ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/wizards/templates/ControlStack.java

/*******************************************************************************
 *  Copyright (c) 2000, 2012 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.pde.internal.ui.wizards.templates;

import java.util.Iterator;
import java.util.Stack;
import org.eclipse.pde.ui.templates.IVariableProvider;

public class ControlStack {
	private Stack<Entry> stack;
	private PreprocessorParser parser;

	class Entry {
		boolean value;
	}

	public ControlStack() {
		stack = new Stack<>();
		parser = new PreprocessorParser();
	}

	public void setValueProvider(IVariableProvider provider) {
		parser.setVariableProvider(provider);
	}

	public void processLine(String line) {
		if (line.startsWith("if")) { //$NON-NLS-1$
			String expression = line.substring(2).trim();
			boolean result = false;
			try {
				result = parser.parseAndEvaluate(expression);
			} catch (Exception e) {
			}
			Entry entry = new Entry();
			entry.value = result;
			stack.push(entry);
		} else if (line.startsWith("else")) { //$NON-NLS-1$
			if (stack.isEmpty() == false) {
				Entry entry = stack.peek();
				entry.value = !entry.value;
			}
		} else if (line.startsWith("endif")) { //$NON-NLS-1$
			// pop the stack
			if (!stack.isEmpty())
				stack.pop();
		} else {
			// a preprocessor comment - ignore it
		}
	}

	public boolean getCurrentState() {
		if (stack.isEmpty())
			return true;
		// All control levels must evaluate to true to
		// return result==true
		for (Iterator<Entry> iter = stack.iterator(); iter.hasNext();) {
			Entry entry = iter.next();
			if (!entry.value)
				return false;
		}
		return true;
	}
}