001: /*
002: * The Apache Software License, Version 1.1
003: *
004: * Copyright (c) 1999 The Apache Software Foundation. All rights
005: * reserved.
006: *
007: * Redistribution and use in source and binary forms, with or without
008: * modification, are permitted provided that the following conditions
009: * are met:
010: *
011: * 1. Redistributions of source code must retain the above copyright
012: * notice, this list of conditions and the following disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The end-user documentation included with the redistribution, if
020: * any, must include the following acknowlegement:
021: * "This product includes software developed by the
022: * Apache Software Foundation (http://www.apache.org/)."
023: * Alternately, this acknowlegement may appear in the software itself,
024: * if and wherever such third-party acknowlegements normally appear.
025: *
026: * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
027: * Foundation" must not be used to endorse or promote products derived
028: * from this software without prior written permission. For written
029: * permission, please contact apache@apache.org.
030: *
031: * 5. Products derived from this software may not be called "Apache"
032: * nor may "Apache" appear in their names without prior written
033: * permission of the Apache Group.
034: *
035: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
036: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
037: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
038: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
039: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
040: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
041: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
042: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
043: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
044: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
045: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
046: * SUCH DAMAGE.
047: * ====================================================================
048: *
049: * This software consists of voluntary contributions made by many
050: * individuals on behalf of the Apache Software Foundation. For more
051: * information on the Apache Software Foundation, please see
052: * <http://www.apache.org/>.
053: *
054: */
055:
056: package org.apache.taglibs.jsptl.tag.jx;
057:
058: import javax.servlet.jsp.*;
059: import javax.servlet.jsp.tagext.*;
060: import org.apache.taglibs.jsptl.lang.support.ExpressionEvaluatorManager;
061:
062: /**
063: * <p>A tag that temporarily "installs" a new ExpressionEvaluator for its
064: * body.</p>
065: *
066: * <p><b>WARNING</b>: This class supports experimentation for the EA1
067: * release of JSPTL; it is not expected to be part of the final RI or
068: * specification.</p>
069: *
070: * @author Shawn Bayern
071: */
072:
073: public class ExpressionLanguageTag extends TagSupport {
074:
075: //*********************************************************************
076: // Internal state
077:
078: // the expression language we want to install
079: private String evaluator;
080:
081: // marks installation success so we know to uninstall
082: private boolean success;
083:
084: //*********************************************************************
085: // Construction and initialization
086:
087: /**
088: * Constructs a new ExpressionLanguageTag. As with TagSupport,
089: * subclasses should not provide other constructors and are expected
090: * to call the superclass constructor.
091: */
092: public ExpressionLanguageTag() {
093: super ();
094: init();
095: }
096:
097: // resets local state
098: private void init() {
099: evaluator = null;
100: success = false;
101: }
102:
103: // Releases any resources we may have (or inherit)
104: public void release() {
105: super .release();
106: init();
107: }
108:
109: //*********************************************************************
110: // Tag logic
111:
112: // Installs the requested expression evaluator
113: public int doStartTag() throws JspException {
114: success = false;
115: ExpressionEvaluatorManager
116: .pushEvaluator(pageContext, evaluator);
117: success = true;
118: return EVAL_BODY_INCLUDE;
119: }
120:
121: // Simply re-throws its Throwable to make sure we don't mask errors
122: public void doCatch(Throwable t) throws Throwable {
123: throw t;
124: }
125:
126: // Makes sure we don't leave an evaluator lying around
127: public void doFinally() {
128: if (success)
129: ExpressionEvaluatorManager.popEvaluator(pageContext);
130: }
131:
132: //*********************************************************************
133: // Accessor methods
134:
135: // for tag attribute
136: public void setEvaluator(String evaluator) {
137: this.evaluator = evaluator;
138: }
139:
140: }
|