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Java > Open Source Codes > bsh > BSHPrimaryExpression


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3  * This file is part of the BeanShell Java Scripting distribution. *
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13  * Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright *
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33
34
35 package bsh;
36
37 class BSHPrimaryExpression extends SimpleNode
38 {
39     BSHPrimaryExpression(int id) { super(id); }
40
41     /**
42         Evaluate to a value object.
43     */
44     public Object JavaDoc eval( CallStack callstack, Interpreter interpreter)
45         throws EvalError
46     {
47         return eval( false, callstack, interpreter );
48     }
49
50     /**
51         Evaluate to a value object.
52     */
53     public LHS toLHS( CallStack callstack, Interpreter interpreter)
54         throws EvalError
55     {
56         Object JavaDoc obj = eval( true, callstack, interpreter );
57
58         if ( ! (obj instanceof LHS) )
59             throw new EvalError("Can't assign to:", this, callstack );
60         else
61             return (LHS)obj;
62     }
63
64     /*
65         Our children are a prefix expression and any number of suffixes.
66         <p>
67
68         We don't eval() any nodes until the suffixes have had an
69         opportunity to work through them. This lets the suffixes decide
70         how to interpret an ambiguous name (e.g. for the .class operation).
71     */
72     private Object JavaDoc eval( boolean toLHS,
73         CallStack callstack, Interpreter interpreter)
74         throws EvalError
75     {
76         Object JavaDoc obj = jjtGetChild(0);
77         int numChildren = jjtGetNumChildren();
78
79         for(int i=1; i<numChildren; i++)
80             obj = ((BSHPrimarySuffix)jjtGetChild(i)).doSuffix(
81                 obj, toLHS, callstack, interpreter);
82
83         /*
84             If the result is a Node eval() it to an object or LHS
85             (as determined by toLHS)
86         */
87         if ( obj instanceof SimpleNode )
88             if ( obj instanceof BSHAmbiguousName )
89                 if ( toLHS )
90                     obj = ((BSHAmbiguousName)obj).toLHS(
91                         callstack, interpreter);
92                 else
93                     obj = ((BSHAmbiguousName)obj).toObject(
94                         callstack, interpreter);
95             else
96                 // Some arbitrary kind of node
97 if ( toLHS )
98                     // is this right?
99 throw new EvalError("Can't assign to prefix.",
100                         this, callstack );
101                 else
102                     obj = ((SimpleNode)obj).eval(callstack, interpreter);
103
104         // return LHS or value object as determined by toLHS
105 if ( obj instanceof LHS )
106             if ( toLHS )
107                 return obj;
108             else
109                 try {
110                     return ((LHS)obj).getValue();
111                 } catch ( UtilEvalError e ) {
112                     throw e.toEvalError( this, callstack );
113                 }
114         else
115             return obj;
116     }
117 }
118
119
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