Java tutorial
/* * $Id: HtmlHandler.java 5771 2006-05-19 12:04:06 +0000 (Fri, 19 May 2006) * joco01 $ $Revision: 6785 $ $Date: 2006-05-25 22:41:52 +0000 (Thu, 25 May * 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.HashMap; import java.util.Map; 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; import wicket.util.collections.ArrayListStack; /** * This is a markup inline filter. It identifies HTML specific issues which make * HTML not 100% xml compliant. E.g. tags like <p> often are missing the * corresponding close tag. * * @author Juergen Donnerstag */ public final class HtmlHandler extends AbstractMarkupFilter { /** Logging */ private static final Log log = LogFactory.getLog(HtmlHandler.class); /** Tag stack to find balancing tags */ final private ArrayListStack<ComponentTag> stack = new ArrayListStack<ComponentTag>(); /** Map of simple tags. */ private static final Map<String, Boolean> doesNotRequireCloseTag = new HashMap<String, Boolean>(); static { // Tags which are allowed not be closed in HTML doesNotRequireCloseTag.put("p", Boolean.TRUE); doesNotRequireCloseTag.put("br", Boolean.TRUE); doesNotRequireCloseTag.put("img", Boolean.TRUE); doesNotRequireCloseTag.put("input", Boolean.TRUE); doesNotRequireCloseTag.put("hr", Boolean.TRUE); doesNotRequireCloseTag.put("link", Boolean.TRUE); doesNotRequireCloseTag.put("meta", Boolean.TRUE); } /** * Construct. * */ public HtmlHandler() { } /** * 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) { // No more tags from the markup. // If there's still a non-simple tag left, it's an error while (stack.size() > 0) { final ComponentTag top = stack.peek(); if (!requiresCloseTag(top.getName())) { stack.pop(); } else { throw new ParseException("Tag " + top + " at " + top.getPos() + " did not have a close tag", top.getPos()); } } return tag; } if (log.isDebugEnabled()) { log.debug("tag: " + tag.toUserDebugString() + ", stack: " + stack); } // Check tag type if (tag.isOpen()) { // Push onto stack stack.push(tag); } else if (tag.isClose()) { // Check that there is something on the stack if (stack.size() > 0) { // Pop the top tag off the stack ComponentTag top = stack.pop(); // If the name of the current close tag does not match the // tag on the stack then we may have a mismatched close tag boolean mismatch = !top.hasEqualTagName(tag); if (mismatch) { top.setHasNoCloseTag(true); // Pop any simple tags off the top of the stack while (mismatch && !requiresCloseTag(top.getName())) { top.setHasNoCloseTag(true); // Pop simple tag top = stack.pop(); // Does new top of stack mismatch too? mismatch = !top.hasEqualTagName(tag); } // If adjusting for simple tags did not fix the problem, // it must be a real mismatch. if (mismatch) { throw new ParseException("Tag " + top.toUserDebugString() + " has a mismatched close tag at " + tag.toUserDebugString(), top.getPos()); } } // Tag matches, so add pointer to matching tag tag.setOpenTag(top); } else { throw new ParseException("Tag " + tag.toUserDebugString() + " does not have a matching open tag", tag.getPos()); } } else if (tag.isOpenClose()) { // Tag closes itself tag.setOpenTag(tag); } return tag; } /** * Gets whether this tag does not require a closing tag. * * @param name * The tag's name, e.g. a, br, div, etc. * @return True if this tag does not require a closing tag */ public static boolean requiresCloseTag(final String name) { return doesNotRequireCloseTag.get(name) == null; } }