org.apache.myfaces.trinidad.webapp.TrinidadTagSupport Maven / Gradle / Ivy
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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.apache.myfaces.trinidad.webapp;
import java.util.Enumeration;
import java.util.Hashtable;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.IterationTag;
import javax.servlet.jsp.tagext.Tag;
/**
* This is the Trinidad version of the JSP TagSupport class.
* The main difference is that this class is NOT implementing the
* Serializable interface.
*
* @author Apache Tomcat team
*/
public class TrinidadTagSupport implements IterationTag
{
/**
* Find the instance of a given class type that is closest to a given
* instance. This method uses the getParent method from the Tag interface.
* This method is used for coordination among cooperating tags.
*
*
* The current version of the specification only provides one formal way of
* indicating the observable type of a tag handler: its tag handler
* implementation class, described in the tag-class subelement of the tag
* element. This is extended in an informal manner by allowing the tag library
* author to indicate in the description subelement an observable type. The
* type should be a subtype of the tag handler implementation class or void.
* This addititional constraint can be exploited by a specialized container
* that knows about that specific tag library, as in the case of the JSP
* standard tag library.
*
*
* When a tag library author provides information on the observable type of a
* tag handler, client programmatic code should adhere to that constraint.
* Specifically, the Class passed to findAncestorWithClass should be a subtype
* of the observable type.
*
*
* @param from
* The instance from where to start looking.
* @param klass
* The subclass of Tag or interface to be matched
* @return the nearest ancestor that implements the interface or is an
* instance of the class specified
*/
public static final Tag findAncestorWithClass(Tag from,
// TCK signature test fails with generics
@SuppressWarnings("unchecked") Class klass)
{
boolean isInterface = false;
if (from == null
|| klass == null
|| (!Tag.class.isAssignableFrom(klass) && !(isInterface = klass
.isInterface())))
{
return null;
}
for (;;)
{
Tag tag = from.getParent();
if (tag == null)
{
return null;
}
if ((isInterface && klass.isInstance(tag))
|| klass.isAssignableFrom(tag.getClass()))
return tag;
else
from = tag;
}
}
/**
* Default constructor, all subclasses are required to define only a public
* constructor with the same signature, and to call the superclass
* constructor.
*
* This constructor is called by the code generated by the JSP translator.
*/
public TrinidadTagSupport()
{
}
/**
* Default processing of the start tag, returning SKIP_BODY.
*
* @return SKIP_BODY
* @throws JspException
* if an error occurs while processing this tag
*
* @see Tag#doStartTag()
*/
public int doStartTag() throws JspException
{
return SKIP_BODY;
}
/**
* Default processing of the end tag returning EVAL_PAGE.
*
* @return EVAL_PAGE
* @throws JspException
* if an error occurs while processing this tag
*
* @see Tag#doEndTag()
*/
public int doEndTag() throws JspException
{
return EVAL_PAGE;
}
/**
* Default processing for a body.
*
* @return SKIP_BODY
* @throws JspException
* if an error occurs while processing this tag
*
* @see IterationTag#doAfterBody()
*/
public int doAfterBody() throws JspException
{
return SKIP_BODY;
}
// Actions related to body evaluation
/**
* Release state.
*
* @see Tag#release()
*/
public void release()
{
parent = null;
id = null;
if (values != null)
{
values.clear();
}
values = null;
}
/**
* Set the nesting tag of this tag.
*
* @param t
* The parent Tag.
* @see Tag#setParent(Tag)
*/
public void setParent(Tag t)
{
parent = t;
}
/**
* The Tag instance most closely enclosing this tag instance.
*
* @see Tag#getParent()
*
* @return the parent tag instance or null
*/
public Tag getParent()
{
return parent;
}
/**
* Set the id attribute for this tag.
*
* @param id
* The String for the id.
*/
public void setId(String id)
{
this.id = id;
}
/**
* The value of the id attribute of this tag; or null.
*
* @return the value of the id attribute, or null
*/
public String getId()
{
return id;
}
/**
* Set the page context.
*
* @param pageContext
* The PageContext.
* @see Tag#setPageContext
*/
public void setPageContext(PageContext pageContext)
{
this.pageContext = pageContext;
}
/**
* Associate a value with a String key.
*
* @param k
* The key String.
* @param o
* The value to associate.
*/
public void setValue(String k, Object o)
{
if (values == null)
{
values = new Hashtable();
}
values.put(k, o);
}
/**
* Get a the value associated with a key.
*
* @param k
* The string key.
* @return The value associated with the key, or null.
*/
public Object getValue(String k)
{
if (values == null)
{
return null;
} else
{
return values.get(k);
}
}
/**
* Remove a value associated with a key.
*
* @param k
* The string key.
*/
public void removeValue(String k)
{
if (values != null)
{
values.remove(k);
}
}
/**
* Enumerate the keys for the values kept by this tag handler.
*
* @return An enumeration of all the keys for the values set, or null or an
* empty Enumeration if no values have been set.
*/
public Enumeration getValues()
{
if (values == null)
{
return null;
}
return values.keys();
}
// private fields
private Tag parent;
private Hashtable values;
/**
* The value of the id attribute of this tag; or null.
*/
protected String id;
// protected fields
/**
* The PageContext.
*/
protected PageContext pageContext;
}