/* 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 <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; | |

} | |

} |