wicket.markup.parser.filter.HtmlProblemFinder.java Source code

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Here is the source code for wicket.markup.parser.filter.HtmlProblemFinder.java

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/*
 * $Id: HtmlProblemFinder.java 4594 2006-02-21 18:20:55 +0000 (Tue, 21 Feb 2006)
 * jdonnerstag $ $Revision: 6785 $ $Date: 2006-02-21 18:20:55 +0000 (Tue, 21 Feb
 * 2006) $
 * 
 * ==============================================================================
 * 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 wicket.markup.parser.filter;

import java.text.ParseException;
import java.util.Iterator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import wicket.markup.ComponentTag;
import wicket.markup.MarkupElement;
import wicket.markup.parser.AbstractMarkupFilter;

/**
 * This is a markup inline filter which by default is not added to the list of
 * markup filter. It can be added by means of subclassing
 * Application.newMarkupParser() like
 * 
 * <pre>
 *        public class MyApplication extends Application
 *        {
 *            ...
 *            public IMarkupFilter[] getAdditionalMarkupHandler()
 *            {
 *                return new IMarkupFilter[] { new HtmlProblemFinder(HtmlProblemFinder.ERR_THROW_EXCEPTION) };
 *            }
 * </pre>
 * 
 * The purpose of the filter is to find possible HTML issues and to log a
 * warning.
 * 
 * @author Juergen Donnerstag
 */
public final class HtmlProblemFinder extends AbstractMarkupFilter {
    /** Logging */
    private static final Log log = LogFactory.getLog(HtmlProblemFinder.class);

    /** Ignore the issue detected */
    public static final int ERR_INGORE = 3;

    /** Log a warning on the issue detected */
    public static final int ERR_LOG_WARN = 2;

    /** Log an error on the issue detected */
    public static final int ERR_LOG_ERROR = 1;

    /** Throw an exception on the issue detected */
    public static final int ERR_THROW_EXCEPTION = 0;

    /** Default behavior in case of a potential HTML issue detected */
    private final int problemEscalation;

    /**
     * Construct.
     * 
     * @param problemEscalation
     *            How to escalate the issue found.
     */
    public HtmlProblemFinder(final int problemEscalation) {
        this.problemEscalation = problemEscalation;
    }

    /**
     * Get the next MarkupElement from the parent MarkupFilter and handle it if
     * the specific filter criteria are met. Depending on the filter, it may
     * return the MarkupElement unchanged, modified or it remove by asking the
     * parent handler for the next tag.
     * 
     * @see wicket.markup.parser.IMarkupFilter#nextTag()
     * @return Return the next eligible MarkupElement
     */
    public MarkupElement nextTag() throws ParseException {
        // Get the next tag. If null, no more tags are available
        final ComponentTag tag = nextComponentTag();
        if (tag == null) {
            return tag;
        }

        // Make sure some typical and may be tricky problems are detected and
        // logged.
        if ("img".equals(tag.getName()) && (tag.isOpen() || tag.isOpenClose())) {
            final String src = tag.getAttributes().getString("src");
            if ((src != null) && (src.trim().length() == 0)) {
                escalateWarning("Attribute 'src' should not be empty. Location: ", tag);
            }
        }

        // Some people are using a dot "wicket.xxx" instead of a colon
        // "wicket:xxx"
        final Iterator iter = tag.getAttributes().keySet().iterator();
        while (iter.hasNext()) {
            String key = (String) iter.next();
            if (key != null) {
                key = key.toLowerCase();
                if (key.startsWith("wicket.")) {
                    escalateWarning("You probably want 'wicket:xxx' rather than 'wicket.xxx'. Location: ", tag);
                }
            }
        }

        return tag;
    }

    /**
     * Handle the issue. Depending the setting either log a warning, an error,
     * throw an exception or ignore it.
     * 
     * @param msg
     *            The message
     * @param tag
     *            The current tag
     * @throws ParseException
     */
    private void escalateWarning(final String msg, final ComponentTag tag) throws ParseException {
        if (problemEscalation == ERR_LOG_WARN) {
            log.warn(msg + tag.toUserDebugString());
        } else if (problemEscalation == ERR_LOG_ERROR) {
            log.error(msg + tag.toUserDebugString());
        } else if (problemEscalation == ERR_INGORE) {
            // no action required
        } else
        // if (problemEscalation == ERR_THROW_EXCEPTION)
        {
            throw new ParseException(msg + tag.toUserDebugString(), tag.getPos());
        }
    }
}