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