1 /* Compare strings while treating digits characters numerically. 2 Copyright (C) 1997, 2002, 2005 Free Software Foundation, Inc. 3 This file is part of the libiberty library. 4 Contributed by Jean-Franois Bignolles <bignolle (at) ecoledoc.ibp.fr>, 1997. 5 6 Libiberty is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Lesser General Public 8 License as published by the Free Software Foundation; either 9 version 2.1 of the License, or (at your option) any later version. 10 11 Libiberty is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Lesser General Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with the GNU C Library; if not, write to the Free 18 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. */ 20 21 #include "libiberty.h" 22 #include "safe-ctype.h" 23 24 /* 25 @deftypefun int strverscmp (const char *@var{s1}, const char *@var{s2}) 26 The @code{strverscmp} function compares the string @var{s1} against 27 @var{s2}, considering them as holding indices/version numbers. Return 28 value follows the same conventions as found in the @code{strverscmp} 29 function. In fact, if @var{s1} and @var{s2} contain no digits, 30 @code{strverscmp} behaves like @code{strcmp}. 31 32 Basically, we compare strings normally (character by character), until 33 we find a digit in each string - then we enter a special comparison 34 mode, where each sequence of digits is taken as a whole. If we reach the 35 end of these two parts without noticing a difference, we return to the 36 standard comparison mode. There are two types of numeric parts: 37 "integral" and "fractional" (those begin with a '0'). The types 38 of the numeric parts affect the way we sort them: 39 40 @itemize @bullet 41 @item 42 integral/integral: we compare values as you would expect. 43 44 @item 45 fractional/integral: the fractional part is less than the integral one. 46 Again, no surprise. 47 48 @item 49 fractional/fractional: the things become a bit more complex. 50 If the common prefix contains only leading zeroes, the longest part is less 51 than the other one; else the comparison behaves normally. 52 @end itemize 53 54 @smallexample 55 strverscmp ("no digit", "no digit") 56 @result{} 0 // @r{same behavior as strcmp.} 57 strverscmp ("item#99", "item#100") 58 @result{} <0 // @r{same prefix, but 99 < 100.} 59 strverscmp ("alpha1", "alpha001") 60 @result{} >0 // @r{fractional part inferior to integral one.} 61 strverscmp ("part1_f012", "part1_f01") 62 @result{} >0 // @r{two fractional parts.} 63 strverscmp ("foo.009", "foo.0") 64 @result{} <0 // @r{idem, but with leading zeroes only.} 65 @end smallexample 66 67 This function is especially useful when dealing with filename sorting, 68 because filenames frequently hold indices/version numbers. 69 @end deftypefun 70 71 */ 72 73 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing 74 fractional parts, S_Z: idem but with leading Zeroes only */ 75 #define S_N 0x0 76 #define S_I 0x4 77 #define S_F 0x8 78 #define S_Z 0xC 79 80 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */ 81 #define CMP 2 82 #define LEN 3 83 84 85 /* Compare S1 and S2 as strings holding indices/version numbers, 86 returning less than, equal to or greater than zero if S1 is less than, 87 equal to or greater than S2 (for more info, see the Glibc texinfo doc). */ 88 89 int 90 strverscmp (const char *s1, const char *s2) 91 { 92 const unsigned char *p1 = (const unsigned char *) s1; 93 const unsigned char *p2 = (const unsigned char *) s2; 94 unsigned char c1, c2; 95 int state; 96 int diff; 97 98 /* Symbol(s) 0 [1-9] others (padding) 99 Transition (10) 0 (01) d (00) x (11) - */ 100 static const unsigned int next_state[] = 101 { 102 /* state x d 0 - */ 103 /* S_N */ S_N, S_I, S_Z, S_N, 104 /* S_I */ S_N, S_I, S_I, S_I, 105 /* S_F */ S_N, S_F, S_F, S_F, 106 /* S_Z */ S_N, S_F, S_Z, S_Z 107 }; 108 109 static const int result_type[] = 110 { 111 /* state x/x x/d x/0 x/- d/x d/d d/0 d/- 112 0/x 0/d 0/0 0/- -/x -/d -/0 -/- */ 113 114 /* S_N */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP, 115 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, 116 /* S_I */ CMP, -1, -1, CMP, +1, LEN, LEN, CMP, 117 +1, LEN, LEN, CMP, CMP, CMP, CMP, CMP, 118 /* S_F */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP, 119 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, 120 /* S_Z */ CMP, +1, +1, CMP, -1, CMP, CMP, CMP, 121 -1, CMP, CMP, CMP 122 }; 123 124 if (p1 == p2) 125 return 0; 126 127 c1 = *p1++; 128 c2 = *p2++; 129 /* Hint: '0' is a digit too. */ 130 state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0)); 131 132 while ((diff = c1 - c2) == 0 && c1 != '\0') 133 { 134 state = next_state[state]; 135 c1 = *p1++; 136 c2 = *p2++; 137 state |= (c1 == '0') + (ISDIGIT (c1) != 0); 138 } 139 140 state = result_type[state << 2 | (((c2 == '0') + (ISDIGIT (c2) != 0)))]; 141 142 switch (state) 143 { 144 case CMP: 145 return diff; 146 147 case LEN: 148 while (ISDIGIT (*p1++)) 149 if (!ISDIGIT (*p2++)) 150 return 1; 151 152 return ISDIGIT (*p2) ? -1 : diff; 153 154 default: 155 return state; 156 } 157 } 158
