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1 package kawa.standard;
2 import kawa.lang.*;
3 import gnu.mapping.*;
4 import gnu.expr.*;
5 import gnu.lists.*;
6
7
8
9 public class define_variable extends Syntax
10 {
11 public static final define_variable define_variable = new define_variable();
12 static { define_variable.setName("define-variable"); }
13
14 public boolean scanForDefinitions (Pair st, java.util.Vector  forms,
15 ScopeExp defs, Translator tr)
16 {
17 if (! (st.cdr instanceof Pair))
18 return super.scanForDefinitions(st, forms, defs, tr);
19 Pair p = (Pair) st.cdr;
20 if (p.car instanceof String || p.car instanceof Symbol)
21 {
22 Object sym = p.car;
23 if (! (defs instanceof ModuleExp))
24 tr.error('e', getName() + " must be at module level");
25 Declaration decl = defs.lookup(sym);
26 if (decl != null)
27 tr.error('e', "duplicate declaration for '"+sym+"'");
28 ModuleExp mod = defs.currentModule();
29 decl = mod.addDeclaration(sym);
30 tr.push(decl);
31 decl.setSimple(false);
32 decl.setPrivate(true);
33 decl.setFlag(Declaration.IS_DYNAMIC);
34 if (mod.isStatic())
35 decl.setFlag(Declaration.STATIC_SPECIFIED);
36 decl.setCanRead(true);
37 decl.setCanWrite(true);
38 decl.setIndirectBinding(true);
39 p = Translator.makePair(p, decl, p.cdr);
40 st = Translator.makePair(st, this, p);
41 }
42 forms.addElement (st);
43 return true;
44 }
45
46 public Expression rewriteForm (Pair form, Translator tr)
47 {
48 Object obj = form.cdr;
49 Expression value = null;
50 Declaration decl = null;
51
52 if (obj instanceof Pair)
53 {
54 Pair p1 = (Pair) obj;
55 obj = p1.car;
56 if (obj instanceof String || obj instanceof Symbol)
57 return tr.syntaxError(getName() + " is only allowed in a <body>");
58 if (obj instanceof Declaration)
59 {
60 decl = (Declaration) p1.car;
61 obj = p1.cdr;
62 if (obj instanceof Pair
63 && (p1 = (Pair) obj).cdr == LList.Empty)
64 value = tr.rewrite (p1.car);
65 else if (obj != LList.Empty)
66 decl = null;
67 }
68 }
69 if (decl == null)
70 return tr.syntaxError ("invalid syntax for "+getName());
71 if (value == null)
72 return QuoteExp.voidExp;
73 SetExp sexp = new SetExp (decl, value);
74 sexp.setDefining (true);
75 sexp.setSetIfUnbound(true);
76
77 if (decl != null)
78 {
79 sexp.setBinding(decl);
80 if (decl.context instanceof ModuleExp
81 && decl.getCanWrite())
82 value = null;
83 decl.noteValue(value);
84 }
85 return sexp;
86 }
87 }
88 |
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