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text-index.c: Skip the byte scan when it's all ASCII
* src/text-index.c (is_close_enough_charpos): Remove unused arg `ti`. (narrow_bytepos_bounds_1, narrow_charpos_bounds_1) (narrow_bytepos_bounds, narrow_charpos_bounds): Don't short-circuit if a known point is exactly equal to what we're looking for, thus don't return value. (text_index_bytepos_to_charpos, text_index_charpos_to_bytepos): Short-circuit here instead after narrowing. Make the two functions more alike. Short-circuit also when the text remaining to scan is all ASCII.
This commit is contained in:
Stefan Monnier
parent
0b780f8619
commit
c8beb5f023
1 changed files with 74 additions and 85 deletions
159
src/text-index.c
159
src/text-index.c
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@ -91,7 +91,9 @@ struct text_index
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enum
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{
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/* Number of bytes in an interval. */
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/* Number of bytes in an interval.
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Tradeoff between cost of the text-index array and cost of scanning
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bytes between the positions recorded in the array. */
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TEXT_INDEX_INTERVAL = 4096,
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/* Default capacity in number of intervals for text indices. */
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@ -116,7 +118,7 @@ static struct text_pos
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beg_pos (const struct buffer *b)
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{
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return (struct text_pos)
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{.charpos = BEG, .bytepos =BEG_BYTE};
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{.charpos = BEG, .bytepos = BEG_BYTE};
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}
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static struct text_pos
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@ -138,8 +140,7 @@ pt_pos (const struct buffer *b)
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necessary. */
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static bool
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is_close_enough_charpos (const struct text_index *ti,
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ptrdiff_t charpos,
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is_close_enough_charpos (ptrdiff_t charpos,
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const struct text_pos pos)
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{
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return eabs (charpos - pos.charpos) < TEXT_INDEX_INTERVAL / 4;
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@ -503,103 +504,77 @@ next_known_text_pos (struct buffer *b, ptrdiff_t entry)
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}
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/* Improve the known bytepos bounds *PREV and *NEXT if KNOWN is closer
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to BYTEPOS. If KNOWN is an exact match for BYTEPOS return true. */
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to BYTEPOS. */
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static bool
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static void
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narrow_bytepos_bounds_1 (const struct text_pos known, struct text_pos *prev,
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struct text_pos *next, const ptrdiff_t bytepos)
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{
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eassert (bytepos >= prev->bytepos && bytepos <= next->bytepos);
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eassert (known.bytepos != TEXT_INDEX_INVALID_POSITION);
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if (known.bytepos == bytepos)
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return true;
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/* If KNOWN is in (PREV, BYTEPOS] it is a better PREV. */
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if (known.bytepos < bytepos
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if (known.bytepos <= bytepos
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&& known.bytepos > prev->bytepos)
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*prev = known;
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/* If KNOWN is in [BYTEPOS NEXT) it is a better NEXT. */
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if (known.bytepos > bytepos
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if (known.bytepos >= bytepos
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&& known.bytepos < next->bytepos)
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*next = known;
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return false;
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}
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/* Improve the known bytepos bounds *PREV and *NEXT of buffer B using
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known positions in B. BYTEPOS is a byte position to convert to a
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character position. If an exact match for BYTEPOS is found, return
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its charpos, otherwise return TEXT_INDEX_INVALID_POSITION. */
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character position. */
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static ptrdiff_t
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static void
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narrow_bytepos_bounds (struct buffer *b, struct text_pos *prev,
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struct text_pos *next, const ptrdiff_t bytepos)
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{
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const struct text_pos pt = pt_pos (b);
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if (narrow_bytepos_bounds_1 (pt, prev, next, bytepos))
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return pt.charpos;
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const struct text_pos gpt = gpt_pos (b);
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if (narrow_bytepos_bounds_1 (gpt, prev, next, bytepos))
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return gpt.charpos;
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narrow_bytepos_bounds_1 (pt_pos (b), prev, next, bytepos);
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narrow_bytepos_bounds_1 (gpt_pos (b), prev, next, bytepos);
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struct text_index *ti = b->text->index;
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if (is_cache_valid (ti)
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&& narrow_bytepos_bounds_1 (ti->cache, prev, next, bytepos))
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return ti->cache.charpos;
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return TEXT_INDEX_INVALID_POSITION;
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if (is_cache_valid (ti))
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narrow_bytepos_bounds_1 (ti->cache, prev, next, bytepos);
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}
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/* Improve the known bytepos bounds *PREV and *NEXT if KNOWN is closer
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to BYTEPOS. If KNOWN is an exact match for BYTEPOS return true. */
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to BYTEPOS. */
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static bool
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static void
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narrow_charpos_bounds_1 (const struct text_pos known, struct text_pos *prev,
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struct text_pos *next, const ptrdiff_t charpos)
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{
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eassert (charpos >= prev->charpos && charpos <= next->charpos);
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eassert (known.charpos != TEXT_INDEX_INVALID_POSITION);
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if (known.charpos == charpos)
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return true;
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/* If KNOWN is in (PREV, BYTEPOS] it is a better PREV. */
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if (known.charpos < charpos
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if (known.charpos <= charpos
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&& known.charpos > prev->charpos)
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*prev = known;
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/* If KNOWN is in [BYTEPOS NEXT) it is a better NEXT. */
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if (known.charpos > charpos
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if (known.charpos >= charpos
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&& known.charpos < next->charpos)
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*next = known;
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return false;
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}
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/* Improve the known bytepos bounds *PREV and *NEXT of buffer B using
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known positions in B. BYTEPOS is a byte position to convert to a
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character position. If an exact match for BYTEPOS is found, return
