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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
11
12 public class fluid_let extends Syntax
13 {
14 public static final fluid_let fluid_let = new fluid_let();
15 static { fluid_let.setName("fluid-set"); }
16
17
18 boolean star;
19
20
22 Expression defaultInit;
23
24 public fluid_let(boolean star, Expression defaultInit)
25 {
26 this.star = star;
27 this.defaultInit = defaultInit;
28 }
29
30 public fluid_let()
31 {
32 this.star = false;
33 }
34
35 public Expression rewrite (Object  obj, Translator tr)
36 {
37 if (! (obj instanceof Pair))
38 return tr.syntaxError ("missing let arguments");
39 Pair pair = (Pair) obj;
40 return rewrite(pair.car, pair.cdr, tr);
41 }
42
43 public Expression rewrite (Object bindings, Object body, Translator tr)
44 {
45 int decl_count = star ? 1 : LList.length (bindings);
46 Expression[] inits = new Expression[decl_count];
47 FluidLetExp let = new FluidLetExp (inits);
48 for (int i = 0; i < decl_count; i++)
49 {
50 Pair bind_pair = (Pair) bindings;
51 Object savePos = tr.pushPositionOf(bind_pair);
52 try
53 {
54 Expression value;
55 Pair binding;
56 Object name = bind_pair.car;
57 if (name instanceof String || name instanceof Symbol)
58 {
59 value = defaultInit;
60 }
61 else if (name instanceof Pair
62 && ((binding = (Pair) name).car instanceof String
63 || binding.car instanceof Symbol
64 || binding.car instanceof SyntaxForm))
65 {
66 name = binding.car;
67 if (name instanceof SyntaxForm)
68 name = ((SyntaxForm)name).form;
69
70 if (binding.cdr == LList.Empty)
71 value = defaultInit;
72 else if (! (binding.cdr instanceof Pair)
73 || (binding = (Pair) binding.cdr).cdr != LList.Empty)
74 return tr.syntaxError("bad syntax for value of " + name
75 + " in " + getName());
76 else
77 value = tr.rewrite(binding.car);
78 }
79 else
80 return tr.syntaxError("invalid " + getName() + " syntax");
81 Declaration decl = let.addDeclaration(name);
82 Declaration found = tr.lexical.lookup(name, false);
83 if (found != null)
84 {
85 if (found.isLexical())
86 found.setIndirectBinding(true);
87 decl.base = found;
88 }
89 decl.setFluid(true);
90 decl.setIndirectBinding(true);
91 if (value == null)
92 value = new ReferenceExp(name);
93 inits[i] = value;
94 decl.noteValue(null);
95 bindings = bind_pair.cdr;
96 }
97 finally
98 {
99 tr.popPositionOf(savePos);
100 }
101 }
102 tr.push(let);
103 if (star && bindings != LList.Empty)
104 let.body = rewrite (bindings, body, tr);
105 else
106 let.body = tr.rewrite_body(body);
107 tr.pop(let);
108 return let;
109 }
110 }
111 |
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Java API By Example, From Geeks To Geeks.