/*
* Copyright (c) 2005, 2007 Borland Software Corporation
*
* 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:
* Radek Dvorak (Borland) - initial API and implementation
*/
package org.eclipse.gmf.internal.validate.expressions;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.InvalidRegistryObjectException;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.gmf.internal.validate.GMFValidationPlugin;
import org.eclipse.osgi.util.NLS;
/**
* This class maintains all contribution to
* <code>org.eclipse.gmf.validate.expressions</code> extension point.
* <p>
* It collects all contributions of all providers at this class initialization
* time. It only creates and caches only descriptors of provider implementations.
* A provider itself is initialized lazily on demand.
*/
public class ExpressionProviderRegistry {
private static final ExpressionProviderRegistry INSTANCE = new ExpressionProviderRegistry();
private Map<String, Descriptor> registry;
private ExpressionProviderRegistry() {
registry = new HashMap<String, Descriptor>();
initialiaze();
}
/**
* Gets the instance of providers registry.
*/
public static ExpressionProviderRegistry getInstance() {
return INSTANCE;
}
/**
* Gets the provider for the given language.
*
* @param language
* the identifier of the language
* @return the provider supporting expressions in the given language or
* <code>null</code> if no such provider is found
*/
public IModelExpressionProvider getProvider(String language) {
Descriptor descriptor = getDescriptor(language);
if(descriptor != null && descriptor.getStatus().isOK()) {
return descriptor.getProvider();
}
return null;
}
/**
* Gets supported expression languages by providers in this registry.
* @return set of language identifiers strings, never <code>null</code>
*/
public Set<String> getLanguages() {
return registry.keySet();
}
/**
* Gets descriptor of the provider supporting the given language.
*
* @param language
* the identifier of the expression language whose provider is to
* be retrieved
* @return corresponding provider descriptor or <code>null</code> if no
* such provider is found.
*/
public Descriptor getDescriptor(String language) {
return registry.get(language);
}
private void initialiaze() {
IConfigurationElement[] configs = Platform.getExtensionRegistry().getConfigurationElementsFor(
Descriptor.GLOBAL_EXTENSION_ID);
for (int i = 0; i < configs.length; i++) {
IConfigurationElement element = configs[i];
Descriptor descriptor = new Descriptor(element);
if(descriptor.getStatus().isOK()) {
String lang = descriptor.getLanguage();
assert lang != null;
Descriptor currentDsc = registry.get(lang);
if(currentDsc == null) {
registry.put(lang, descriptor);
} else {
String message = NLS.bind(Messages.providerAlreadyExistsIgnore, new Object[] {
currentDsc.getProviderClassName(), lang,
descriptor.getProviderClassName()
});
GMFValidationPlugin.log(GMFValidationPlugin.createStatus(IStatus.ERROR, 0, message, null));
}
}
}
registry = Collections.unmodifiableMap(registry);
}
static class Descriptor {
static final String EXTENSION_ID = "expressionProviders"; //$NON-NLS-1$
static final String GLOBAL_EXTENSION_ID = GMFValidationPlugin.getPluginId() + "." + EXTENSION_ID; //$NON-NLS-1$
public static final String ATTR_CLASS = "class"; //$NON-NLS-1$
public static final String ATTR_LANGUAGE = "language"; //$NON-NLS-1$
public static final String ATTR_REQUIRES_MODEL_CLASS = "requiresModelClass"; //$NON-NLS-1$
public static final String ATTR_NAME = "name"; //$NON-NLS-1$
public static final String ATTR_DESCRIPTION = "description"; //$NON-NLS-1$
public static final String ATTR_LOOSELY_TYPED = "isLooselyTyped"; //$NON-NLS-1$
private IConfigurationElement configElement;
private String language;
private String className;
private boolean modelReflection;
private boolean isLooselyTyped;
private String name;
private String description;
private IStatus status;
private IModelExpressionProvider provider;
Descriptor(IConfigurationElement config) {
this.status = Status.OK_STATUS;
try {
configure(config);
} catch (InvalidRegistryObjectException e) {
GMFValidationPlugin.log(IStatus.ERROR, Messages.initDescriptorFailure, e);
}
}
public IStatus getStatus() {
return status;
}
public String getLanguage() {
return language;
}
public boolean supportsModelReflection() {
return modelReflection;
}
public boolean isLooselyTyped() {
return isLooselyTyped;
}
public String getProviderClassName() {
return className;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
IModelExpressionProvider getProvider() {
if(provider == null && getStatus().isOK()) {
try {
provider = (IModelExpressionProvider)configElement.createExecutableExtension(ATTR_CLASS);
} catch(CoreException e) {
String message = NLS.bind(Messages.providerCreationFailure, getProviderClassName());
GMFValidationPlugin.log(IStatus.ERROR, message, e);
}
}
return provider;
}
private void configure(IConfigurationElement config) {
this.configElement = config;
language = configElement.getAttribute(ATTR_LANGUAGE);
if(language == null || language.trim().length() == 0) {
this.status = GMFValidationPlugin.createStatus(IStatus.ERROR, 0,
Messages.missingProviderLanguage, null);
}
className = config.getAttribute(ATTR_CLASS);
if(className == null || className.trim().length() == 0) {
this.status = GMFValidationPlugin.createStatus(IStatus.ERROR, 0,
Messages.missingProviderClass, null);
}
modelReflection = "true".equals(config.getAttribute(ATTR_REQUIRES_MODEL_CLASS)); //$NON-NLS-1$
isLooselyTyped = "true".equals(config.getAttribute(ATTR_LOOSELY_TYPED)); //$NON-NLS-1$
name = config.getAttribute(ATTR_NAME);
description = config.getAttribute(ATTR_DESCRIPTION);
}
}
}
