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Diffstat (limited to 'libiberty/strverscmp.c')
| -rw-r--r-- | libiberty/strverscmp.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/libiberty/strverscmp.c b/libiberty/strverscmp.c new file mode 100644 index 0000000..2c6fe8a --- /dev/null +++ b/libiberty/strverscmp.c @@ -0,0 +1,157 @@ +/* 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., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 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; + } +} |