// Copyright 2009 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.base;
import org.apache.tapestry5.BindingConstants;
import org.apache.tapestry5.Block;
import org.apache.tapestry5.ComponentResources;
import org.apache.tapestry5.MarkupWriter;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.annotations.SupportsInformalParameters;
import org.apache.tapestry5.ioc.annotations.Inject;
/**
* Base class for {@link org.apache.tapestry5.corelib.components.If} and {@link org.apache.tapestry5.corelib.components.Unless}.
* Will render its body or the block from its else parameter. If it renders anything and it has an element name, then
* it renders the element and its informal parameters.
*/
@SupportsInformalParameters
public abstract class AbstractConditional
{
@Inject
private ComponentResources resources;
/**
* Performs the test via the parameters; return true to render the body of the component, false to render the else
* block (or nothing).
*
* @return true to render body
*/
protected abstract boolean test();
/**
* An alternate {@link org.apache.tapestry5.Block} to render if {@link #test()} is false. The default, null, means
* render nothing in that situation.
*/
@Parameter(name = "else", defaultPrefix = BindingConstants.LITERAL)
private Block elseBlock;
private boolean renderTag;
/**
* Returns null if the {@link #test()} is true, which allows normal rendering (of the body). If the test parameter
* is false, returns the else parameter (this may also be null).
*/
Object beginRender(MarkupWriter writer)
{
Block toRender = test() ? resources.getBody() : elseBlock;
String elementName = resources.getElementName();
renderTag = toRender != null && elementName != null;
if (renderTag)
{
writer.element(elementName);
resources.renderInformalParameters(writer);
}
return toRender;
}
/**
* If {@link #test()} is true, then the body is rendered, otherwise not. The component does not have a template or
* do any other rendering besides its body.
*/
boolean beforeRenderBody()
{
return false;
}
void afterRenderBody(MarkupWriter writer)
{
if (renderTag)
writer.end();
}
}