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 java.util.*;
059: import javax.servlet.jsp.*;
060: import javax.servlet.jsp.tagext.*;
061: import javax.servlet.jsptl.IteratorTag;
062: import org.apache.taglibs.jsptl.tag.common.*;
063: import org.apache.taglibs.jsptl.lang.support.ExpressionEvaluatorManager;
064:
065: /**
066: * <p>A handler for <forEach> that accepts attributes as Strings
067: * and evaluates them as expressions at runtime.</p>
068: *
069: * @author Shawn Bayern
070: */
071:
072: public class ForEachTag extends ForEachSupport implements IteratorTag,
073: BodyTag {
074:
075: //*********************************************************************
076: // 'Private' state (implementation details)
077:
078: private String begin_; // stores EL-based property
079: private String end_; // stores EL-based property
080: private String step_; // stores EL-based property
081: private String items_; // stores EL-based property
082:
083: //*********************************************************************
084: // Constructor
085:
086: /**
087: * Constructs a new IteratorTagSupport. As with TagSupport, subclasses
088: * should not provide other constructors and are expected to call
089: * the superclass constructor
090: */
091: public ForEachTag() {
092: super ();
093: init();
094: }
095:
096: //*********************************************************************
097: // Tag logic
098:
099: /* Begins iterating by processing the first item. */
100: public int doStartTag() throws JspException {
101:
102: // evaluate any expressions we were passed, once per invocation
103: evaluateExpressions();
104:
105: // chain to the parent implementation
106: return super .doStartTag();
107: }
108:
109: // Releases any resources we may have (or inherit)
110: public void release() {
111: super .release();
112: init();
113: }
114:
115: //*********************************************************************
116: // Accessor methods
117:
118: // for EL-based attribute
119: public void setBegin(String begin_) {
120: this .begin_ = begin_;
121: this .beginSpecified = true;
122: }
123:
124: // for EL-based attribute
125: public void setEnd(String end_) {
126: this .end_ = end_;
127: this .endSpecified = true;
128: }
129:
130: // for EL-based attribute
131: public void setStep(String step_) {
132: this .step_ = step_;
133: this .stepSpecified = true;
134: }
135:
136: public void setItems(String items_) {
137: this .items_ = items_;
138: }
139:
140: //*********************************************************************
141: // Private (utility) methods
142:
143: // (re)initializes state (during release() or construction)
144: private void init() {
145: // defaults for interface with page author
146: begin_ = null; // (no expression)
147: end_ = null; // (no expression)
148: step_ = null; // (no expression)
149: items_ = null; // (no expression)
150: }
151:
152: /* Evaluates expressions as necessary */
153: private void evaluateExpressions() throws JspException {
154: /*
155: * Note: we don't check for type mismatches here; we assume
156: * the expression evaluator will return the expected type
157: * (by virtue of knowledge we give it about what that type is).
158: * A ClassCastException here is truly unexpected, so we let it
159: * propagate up.
160: */
161:
162: if (begin_ != null) {
163: Object r = ExpressionEvaluatorManager.evaluate("begin",
164: begin_, Integer.class, this , pageContext);
165: if (r == null)
166: throw new NullAttributeException("forEach", "begin");
167: begin = ((Integer) r).intValue();
168: validateBegin();
169: }
170:
171: if (end_ != null) {
172: Object r = ExpressionEvaluatorManager.evaluate("end", end_,
173: Integer.class, this , pageContext);
174: if (r == null)
175: throw new NullAttributeException("forEach", "end");
176: end = ((Integer) r).intValue();
177: validateEnd();
178: }
179:
180: if (step_ != null) {
181: Object r = ExpressionEvaluatorManager.evaluate("step",
182: step_, Integer.class, this , pageContext);
183: if (r == null)
184: throw new NullAttributeException("forEach", "step");
185: step = ((Integer) r).intValue();
186: validateStep();
187: }
188:
189: if (items_ != null) {
190: rawItems = ExpressionEvaluatorManager.evaluate("items",
191: items_, Object.class, this , pageContext);
192: if (rawItems == null)
193: throw new NullAttributeException("forEach", "items");
194: }
195: }
196: }
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