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.variables.IValueVariable;
import org.eclipse.core.variables.IValueVariableInitializer;
import org.eclipse.core.variables.VariablesPlugin;
import org.eclipse.osgi.util.NLS;

Implementation of a value variable.
/**
 * Implementation of a value variable.
 */
public class ContributedValueVariable extends StringVariable implements IValueVariable {

	
Variable value or null if none
/**
	 * Variable value or <code>null</code> if none
	 */
	private String fValue;

	
Whether this variable's value has been initialized
/**
	 * Whether this variable's value has been initialized
	 */
	private boolean fInitialized = false;

	
Whether this variable is read only.  If true, users cannot change the value.
/**
	 * Whether this variable is read only.  If true, users cannot change the value.
	 */
	private boolean fReadOnly;

	
Constructs a new value variable with the given name, description, read only
property and associated configuration element.  The value will be initialized
from the configuration element the first time getValue() is called.
Params:
name – variable name
description – variable description or null
readOnly – whether the variable should be a read only variable
configurationElement – configuration element/**
	 * Constructs a new value variable with the given name, description, read only
	 * property and associated configuration element.  The value will be initialized
	 * from the configuration element the first time getValue() is called.
	 *
	 * @param name variable name
	 * @param description variable description or <code>null</code>
	 * @param readOnly whether the variable should be a read only variable
	 * @param configurationElement configuration element
	 */
	public ContributedValueVariable(String name, String description, boolean readOnly, IConfigurationElement configurationElement) {
		super(name, description, configurationElement);
		fReadOnly = readOnly;
	}

	@Override
	public void setValue(String value) {
		if (!isReadOnly() || !isInitialized()){
			fValue = value;
			setInitialized(true);
			StringVariableManager.getDefault().notifyChanged(this);
		}
	}

	@Override
	public String getValue() {
		if (!isInitialized()) {
			initialize();
		}
		return fValue;
	}

	
Initialize this variable's value from the configuration element.
/**
	 * Initialize this variable's value from the configuration element.
	 */
	private void initialize() {
		if (getConfigurationElement() != null) {
			// check for a explicit value specified in plug-in XML
			String value = getConfigurationElement().getAttribute("initialValue"); //$NON-NLS-1$
			if (value == null) {
				// check for initializer
				String className = getConfigurationElement().getAttribute("initializerClass"); //$NON-NLS-1$
				if (className != null) {
					try {
						Object object = getConfigurationElement().createExecutableExtension("initializerClass"); //$NON-NLS-1$
						if (object instanceof IValueVariableInitializer) {
							IValueVariableInitializer initializer = (IValueVariableInitializer)object;
							initializer.initialize(this);
						} else {
							VariablesPlugin.logMessage(NLS.bind("Unable to initialize variable {0} - initializer must be an instance of IValueVariableInitializer.", new String[]{getName()}), null); //$NON-NLS-1$
						}
					} catch (CoreException e) {
						VariablesPlugin.logMessage(NLS.bind("Unable to initialize variable {0}",new String[]{getName()}), e); //$NON-NLS-1$
					}
				}
			} else {
				setValue(value);
			}
		}
		setInitialized(true);
	}

	
Returns whether this variable has been initialized with a value by one of:

setValue(String)
its configuration element's initialValue attribute
its configuration element's initializer

Returns:
whether this variable has been initialized with a value/**
	 * Returns whether this variable has been initialized with a value by one of:
	 * <ul>
	 * <li><code>setValue(String)</code></li>
	 * <li>its configuration element's <code>initialValue</code> attribute</li>
	 * <li>its configuration element's initializer</li>
	 * </ul>
	 * @return whether this variable has been initialized with a value
	 */
	protected boolean isInitialized() {
		return fInitialized;
	}

	
Sets whether this variable has been initialized with a value.
Params:
initialized – whether this variable has been initialized/**
	 * Sets whether this variable has been initialized with a value.
	 *
	 * @param initialized whether this variable has been initialized
	 */
	protected void setInitialized(boolean initialized) {
		fInitialized = initialized;
	}

	@Override
	public boolean isReadOnly() {
		return fReadOnly;
	}

	@Override
	public boolean isContributed() {
		return getConfigurationElement() != null;
	}

}