/*
* $Id: Push.java 651946 2008-04-27 13:41:38Z apetrelli $
*
* 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.struts2.components;
import java.io.Writer;
import org.apache.struts2.views.annotations.StrutsTag;
import org.apache.struts2.views.annotations.StrutsTagAttribute;
import com.opensymphony.xwork2.util.ValueStack;
/**
* <!-- START SNIPPET: javadoc -->
* <p>Push value on stack for simplified usage.</p>
* <!-- END SNIPPET: javadoc -->
*
* <!-- START SNIPPET: params -->
* <ul>
* <li>value* (Object) - value to be pushed into the top of the stack</li>
* </ul>
* <!-- END SNIPPET: params -->
*
*
* <p/> <b>Examples</b>
* <pre>
* <!-- START SNIPPET: example1 -->
* <s:push value="user">
* <s:propery value="firstName" />
* <s:propery value="lastName" />
* </s:push>
* <!-- END SNIPPET: example1 -->
* </pre>
*
* <!-- START SNIPPET: example1description -->
* Pushed user into the stack, and hence property tag could access user's properties
* (firstName, lastName etc) since user is not at the top of the stack
* <!-- END SNIPPET: example1description -->
*
* <pre>
* <!-- START SNIPPET: example2 -->
* <s:push value="myObject"> ----- (1)
* <s:bean name="jp.SomeBean" var="myBean"/> ----- (2)
* <s:param name="myParam" value="top"/> ----- (3)
* </s:bean>
* </s:push>
* <!-- END SNIPPET: example2 -->
* </pre>
*
* <pre>
* <!-- START SNIPPET: example2description -->
* when in (1), myObject is at the top of the stack
* when in (2), jp.SomeBean is in the top of stack, also in stack's context with key myBean
* when in (3), top will get the jp.SomeBean instance
* <!-- END SNIPPET: example2description -->
* </pre>
*
* <pre>
* <!-- START SNIPPET: example3 -->
* <s:push value="myObject"> ---(A)
* <s:bean name="jp.SomeBean" var="myBean"/> ---(B)
* <s:param name="myParam" value="top.mySomeOtherValue"/> ---(C)
* </s:bean>
* </s:push>
* <!-- END SNIPPET: example3 -->
* </pre>
*
* <pre>
* <!-- START SNIPPET: example3description -->
* when in (A), myObject is at the top of the stack
* when in (B), jp.SomeBean is at the top of the stack, also in context with key myBean
* when in (C), top refers to jp.SomeBean instance. so top.mySomeOtherValue would invoke SomeBean's mySomeOtherValue() method
* <!-- END SNIPPET: example3description -->
* </pre>
*
* <pre>
* <!-- START SNIPPET: example4 -->
* <s:push value="myObject"> ---- (i)
* <s:bean name="jp.SomeBean" var="myBean"/> ---- (ii)
* <s:param name="myParam" value="[1].top"/> -----(iii)
* </s:bean>
* </s:push>
* <!-- END SNIPPET: example4 -->
* </pre>
*
* <pre>
* <!-- START SNIPPET: example4description -->
* when in (i), myObject is at the top of the stack
* when in (ii), jp.SomeBean is at the top of the stack, followed by myObject
* when in (iii), [1].top will returned top of the cut of stack starting from myObject, namely myObject itself
* <!-- END SNIPPET: example4description -->
* </pre>
*
*/
@StrutsTag(name="push", tldTagClass="org.apache.struts2.views.jsp.PushTag", description="Push value on stack for simplified usage.")
public class Push extends Component {
protected String value;
protected boolean pushed;
public Push(ValueStack stack) {
super(stack);
}
public boolean start(Writer writer) {
boolean result = super.start(writer);
ValueStack stack = getStack();
if (stack != null) {
stack.push(findValue(value, "value", "You must specify a value to push on the stack. Example: person"));
pushed = true;
} else {
pushed = false; // need to ensure push is assigned, otherwise we may have a leftover value
}
return result;
}
public boolean end(Writer writer, String body) {
ValueStack stack = getStack();
if (pushed && (stack != null)) {
stack.pop();
}
return super.end(writer, body);
}
@StrutsTagAttribute(description="Value to push on stack", required=true)
public void setValue(String value) {
this.value = value;
}
}
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