XSLCallTemplate


1   package com.icl.saxon.style;
2   import com.icl.saxon.tree.AttributeCollection;
3   import com.icl.saxon.tree.NodeImpl;
4   import com.icl.saxon.*;
5   import com.icl.saxon.om.*;
6   import com.icl.saxon.expr.*;
7   import javax.xml.transform.*;
8   import java.util.*;
9   import java.io.*;
10  
11  /**
12  * An xsl:call-template element in the stylesheet
13  */
14  
15  public class XSLCallTemplate extends StyleElement {
16  
17      private int calledTemplateFingerprint = -1;   // the fingerprint of the called template 
18      private XSLTemplate template = null;
19      private boolean useTailRecursion = false;
20      private Expression calledTemplateExpression;    // allows name to be an AVT
21      private String   calledTemplateName = null;       // used only for diagnostics
22  
23      /**
24      * Determine whether this node is an instruction.
25      * @return true - it is an instruction
26      */
27  
28      public boolean isInstruction() {
29          return true;
30      }
31  
32      /**
33      * Determine whether this element does any processing after instantiating any children.
34      * This implementation says it doesn't, thus enabling tail recursion.
35      */
36  
37      public boolean doesPostProcessing() {
38          return false;
39      }
40  
41      public void prepareAttributes() throws TransformerConfigurationException {
42  
43          StandardNames sn = getStandardNames();
44          AttributeCollection atts = getAttributeList();
45  
46          String   allowAVTatt = null;
47          String   nameAttribute = null;
48          
49          for (int a=0; a<atts.getLength(); a++) {
50              int nc = atts.getNameCode(a);
51              int f = nc & 0xfffff;
52              if (f==sn.NAME) {
53                  nameAttribute = atts.getValue(a);
54              } else if (f==sn.SAXON_ALLOW_AVT) {
55                  allowAVTatt = atts.getValue(a);
56              } else {
57                  checkUnknownAttribute(nc);
58              }
59          }
60  
61          if (nameAttribute==null) {
62              reportAbsence("name");
63              return;
64          }
65          
66          boolean allowAVT = (allowAVTatt != null && allowAVTatt.equals("yes"));
67          if (allowAVT) {
68              calledTemplateExpression = makeAttributeValueTemplate(nameAttribute);
69          } else {
70              if (!Name.isQName(nameAttribute)) {
71                  compileError("Name of called template must be a valid QName");
72              }
73              calledTemplateName = nameAttribute;
74              try {
75                  calledTemplateFingerprint = 
76                      makeNameCode(nameAttribute, false) & 0xfffff;
77              } catch (NamespaceException err) {
78                  compileError(err.getMessage());
79              }
80          }
81      }
82  
83      public void validate() throws TransformerConfigurationException {
84          checkWithinTemplate();
85  
86          if (calledTemplateExpression==null) {
87              template = findTemplate(calledTemplateFingerprint);
88  
89              // Use tail recursion if the template is calling itself, and if neither this instruction
90              // nor any ancestor instruction has a following sibling. Avoid tail recursion if called
91              // within any element that needs to do further processing after instantiating its children,
92              // e.g. a literal result element, which needs to write out the end tag
93  
94              if (Navigator.isAncestor(template, this)) {
95                  useTailRecursion = true;
96                  StyleElement n = this;
97                  while (n!=template) {
98                      if ((n.isInstruction() && n.getNextSibling()!=null) ||
99                               n.doesPostProcessing()) {
100                         useTailRecursion = false;
101                         break;
102                     }
103                     n = (StyleElement)n.getParentNode();
104                 }
105                 // System.err.println((useTailRecursion ? "" : "NOT ") + "Using tail recursion at line " + getLineNumber());
106             }
107         }
108 
109     }
110 
111     private XSLTemplate findTemplate(int fingerprint) 
112     throws TransformerConfigurationException {
113         
114         XSLStyleSheet stylesheet = getPrincipalStyleSheet();        
115         Vector toplevel = stylesheet.getTopLevel();
116     
117         // search for a matching template name, starting at the end in case of duplicates.
118         // this also ensures we get the one with highest import precedence.
119 
120         for (int i=toplevel.size()-1; i>=0; i--) {
121             if (toplevel.elementAt(i) instanceof XSLTemplate) {
122                 XSLTemplate t = (XSLTemplate)toplevel.elementAt(i);
123                 if (t.getTemplateFingerprint() == fingerprint) {   
124                     return t;
125                 }
126             }
127         }
128         compileError("No template exists named " + calledTemplateName);
129         return null;
130     }
131 
132     public void process(Context context) throws TransformerException
133     {
134         // if name is determined dynamically, determine it now
135 
136         XSLTemplate target = template;
137         if (calledTemplateExpression != null) {
138             String   qname = calledTemplateExpression.evaluateAsString(context);
139             if (!Name.isQName(qname)) {
140                 throw styleError("Invalid template name: " + qname);
141             }
142             int fprint;
143             try {
144                 fprint = makeNameCode(qname, false) & 0xfffff;
145             } catch (NamespaceException err) {
146                 throw styleError(err.getMessage());
147             } 
148             target = findTemplate(fprint);
149             if (target==null) {
150                 throw styleError("Template " + qname + " has not been defined");
151             }
152         }
153 
154         // handle parameters if any
155         
156         ParameterSet params = null;
157         
158         if (hasChildNodes()) {
159             NodeImpl child = (NodeImpl)getFirstChild();
160             params = new ParameterSet();
161             while (child != null) {
162                 if (child instanceof XSLWithParam) {    // currently always true
163                     XSLWithParam param = (XSLWithParam)child;
164                     params.put(param.getVariableFingerprint(), param.getParamValue(context));
165                 }
166                 child = (NodeImpl)child.getNextSibling();
167             }
168         }
169 
170         // Call the named template
171 
172         if (useTailRecursion) {
173             if (params==null) {                 // bug 490967
174                 params = new ParameterSet();
175             }
176             context.setTailRecursion(params);
177             // we now just let the stack unwind until we get back to the xsl:template element;
178             // at that point the template will detect that there has been a tail-recursive call,
179             // and iterate to achieve the effect of calling itself.
180         } else {
181             Bindery bindery = context.getBindery();
182             bindery.openStackFrame(params);
183 
184             if (context.getController().isTracing()) { // e.g. FIXME: trace tail recursion
185                 target.traceExpand(context);
186             } else {
187                 target.expand(context);
188             }
189             
190             bindery.closeStackFrame();
191         }
192 
193     }
194 
195 }
196 
197 //
198 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
199 // you may not use this file except in compliance with the License. You may obtain a copy of the
200 // License at http://www.mozilla.org/MPL/ 
201 //
202 // Software distributed under the License is distributed on an "AS IS" basis,
203 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
204 // See the License for the specific language governing rights and limitations under the License. 
205 //
206 // The Original Code is: all this file. 
207 //
208 // The Initial Developer of the Original Code is
209 // Michael Kay of International Computers Limited (mhkay@iclway.co.uk).
210 //
211 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved. 
212 //
213 // Contributor(s): none. 
214 //
215
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