lambda.y

   1 %{
   2 #include "lambda.h"
   3 #include "lambda.tab.h"
   4 #include "mem.h"
   5
   6 struct lambda *result;
   7 struct decllist *decls = NULL;
   8 extern int yylex();
   9
  10 int yydebug=1;
  11 void yyerror(const char *str)
  12 {
  13         fprintf(stderr, "parse error: %s\n", str);
  14 }
  15
  16 int yywrap()
  17 {
  18         return 1;
  19 }
  20
  21 struct lambda *make_lambda()
  22 {
  23         return malloc(sizeof (struct lambda));
  24 }
  25
  26 struct lambda *make_ident(char *i)
  27 {
  28         struct lambda *r = make_lambda();
  29         r->which = lambda_ident;
  30         r->data.identifier = strdup(i);
  31         return r;
  32 }
  33
  34 struct lambda *make_abstraction(char *i, struct lambda *t)
  35 {
  36         struct lambda *r = make_lambda();
  37         r->which = lambda_abs;
  38         r->data.abstraction.ident = strdup(i);
  39         r->data.abstraction.expr = t;
  40         return r;
  41 }
  42
  43 struct lambda *make_application(struct lambda *t1, struct lambda *t2)
  44 {
  45         struct lambda *r = make_lambda();
  46         r->which = lambda_app;
  47         r->data.application.expr1 = t1;
  48         r->data.application.expr2 = t2;
  49         return r;
  50 }
  51
  52 void decls_prepend(char *ident, struct lambda *value)
  53 {
  54         printf("add: %s\n", ident);
  55         struct decllist *head = malloc(sizeof (struct decllist));
  56         head->next = decls;
  57         head->ident = ident;
  58         head->value = value;
  59         decls = head;
  60 }
  61
  62 struct lambda *decls_lookup(char *ident)
  63 {
  64         printf("lookup: %s\n", ident);
  65         struct decllist *c = decls;
  66         while(c != NULL){
  67                 if(strcmp(c->ident, ident) == 0)
  68                         return copy(c->value);
  69                 c = c->next;
  70         }
  71         printf("Notfound\n");
  72         return make_ident(ident);
  73 }
  74
  75 %}
  76
  77 %token LAMBDA DOT OBRACE CBRACE IDENT FUNC SEMICOLON ASSIGN
  78
  79 %%
  80
  81 lambda
  82         : decl lambda
  83         | term
  84                 { result = $$; }
  85 decl
  86         : FUNC ASSIGN term SEMICOLON
  87                 { decls_prepend($1->data.identifier, $3); }
  88 term
  89         : term appterm
  90                 { $$ = make_application($1, $2); }
  91         | appterm
  92                 { $$ = $1; }
  93 appterm
  94         : FUNC
  95                 {
  96                         $$ = decls_lookup($1->data.identifier);
  97                         lambda_free($1);
  98                 }
  99         | IDENT
 100                 {
 101                         $$ = make_ident($1->data.identifier);
 102                         lambda_free($1);
 103                 }
 104         | LAMBDA IDENT DOT term
 105                 {
 106                         $$ = make_abstraction($2->data.identifier, $4);
 107                         lambda_free($2);
 108                 }
 109         | OBRACE term CBRACE
 110                 { $$ = $2; }