/********** parser.c *************************/

#include "global.h"
int lookahead;

void parse(void)    /* analyse et traduit la liste */ 
{           /* d'expressions*/
  lookahead = lexan();
   while (lookahead != DONE ) {
     expr(); match(';');
   }
}

void expr(void)
{
   int t;
   term();
   while(1)
     switch (lookahead) {
     case '+': case '-':
       t = lookahead;
       match(lookahead); term(); emit(t, NONE);
       continue;
     default:
       return;
     }
}

void term(void)
{
     int t;
     factor();
     while(1)
       switch(lookahead) {
       case '*': case '/': case DIV: case MOD:
         t = lookahead;
         match(lookahead); factor(); emit(t, NONE);
         continue;
       default:
         return;
       }
}

void factor(void)
{
     switch(lookahead) {
         case '(':
            match('(');expr();match(')');break;
         case NUM:
            emit(NUM, tokenval); match(NUM); break;
         case ID:
            emit(ID, tokenval); match(ID); break;
         default:
            error("syntax error");
     }
}

void match(int t)

{
     if (lookahead == t)
       lookahead = lexan();
     else error("syntax error");
}