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      1 /*
      2  * Licensed to the Apache Software Foundation (ASF) under one
      3  * or more contributor license agreements. See the NOTICE file
      4  * distributed with this work for additional information
      5  * regarding copyright ownership. The ASF licenses this file
      6  * to you under the Apache License, Version 2.0 (the  "License");
      7  * you may not use this file except in compliance with the License.
      8  * You may obtain a copy of the License at
      9  *
     10  *     http://www.apache.org/licenses/LICENSE-2.0
     11  *
     12  * Unless required by applicable law or agreed to in writing, software
     13  * distributed under the License is distributed on an "AS IS" BASIS,
     14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15  * See the License for the specific language governing permissions and
     16  * limitations under the License.
     17  */
     18 /*
     19  * $Id: FuncExtFunctionAvailable.java 468655 2006-10-28 07:12:06Z minchau $
     20  */
     21 package org.apache.xpath.functions;
     22 
     23 import org.apache.xalan.templates.Constants;
     24 import org.apache.xpath.ExtensionsProvider;
     25 import org.apache.xpath.XPathContext;
     26 import org.apache.xpath.compiler.FunctionTable;
     27 import org.apache.xpath.objects.XBoolean;
     28 import org.apache.xpath.objects.XObject;
     29 
     30 /**
     31  * Execute the ExtFunctionAvailable() function.
     32  * @xsl.usage advanced
     33  */
     34 public class FuncExtFunctionAvailable extends FunctionOneArg
     35 {
     36     static final long serialVersionUID = 5118814314918592241L;
     37 
     38     transient private FunctionTable m_functionTable = null;
     39 
     40   /**
     41    * Execute the function.  The function must return
     42    * a valid object.
     43    * @param xctxt The current execution context.
     44    * @return A valid XObject.
     45    *
     46    * @throws javax.xml.transform.TransformerException
     47    */
     48   public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
     49   {
     50 
     51     String prefix;
     52     String namespace;
     53     String methName;
     54 
     55     String fullName = m_arg0.execute(xctxt).str();
     56     int indexOfNSSep = fullName.indexOf(':');
     57 
     58     if (indexOfNSSep < 0)
     59     {
     60       prefix = "";
     61       namespace = Constants.S_XSLNAMESPACEURL;
     62       methName = fullName;
     63     }
     64     else
     65     {
     66       prefix = fullName.substring(0, indexOfNSSep);
     67       namespace = xctxt.getNamespaceContext().getNamespaceForPrefix(prefix);
     68       if (null == namespace)
     69         return XBoolean.S_FALSE;
     70         methName = fullName.substring(indexOfNSSep + 1);
     71     }
     72 
     73     if (namespace.equals(Constants.S_XSLNAMESPACEURL))
     74     {
     75       try
     76       {
     77         if (null == m_functionTable) m_functionTable = new FunctionTable();
     78         return m_functionTable.functionAvailable(methName) ? XBoolean.S_TRUE : XBoolean.S_FALSE;
     79       }
     80       catch (Exception e)
     81       {
     82         return XBoolean.S_FALSE;
     83       }
     84     }
     85     else
     86     {
     87       //dml
     88       ExtensionsProvider extProvider = (ExtensionsProvider)xctxt.getOwnerObject();
     89       return extProvider.functionAvailable(namespace, methName)
     90              ? XBoolean.S_TRUE : XBoolean.S_FALSE;
     91     }
     92   }
     93 
     94   /**
     95    * The function table is an instance field. In order to access this instance
     96    * field during evaluation, this method is called at compilation time to
     97    * insert function table information for later usage. It should only be used
     98    * during compiling of XPath expressions.
     99    * @param aTable an instance of the function table
    100    */
    101   public void setFunctionTable(FunctionTable aTable){
    102           m_functionTable = aTable;
    103   }
    104 }
    105