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Java > Open Source Codes > freemarker > core > NewBI


1 /*
2  * Copyright (c) 2003 The Visigoth Software Society. All rights
3  * reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  *
12  * 2. Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in
14  * the documentation and/or other materials provided with the
15  * distribution.
16  *
17  * 3. The end-user documentation included with the redistribution, if
18  * any, must include the following acknowledgement:
19  * "This product includes software developed by the
20  * Visigoth Software Society (http://www.visigoths.org/)."
21  * Alternately, this acknowledgement may appear in the software itself,
22  * if and wherever such third-party acknowledgements normally appear.
23  *
24  * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
25  * project contributors may be used to endorse or promote products derived
26  * from this software without prior written permission. For written
27  * permission, please contact visigoths@visigoths.org.
28  *
29  * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
30  * nor may "FreeMarker" or "Visigoth" appear in their names
31  * without prior written permission of the Visigoth Software Society.
32  *
33  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
34  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
36  * DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
37  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
38  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
39  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
40  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
41  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
42  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
43  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44  * SUCH DAMAGE.
45  * ====================================================================
46  *
47  * This software consists of voluntary contributions made by many
48  * individuals on behalf of the Visigoth Software Society. For more
49  * information on the Visigoth Software Society, please see
50  * http://www.visigoths.org/
51  */

52
53 package freemarker.core;
54
55 import java.util.List JavaDoc;
56
57 import freemarker.ext.beans.BeansWrapper;
58 import freemarker.template.ObjectWrapper;
59 import freemarker.template.TemplateException;
60 import freemarker.template.TemplateMethodModelEx;
61 import freemarker.template.TemplateModel;
62 import freemarker.template.TemplateModelException;
63 import freemarker.template.TemplateScalarModel;
64 import freemarker.template.utility.ClassUtil;
65
66 /**
67  * A built-in that allows us to instantiate an instance of a java class.
68  * Usage is something like:
69  * <#assign foobar = "foo.bar.MyClass"?new() />
70  */

71
72 class NewBI extends BuiltIn
73 {
74     
75     static final Class JavaDoc TM_CLASS = TemplateModel.class;
76     static final Class JavaDoc BEAN_MODEL_CLASS = freemarker.ext.beans.BeanModel.class;
77     static Class JavaDoc JYTHON_MODEL_CLASS;
78     static {
79         try {
80             JYTHON_MODEL_CLASS = Class.forName("freemarker.ext.jython.JythonModel");
81         } catch (Throwable JavaDoc e) {
82             JYTHON_MODEL_CLASS = null;
83         }
84     }
85     
86     TemplateModel _getAsTemplateModel(Environment env)
87             throws TemplateException
88     {
89         TemplateModel tm = target.getAsTemplateModel(env);
90         String JavaDoc classname = null;
91         try {
92             classname = ((TemplateScalarModel) tm).getAsString();
93         }
94         catch (ClassCastException JavaDoc cce) {
95             invalidTypeException(tm, target, env, "string");
96         }
97         catch (NullPointerException JavaDoc npe) {
98             throw new InvalidReferenceException(getStartLocation()
99                 + "\nCould not resolve expression: " + target, env);
100         }
101         return new ConstructorFunction(classname, env);
102     }
103
104     class ConstructorFunction implements TemplateMethodModelEx {
105
106         private final Class JavaDoc cl;
107         private final Environment env;
108         
109         public ConstructorFunction(String JavaDoc classname, Environment env) throws TemplateException {
110             this.env = env;
111             try {
112                 cl = ClassUtil.forName(classname);
113                 if (!TM_CLASS.isAssignableFrom(cl)) {
114                     throw new TemplateException("Class " + cl.getName() + " does not implement freemarker.template.TemplateModel", env);
115                 }
116                 if (BEAN_MODEL_CLASS.isAssignableFrom(cl)) {
117                     throw new TemplateException("Bean Models cannot be instantiated using the ?new built-in", env);
118                 }
119                 if (JYTHON_MODEL_CLASS != null && JYTHON_MODEL_CLASS.isAssignableFrom(cl)) {
120                     throw new TemplateException("Jython Models cannot be instantiated using the ?new built-in", env);
121                 }
122             }
123             catch (ClassNotFoundException JavaDoc cnfe) {
124                 throw new TemplateException(cnfe, env);
125             }
126         }
127
128         public Object JavaDoc exec(List JavaDoc arguments) throws TemplateModelException {
129             ObjectWrapper ow = env.getObjectWrapper();
130             BeansWrapper bw =
131                 ow instanceof BeansWrapper
132                 ? (BeansWrapper)ow
133                 : BeansWrapper.getDefaultInstance();
134             return (TemplateModel) bw.newInstance(cl, arguments);
135         }
136     }
137 }
138
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