I hereby relicense all my work on Sortix under the ISC license as below. All Sortix contributions by other people are already under this license, are not substantial enough to be copyrightable, or have been removed. All imported code from other projects is compatible with this license. All GPL licensed code from other projects had previously been removed. Copyright 2011-2016 Jonas 'Sortie' Termansen and contributors. Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
112 lines
3.5 KiB
C
112 lines
3.5 KiB
C
/*
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* Copyright (c) 2013 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* string/strverscmp.c
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* Compares two version strings.
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*/
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#include <stdbool.h>
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#include <string.h>
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static bool is_number(char c)
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{
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return '0' <= c && c <= '9';
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}
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static int to_number(char c)
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{
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return c - '0';
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}
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int strverscmp(const char* a, const char* b)
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{
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for ( size_t i = 0; true; i++ )
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{
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// Be a regular strcmp if the strings are equal.
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if ( a[i] == '\0' && b[i] == '\0' )
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return 0;
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if ( a[i] == b[i] )
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continue;
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// Be a regular strcmp if no digits are involed when they differ.
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bool version_string = is_number(a[i]) && is_number(b[i]);
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if ( !version_string && a[i] < b[i] )
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return -1;
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if ( !version_string && a[i] > b[i] )
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return 1;
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// Because the number of leading zeroes matter, we have to find the
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// entire numeric block we are currently within. We know the strings are
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// equal until i, so we can simply find the number of shared digits by
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// looking in the first string.
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size_t digits_start = i;
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while ( digits_start && is_number(a[digits_start-1]) )
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digits_start--;
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size_t shared_digits = i - digits_start;
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// Find the number of shared leading zeroes.
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size_t shared_zeroes = 0;
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while ( shared_zeroes < shared_digits &&
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to_number(a[digits_start + shared_zeroes]) == 0 )
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shared_zeroes++;
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// Try to expand the leading zeroes amount into a.
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size_t a_zeroes = shared_zeroes;
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while ( is_number(a[digits_start + a_zeroes]) == 0 )
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a_zeroes++;
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// Try to expand the leading zeroes amount into b.
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size_t b_zeroes = shared_zeroes;
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while ( is_number(b[digits_start + b_zeroes]) == 0 )
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b_zeroes++;
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// We treat strings with leading zeroes as if they have a decimal point
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// in front of them, so strings with more zeroes sort lower.
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if ( a_zeroes > b_zeroes )
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return -1;
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if ( b_zeroes > a_zeroes )
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return 1;
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// Find the number of consecutive digits in a where the strings differ.
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size_t a_digits = a_zeroes;
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while ( is_number(a[digits_start + a_digits]) )
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a_digits++;
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// Find the number of consecutive digits in b where the strings differ.
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size_t b_digits = b_zeroes;
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while ( is_number(b[digits_start + b_digits]) )
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b_digits++;
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// We know the strings have the same amount of leading zeroes, so we
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// so if a a block is longer than the other, then the value must be
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// longer as well.
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if ( a_digits < b_digits )
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return -1;
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if ( b_digits < a_digits )
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return 1;
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// Finally run through the strings from where they differ and sort them
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// numerically. We know this terminates because the strings differ. The
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// strings have the same amount of digits, so comparing them is easy.
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for ( size_t n = shared_zeroes; true; n++ )
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{
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if ( a[digits_start + n] < b[digits_start + n] )
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return -1;
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if ( b[digits_start + n] < a[digits_start + n] )
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return 1;
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}
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}
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}
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