bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/decorators/DecoratorRegistryReader.java

package org.eclipse.ui.internal.decorators;

/************************************************************************
Copyright (c) 2000, 2002 IBM Corporation and others.
All rights reserved.   This program and the accompanying materials
are made available under the terms of the Common Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/cpl-v10.html

Contributors:
    IBM - Initial implementation
************************************************************************/

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IPluginRegistry;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.internal.ActionExpression;
import org.eclipse.ui.internal.registry.RegistryReader;
import org.eclipse.ui.internal.registry.WizardsRegistryReader;

/**
 * The DecoratorRegistryReader is the class that reads the
 * decorator descriptions from the registry
 */

class DecoratorRegistryReader extends RegistryReader {

	//The registry values are the ones read from the registry
	static Collection values;
	static Collection ids;

	private static String EXTENSION_ID = "decorators"; //$NON-NLS-1$
	private static String ATT_LABEL = "label"; //$NON-NLS-1$
	private static String ATT_ADAPTABLE = "adaptable"; //$NON-NLS-1$
	private static String ATT_ID = "id"; //$NON-NLS-1$
	private static String ATT_DESCRIPTION = "description"; //$NON-NLS-1$
	private static String ATT_ICON = "icon"; //$NON-NLS-1$
	private static String ATT_QUADRANT = "quadrant"; //$NON-NLS-1$
	private static String ATT_LOCATION = "location"; //$NON-NLS-1$
	private static String ATT_ENABLED = "state"; //$NON-NLS-1$
	private static String CHILD_ENABLEMENT = "enablement"; //$NON-NLS-1$
	private static String P_TRUE = "true"; //$NON-NLS-1$
	private static String ATT_OBJECT_CLASS = "objectClass"; //$NON-NLS-1$
	private static String ATT_LIGHTWEIGHT = "lightweight"; //$NON-NLS-1$

	//Constants for quadrants
	public static final int TOP_LEFT = 0;
	public static final int TOP_RIGHT = 1;
	public static final int BOTTOM_LEFT = 2;
	public static final int BOTTOM_RIGHT = 3;
	public static final int UNDERLAY = 4;

	//Constants for quadrants
	private static final String TOP_LEFT_STRING = "TOP_LEFT";
	private static final String TOP_RIGHT_STRING = "TOP_RIGHT";
	private static final String BOTTOM_LEFT_STRING = "BOTTOM_LEFT";
	private static final String BOTTOM_RIGHT_STRING = "BOTTOM_RIGHT";
	private static final String UNDERLAY_STRING = "UNDERLAY";

	/**
	 * Constructor for DecoratorRegistryReader.
	 */
	protected DecoratorRegistryReader() {
		super();
	}

	/*
	 * @see RegistryReader#readElement(IConfigurationElement)
	 */
	protected boolean readElement(IConfigurationElement element) {

		String name = element.getAttribute(ATT_LABEL);

		String id = element.getAttribute(ATT_ID);
		if(ids.contains(id)){
			logDuplicateId(element);
			return false;
		}
		ids.add(id);

		String description = ""; //$NON-NLS-1$

		IConfigurationElement[] descriptions =
			element.getChildren(ATT_DESCRIPTION);

		if (descriptions.length > 0)
			description = descriptions[0].getValue();

		boolean adaptable = P_TRUE.equals(element.getAttribute(ATT_ADAPTABLE));

		boolean enabled = P_TRUE.equals(element.getAttribute(ATT_ENABLED));

		ActionExpression enablementExpression;

		IConfigurationElement[] enablement =
			element.getChildren(CHILD_ENABLEMENT);
		if (enablement.length == 0) {
			String className = element.getAttribute(ATT_OBJECT_CLASS);
			if (className == null) {
				logMissingElement(element, CHILD_ENABLEMENT);
				return false;
			} else
				enablementExpression =
					new ActionExpression(ATT_OBJECT_CLASS, className);
		} else
			enablementExpression = new ActionExpression(enablement[0]);

		boolean noClass =
			element.getAttribute(WizardsRegistryReader.ATT_CLASS) == null;

		//Lightweight or Full? It is lightweight if it is declared lightweight or if there is no class
		if (P_TRUE.equals(element.getAttribute(ATT_LIGHTWEIGHT)) || noClass) {

			int quadrant =
				getLocationConstant(element.getAttribute(ATT_LOCATION),element);
			String iconPath = element.getAttribute(ATT_ICON);
			
			if (noClass && iconPath == null) {
				logMissingElement(element, ATT_ICON);
				return false;
			}

			values.add(
				new LightweightDecoratorDefinition(
					id,
					name,
					description,
					enablementExpression,
					adaptable,
					enabled,
					quadrant,
					iconPath,
					element));
		} else {
			values.add(
				new FullDecoratorDefinition(
					id,
					name,
					description,
					enablementExpression,
					adaptable,
					enabled,
					element));
		}

		return true;

	}

	/**
	 * Read the decorator extensions within a registry and set 
	 * up the registry values.
	 */
	Collection readRegistry(IPluginRegistry in) {
		values = new ArrayList();
		ids = new HashSet();
		readRegistry(in, PlatformUI.PLUGIN_ID, EXTENSION_ID);
		return values;
	}

	/**
	 * Get the constant value based on the location supplied. Default to bottom
	 * right.
	 */
	private int getLocationConstant(String locationDefinition, IConfigurationElement element) {
		
		//Backwards compatibility
		if(locationDefinition == null)
			locationDefinition = element.getAttribute(ATT_QUADRANT);
			
		if (TOP_RIGHT_STRING.equals(locationDefinition))
			return TOP_RIGHT;
		if (TOP_LEFT_STRING.equals(locationDefinition))
			return TOP_LEFT;
		if (BOTTOM_LEFT_STRING.equals(locationDefinition))
			return BOTTOM_LEFT;
		if (UNDERLAY_STRING.equals(locationDefinition))
			return UNDERLAY;
		return BOTTOM_RIGHT;

	}
	
	/**
	 * Logs a registry error when the configuration element is unknown.
	 */
	protected void logDuplicateId(IConfigurationElement element) {
		logError(element, "Duplicate id found: " + element.getAttribute(ATT_ID));//$NON-NLS-1$
	}

}