Category : Miscellaneous Language Source Code
Archive   : PCLEX.ZIP
Filename : CSTOCK.L

/*
* Lexical Analyzer for C Library Driver
* - evaluates C chars, strings, ints, and floats
* - accepts unquoted chars and strings of printing characters
*/

ascii [\0-\177] /* Any ASCII character */
white [\n\r\t ] /* The white spaces */
sign [-+] /* Numeric signs */
digit [0-9] /* The digits */
hexdigit [0-9A-Fa-f] /* The hexadecimal digits */
hexflag [Xx] /* Indicator of a hexadecimal constant */
expflag [Ee] /* Indicator of a floating exponent */

t_atom [!-~] /* All the printing characters */
text [!#-&(-/:-~]{t_atom}* /* Text can't start with a digit, " or ' */

e_particle "\\"{ascii} /* An escaped ascii character */
s_particle [^\\"] /* Anything besides an escape or quote */
c_particle [^\\'] /* Anything besides an escape or apostrophe */

c_atom {e_particle}|{c_particle} /* Anything but end of char */
s_atom {e_particle}|{s_particle} /* Anything but end of string */

string \"{s_atom}*\"
char \'{c_atom}\'

%{

#undef input

int yyival;
float yyfval;

float pow();
%}
%%

ARG {return(ARG);}
PRINTF {return(PTF);}
ISLOWER {return(ILO);}
EXIT {return(EXT);}

'-'?{digit}{hexflag}?{hexdigit}* {
{
register char *p = yytext;
int minus = FALSE;
int base;

yyival = 0;
if(*p == '-') {
++p;
minus = TRUE;
}
base = 10;
if(*p == '0') {
++p;
if(*p == 'X' || *p == 'x') {
++p;
base = 16;
}
else
base = 8;
}
do {
yyival = base*yyival + hex(*p);
} while(*++p);
if(minus) yyival = -yyival;
printf("\nLEX/ICON: %s is %d (decimal)\n", yytext, yyival);
return(ICON);
}
}

'-'?{digit}+"."?{digit}*{expflag}*{sign}?{digit}* {
{
register char *p = yytext;
float divisor = 10.0, multiplier = 0.0;
int minus = FALSE, expminus = FALSE;
int decimal = FALSE, exponent = FALSE;

yyfval = 0.0;
if(*p == '-') {
++p;
minus = TRUE;
}
do {
switch(*p) {
case '.':
decimal = TRUE;
break;
case 'e':
case 'E': exponent = TRUE;
if(*(p+1) == '-' || *(p+1) == '+')
expminus = (*++p == '-') ? TRUE : FALSE;
break;

default:
if(!decimal && ! exponent) {
yyfval = 10. * (yyfval) + (*p - '0');
break;
}
else if(!exponent) {
yyfval = yyfval + (*p - '0')/divisor;
divisor *= 10.;
break;
} else
multiplier = 10. * multiplier + (*p - '0');
}
} while (*++p);
if (minus)
yyfval = -yyfval;
if (expminus)
multiplier = -multiplier;
if(exponent)
yyfval = yyfval * pow(10., multiplier);
printf("\nLEX/FCON: %s is %f\n", yytext, yyfval);
return(FCON);
}
}

{text} {
if(strlen(yytext) == 1) {
printf("\nLEX/CCON: '%s'\n", yytext);
return(CCON);
}
else {
printf("\nLEX/SCON: \"%s\"\n", yytext);
return(SCON);
}
}

{string} {
strcpy(yytext, yytext+1);
yytext[yyleng-1] = NULL;
descape(yytext);
printf("\nLEX/SCON: \"%s\"\n", yytext);
return(SCON);
}

{char} {
strcpy(yytext, yytext+1);
yytext[yyleng-1] = NULL;
escape(yytext);
printf("\nLEX/CCON: '%s'\n", yytext);
return(CCON);
}

{white}+ ;

%%

input(){
static int newline = TRUE;
register int c;


if(newline)
printf("%s>", "C Lib");

if((c = getc(lexin)) == '\n')
newline = TRUE;
else
newline = FALSE;

return(c);
}

/*
** Translate escape sequences in a character string
*/
descape(str)
register char* str;
{
register char* s;
int i;

for (s = str; *str; s++, str++) {
if(*str != '\\')
*s = *str;
else if (0 <= (i = ndex("'\"bnrtf", *++str)))
*s = "'\"\b\n\r\t\f"[i];
else if (isdigit(*str)) {
register BYTE d;
*s = *str - '0';
for (i=0; (d = *(str+1)) && isdigit(d) && i < 3; i++, str++)
*s = (*s << 3) + d - '0';
}
}
*s = '\0';
}

/*
** Find the index of a character in a string
*/
int ndex(str, chr)
register char* str;
char chr;
{
register int i;

for (i = 0; *str; i++, str++)
if(*str == chr) return(i);
return(-1);
}

/*
** Convert a hex digit (ASCII)
*/
int hex(c)
register char c;
{
if (isdigit(c))
return (c - '0');
else if ('a' <= c && c <= 'f')
return (c + 10 - 'a');
else if ('A' <= c && c <= 'F')
return (c + 10 - 'A');
else
return(0);
}