com.google.gwt.dom.client.HeadingElement.java Source code

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Here is the source code for com.google.gwt.dom.client.HeadingElement.java

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/*
 * Copyright 2008 Google Inc.
 * 
 * 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.google.gwt.dom.client;

import java.util.Locale;

import com.google.gwt.core.client.JavaScriptObject;

/**
 * For the H1 to H6 elements.
 * 
 * @see <a href=
 *      "http://www.w3.org/TR/1999/REC-html401-19991224/struct/global.html#edef-H1">
 *      W3C HTML Specification</a>
 */
@TagName({ HeadingElement.TAG_H1, HeadingElement.TAG_H2, HeadingElement.TAG_H3, HeadingElement.TAG_H4,
        HeadingElement.TAG_H5, HeadingElement.TAG_H6 })
public class HeadingElement extends Element {
    static final String[] TAGS = { HeadingElement.TAG_H1, HeadingElement.TAG_H2, HeadingElement.TAG_H3,
            HeadingElement.TAG_H4, HeadingElement.TAG_H5, HeadingElement.TAG_H6 };

    public static final String TAG_H1 = "h1";

    public static final String TAG_H2 = "h2";

    public static final String TAG_H3 = "h3";

    public static final String TAG_H4 = "h4";

    public static final String TAG_H5 = "h5";

    public static final String TAG_H6 = "h6";

    /**
     * Assert that the given {@link Element} is compatible with this class and
     * automatically typecast it.
     */
    public static HeadingElement as(Element elem) {
        if (HeadingElement.class.desiredAssertionStatus()) {
            assert is(elem);
        }
        return (HeadingElement) elem;
    }

    /**
     * Determine whether the given {@link Element} can be cast to this class. A
     * <code>null</code> node will cause this method to return
     * <code>false</code>.
     */
    public static boolean is(Element elem) {
        if (elem == null) {
            return false;
        }
        String tag = elem.getTagName().toLowerCase(Locale.ROOT);
        if (tag.length() != 2) {
            return false;
        }
        if (tag.charAt(0) != 'h') {
            return false;
        }
        int n = Integer.parseInt(tag.substring(1, 2));
        if (n < 1 || n > 6) {
            return false;
        }
        return true;
    }

    /**
     * Determines whether the given {@link JavaScriptObject} can be cast to this
     * class. A <code>null</code> object will cause this method to return
     * <code>false</code>.
     */
    public static boolean is(JavaScriptObject o) {
        if (Element.is(o)) {
            return is(Element.as(o));
        }
        return false;
    }

    /**
     * Determine whether the given {@link Node} can be cast to this class. A
     * <code>null</code> node will cause this method to return
     * <code>false</code>.
     */
    public static boolean is(Node node) {
        if (Element.is(node)) {
            return is((Element) node);
        }
        return false;
    }

    protected HeadingElement() {
    }
}