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package com.sun.faces.taglib.jsf_core;
import javax.el.ELContext;
import javax.el.ValueExpression;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.webapp.UIComponentELTag;
import javax.faces.webapp.UIComponentClassicTagBase;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import com.sun.faces.util.MessageUtils;
/**
* <p>Tag implementation that adds an attribute with a specified name
* and String value to the component whose tag it is nested inside,
* if the component does not already contain an attribute with the
* same name. This tag creates no output to the page currently
* being created.</p>
*
*/
public class AttributeTag extends TagSupport {
// ------------------------------------------------------------- Attributes
/**
* <p>The name of the attribute to be created, if not already present.
*/
private ValueExpression name = null;
/**
* <p>Set the attribute name.</p>
*
* @param name The new attribute name
*/
public void setName(ValueExpression name) {
this.name = name;
}
/**
* <p>The value to be associated with this attribute, if it is created.</p>
*/
private ValueExpression value = null;
/**
* <p>Set the attribute value.</p>
*
* @param value The new attribute value
*/
public void setValue(ValueExpression value) {
this.value = value;
}
// -------------------------------------------------------- Methods from Tag
/**
* <p>Register the specified attribute name and value with the
* {@link UIComponent} instance associated with our most immediately
* surrounding {@link UIComponentClassicTagBase} instance, if this
* {@link UIComponent} does not already have a value for the
* specified attribute name.</p>
*
* @exception JspException if a JSP error occurs
*/
public int doStartTag() throws JspException {
// Locate our parent UIComponentTagBase
UIComponentClassicTagBase tag =
UIComponentELTag.getParentUIComponentClassicTagBase(pageContext);
if (tag == null) {
String message = MessageUtils.getExceptionMessageString
(MessageUtils.NOT_NESTED_IN_UICOMPONENT_TAG_ERROR_MESSAGE_ID);
throw new JspException(message);
}
// Add this attribute if it is not already defined
UIComponent component = tag.getComponentInstance();
if (component == null) {
String message = MessageUtils.getExceptionMessageString
(MessageUtils.NO_COMPONENT_ASSOCIATED_WITH_UICOMPONENT_TAG_MESSAGE_ID);
throw new JspException(message);
}
FacesContext context = FacesContext.getCurrentInstance();
ELContext elContext = context.getELContext();
String nameVal = null;
Object valueVal = null;
boolean isLiteral = false;
if (name != null) {
nameVal = (String) name.getValue(elContext);
}
if (value != null) {
if (isLiteral = value.isLiteralText()) {
valueVal = value.getValue(elContext);
}
}
if (component.getAttributes().get(nameVal) == null) {
if (isLiteral) {
component.getAttributes().put(nameVal, valueVal);
}
else {
component.setValueExpression(nameVal, value);
}
}
return (SKIP_BODY);
}
public int doEndTag() throws JspException {
this.release();
return (EVAL_PAGE);
}
/**
* <p>Release references to any acquired resources.
*/
public void release() {
this.name = null;
this.value = null;
} // END release
}