@ -563,6 +563,8 @@ my_bool my_like_range_mb(CHARSET_INFO *cs,
char * min_end = min_str + res_length ;
char * max_end = max_str + res_length ;
uint maxcharlen = res_length / cs - > mbmaxlen ;
const char * contraction_flags = cs - > contractions ?
( ( const char * ) cs - > contractions ) + 0x40 * 0x40 : NULL ;
for ( ; ptr ! = end & & min_str ! = min_end & & maxcharlen ; maxcharlen - - )
{
@ -571,6 +573,7 @@ my_bool my_like_range_mb(CHARSET_INFO *cs,
ptr + + ; /* Skip escape */
else if ( * ptr = = w_one | | * ptr = = w_many ) /* '_' and '%' in SQL */
{
fill_max_and_min :
/*
Calculate length of keys :
' a \ 0 \ 0. . . is the smallest possible string when we have space expand
@ -602,8 +605,74 @@ my_bool my_like_range_mb(CHARSET_INFO *cs,
* min_str + + = * max_str + + = * ptr + + ;
}
else
* min_str + + = * max_str + + = * ptr + + ;
{
/*
Special case for collations with contractions .
For example , in Chezh , ' ch ' is a separate letter
which is sorted between ' h ' and ' i ' .
If the pattern ' abc % ' , ' c ' at the end can mean :
- letter ' c ' itself ,
- beginning of the contraction ' ch ' .
If we simply return this LIKE range :
' abc \ min \ min \ min ' and ' abc \ max \ max \ max '
then this query : SELECT * FROM t1 WHERE a LIKE ' abc % '
will only find values starting from ' abc [ ^ h ] ' ,
but won ' t find values starting from ' abch ' .
We must ignore contraction heads followed by w_one or w_many .
( ' Contraction head ' means any letter which can be the first
letter in a contraction )
For example , for Czech ' abc % ' , we will return LIKE range ,
which is equal to LIKE range for ' ab % ' :
' ab \ min \ min \ min \ min ' and ' ab \ max \ max \ max \ max ' .
*/
if ( contraction_flags & & ptr + 1 < end & &
contraction_flags [ ( uchar ) * ptr ] )
{
/* Ptr[0] is a contraction head. */
if ( ptr [ 1 ] = = w_one | | ptr [ 1 ] = = w_many )
{
/* Contraction head followed by a wildcard, quit. */
goto fill_max_and_min ;
}
/*
Some letters can be both contraction heads and contraction tails .
For example , in Danish ' aa ' is a separate single letter which
is sorted after ' z ' . So ' a ' can be both head and tail .
If ptr [ 0 ] + ptr [ 1 ] is a contraction ,
then put both letters together .
If ptr [ 1 ] can be a contraction part , but ptr [ 0 ] + ptr [ 1 ]
is not a contraction , then we put only ptr [ 0 ] ,
and continue with ptr [ 1 ] on the next loop .
*/
if ( contraction_flags [ ( uchar ) ptr [ 1 ] ] & &
cs - > contractions [ ( * ptr - 0x40 ) * 0x40 + ptr [ 1 ] - 0x40 ] )
{
/* Contraction found */
if ( maxcharlen = = 1 | | min_str + 1 > = min_end )
{
/* Both contraction parts don't fit, quit */
goto fill_max_and_min ;
}
/* Put contraction head */
* min_str + + = * max_str + + = * ptr + + ;
maxcharlen - - ;
}
}
/* Put contraction tail, or a single character */
* min_str + + = * max_str + + = * ptr + + ;
}
}
* min_length = * max_length = ( uint ) ( min_str - min_org ) ;
unknown
19 years ago