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Diffstat (limited to 'strings/strcoll.ic')
| -rw-r--r-- | strings/strcoll.ic | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/strings/strcoll.ic b/strings/strcoll.ic new file mode 100644 index 00000000000..4bced593a23 --- /dev/null +++ b/strings/strcoll.ic @@ -0,0 +1,275 @@ +/* + Copyright (c) 2015, MariaDB Foundation + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; version 2 of the License. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +*/ + + +#ifndef MY_FUNCTION_NAME +#error MY_FUNCTION_NAME is not defined +#endif + + +/* + The weight for automatically padded spaces when comparing strings with + the PAD SPACE property. + Should normally be equal to the weight of a regular space. +*/ +#ifndef WEIGHT_PAD_SPACE +#define WEIGHT_PAD_SPACE (' ') +#endif + + +/* + Weight of an illegal byte, must follow these rules: + 1. Must be greater than weight of any normal character in the collation. + 2. Two different bad bytes must have different weights and must be + compared in their binary order. + + Depends on mbmaxlen of the character set, as well as how the collation + sorts various single-byte and multi-byte character blocks. + + The macro below is the default definition, it is suitable for mbmaxlen=2 + character sets that sort all multi-byte characters after all single-byte + characters: big5, euckr, gb2312, gbk. + + All mbmaxlen>2 character sets must provide their own definitions. + All collations that have a more complex order (than just MB1 followed by MB2) + must also provide their own definitions (see definitions for + cp932_japanese_ci and sjis_japanese_ci as examples of a more complex order). +*/ +#ifndef WEIGHT_ILSEQ +#define WEIGHT_ILSEQ(x) (0xFF00 + (x)) +#endif + + +/** + Scan a valid character, or a bad byte, or an auto-padded space + from a string and calculate the weight of the scanned sequence. + + @param [OUT] weight - the weight is returned here + @param str - the string + @param end - the end of the string + @return - the number of bytes scanned + + The including source file must define the following macros: + IS_MB1_CHAR(b0) - for character sets that have MB1 characters + IS_MB1_MB2HEAD_GAP(b0) - optional, for better performance + IS_MB2_CHAR(b0,b1) - for character sets that have MB2 characters + IS_MB3_CHAR(b0,b1,b2) - for character sets that have MB3 characters + IS_MB4_CHAR(b0,b1,b2,b3) - for character sets with have MB4 characters + WEIGHT_PAD_SPACE + WEIGHT_MB1(b0) - for character sets that have MB1 characters + WEIGHT_MB2(b0,b1) - for character sets that have MB2 characters + WEIGHT_MB3(b0,b1,b2) - for character sets that have MB3 characters + WEIGHT_MB4(b0,b1,b2,b3) - for character sets that have MB4 characters + WEIGHT_ILSEQ(x) +*/ +static inline uint +MY_FUNCTION_NAME(scan_weight)(int *weight, const uchar *str, const uchar *end) +{ + if (str >= end) + { + *weight= WEIGHT_PAD_SPACE; + return 0; + } + +#ifdef IS_MB1_CHAR + if (IS_MB1_CHAR(*str)) + { + *weight= WEIGHT_MB1(*str); /* A valid single byte character*/ + return 1; + } +#endif + +#ifdef IS_MB1_MBHEAD_UNUSED_GAP + /* + Quickly filter out unused bytes that are neither MB1 nor MBHEAD. + E.g. [0x80..0xC1] in utf8. This allows using simplified conditions + in IS_MB2_CHAR(), IS_MB3_CHAR(), etc. + */ + if (IS_MB1_MBHEAD_UNUSED_GAP(*str)) + goto bad; +#endif + +#ifdef IS_MB2_CHAR + if (str + 2 > end) /* The string ended unexpectedly */ + goto bad; /* Treat as a bad byte */ + + if (IS_MB2_CHAR(str[0], str[1])) + { + *weight= WEIGHT_MB2(str[0], str[1]); + return 2; /* A valid two-byte character */ + } +#endif + +#ifdef IS_MB3_CHAR + if (str + 3 > end) /* Incomplete three-byte character */ + goto bad; + + if (IS_MB3_CHAR(str[0], str[1], str[2])) + { + *weight= WEIGHT_MB3(str[0], str[1], str[2]); + return 3; /* A valid three-byte character */ + } +#endif + +#ifdef IS_MB4_CHAR + if (str + 4 > end) /* Incomplete four-byte character */ + goto bad; + + if (IS_MB4_CHAR(str[0], str[1], str[2], str[3])) + { + *weight= WEIGHT_MB4(str[0], str[1], str[2], str[3]); + return 4; /* A valid four-byte character */ + } + +#endif + +bad: + *weight= WEIGHT_ILSEQ(str[0]); /* Bad byte */ + return 1; +} + + +/** + Compare two strings according to the collation, + without handling the PAD SPACE property. + + Note, cs->coll->strnncoll() is usually used to compare identifiers. + Perhaps we should eventually (in 10.2?) create a new collation + my_charset_utf8_general_ci_no_pad and have only one comparison function + in MY_COLLATION_HANDLER. + + @param cs - the character set and collation + @param a - the left string + @param a_length - the length of the left string + @param b - the right string + @param b_length - the length of the right string + @param b_is_prefix - if the caller wants to check if "b" is a prefix of "a" + @return - the comparison result +*/ +static int +MY_FUNCTION_NAME(strnncoll)(CHARSET_INFO *cs __attribute__((unused)), + const uchar *a, size_t a_length, + const uchar *b, size_t b_length, + my_bool b_is_prefix) +{ + const uchar *a_end= a + a_length; + const uchar *b_end= b + b_length; + for ( ; ; ) + { + int a_weight, b_weight, res; + uint a_wlen= MY_FUNCTION_NAME(scan_weight)(&a_weight, a, a_end); + uint b_wlen= MY_FUNCTION_NAME(scan_weight)(&b_weight, b, b_end); + /* + a_wlen b_wlen Comment + ------ ------ ------- + 0 0 Strings ended simultaneously, "a" and "b" are equal. + 0 >0 "a" is a prefix of "b", so "a" is smaller. + >0 0 "b" is a prefix of "a", check b_is_prefix. + >0 >0 Two weights were scanned, check weight difference. + */ + if (!a_wlen) + return b_wlen ? -b_weight : 0; + + if (!b_wlen) + return b_is_prefix ? 0 : a_weight; + + if ((res= (a_weight - b_weight))) + return res; + /* + None of the strings has ended yet. + */ + DBUG_ASSERT(a < a_end); + DBUG_ASSERT(b < b_end); + a+= a_wlen; + b+= b_wlen; + } + DBUG_ASSERT(0); + return 0; +} + + +/** + Compare two strings according to the collation, with PAD SPACE handling. + + @param cs - the character set and collation + @param a - the left string + @param a_length - the length of the left string + @param b - the right string + @param b_length - the length of the right string + @param diff_if_only_endspace_difference - not used in the code. + TODO: this should be eventually removed (in 10.2?) + @return - the comparison result +*/ + +static int +MY_FUNCTION_NAME(strnncollsp)(CHARSET_INFO *cs __attribute__((unused)), + const uchar *a, size_t a_length, + const uchar *b, size_t b_length, + my_bool diff_if_only_endspace_difference + __attribute__((unused))) +{ + const uchar *a_end= a + a_length; + const uchar *b_end= b + b_length; + for ( ; ; ) + { + int a_weight, b_weight, res; + uint a_wlen= MY_FUNCTION_NAME(scan_weight)(&a_weight, a, a_end); + uint b_wlen= MY_FUNCTION_NAME(scan_weight)(&b_weight, b, b_end); + if ((res= (a_weight - b_weight))) + { + /* + Got two different weights. Each weight can be generated by either of: + - a real character + - a bad byte sequence or an incomplete byte sequence + - an auto-generated trailing space (PAD SPACE) + It does not matter how exactly each weight was generated. + Just return the weight difference. + */ + return res; + } + if (!a_wlen && !b_wlen) + { + /* + Got two auto-generated trailing spaces, i.e. + both strings have now ended, so they are equal. + */ + DBUG_ASSERT(a == a_end); + DBUG_ASSERT(b == b_end); + return 0; + } + /* + At least one of the strings has not ended yet, continue comparison. + */ + DBUG_ASSERT(a < a_end || b < b_end); + a+= a_wlen; + b+= b_wlen; + } + DBUG_ASSERT(0); + return 0; +} + +/* + We usually include this file at least two times from the same source file, + for the _ci and the _bin collations. Prepare for the second inclusion. +*/ +#undef MY_FUNCTION_NAME +#undef WEIGHT_ILSEQ +#undef WEIGHT_MB1 +#undef WEIGHT_MB2 +#undef WEIGHT_MB3 +#undef WEIGHT_MB4 +#undef WEIGHT_PAD_SPACE |