Selector.java

/*
 * Copyright 2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * 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 jdave.wicket;

import java.util.ArrayList;
import java.util.List;
import org.apache.wicket.Component;
import org.apache.wicket.MarkupContainer;
import org.apache.wicket.Component.IVisitor;
import org.hamcrest.Matcher;
import org.hamcrest.Matchers;

/**
 * @author Joni Freeman
 * @author Timo Rantalaiho
 */
public class Selector {
    // Note that the redundant type parameters in several methods are needed
    // because of this javac bug:
    // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6302954

    public <T extends Component, X extends Component> X first(final MarkupContainer root,
            final Class<T> componentType, final Matcher<?> matcher) {
        return this.<T, X> selectFirst(root, componentType,
                new ComponentsModelMatchesTo<T>(matcher));
    }

    public <T extends Component, X extends Component> List<X> all(final MarkupContainer root,
            final Class<T> componentType, final Matcher<?> matcher) {
        return selectAll(root, componentType, new ComponentsModelMatchesTo<T>(matcher));
    }

    public <T extends Component, X extends Component> X first(final MarkupContainer root,
            final Class<T> componentType, final String wicketId, final Matcher<?> modelMatcher) {
        final Matcher<T> bothMatcher = combine(modelMatcher, wicketId);
        return this.<T, X> selectFirst(root, componentType, bothMatcher);
    }

    public <T extends Component, X extends Component> List<X> all(final MarkupContainer root,
            final Class<T> componentType, final String wicketId, final Matcher<?> modelMatcher) {
        final Matcher<T> bothMatcher = combine(modelMatcher, wicketId);
        return selectAll(root, componentType, bothMatcher);
    }

    private <T extends Component, X extends Component> List<X> selectAll(
            final MarkupContainer root, final Class<T> componentType,
            final Matcher<T> componentMatcher) {
        final CollectingVisitor<T, X> visitor = new CollectingVisitor<T, X>(componentMatcher);
        return visitor.selectFrom(root, componentType, IVisitor.CONTINUE_TRAVERSAL);
    }

    private <T extends Component, X extends Component> X selectFirst(final MarkupContainer root,
            final Class<T> componentType, final Matcher<T> componentMatcher) {
        final CollectingVisitor<T, X> visitor = new CollectingVisitor<T, X>(componentMatcher);
        final List<X> firstMatch = visitor.selectFrom(root, componentType, IVisitor.STOP_TRAVERSAL);
        if (firstMatch.isEmpty()) {
            return null;
        }
        return firstMatch.get(0);
    }

    @SuppressWarnings("unchecked")
    private <T extends Component> Matcher<T> combine(final Matcher<?> modelMatcher,
            final String wicketId) {
        return Matchers.allOf(new ComponentsModelMatchesTo<T>(modelMatcher),
                new WicketIdEqualsTo<T>(wicketId));
    }

    /**
     * Not thread safe.
     */
    private class CollectingVisitor<T extends Component, X extends Component> implements
            IVisitor<T> {
        private final Matcher<T> componentMatcher;
        private final List<X> matches = new ArrayList<X>();
        private Object actionOnMatch;

        public CollectingVisitor(final Matcher<T> componentMatcher) {
            this.componentMatcher = componentMatcher;
        }

        @SuppressWarnings( { "unchecked" })
        public Object component(final Component component) {
            if (componentMatcher.matches(component)) {
                matches.add((X) component);
                return actionOnMatch;
            }
            return CONTINUE_TRAVERSAL;
        }

        public List<X> selectFrom(final MarkupContainer root, final Class<T> componentType,
                final Object actionOnMatch) {
            this.actionOnMatch = actionOnMatch;
            root.visitChildren(componentType, this);
            return matches;
        }
    }
}