PseudoClassSpecifierChecker.java

/**
 * Modification from original by Gist Labs, LLC (http://gistlabs.com)
 * 
 * Copyright (c) 2009-2012, Christer Sandberg
 * 
 * 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 com.gistlabs.mechanize.util.css_query;

import java.util.Collection;
import java.util.LinkedHashSet;

import se.fishtank.css.selectors.specifier.PseudoClassSpecifier;
import se.fishtank.css.util.Assert;

import com.gistlabs.mechanize.util.css_query.NodeHelper.Index;


public class PseudoClassSpecifierChecker<Node> extends AbstractChecker<Node> {

	/** The pseudo-class specifier to check against. */
	protected final PseudoClassSpecifier specifier;

	/**
	 * Create a new instance.
	 * 
	 * @param specifier The pseudo-class specifier to check against.
	 */
	public PseudoClassSpecifierChecker(final NodeHelper<Node> helper, final PseudoClassSpecifier specifier) {
		super(helper);
		Assert.notNull(specifier, "specifier is null!");
		this.specifier = specifier;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public Collection<Node> check(final Collection<Node> nodes) {
		Assert.notNull(nodes, "nodes is null!");
		this.nodes = nodes;

		this.result = new LinkedHashSet<Node>();

		String value = specifier.getValue();
		if ("empty".equals(value))
			addEmptyElements();
		else if ("first-child".equals(value))
			addFirstChildElements();
		else if ("first-of-type".equals(value))
			addFirstOfType();
		else if ("last-child".equals(value))
			addLastChildElements();
		else if ("last-of-type".equals(value))
			addLastOfType();
		else if ("only-child".equals(value))
			addOnlyChildElements();
		else if ("only-of-type".equals(value))
			addOnlyOfTypeElements();
		else if ("root".equals(value))
			addRootElement();
		else
			throw new RuntimeException("Unknown pseudo class: " + value);

		return result;
	}

	/**
	 * Add {@code :empty} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#empty-pseudo"><code>:empty</code> pseudo-class</a>
	 */
	private void addEmptyElements() {
		for (Node node : nodes)
			if (helper.isEmpty(node))
				result.add(node);
	}

	/**
	 * Add {@code :first-child} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#first-child-pseudo"><code>:first-child</code> pseudo-class</a>
	 */
	private void addFirstChildElements() {
		for (Node node : nodes) {
			Index index = helper.getIndexInParent(node, false);
			if (index.index == 0)
				result.add(node);
		}
	}

	/**
	 * Add {@code :first-of-type} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#first-of-type-pseudo"><code>:first-of-type</code> pseudo-class</a>
	 */
	private void addFirstOfType() {
		for (Node node : nodes) {
			Index index = helper.getIndexInParent(node, true);
			if (index.index == 0)
				result.add(node);
		}
	}

	/**
	 * Add {@code :last-child} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#last-child-pseudo"><code>:last-child</code> pseudo-class</a>
	 */
	private void addLastChildElements() {
		for (Node node : nodes) {
			Index index = helper.getIndexInParent(node, false);
			if (index.index == (index.size-1))
				result.add(node);
		}
	}

	/**
	 * Add {@code :last-of-type} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#last-of-type-pseudo"><code>:last-of-type</code> pseudo-class</a>
	 */
	private void addLastOfType() {
		for (Node node : nodes) {
			Index index = helper.getIndexInParent(node, true);
			if (index.index == (index.size-1))
				result.add(node);
		}
	}

	/**
	 * Add {@code :only-child} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#only-child-pseudo"><code>:only-child</code> pseudo-class</a>
	 */
	private void addOnlyChildElements() {
		for (Node node : nodes) {
			Index index = helper.getIndexInParent(node, false);
			if (index.size==1)
				result.add(node);
		}
	}

	/**
	 * Add {@code :only-of-type} elements.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#only-of-type-pseudo"><code>:only-of-type</code> pseudo-class</a>
	 */
	private void addOnlyOfTypeElements() {
		for (Node node : nodes) {
			Index index = helper.getIndexInParent(node, true);
			if (index.size==1)
				result.add(node);
		}
	}

	/**
	 * Add the {@code :root} element.
	 * 
	 * @see <a href="http://www.w3.org/TR/css3-selectors/#root-pseudo"><code>:root</code> pseudo-class</a>
	 */
	private void addRootElement() {
		Node root = helper.getRoot();
		if (root != null)
			result.add(root);
	}
}