// Copyright 2004, 2005 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.tapestry.form;
import java.util.HashSet;
import java.util.Set;
import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.tapestry.IForm;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.Tapestry;
/**
* Implements a component that manages an HTML <select> form element. The most common
* situation, using a <select> to set a specific property of some object, is best handled
* using a {@link PropertySelection}component. [ <a
* href="../../../../../ComponentReference/Select.html">Component Reference </a>]
* <p>
* Otherwise, this component is very similar to {@link RadioGroup}.
*
* @author Howard Lewis Ship
*/
public abstract class Select extends AbstractFormComponent
{
private boolean _rewinding;
private boolean _rendering;
private Set _selections;
private int _nextOptionId;
/**
* Used by the <code>Select</code> to record itself as a {@link IRequestCycle}attribute, so
* that the {@link Option}components it wraps can have access to it.
*/
private final static String ATTRIBUTE_NAME = "org.apache.tapestry.active.Select";
public static Select get(IRequestCycle cycle)
{
return (Select) cycle.getAttribute(ATTRIBUTE_NAME);
}
public abstract boolean isDisabled();
public abstract boolean isMultiple();
public boolean isRewinding()
{
if (!_rendering)
throw Tapestry.createRenderOnlyPropertyException(this, "rewinding");
return _rewinding;
}
public String getNextOptionId()
{
if (!_rendering)
throw Tapestry.createRenderOnlyPropertyException(this, "nextOptionId");
// Return it as a hex value.
return Integer.toString(_nextOptionId++);
}
public boolean isSelected(String value)
{
if (_selections == null)
return false;
return _selections.contains(value);
}
/**
* Renders the <option> element, or responds when the form containing the element is
* submitted (by checking {@link IForm#isRewinding()}.
*/
protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
{
IForm form = getForm(cycle);
if (form.wasPrerendered(writer, this))
return;
if (cycle.getAttribute(ATTRIBUTE_NAME) != null)
throw new ApplicationRuntimeException(Tapestry.getMessage("Select.may-not-nest"), this,
null, null);
// It isn't enough to know whether the cycle in general is rewinding, need to know
// specifically if the form which contains this component is rewinding.
_rewinding = form.isRewinding();
// Used whether rewinding or not.
String name = form.getElementId(this);
cycle.setAttribute(ATTRIBUTE_NAME, this);
if (_rewinding)
{
_selections = buildSelections(cycle, name);
}
else
{
writer.begin("select");
writer.attribute("name", name);
if (isMultiple())
writer.attribute("multiple", "multiple");
if (isDisabled())
writer.attribute("disabled", "disabled");
renderInformalParameters(writer, cycle);
}
_rendering = true;
_nextOptionId = 0;
renderBody(writer, cycle);
if (!_rewinding)
{
writer.end();
}
cycle.removeAttribute(ATTRIBUTE_NAME);
}
protected void cleanupAfterRender(IRequestCycle cycle)
{
_rendering = false;
_selections = null;
super.cleanupAfterRender(cycle);
}
/**
* Cut-and-paste with {@link RadioGroup}!
*/
private Set buildSelections(IRequestCycle cycle, String parameterName)
{
String[] parameters = cycle.getParameters(parameterName);
if (parameters == null)
return null;
int length = parameters.length;
int size = (parameters.length > 30) ? 101 : 7;
Set result = new HashSet(size);
for (int i = 0; i < length; i++)
result.add(parameters[i]);
return result;
}
}