/*
* $Header: /home/cvs/jakarta-struts/src/share/org/apache/struts/taglib/logic/IterateTag.java,v 1.11.2.1 2001/06/14 04:24:27 martinc Exp $
* $Revision: 1.11.2.1 $
* $Date: 2001/06/14 04:24:27 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Struts", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
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*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.struts.taglib.logic;
import java.util.Arrays;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.BodyTagSupport;
import org.apache.struts.util.IteratorAdapter;
import org.apache.struts.util.MessageResources;
import org.apache.struts.util.PropertyUtils;
import org.apache.struts.util.RequestUtils;
import org.apache.struts.util.ResponseUtils;
/**
* Custom tag that iterates the elements of a collection, which can be
* either an attribute or the property of an attribute. The collection
* can be any of the following: an array of objects, an Enumeration,
* an Iterator, a Collection (which includes Lists, Sets and Vectors),
* or a Map (which includes Hashtables) whose elements will be iterated over.
*
* @author Craig R. McClanahan
* @version $Revision: 1.11.2.1 $ $Date: 2001/06/14 04:24:27 $
*/
public class IterateTag extends BodyTagSupport {
// ----------------------------------------------------- Instance Variables
/**
* Iterator of the elements of this collection, while we are actually
* running.
*/
protected Iterator iterator = null;
/**
* The number of elements we have already rendered.
*/
protected int lengthCount = 0;
/**
* The actual length value (calculated in the start tag).
*/
protected int lengthValue = 0;
/**
* The message resources for this package.
*/
protected static MessageResources messages =
MessageResources.getMessageResources
("org.apache.struts.taglib.logic.LocalStrings");
/**
* The actual offset value (calculated in the start tag).
*/
protected int offsetValue = 0;
/**
* Has this tag instance been started?
*/
protected boolean started = false;
// ------------------------------------------------------------- Properties
/**
* The collection over which we will be iterating.
*/
protected Object collection = null;
public Object getCollection() {
return (this.collection);
}
public void setCollection(Object collection) {
this.collection = collection;
}
/**
* The name of the scripting variable to be exposed.
*/
protected String id = null;
public String getId() {
return (this.id);
}
public void setId(String id) {
this.id = id;
}
/**
* <p>Return the zero-relative index of the current iteration through the
* loop. If you specify an <code>offset</code>, the first iteration
* through the loop will have that value; otherwise, the first iteration
* will return zero.</p>
*
* <p>This property is read-only, and gives nested custom tags access to
* this information. Therefore, it is <strong>only</strong> valid in
* between calls to <code>doStartTag()</code> and <code>doEndTag()</code>.
* </p>
*/
public int getIndex() {
if (started)
return (offsetValue + lengthCount - 1);
else
return (0);
}
/**
* The name of the scripting variable to be exposed as the current index.
*/
protected String indexId = null;
public String getIndexId() {
return (this.indexId);
}
public void setIndexId(String indexId) {
this.indexId = indexId;
}
/**
* The length value or attribute name (<=0 means no limit).
*/
protected String length = null;
public String getLength() {
return (this.length);
}
public void setLength(String length) {
this.length = length;
}
/**
* The name of the collection or owning bean.
*/
protected String name = null;
public String getName() {
return (this.name);
}
public void setName(String name) {
this.name = name;
}
/**
* The starting offset (zero relative).
*/
protected String offset = null;
public String getOffset() {
return (this.offset);
}
public void setOffset(String offset) {
this.offset = offset;
}
/**
* The property name containing the collection.
*/
protected String property = null;
public String getProperty() {
return (this.property);
}
public void setProperty(String property) {
this.property = property;
}
/**
* The scope of the bean specified by the name property, if any.
*/
protected String scope = null;
public String getScope() {
return (this.scope);
}
public void setScope(String scope) {
this.scope = scope;
}
/**
* The Java class of each exposed element of the collection.
