com.google.dart.tools.ui.internal.text.folding.JavaFoldingStructureProviderRegistry.java Source code

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Here is the source code for com.google.dart.tools.ui.internal.text.folding.JavaFoldingStructureProviderRegistry.java

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/*
 * Copyright (c) 2012, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.tools.ui.internal.text.folding;

import com.google.dart.tools.ui.DartToolsPlugin;
import com.google.dart.tools.ui.Messages;
import com.google.dart.tools.ui.PreferenceConstants;
import com.google.dart.tools.ui.text.folding.IDartFoldingStructureProvider;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.preference.IPreferenceStore;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * 
 */
public class JavaFoldingStructureProviderRegistry {

    private static final String EXTENSION_POINT = "foldingStructureProviders"; //$NON-NLS-1$

    /** The map of descriptors, indexed by their identifiers. */
    private Map<String, JavaFoldingStructureProviderDescriptor> fDescriptors;

    /**
     * Creates a new instance.
     */
    public JavaFoldingStructureProviderRegistry() {
    }

    /**
     * Instantiates and returns the provider that is currently configured in the preferences.
     * 
     * @return the current provider according to the preferences
     */
    public IDartFoldingStructureProvider getCurrentFoldingProvider() {
        IPreferenceStore preferenceStore = DartToolsPlugin.getDefault().getPreferenceStore();
        String currentProviderId = preferenceStore.getString(PreferenceConstants.EDITOR_FOLDING_PROVIDER);
        JavaFoldingStructureProviderDescriptor desc = getFoldingProviderDescriptor(currentProviderId);

        // Fallback to default if extension has gone
        if (desc == null) {
            String message = Messages.format(
                    FoldingMessages.JavaFoldingStructureProviderRegistry_warning_providerNotFound_resetToDefault,
                    currentProviderId);
            DartToolsPlugin
                    .log(new Status(IStatus.WARNING, DartToolsPlugin.getPluginId(), IStatus.OK, message, null));

            String defaultProviderId = preferenceStore
                    .getDefaultString(PreferenceConstants.EDITOR_FOLDING_PROVIDER);

            desc = getFoldingProviderDescriptor(defaultProviderId);
            Assert.isNotNull(desc);

            preferenceStore.setToDefault(PreferenceConstants.EDITOR_FOLDING_PROVIDER);
        }

        try {
            return desc.createProvider();
        } catch (CoreException e) {
            DartToolsPlugin.log(e);
            return null;
        }
    }

    /**
     * Returns the folding provider descriptor with identifier <code>id</code> or <code>null</code> if
     * no such provider is registered.
     * 
     * @param id the identifier for which a provider is wanted
     * @return the corresponding provider descriptor, or <code>null</code> if none can be found
     */
    public JavaFoldingStructureProviderDescriptor getFoldingProviderDescriptor(String id) {
        synchronized (this) {
            ensureRegistered();
            return fDescriptors.get(id);
        }
    }

    /**
     * Returns an array of <code>JavaFoldingStructureProviderDescriptor</code> describing all
     * extension to the <code>foldingProviders</code> extension point.
     * 
     * @return the list of extensions to the <code>quickDiffReferenceProvider</code> extension point
     */
    public JavaFoldingStructureProviderDescriptor[] getFoldingProviderDescriptors() {
        synchronized (this) {
            ensureRegistered();
            return fDescriptors.values().toArray(new JavaFoldingStructureProviderDescriptor[fDescriptors.size()]);
        }
    }

    /**
     * Reads all extensions.
     * <p>
     * This method can be called more than once in order to reload from a changed extension registry.
     * </p>
     */
    public void reloadExtensions() {
        IExtensionRegistry registry = Platform.getExtensionRegistry();
        Map<String, JavaFoldingStructureProviderDescriptor> map = new HashMap<String, JavaFoldingStructureProviderDescriptor>();

        IConfigurationElement[] elements = registry.getConfigurationElementsFor(DartToolsPlugin.getPluginId(),
                EXTENSION_POINT);
        for (int i = 0; i < elements.length; i++) {
            JavaFoldingStructureProviderDescriptor desc = new JavaFoldingStructureProviderDescriptor(elements[i]);
            map.put(desc.getId(), desc);
        }

        synchronized (this) {
            fDescriptors = Collections.unmodifiableMap(map);
        }
    }

    /**
     * Ensures that the extensions are read and stored in <code>fDescriptors</code>.
     */
    private void ensureRegistered() {
        if (fDescriptors == null) {
            reloadExtensions();
        }
    }

}