IncQueryObservables.java

/*******************************************************************************
 * Copyright (c) 2010-2012, Abel Hegedus, Istvan Rath and Daniel Varro
 * 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:
 *   Abel Hegedus - initial API and implementation
 *******************************************************************************/
package org.eclipse.incquery.databinding.runtime.api;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.databinding.observable.list.IObservableList;
import org.eclipse.core.databinding.observable.set.IObservableSet;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.observable.value.IValueChangeListener;
import org.eclipse.emf.common.notify.Notifier;
import org.eclipse.emf.databinding.EMFProperties;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EStructuralFeature;
import org.eclipse.incquery.databinding.runtime.adapter.DatabindingAdapterUtil;
import org.eclipse.incquery.databinding.runtime.collection.ObservablePatternMatchList;
import org.eclipse.incquery.databinding.runtime.collection.ObservablePatternMatchSet;
import org.eclipse.incquery.runtime.api.IMatcherFactory;
import org.eclipse.incquery.runtime.api.IPatternMatch;
import org.eclipse.incquery.runtime.api.IncQueryMatcher;

/**
 * Utility class for observing EMF-IncQuery related objects, such as match sets, match parameters.
 * 
 * @author Abel Hegedus
 * 
 */
public class IncQueryObservables {

    /**
     * Hidden constructor for utility class
     */
    private IncQueryObservables() {

    }

    /**
     * Create an observable list of the match set of the given query on the selected notifier.
     * 
     * <p>
     * The matches are ordered by appearance, so a new match is always put on the end of the list.
     * 
     * <p>
     * Use the generated matcher factories for initialization, in the generic case, you may have to accept an unchecked
     * invocation (or use the Generic classes if you are sure).
     * 
     * @param factory
     *            the matcher factory for the query to observe
     * @param notifier
     *            the notifier to use for the matcher
     * @return an observable list of matches
     */
    public static <Match extends IPatternMatch, Matcher extends IncQueryMatcher<Match>> IObservableList observeMatchesAsList(
            IMatcherFactory<Matcher> factory, Notifier notifier) {
        return new ObservablePatternMatchList<Match>(factory, notifier);
    }

    /**
     * Create an observable set of the match set of the given query on the selected notifier.
     * 
     * <p>
     * Use the generated matcher factories for initialization, in the generic case, you may have to accept an unchecked
     * invocation (or use the Generic classes if you are sure).
     * 
     * @param factory
     *            the matcher factory for the query to observe
     * @param notifier
     *            the notifier to use for the matcher
     * @return an observable set of matches
     */
    public static <Match extends IPatternMatch, Matcher extends IncQueryMatcher<Match>> IObservableSet observeMatchesAsSet(
            IMatcherFactory<Matcher> factory, Notifier notifier) {
        return new ObservablePatternMatchSet<Match>(factory, notifier);
    }

    /**
     * Registers the given changeListener for the appropriate features of the given signature. The features will be
     * computed based on the message parameter.
     * 
     * @param signature
     *            the signature instance
     * @param changeListener
     *            the changle listener
     * @param message
     *            the message which can be found in the appropriate PatternUI annotation
     * @return the list of IObservableValue instances for which the IValueChangeListener was registered
     */
    public static List<IObservableValue> observeFeatures(IPatternMatch match, IValueChangeListener changeListener,
            String message) {
        List<IObservableValue> affectedValues = new ArrayList<IObservableValue>();
        if (message != null) {
            String[] tokens = message.split("\\$");

            for (int i = 0; i < tokens.length; i++) {

                // odd tokens
                if (i % 2 != 0) {
                    IObservableValue value = IncQueryObservables.getObservableValue(match, tokens[i]);
                    if (value != null) {
                        value.addValueChangeListener(changeListener);
                        affectedValues.add(value);
                    }
                }
            }
        }
        return affectedValues;
    }

    /**
     * Registers the given change listener on the given object's all accessible fields. This function uses Java
     * Reflection.
     * 
     * @param changeListener
     *            the changle listener
     * @param object
     *            the observed object
     * @return the list of IObservableValue instances for which the IValueChangeListener was registered
     */
    public static List<IObservableValue> observeAllAttributes(IValueChangeListener changeListener, Object object) {
        List<IObservableValue> affectedValues = new ArrayList<IObservableValue>();
        if (object instanceof EObject) {
            for (EStructuralFeature feature : ((EObject) object).eClass().getEAllStructuralFeatures()) {
                IObservableValue val = EMFProperties.value(feature).observe(object);
                affectedValues.add(val);
                val.addValueChangeListener(changeListener);
            }
        }
        return affectedValues;
    }

    /**
     * Returns an IObservableValue for the given match based on the given expression. If an attribute is not present in
     * the expression than it tries with the 'name' attribute. If it is not present the returned value will be null.
     * 
     * @param match
     *            the match object
     * @param expression
     *            the expression
     * @return IObservableValue instance or null
     */
    public static IObservableValue getObservableValue(IPatternMatch match, String expression) {
        IObservableValue val = null;
        String[] objectTokens = expression.split("\\.");

        if (objectTokens.length > 0) {
            Object o = null;
            EStructuralFeature feature = null;

            if (objectTokens.length == 2) {
                o = match.get(objectTokens[0]);
                feature = DatabindingAdapterUtil.getFeature(o, objectTokens[1]);
            }
            if (objectTokens.length == 1) {
                o = match.get(objectTokens[0]);
                feature = DatabindingAdapterUtil.getFeature(o, "name");
            }
            if (o != null && feature != null) {
                val = EMFProperties.value(feature).observe(o);
            }
        }

        return val;
    }

}