*/
protected String type = null;
public String getType() {
return (this.type);
}
public void setType(String type) {
this.type = type;
}
// --------------------------------------------------------- Public Methods
/**
* Construct an iterator for the specified collection, and begin
* looping through the body once per element.
*
* @exception JspException if a JSP exception has occurred
*/
public int doStartTag() throws JspException {
// Acquire the collection we are going to iterate over
Object collection = this.collection;
if (collection == null)
collection =
RequestUtils.lookup(pageContext, name, property, scope);
if (collection == null) {
JspException e = new JspException
(messages.getMessage("iterate.collection"));
RequestUtils.saveException(pageContext, e);
throw e;
}
// Construct an iterator for this collection
if (collection.getClass().isArray())
collection = Arrays.asList((Object[]) collection);
if (collection instanceof Collection)
iterator = ((Collection) collection).iterator();
else if (collection instanceof Iterator)
iterator = (Iterator) collection;
else if (collection instanceof Map)
iterator = ((Map) collection).entrySet().iterator();
else if (collection instanceof Enumeration)
iterator = new IteratorAdapter((Enumeration)collection);
else {
JspException e = new JspException
(messages.getMessage("iterate.iterator"));
RequestUtils.saveException(pageContext, e);
throw e;
}
// Calculate the starting offset
if (offset == null)
offsetValue = 0;
else {
try {
offsetValue = Integer.parseInt(offset);
} catch (NumberFormatException e) {
Integer offsetObject =
(Integer) pageContext.findAttribute(offset);
if (offsetObject == null)
offsetValue = 0;
else
offsetValue = offsetObject.intValue();
}
}
if (offsetValue < 0)
offsetValue = 0;
// Calculate the rendering length
if (length == null)
lengthValue = 0;
else {
try {
lengthValue = Integer.parseInt(length);
} catch (NumberFormatException e) {
Integer lengthObject =
(Integer) pageContext.findAttribute(length);
if (lengthObject == null)
lengthValue = 0;
else
lengthValue = lengthObject.intValue();
}
}
if (lengthValue < 0)
lengthValue = 0;
lengthCount = 0;
// Skip the leading elements up to the starting offset
for (int i = 0; i < offsetValue; i++) {
if (iterator.hasNext()) {
Object element = iterator.next();
}
}
// Store the first value and evaluate, or skip the body if none
if (iterator.hasNext()) {
Object element = iterator.next();
if (element == null)
pageContext.removeAttribute(id);
else
pageContext.setAttribute(id, element);
lengthCount++;
started = true;
if (indexId != null)
pageContext.setAttribute(indexId, new Integer(getIndex()));
return (EVAL_BODY_TAG);
} else
return (SKIP_BODY);
}
/**
* Make the next collection element available and loop, or
* finish the iterations if there are no more elements.
*
* @exception JspException if a JSP exception has occurred
*/
public int doAfterBody() throws JspException {
// Render the output from this iteration to the output stream
if (bodyContent != null) {
ResponseUtils.writePrevious(pageContext, bodyContent.getString());
bodyContent.clearBody();
}
// Decide whether to iterate or quit
if ((lengthValue > 0) && (lengthCount >= lengthValue))
return (SKIP_BODY);
if (iterator.hasNext()) {
Object element = iterator.next();
if (element == null)
pageContext.removeAttribute(id);
else
pageContext.setAttribute(id, element);
lengthCount++;
if (indexId != null)
pageContext.setAttribute(indexId, new Integer(getIndex()));
return (EVAL_BODY_TAG);
} else
return (SKIP_BODY);
}
/**
* Clean up after processing this enumeration.
*
* @exception JspException if a JSP exception has occurred
*/
public int doEndTag() throws JspException {
// Clean up our started state
started = false;
// Continue processing this page
return (EVAL_PAGE);
}
/**
* Release all allocated resources.
*/
public void release() {
super.release();
iterator = null;
lengthCount = 0;
lengthValue = 0;
offsetValue = 0;
id = null;
collection = null;
length = null;
name = null;
offset = null;
property = null;
scope = null;
started = false;
}
}