lambda.y

   1 %{
   2 #include "lambda.h"
   3 #include "lambda.tab.h"
   4 #include "mem.h"
   5 #include "print.h"
   6
   7 struct lambda *result;
   8 struct decllist *decls = NULL;
   9 extern int yylex();
  10
  11 int yydebug=1;
  12 void yyerror(const char *str)
  13 {
  14         fprintf(stderr, "parse error: %s\n", str);
  15 }
  16
  17 int yywrap()
  18 {
  19         return 1;
  20 }
  21
  22 struct lambda *make_lambda()
  23 {
  24         return malloc(sizeof (struct lambda));
  25 }
  26
  27 struct lambda *make_ident(char *i)
  28 {
  29         struct lambda *r = make_lambda();
  30         r->which = lambda_ident;
  31         r->data.identifier.ident = strdup(i);
  32         r->data.identifier.revision = 0;
  33         return r;
  34 }
  35
  36 struct lambda *make_abstraction(char *i, struct lambda *t)
  37 {
  38         struct lambda *r = make_lambda();
  39         r->which = lambda_abs;
  40         r->data.abstraction.ident = strdup(i);
  41         r->data.abstraction.expr = t;
  42         return r;
  43 }
  44
  45 struct lambda *make_application(struct lambda *t1, struct lambda *t2)
  46 {
  47         struct lambda *r = make_lambda();
  48         r->which = lambda_app;
  49         r->data.application.expr1 = t1;
  50         r->data.application.expr2 = t2;
  51         return r;
  52 }
  53
  54 void decls_prepend(char *ident, struct lambda *value)
  55 {
  56         struct decllist *head = malloc(sizeof (struct decllist));
  57         head->next = decls;
  58         head->ident = ident;
  59         head->value = value;
  60         printf("Declared %s as ", ident);
  61         lambda_print(value);
  62         decls = head;
  63 }
  64
  65 struct lambda *decls_lookup(char *ident)
  66 {
  67         struct decllist *c = decls;
  68         while(c != NULL){
  69                 if(strcmp(c->ident, ident) == 0)
  70                         return copy(c->value);
  71                 c = c->next;
  72         }
  73         return make_ident(ident);
  74 }
  75
  76 %}
  77
  78 %token LAMBDA DOT OBRACE CBRACE IDENT FUNC SEMICOLON ASSIGN
  79
  80 %%
  81
  82 lambda
  83         : decl lambda
  84         | term
  85                 { result = $$; }
  86 decl
  87         : FUNC ASSIGN term SEMICOLON
  88                 { decls_prepend($1->data.identifier.ident, $3); }
  89 term
  90         : term appterm
  91                 { $$ = make_application($1, $2); }
  92         | appterm
  93                 { $$ = $1; }
  94 appterm
  95         : FUNC
  96                 {
  97                         $$ = decls_lookup($1->data.identifier.ident);
  98                         lambda_free($1);
  99                 }
 100         | IDENT
 101                 {
 102                         $$ = make_ident($1->data.identifier.ident);
 103                         lambda_free($1);
 104                 }
 105         | LAMBDA abstraction
 106                 { $$ = $2; }
 107         | OBRACE term CBRACE
 108                 { $$ = $2; }
 109 abstraction
 110         : IDENT abstraction
 111                 {
 112                         $$ = make_abstraction($1->data.identifier.ident, $2);
 113                         lambda_free($1);
 114                 }
 115         | DOT term
 116                 { $$ = $2; }