Copyright (c) 2000, 2013 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.internal.variables;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.variables.IDynamicVariable;
import org.eclipse.core.variables.IDynamicVariableResolver;
import org.eclipse.core.variables.VariablesPlugin;
import org.eclipse.osgi.util.NLS;

Dynamic variable
/**
 * Dynamic variable
 */
public class DynamicVariable extends StringVariable implements IDynamicVariable {

	
Resolver, or null until needed
/**
	 * Resolver, or <code>null</code> until needed
	 */
	private IDynamicVariableResolver fResolver;

	@Override
	public String getValue(String argument) throws CoreException {
		if (!supportsArgument()) {
			// check for an argument - not supported
			if (argument != null && argument.length() > 0) {
				throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind(VariablesMessages.DynamicVariable_0, new String[]{argument, getName()}), null));
			}
		}
		if (fResolver == null) {
			String name = getConfigurationElement().getAttribute("resolver"); //$NON-NLS-1$
			if (name == null) {
				throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind("Contributed context variable {0} must specify a resolver.",new String[]{getName()}), null)); //$NON-NLS-1$
			}
			Object object = getConfigurationElement().createExecutableExtension("resolver"); //$NON-NLS-1$
			if (object instanceof IDynamicVariableResolver) {
				fResolver = (IDynamicVariableResolver)object;
			} else {
				throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind("Contributed context variable resolver for {0} must be an instance of IContextVariableResolver.",new String[]{getName()}), null)); //$NON-NLS-1$
			}
		}
		try {
			return fResolver.resolveValue(this, argument);
		} catch (RuntimeException e) {
			throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind("Error while evaluating variable {0}.",new String[]{getName()}), e)); //$NON-NLS-1$
		}
	}

	
Constructs a new context variable.
Params:
name – variable name
description – variable description or null
configurationElement – configuration element/**
	 * Constructs a new context variable.
	 *
	 * @param name variable name
	 * @param description variable description or <code>null</code>
	 * @param configurationElement configuration element
	 */
	public DynamicVariable(String name, String description, IConfigurationElement configurationElement) {
		super(name, description, configurationElement);
	}

	@Override
	public boolean supportsArgument() {
		String arg = getConfigurationElement().getAttribute("supportsArgument"); //$NON-NLS-1$
		return arg == null || Boolean.valueOf(arg).booleanValue();
	}

}