BSD 4_3_Reno release

[unix-history] / usr / src / pgrm / cpp / yylex.c

#ifndef lint
static char sccsid[] = "@(#)yylex.c     1.4 10/15/86";
#endif lint

#define isid(a)  ((fastab+COFF)[a]&IB)
#define IB 1
/*      #if '\377' < 0          it would be nice if this worked properly!!!!! */
#if pdp11 | vax | mc68000 | tahoe
#define COFF 128
#else
#define COFF 0
#endif

yylex() {
       static int ifdef=0;
       static char *op2[]={"||",  "&&" , ">>", "<<", ">=", "<=", "!=", "=="};
       static int  val2[]={OROR, ANDAND,  RS,   LS,   GE,   LE,   NE,   EQ};
       static char *opc="b\bt\tn\nf\fr\r\\\\";
       extern char fastab[];
       extern char *outp,*inp,*newp; extern int flslvl;
       register char savc, *s; char *skipbl(); int val;
       register char **p2;
       struct symtab {
               char *name;
               char *value;
       } *sp, *lookup();

for (;;) {
       extern int passcom;             /* this crap makes #if's work */
       int opt_passcom = passcom;      /* even with -C option */
       passcom = 0;                    /* (else comments make syntax errs) */
       newp=skipbl(newp);
       passcom = opt_passcom;          /* nb: lint uses -C so its useful! */
       if (*inp=='\n') return(stop);   /* end of #if */
       savc= *newp; *newp='\0';
       for (p2=op2+8; --p2>=op2; )     /* check 2-char ops */
               if (0==strcmp(*p2,inp)) {val=val2[p2-op2]; goto ret;}
       s="+-*/%<>&^|?:!~(),";  /* check 1-char ops */
       while (*s) if (*s++== *inp) {val= *--s; goto ret;}
       if (*inp<='9' && *inp>='0') {/* a number */
               if (*inp=='0') yylval= (inp[1]=='x' || inp[1]=='X') ?
                       tobinary(inp+2,16) : tobinary(inp+1,8);
               else yylval=tobinary(inp,10);
               val=number;
       } else if (isid(*inp)) {
               if (0==strcmp(inp,"defined")) {ifdef=1; ++flslvl; val=DEFINED;}
               else {
                       sp=lookup(inp,-1); if (ifdef!=0) {ifdef=0; --flslvl;}
                       yylval= (sp->value==0) ? 0 : 1;
                       val=number;
               }
       } else  if (*inp=='\'') {/* character constant */
               val=number;
               if (inp[1]=='\\') {/* escaped */
                       char c; if (newp[-1]=='\'') newp[-1]='\0';
                       s=opc;
                       while (*s) if (*s++!=inp[2]) ++s; else {yylval= *s; goto ret;}
                       if (inp[2]<='9' && inp[2]>='0') yylval=c=tobinary(inp+2,8);
                       else yylval=inp[2];
               } else yylval=inp[1];
       } else if (0==strcmp("\\\n",inp)) {*newp=savc; continue;}
       else {
               *newp=savc; pperror("Illegal character %c in preprocessor if", *inp);
               continue;
       }
ret:
       *newp=savc; outp=inp=newp; return(val);
}
}

tobinary(st, b) char *st; {
       int n, c, t;
       char *s;
       n=0;
       s=st;
       while (c = *s++) {
       switch(c) {
               case '0': case '1': case '2': case '3': case '4': 
               case '5': case '6': case '7': case '8': case '9': 
                       t = c-'0'; break;
               case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': 
                       t = c-'a'+10; if (b>10) break;
               case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': 
                       t = c - 'A'+10; if (b>10) break;
               default:
                       t = -1;
                       if ( c=='l' || c=='L') if (*s=='\0') break;
                       pperror("Illegal number %s", st);
       }
       if (t<0) break;
       n = n*b+t;
       }
return(n);
}