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5191 | serge | 1 | /* Compare strings while treating digits characters numerically. |
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 |
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5 | |||
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 | |||
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 | |||
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 | |||
21 | #include "libiberty.h" |
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22 | #include "safe-ctype.h" |
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23 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
71 | */ |
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72 | |||
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 | |||
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 | |||
84 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
124 | if (p1 == p2) |
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125 | return 0; |
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126 | |||
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 | |||
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 | |||
140 | state = result_type[state << 2 | (((c2 == '0') + (ISDIGIT (c2) != 0)))]; |
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141 | |||
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 | |||
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 | |||
152 | return ISDIGIT (*p2) ? -1 : diff; |
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153 | |||
154 | default: |
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155 | return state; |
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156 | } |
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157 | }><>0>>0> |