/* Compare strings while treating digits characters numerically.
Copyright 1997, 2002, 2005 Free Software Foundation, Inc.
This file is part of the libiberty library.
Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.
*/
/*
@deftypefun int strverscmp (const char *@var{s1}, const char *@var{s2})
The @code{strverscmp} function compares the string @var{s1} against
@var{s2}, considering them as holding indices/version numbers. Return
value follows the same conventions as found in the @code{strverscmp}
function. In fact, if @var{s1} and @var{s2} contain no digits,
@code{strverscmp} behaves like @code{strcmp}.
Basically, we compare strings normally (character by character), until
we find a digit in each string - then we enter a special comparison
mode, where each sequence of digits is taken as a whole. If we reach the
end of these two parts without noticing a difference, we return to the
standard comparison mode. There are two types of numeric parts:
"integral" and "fractional" (those begin with a '0'). The types
of the numeric parts affect the way we sort them:
@itemize @bullet
@item
integral/integral: we compare values as you would expect.
@item
fractional/integral: the fractional part is less than the integral one.
Again, no surprise.
@item
fractional/fractional: the things become a bit more complex.
If the common prefix contains only leading zeroes, the longest part is less
than the other one; else the comparison behaves normally.
@end itemize
@smallexample
strverscmp ("no digit", "no digit")
@result{} 0 // @r{same behavior as strcmp.}
strverscmp ("item#99", "item#100")
@result{} <0 // @r{same prefix, but 99 < 100.}
strverscmp ("alpha1", "alpha001")
@result{} >0 // @r{fractional part inferior to integral one.}
strverscmp ("part1_f012", "part1_f01")
@result{} >0 // @r{two fractional parts.}
strverscmp ("foo.009", "foo.0")
@result{} <0 // @r{idem, but with leading zeroes only.}
@end smallexample
This function is especially useful when dealing with filename sorting,
because filenames frequently hold indices/version numbers.
@end deftypefun
*/
#include "stdhdr.h"
//#include "libiberty.h"
/* states: S_N: normal, S_I: comparing integral part, S_F: comparing
fractional parts, S_Z: idem but with leading Zeroes only */
#define S_N 0x0
#define S_I 0x4
#define S_F 0x8
#define S_Z 0xC
/* result_type: CMP: return diff; LEN: compare using len_diff/diff */
#define CMP 2
#define LEN 3
/* ISDIGIT differs from isdigit, as follows:
- Its arg may be any int or unsigned; it need not be an unsigned char.
- It's guaranteed to evaluate its argument exactly once.
- It's typically faster.
POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
ISDIGIT_LOCALE unless it's important to use the locale's definition
of `digit' even when the host does not conform to POSIX. */
#define ISDIGIT(c) (((unsigned)(c) - '0') <= 9)
/* Compare S1 and S2 as strings holding indices/version numbers,
returning less than, equal to or greater than zero if S1 is less than,
equal to or greater than S2 (for more info, see the Glibc texinfo doc). */
FUNC(int) strverscmp (const char *s1, const char *s2) {
const unsigned char *p1 = (const unsigned char *) s1;
const unsigned char *p2 = (const unsigned char *) s2;
unsigned char c1, c2;
int state;
int diff;
/* Symbol(s) 0 [1-9] others (padding)
Transition (10) 0 (01) d (00) x (11) - */
static const unsigned next_state[] =
{
/* state x d 0 - */
/* S_N */ S_N, S_I, S_Z, S_N,
/* S_I */ S_N, S_I, S_I, S_I,
/* S_F */ S_N, S_F, S_F, S_F,
/* S_Z */ S_N, S_F, S_Z, S_Z
};
static const int result_type[] =
{
/* state x/x x/d x/0 x/- d/x d/d d/0 d/-
0/x 0/d 0/0 0/- -/x -/d -/0 -/- */
/* S_N */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
/* S_I */ CMP, -1, -1, CMP, +1, LEN, LEN, CMP,
+1, LEN, LEN, CMP, CMP, CMP, CMP, CMP,
/* S_F */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
/* S_Z */ CMP, +1, +1, CMP, -1, CMP, CMP, CMP,
-1, CMP, CMP, CMP
};
if (p1 == p2)
return 0;
c1 = *p1++;
c2 = *p2++;
/* Hint: '0' is a digit too. */
state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0));
while ((diff = c1 - c2) == 0 && c1 != '\0')
{
state = next_state[state];
c1 = *p1++;
c2 = *p2++;
state |= (c1 == '0') + (ISDIGIT (c1) != 0);
}
state = result_type[state << 2 | (((c2 == '0') + (ISDIGIT (c2) != 0)))];
switch (state)
{
case CMP:
return diff;
case LEN:
while (ISDIGIT (*p1++))
if (!ISDIGIT (*p2++))
return 1;
return ISDIGIT (*p2) ? -1 : diff;
default:
return state;
}
}
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