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1 package kawa.standard;
2 import kawa.lang.*;
3 import gnu.lists.*;
4 import gnu.mapping.*;
5 import gnu.expr.*;
6 import java.util.Stack  ;
7
8
14
15 public class let extends Syntax
16 {
17 public static final let let = new let();
18 static { let.setName("let"); }
19
20 public Expression rewrite (Object obj, Translator tr)
21 {
22 if (! (obj instanceof Pair))
23 return tr.syntaxError ("missing let arguments");
24 Pair pair = (Pair) obj;
25 Object bindings = pair.car;
26 Object body = pair.cdr;
27 int decl_count = Translator.listLength(bindings);
28 if (decl_count < 0)
29 return tr.syntaxError("bindings not a proper list");
30
31 Expression[] inits = new Expression[decl_count];
32 LetExp let = new LetExp (inits);
33 Stack renamedAliases = null;
34 int renamedAliasesCount = 0;
35 SyntaxForm syntaxRest = null;
36 for (int i = 0; i < decl_count; i++)
37 {
38 while (bindings instanceof SyntaxForm)
39 {
40 syntaxRest = (SyntaxForm) bindings;
41 bindings = syntaxRest.form;
42 }
45 Pair bind_pair = (Pair) bindings;
46 Object bind_pair_car = bind_pair.car;
47 SyntaxForm syntax = syntaxRest;
48 if (bind_pair_car instanceof SyntaxForm)
49 {
50 syntax = (SyntaxForm) bind_pair_car;
51 bind_pair_car = syntax.form;
52 }
53 if (! (bind_pair_car instanceof Pair))
54 return tr.syntaxError ("let binding is not a pair:"+bind_pair_car);
55 Pair binding = (Pair) bind_pair_car;
56 Object name = binding.car;
57 TemplateScope templateScope;
58 if (name instanceof SyntaxForm)
59 {
60 SyntaxForm sf = (SyntaxForm) name;
61 name = sf.form;
62 templateScope = sf.scope;
63 }
64 else
65 templateScope = syntax == null ? null : syntax.scope;
66 if (! (name instanceof String ) && ! (name instanceof Symbol))
67 return tr.syntaxError("variable "+name+" in let binding is not a symbol: "+obj);
68
69 Declaration decl = let.addDeclaration(name);
70
71 if (templateScope != null)
72 {
73 Declaration alias = tr.makeRenamedAlias(decl, templateScope);
74 if (renamedAliases == null)
75 renamedAliases = new Stack ();
76 renamedAliases.push(alias);
77 renamedAliasesCount++;
78 }
79
80 Object binding_cdr = binding.cdr;
81 while (binding_cdr instanceof SyntaxForm)
82 {
83 syntax = (SyntaxForm) binding_cdr;
84 binding_cdr = syntax.form;
85 }
86 if (! (binding_cdr instanceof Pair))
87 return tr.syntaxError("let has no value for '"+name+"'");
88 binding = (Pair) binding_cdr;
89 binding_cdr = binding.cdr;
90 Pair init;
91 while (binding_cdr instanceof SyntaxForm)
92 {
93 syntax = (SyntaxForm) binding_cdr;
94 binding_cdr = syntax.form;
95 }
96 if (tr.matches(binding.car, "::"))
97 {
98 if (! (binding_cdr instanceof Pair)
99 || (binding = (Pair) binding_cdr).cdr == LList.Empty)
100 return tr.syntaxError("missing type after '::' in let");
101 binding_cdr = binding.cdr;
102 while (binding_cdr instanceof SyntaxForm)
103 {
104 syntax = (SyntaxForm) binding_cdr;
105 binding_cdr = syntax.form;
106 }
107 }
108 if (binding_cdr == LList.Empty)
109 {
110 init = binding;
111 }
112 else if (binding_cdr instanceof Pair)
113 {
114 decl.setType(tr.exp2Type(binding));
115 decl.setFlag(Declaration.TYPE_SPECIFIED);
116 init = (Pair) binding_cdr;
117 }
118 else
119 return tr.syntaxError("let binding for '"+name+"' is improper list");
120 inits[i] = tr.rewrite_car (init, syntax);
121 if (init.cdr != LList.Empty)
122 return tr.syntaxError("junk after declaration of "+name);
123 decl.noteValue (inits[i]);
124 bindings = bind_pair.cdr;
125 }
126
127 for (int i = renamedAliasesCount; --i >= 0; )
128 tr.pushRenamedAlias((Declaration) renamedAliases.pop());
129
130 tr.push(let);
131 let.body = tr.rewrite_body(body);
132 tr.pop(let);
133 tr.popRenamedAlias(renamedAliasesCount);
134
135 return let;
136 }
137 }
138 |
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