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Don't optimize prematurely in text_index_charpos_to_bytepos

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* src/text-index.c (text_index_bytepos_to_charpos): Add a const.
(bytepos_of_head): Removed.
(text_index_charpos_to_bytepos): Don't be clever about choosing
to scan forward or backward.
(bytepos_forward_to_charpos): Use char_start_bytepos.
This commit is contained in:
Gerd Möllmann 2025-04-26 21:20:22 +02:00
parent d4879b59a2
commit c38027f0b8
1 changed files with 8 additions and 18 deletions
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26
src/text-index.c
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@ -457,7 +457,7 @@ bytepos_forward_to_charpos (struct buffer *b, const struct text_pos from,
ptrdiff_t to_charpos)
{
eassert (from.charpos < to_charpos);
ptrdiff_t bytepos = from.bytepos;
ptrdiff_t bytepos = char_start_bytepos (b, from.bytepos);
ptrdiff_t charpos = from.charpos;
while (charpos < to_charpos)
{
@ -620,7 +620,7 @@ buf_bytepos_to_charpos (struct buffer *b, const ptrdiff_t bytepos)
/* Scan forward if the distance to the previous known position is
smaller than the distance to the next known position. */
ptrdiff_t charpos
const ptrdiff_t charpos
= (bytepos - prev.bytepos < next.bytepos - bytepos)
? charpos_forward_to_bytepos (b, prev, bytepos)
: charpos_backward_to_bytepos (b, next, bytepos);
@ -629,14 +629,6 @@ buf_bytepos_to_charpos (struct buffer *b, const ptrdiff_t bytepos)
return charpos;
}
static ptrdiff_t
bytepos_of_head (struct buffer *b, ptrdiff_t bytepos)
{
while (!CHAR_HEAD_P (BUF_FETCH_BYTE (b, bytepos)))
--bytepos;
return bytepos;
}
/* Return the byte position in buffer B corresponding to character
position CHARPOS. */
@ -684,14 +676,12 @@ buf_charpos_to_bytepos (struct buffer *b, const ptrdiff_t charpos)
return prev.bytepos + (charpos - prev.charpos); /* ASCII-only! */
}
/* Don't scan forward if CHARPOS is exactly on the previous known
position because the index bytepos can be in the middle of a
character, which is found by scanning backwards. */
ptrdiff_t bytepos
= (charpos == prev.charpos ? bytepos_of_head (b, prev.bytepos)
: (charpos - prev.charpos < next.charpos - charpos
? bytepos_forward_to_charpos (b, prev, charpos)
: bytepos_backward_to_charpos (b, next, charpos)));
/* Scan forward if the distance to the previous known position is
smaller than the distance to the next known position. */
const ptrdiff_t bytepos
= (charpos - prev.charpos < next.charpos - charpos
? bytepos_forward_to_charpos (b, prev, charpos)
: bytepos_backward_to_charpos (b, next, charpos));
cache (ti, charpos, bytepos);
return bytepos;