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%{
#include "main.h"
#include <stdio.h>
#define code2(c1,c2) code(c1); code(c2)
#define code3(c1,c2,c3) code(c1); code(c2); code(c3)
%}
%union {
Symbol *sym; /* symbol table pointer */
double val;
Inst *inst; /* machine instruction */
}
%token <sym> NUMBER VAR BLTIN UNDEF
%right '='
%left '+' '-'
%left '*' '/'
%left UNARYMINUS
%right '^' /* exponentiation */
%%
list: /* nothing */
| list '\n'
| list asgn '\n' { code2(mypop, STOP); return 1; }
| list expr '\n' { code2(print, STOP); return 1; }
| list error '\n' { yyerrok; }
;
asgn: VAR '=' expr { code3(varpush,(Inst)$1,assign); }
;
expr: NUMBER { code2(constpush, (Inst)$1); }
| VAR { code3(varpush, (Inst)$1, eval); }
| asgn
| BLTIN '(' expr ')' { code2(bltin, (Inst)$1->value.ptr); }
| '(' expr ')'
| expr '+' expr { code(add); }
| expr '-' expr { code(sub); }
| expr '*' expr { code(mul); }
| expr '/' expr { code(mydiv); }
| expr '^' expr { code(power); }
| '-' expr %prec UNARYMINUS { code(negate); }
;
%%
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