BSHType


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13   *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
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28   *  Patrick Niemeyer (pat@pat.net)                                           *
29   *  Author of Learning Java, O'Reilly & Associates                           *
30   *  http://www.pat.net/~pat/                                                 *
31   *                                                                           *
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33  
34  
35  package bsh;
36  
37  import java.lang.reflect.Array  ;
38  
39  class BSHType extends SimpleNode 
40      implements BshClassManager.Listener
41  {
42      /**
43          baseType is used during evaluation of full type and retained for the
44          case where we are an array type.
45          In the case where we are not an array this will be the same as type.
46      */
47      private Class   baseType;
48      /** 
49          If we are an array type this will be non zero and indicate the 
50          dimensionality of the array.  e.g. 2 for String[][];
51      */
52      private int arrayDims;
53  
54      /** 
55          Internal cache of the type.  Cleared on classloader change.
56      */
57      private Class   type;
58  
59      String   descriptor;
60  
61      BSHType(int id) { 
62          super(id); 
63      }
64  
65      /**
66          Used by the grammar to indicate dimensions of array types 
67          during parsing.
68      */
69      public void addArrayDimension() { 
70          arrayDims++; 
71      }
72  
73      SimpleNode getTypeNode() {
74          return (SimpleNode)jjtGetChild(0);
75      }
76  
77      /**
78           Returns a class descriptor for this type.
79           If the type is an ambiguous name (object type) evaluation is 
80           attempted through the namespace in order to resolve imports.
81           If it is not found and the name is non-compound we assume the default
82           package for the name.
83      */
84      public String   getTypeDescriptor( 
85          CallStack callstack, Interpreter interpreter, String   defaultPackage ) 
86      {
87          // return cached type if available
88          if ( descriptor != null )
89              return descriptor;
90  
91          String   descriptor;
92          //  first node will either be PrimitiveType or AmbiguousName
93          SimpleNode node = getTypeNode();
94          if ( node instanceof BSHPrimitiveType )
95              descriptor = getTypeDescriptor( ((BSHPrimitiveType)node).type );
96          else 
97          {
98              String   clasName = ((BSHAmbiguousName)node).text;
99              BshClassManager bcm = interpreter.getClassManager();
100             // Note: incorrect here - we are using the hack in bsh class
101             // manager that allows lookup by base name.  We need to eliminate
102             // this limitation by working through imports.  See notes in class
103             // manager.
104             String   definingClass = bcm.getClassBeingDefined( clasName );
105 
106             Class   clas = null;
107             if ( definingClass == null )
108             {
109                 try {
110                     clas = ((BSHAmbiguousName)node).toClass( 
111                         callstack, interpreter );
112                 } catch ( EvalError e ) {
113                     //throw new InterpreterError("unable to resolve type: "+e);
114                     // ignore and try default package
115                     //System.out.println("BSHType: "+node+" class not found");
116                 }
117             } else
118                 clasName = definingClass;
119 
120             if ( clas != null )
121             {
122                 //System.out.println("found clas: "+clas);
123                 descriptor = getTypeDescriptor( clas );
124             }else
125             {
126                 if ( defaultPackage == null || Name.isCompound( clasName ) )
127                     descriptor = "L" + clasName.replace('.','/') + ";";
128                 else
129                     descriptor = 
130                         "L"+defaultPackage.replace('.','/')+"/"+clasName + ";";
131             }
132         }
133 
134         for(int i=0; i<arrayDims; i++)
135             descriptor = "["+descriptor;
136 
137         this.descriptor = descriptor;
138     //System.out.println("BSHType: returning descriptor: "+descriptor);
139         return descriptor;
140     }
141 
142     public Class   getType( CallStack callstack, Interpreter interpreter ) 
143         throws EvalError
144     {
145         // return cached type if available
146         if ( type != null )
147             return type;
148 
149         //  first node will either be PrimitiveType or AmbiguousName
150         SimpleNode node = getTypeNode();
151         if ( node instanceof BSHPrimitiveType )
152             baseType = ((BSHPrimitiveType)node).getType();
153         else 
154             baseType = ((BSHAmbiguousName)node).toClass( 
155                 callstack, interpreter );
156 
157         if ( arrayDims > 0 ) {
158             try {
159                 // Get the type by constructing a prototype array with
160                 // arbitrary (zero) length in each dimension.
161                 int[] dims = new int[arrayDims]; // int array default zeros
162                 Object   obj = Array.newInstance(baseType, dims);
163                 type = obj.getClass(); 
164             } catch(Exception   e) {
165                 throw new EvalError("Couldn't construct array type", 
166                     this, callstack );
167             }
168         } else
169             type = baseType;
170 
171         // hack... sticking to first interpreter that resolves this
172         // see comments on type instance variable
173         interpreter.getClassManager().addListener(this);
174 
175         return type;
176     }
177 
178     /**
179         baseType is used during evaluation of full type and retained for the
180         case where we are an array type.
181         In the case where we are not an array this will be the same as type.
182     */
183     public Class   getBaseType() {
184         return baseType;
185     }
186     /** 
187         If we are an array type this will be non zero and indicate the 
188         dimensionality of the array.  e.g. 2 for String[][];
189     */
190     public int getArrayDims() {
191         return arrayDims;
192     }
193 
194     public void classLoaderChanged() {
195         type = null;
196         baseType = null;
197     }
198 
199     public static String   getTypeDescriptor( Class   clas ) 
200     {
201         if ( clas == Boolean.TYPE ) return "Z";
202         if ( clas == Character.TYPE ) return "C"; 
203         if ( clas == Byte.TYPE ) return "B";
204         if ( clas == Short.TYPE ) return "S";
205         if ( clas == Integer.TYPE ) return "I";
206         if ( clas == Long.TYPE ) return "J";
207         if ( clas == Float.TYPE ) return "F";
208         if ( clas == Double.TYPE ) return "D";
209         if ( clas == Void.TYPE ) return "V";
210     // Is getName() ok?  test with 1.1
211         String   name = clas.getName().replace('.','/');
212 
213         if ( name.startsWith("[") || name.endsWith(";") )
214             return name;
215         else
216             return "L"+ name.replace('.','/') +";";
217     }
218 }
219
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