strnatcmp.c File Reference

#include <stddef.h>
#include <ctype.h>
#include "strnatcmp.h"

Include dependency graph for strnatcmp.c:

Functions
static int	nat_isdigit (nat_char a)
static int	nat_isspace (nat_char a)
static nat_char	nat_toupper (nat_char a)
static int	compare_right (nat_char const *a, nat_char const *b)
static int	compare_left (nat_char const *a, nat_char const *b)
static int	strnatcmp0 (nat_char const *a, nat_char const *b, int fold_case)
int	strnatcmp (nat_char const *a, nat_char const *b)
int	strnatcasecmp (nat_char const *a, nat_char const *b)

Function Documentation

compare_left()

static int compare_left ( nat_char const *  a, nat_char const *  b  )

static

{
     /* Compare two left-aligned numbers: the first to have a
        different value wins. */
     for (;; a++, b++) {
          if (!nat_isdigit(*a)  &&  !nat_isdigit(*b))
               return 0;
          if (!nat_isdigit(*a))
               return -1;
          if (!nat_isdigit(*b))
               return +1;
          if (*a < *b)
               return -1;
          if (*a > *b)
               return +1;
     }
 
     return 0;
}

compare_right()

static int compare_right ( nat_char const *  a, nat_char const *  b  )

static

{
     int bias = 0;
 
     /* The longest run of digits wins.  That aside, the greatest
        value wins, but we can't know that it will until we've scanned
        both numbers to know that they have the same magnitude, so we
        remember it in BIAS. */
     for (;; a++, b++) {
          if (!nat_isdigit(*a)  &&  !nat_isdigit(*b))
               return bias;
          if (!nat_isdigit(*a))
               return -1;
          if (!nat_isdigit(*b))
               return +1;
          if (*a < *b) {
               if (!bias)
                    bias = -1;
          } else if (*a > *b) {
               if (!bias)
                    bias = +1;
          } else if (!*a  &&  !*b)
               return bias;
     }
 
     return 0;
}

nat_isdigit()

static int nat_isdigit ( nat_char  a )

inlinestatic

{
     return isdigit((unsigned char) a);
}

nat_isspace()

static int nat_isspace ( nat_char  a )

inlinestatic

{
     return isspace((unsigned char) a);
}

nat_toupper()

static nat_char nat_toupper ( nat_char  a )

inlinestatic

{
     return toupper((unsigned char) a);
}

strnatcasecmp()

int strnatcasecmp	(	nat_char const *	a,
		nat_char const *	b
	)

                                                    {
     return strnatcmp0(a, b, 1);
}

strnatcmp()

int strnatcmp	(	nat_char const *	a,
		nat_char const *	b
	)

                                                {
     return strnatcmp0(a, b, 0);
}

strnatcmp0()

static int strnatcmp0 ( nat_char const *  a, nat_char const *  b, int  fold_case  )

static

{
     int ai, bi;
     nat_char ca, cb;
     int fractional, result;
 
     ai = bi = 0;
     while (1) {
          ca = a[ai]; cb = b[bi];
 
          /* skip over leading spaces or zeros */
          while (nat_isspace(ca))
               ca = a[++ai];
 
          while (nat_isspace(cb))
               cb = b[++bi];
 
          /* process run of digits */
          if (nat_isdigit(ca)  &&  nat_isdigit(cb)) {
               fractional = (ca == '0' || cb == '0');
 
               if (fractional) {
                    if ((result = compare_left(a+ai, b+bi)) != 0)
                         return result;
               } else {
                    if ((result = compare_right(a+ai, b+bi)) != 0)
                         return result;
               }
          }
 
          if (!ca && !cb) {
               /* The strings compare the same.  Perhaps the caller
                  will want to call strcmp to break the tie. */
               return 0;
          }
 
          if (fold_case) {
               ca = nat_toupper(ca);
               cb = nat_toupper(cb);
          }
 
          if (ca < cb)
               return -1;
 
          if (ca > cb)
               return +1;
 
          ++ai; ++bi;
     }
}