionContext ctx);

    private void notifyEnter(XpandExecutionContext ctx) {
    	EvaluationListener l = ctx.getEvaluationListener();
    	if (l != null) {
    		l.enter(this, ctx);
    	}
    }

    private void notifyLeave(XpandExecutionContext ctx) {
    	EvaluationListener l = ctx.getEvaluationListener();
    	if (l != null) {
    		l.leave(this, ctx);
    	}
    }
}