| // Copyright 2009, 2010 The Apache Software Foundation |
| // |
| // 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 org.apache.tapestry5.corelib.internal; |
| |
| import org.apache.tapestry5.MarkupWriter; |
| import org.apache.tapestry5.MarkupWriterListener; |
| import org.apache.tapestry5.dom.Element; |
| import org.apache.tapestry5.ioc.internal.util.OneShotLock; |
| import org.apache.tapestry5.services.HiddenFieldLocationRules; |
| |
| /** |
| * Used to position a hidden field (as part of a form-related component). Hidden fields are not allowed to go just |
| * anywhere, there are rules, dictated by the (X)HTML schema, about where they are allowed. We use the |
| * {@link org.apache.tapestry5.MarkupWriterListener} interface to monitor elements as they are started and ended to find |
| * a |
| * place to put content. |
| */ |
| public class HiddenFieldPositioner |
| { |
| /** |
| * The type of element to create. |
| */ |
| private static final String ELEMENT = "input"; |
| |
| private final MarkupWriter writer; |
| |
| private final HiddenFieldLocationRules rules; |
| |
| private final OneShotLock lock = new OneShotLock(); |
| |
| private Element hiddenFieldElement; |
| |
| private final MarkupWriterListener listener = new MarkupWriterListener() |
| { |
| public void elementDidStart(Element element) |
| { |
| if (rules.placeHiddenFieldInside(element)) |
| { |
| hiddenFieldElement = element.element(ELEMENT); |
| writer.removeListener(this); |
| } |
| } |
| |
| public void elementDidEnd(Element element) |
| { |
| if (rules.placeHiddenFieldAfter(element)) |
| { |
| hiddenFieldElement = element.getContainer().element(ELEMENT); |
| writer.removeListener(this); |
| } |
| } |
| }; |
| |
| public HiddenFieldPositioner(MarkupWriter writer, HiddenFieldLocationRules rules) |
| { |
| this.writer = writer; |
| this.rules = rules; |
| |
| this.writer.addListener(listener); |
| } |
| |
| /** |
| * Returns the hidden field element, which can have its attributes filled in. |
| * |
| * @return the element |
| * @throws IllegalStateException |
| * if the element was not positioned |
| */ |
| public Element getElement() |
| { |
| lock.lock(); |
| |
| // Remove the listener if it hasn't been removed already. |
| |
| writer.removeListener(listener); |
| |
| if (hiddenFieldElement == null) |
| throw new IllegalStateException( |
| "The rendered content did not include any elements that allow for the positioning of the hidden form field's element."); |
| |
| return hiddenFieldElement; |
| } |
| |
| /** |
| * Discard this positioner (an alternative to invoking {@link #getElement()}). |
| * If an {@link Element} has been created for the hidden field, that |
| * element is removed. |
| * |
| * @since 5.2.0 |
| */ |
| public void discard() |
| { |
| lock.lock(); |
| |
| if (hiddenFieldElement != null) |
| hiddenFieldElement.remove(); |
| |
| writer.removeListener(listener); |
| } |
| |
| } |