org.waveprotocol.wave.client.common.webdriver.DebugClassHelper.java Source code

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Here is the source code for org.waveprotocol.wave.client.common.webdriver.DebugClassHelper.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.waveprotocol.wave.client.common.webdriver;

import com.google.common.base.Preconditions;
import com.google.gwt.dom.client.Element;
import com.google.gwt.user.client.ui.UIObject;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

/**
 * Helper methods for adding debugclasses to the DOM Elements.
 *
 */
public class DebugClassHelper {

    /** The name of the debug-class attribute. */
    private static final String DEBUG_CLASS_ATTRIBUTE = "dc";
    /** Whether debug class should be set (e.g. for testing purposes). */
    private static boolean debugClassEnabled = false;

    /** Disallow construction. */
    private DebugClassHelper() {
    }

    /**
     * Adds a debug class to a UIObject.
     *
     * @param uiObject the object to modify
     * @param debugClass to be added
     */
    public static final void addDebugClass(UIObject uiObject, String debugClass) {
        Preconditions.checkNotNull(uiObject, "uiObject cannot be null");
        addDebugClass(uiObject.getElement(), debugClass);
    }

    /**
     * Adds a debug class to an Element.
     *
     * @param elem the object to modify
     * @param debugClass to be added
     */
    public static final void addDebugClass(Element elem, String debugClass) {
        Preconditions.checkNotNull(elem, "addDebugClass: Element must not be null");
        if (debugClassEnabled) {
            Set<String> debugClasses = getDebugClasses(elem);
            if (debugClasses.add(debugClass)) {
                elem.setAttribute(DEBUG_CLASS_ATTRIBUTE, joinDebugClasses(debugClasses));
            }
        }
    }

    /**
     * Replaces a debug class name from an Element with another one.
     *
     * @param elem the object to modify
     * @param oldClassName previous class name to be removed
     * @param newClassName new class name to be added
     */
    public static final void replaceDebugClass(Element elem, String oldClassName, String newClassName) {
        Preconditions.checkNotNull(elem, "replaceDebugClass: Element must not be null");
        if (debugClassEnabled) {
            Set<String> debugClasses = getDebugClasses(elem);
            boolean removed = debugClasses.remove(oldClassName);
            // if no change happened in the debugClasses, do nothing
            if (debugClasses.add(newClassName) || removed) {
                elem.setAttribute(DEBUG_CLASS_ATTRIBUTE, joinDebugClasses(debugClasses));
            }
        }
    }

    /**
     * Removes a debug class from a UIObject.
     *
     * @param uiObject the object to modify
     * @param debugClass to be removed
     */
    public static final void removeDebugClass(UIObject uiObject, String debugClass) {
        Preconditions.checkNotNull(uiObject, "uiObject cannot be null");
        removeDebugClass(uiObject.getElement(), debugClass);
    }

    /**
     * Remove a debug class from an Element.
     *
     * @param elem the object to modify
     * @param debugClass to be removed
     */
    public static final void removeDebugClass(Element elem, String debugClass) {
        if (debugClassEnabled && null != elem) {
            Set<String> debugClasses = getDebugClasses(elem);
            if (debugClasses.remove(debugClass)) {
                elem.setAttribute(DEBUG_CLASS_ATTRIBUTE, joinDebugClasses(debugClasses));
            }
        }
    }

    /**
     * Removes all debug classes from a UIObject.
     * @param uiObject The UIObject to remove debug classes from.
     */
    public static void clearDebugClasses(UIObject uiObject) {
        clearDebugClasses(uiObject.getElement());
    }

    /**
     * Removes all debug classes from an Element.
     * @param elem The element to remove debug classes from.
     */
    public static void clearDebugClasses(Element elem) {
        elem.removeAttribute(DEBUG_CLASS_ATTRIBUTE);
    }

    /**
     * Join a set of Strings into a space-separated String.
     * @param debugClasses to be joined
     * @return a String of debug classes
     */
    private static final String joinDebugClasses(Set<String> debugClasses) {
        StringBuilder result = new StringBuilder();
        for (String debugClass : debugClasses) {
            result.append(debugClass);
            result.append(" ");
        }
        return result.toString().trim();
    }

    /**
     * Get a set of debug classes present in an element.
     * @param elem from which debug classes will be read from
     * @return the set of debug classes
     */
    private static final Set<String> getDebugClasses(Element elem) {
        Set<String> result = new HashSet<String>();
        String debugClasses = elem.getAttribute(DEBUG_CLASS_ATTRIBUTE);
        result.addAll(Arrays.asList(debugClasses.split(" ")));
        return result;
    }

    /**
     * Set whether to enable debug classes (for testing purposes).
     *
     * @param enableDebugClass the new value
     */
    public static void setDebugClassEnabled(boolean enableDebugClass) {
        debugClassEnabled = enableDebugClass;
    }
}