Re: [v9.2] make_greater_string() does not return a string in some cases

Hello, I feel at a loss what to do...

> I thought that code was looking for 0xED/0xF4 in the second position,
> but it's actually looking for them in the first position, which makes
> vastly more sense.  Whee!

Anyway, I try to describe another aspect of this code a the present.

The switch block in the g_utf8_increnet is a folded code of five
individual manipulation according to the byte-length of the
sequence. The separation presupposes the input bytes and length
formes a valid utf-8 sequence.

For a character more than 5 byte length, retunes false.

For 4 bytes, the sequence ranges between U+10000 and U+1fffff.
 If charptr[3] is less than 0xbf, increment it and return true.
 Else assign 0x80 to charptr[3] and then if charptr[2] is less than 0xbf increment it and return true.
 Else assign 0x80 to charptr[2] and then,   if (charptr[1] is less than 0x8f when charptr[0] == 0xf4) or
(charptr[1]is less than 0xbf when charptr[0] != 0xf4)     increment it and return true.
 
 Else assign 0x80 to charptr[1] and then if charptr[0] is not 0xf4 increment it and return true.
 Else the input sequence must be 0xf4 0x8f 0xbf 0xbf which represents U+10ffff and this is the upper limit of UTF-8
representation.Restore the sequnce and return false.
 


for 3 bytes, the sequence ranges between u+800 and u+ffff.
 If charptr[2] is less than 0xbf increment it and reutrn true.
 Else assign 0x80 to charptr[2] and then,   if (charptr[1] is less than 0x9f when charptr[0] == 0xed) or
(charptr[1]is less than 0xbf when charptr[0] != 0xed)      increment it and return true.
 
   The sequence 0xed 0x9f 0xbf represents U+d7ff will   incremented to 0xef 0x80 0x80 (U+f000) at the end.
 Else assign 0x80 to charptr[1] and then if charptr[0] is not 0xef increment it and return true.
 Else the input sequence must be 0xef 0xbf 0xbf which represents U+ffff and the next UTF8 sequence has the length of 4.
Restorethe sequnce and return false.
 


For 2 bytes, the sequence ranges between U+80 and U+7ff.
 If charptr[1] is less than 0xbf increment it and reutrn true.
 Else assign 0x80 to charptr[1] and then if charptr[0] is not 0xdf increment it and return true.
 Else the input sequence must be 0xdf 0xbf which reporesents U+7ff and next UTF8 sequence has the length of 3.  Restore
thesequence and return false.
 


For 1 byte, the byte ranges between U+0 and U+7f.
 If charptr[0] is less than 0x7f increment it and return true.
 Else the input sequence must be 0x7f which represents U+7f and next UTF8 sequence has the length of 2. Restore the
sequenceand return false.
 

-- 
Kyotaro Horiguchi