/* Compare strings while treating digits characters numerically. Copyright (C) 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. Libiberty is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. Libiberty is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "libiberty.h" #include "safe-ctype.h" /* @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 */ /* 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 /* 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). */ 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 int 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; } }