1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Copyright 2001-2004 The Apache Software Foundation.
   7  *
   8  * Licensed under the Apache License, Version 2.0 (the "License");
   9  * you may not use this file except in compliance with the License.
  10  * You may obtain a copy of the License at
  11  *
  12  *     http://www.apache.org/licenses/LICENSE-2.0
  13  *
  14  * Unless required by applicable law or agreed to in writing, software
  15  * distributed under the License is distributed on an "AS IS" BASIS,
  16  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  17  * See the License for the specific language governing permissions and
  18  * limitations under the License.
  19  */
  20 /*
  21  * $Id: VariableRefBase.java,v 1.5 2005/09/28 13:48:18 pvedula Exp $
  22  */
  23 
  24 package com.sun.org.apache.xalan.internal.xsltc.compiler;
  25 
  26 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
  27 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
  28 
  29 /**
  30  * @author Morten Jorgensen
  31  * @author Santiago Pericas-Geertsen
  32  */
  33 class VariableRefBase extends Expression {
  34 
  35     /**
  36      * A reference to the associated variable.
  37      */
  38     protected VariableBase _variable;
  39 
  40     /**
  41      * A reference to the enclosing expression/instruction for which a
  42      * closure is needed (Predicate, Number or Sort).
  43      */
  44     protected Closure _closure = null;
  45 
  46     public VariableRefBase(VariableBase variable) {
  47         _variable = variable;
  48         variable.addReference(this);
  49     }
  50 
  51     public VariableRefBase() {
  52         _variable = null;
  53     }
  54 
  55     /**
  56      * Returns a reference to the associated variable
  57      */
  58     public VariableBase getVariable() {
  59         return _variable;
  60     }
  61 
  62     /**
  63      * If this variable reference is in a top-level element like
  64      * another variable, param or key, add a dependency between
  65      * that top-level element and the referenced variable. For
  66      * example,
  67      *
  68      *   <xsl:variable name="x" .../>
  69      *   <xsl:variable name="y" select="$x + 1"/>
  70      *
  71      * and assuming this class represents "$x", add a reference
  72      * between variable y and variable x.
  73      */
  74     public void addParentDependency() {
  75         SyntaxTreeNode node = this;
  76         while (node != null && node instanceof TopLevelElement == false) {
  77             node = node.getParent();
  78         }
  79 
  80         TopLevelElement parent = (TopLevelElement) node;
  81         if (parent != null) {
  82             VariableBase var = _variable;
  83             if (_variable._ignore) {
  84                 if (_variable instanceof Variable) {
  85                     var = parent.getSymbolTable()
  86                                 .lookupVariable(_variable._name);
  87                 } else if (_variable instanceof Param) {
  88                     var = parent.getSymbolTable().lookupParam(_variable._name);
  89                 }
  90             }
  91 
  92             parent.addDependency(var);
  93         }
  94     }
  95 
  96     /**
  97      * Two variable references are deemed equal if they refer to the
  98      * same variable.
  99      */
 100     public boolean equals(Object obj) {
 101         try {
 102             return (_variable == ((VariableRefBase) obj)._variable);
 103         }
 104         catch (ClassCastException e) {
 105             return false;
 106         }
 107     }
 108 
 109     /**
 110      * Returns a string representation of this variable reference on the
 111      * format 'variable-ref(<var-name>)'.
 112      * @return Variable reference description
 113      */
 114     public String toString() {
 115         return "variable-ref("+_variable.getName()+'/'+_variable.getType()+')';
 116     }
 117 
 118     public Type typeCheck(SymbolTable stable)
 119         throws TypeCheckError
 120     {
 121         // Returned cached type if available
 122         if (_type != null) return _type;
 123 
 124         // Find nearest closure to add a variable reference
 125         if (_variable.isLocal()) {
 126             SyntaxTreeNode node = getParent();
 127             do {
 128                 if (node instanceof Closure) {
 129                     _closure = (Closure) node;
 130                     break;
 131                 }
 132                 if (node instanceof TopLevelElement) {
 133                     break;      // way up in the tree
 134                 }
 135                 node = node.getParent();
 136             } while (node != null);
 137 
 138             if (_closure != null) {
 139                 _closure.addVariable(this);
 140             }
 141         }
 142 
 143         // Attempt to get the cached variable type
 144         _type = _variable.getType();
 145 
 146         // If that does not work we must force a type-check (this is normally
 147         // only needed for globals in included/imported stylesheets
 148         if (_type == null) {
 149             _variable.typeCheck(stable);
 150             _type = _variable.getType();
 151         }
 152 
 153         // If in a top-level element, create dependency to the referenced var
 154         addParentDependency();
 155 
 156         // Return the type of the referenced variable
 157         return _type;
 158     }
 159 
 160 }