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its charpos, otherwise return TEXT_INDEX_INVALID_POSITION. */
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character position. */
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static ptrdiff_t
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static void
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narrow_charpos_bounds (struct buffer *b, struct text_pos *prev,
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struct text_pos *next, const ptrdiff_t charpos)
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{
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const struct text_pos pt = pt_pos (b);
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if (narrow_charpos_bounds_1 (pt, prev, next, charpos))
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return pt.bytepos;
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const struct text_pos gpt = gpt_pos (b);
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if (narrow_charpos_bounds_1 (gpt, prev, next, charpos))
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return gpt.bytepos;
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narrow_charpos_bounds_1 (pt_pos (b), prev, next, charpos);
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narrow_charpos_bounds_1 (gpt_pos (b), prev, next, charpos);
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struct text_index *ti = b->text->index;
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if (is_cache_valid (ti)
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&& narrow_charpos_bounds_1 (ti->cache, prev, next, charpos))
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return ti->cache.bytepos;
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return TEXT_INDEX_INVALID_POSITION;
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if (is_cache_valid (ti))
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narrow_charpos_bounds_1 (ti->cache, prev, next, charpos);
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}
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/* Return the character position in buffer B corresponding to
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@ -608,6 +583,7 @@ narrow_charpos_bounds (struct buffer *b, struct text_pos *prev,
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ptrdiff_t
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buf_bytepos_to_charpos (struct buffer *b, const ptrdiff_t bytepos)
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{
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/* FIXME: Can BYTEPOS ever be outside of BEGV_BYTE..ZV_BYTE? */
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/* If this buffer has as many characters as bytes, each character must
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be one byte. This takes care of the case where
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enable-multibyte-characters is nil. */
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@ -615,30 +591,39 @@ buf_bytepos_to_charpos (struct buffer *b, const ptrdiff_t bytepos)
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if (z.charpos == z.bytepos)
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return bytepos;
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/* BYTEPOS == Z_BYTE, and BYTEPOS is an interval boundary,
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then BYTEPOS does not have an index entry because we don't want
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extra entries for (Z, Z_BYTE). Changing that would be possible
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but leads to more code than this if-statement, so it's probably
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not worth it. */
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if (bytepos == z.bytepos)
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return z.charpos;
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/* Begin with the interval (BEG, Z), and improve on that by taking known
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positions into account like PT, GPT and the cache. This might
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already find the answer. */
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struct text_index *ti = ensure_has_index (b);
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struct text_pos prev = beg_pos (b);
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struct text_pos next = z;
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narrow_bytepos_bounds (b, &prev, &next, bytepos);
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/* Z_BYTE does not have an index entry because we don't want
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extra entries for (Z, Z_BYTE), so short-circuit *before* looking
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up the index. Changing that would be possible but leads to more
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code than this if-statement, so it's probably not worth it. */
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if (next.bytepos == bytepos)
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return next.charpos;
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ensure_bytepos_indexed (b, bytepos);
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struct text_index *ti = b->text->index;
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const ptrdiff_t entry = index_bytepos_entry (ti, bytepos);
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struct text_pos prev = index_text_pos (ti, entry);
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struct text_pos next = next_known_text_pos (b, entry);
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narrow_bytepos_bounds_1 (index_text_pos (ti, entry), &prev, &next, bytepos);
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narrow_bytepos_bounds_1 (next_known_text_pos (b, entry),
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&prev, &next, bytepos);
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ptrdiff_t charpos = narrow_bytepos_bounds (b, &prev, &next, bytepos);
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if (charpos != TEXT_INDEX_INVALID_POSITION)
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return charpos;
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if (next.charpos - prev.charpos == next.bytepos - prev.bytepos
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/* Beware: NEXT and PREV can be in the middle of multibyte chars! */
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&& CHAR_HEAD_P (BUF_FETCH_BYTE (b, prev.bytepos)))
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return prev.charpos + (bytepos - prev.bytepos); /* ASCII-only! */
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/* Scan forward if the distance to the previous known position is
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smaller than the distance to the next known position. */
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if (bytepos - prev.bytepos < next.bytepos - bytepos)
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charpos = charpos_forward_to_bytepos (b, prev, bytepos);
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else
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charpos = charpos_backward_to_bytepos (b, next, bytepos);
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ptrdiff_t charpos
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= (bytepos - prev.bytepos < next.bytepos - bytepos)
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? charpos_forward_to_bytepos (b, prev, bytepos)
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: charpos_backward_to_bytepos (b, next, bytepos);
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cache (ti, charpos, bytepos);
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return charpos;
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@ -650,6 +635,7 @@ buf_bytepos_to_charpos (struct buffer *b, const ptrdiff_t bytepos)
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ptrdiff_t
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buf_charpos_to_bytepos (struct buffer *b, const ptrdiff_t charpos)
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{
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/* FIXME: Can CHARPOS ever be outside of BEGV..ZV? */
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/* If this buffer has as many characters as bytes, each character must
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be one byte. This takes care of the case where
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enable-multibyte-characters is nil. */
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@ -657,25 +643,24 @@ buf_charpos_to_bytepos (struct buffer *b, const ptrdiff_t charpos)
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if (z.charpos == z.bytepos)
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return charpos;
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if (charpos == z.charpos)
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return z.bytepos;
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ensure_charpos_indexed (b, charpos);
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/* Begin with the interval (BEG, Z), and improve on that by taking known
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positions into account like PT, GPT and the cache. This might
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already find the bytepos. */
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already find the answer. */
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struct text_index *ti = ensure_has_index (b);
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struct text_pos prev = beg_pos (b);
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struct text_pos next = z;
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ptrdiff_t bytepos = narrow_charpos_bounds (b, &prev, &next, charpos);
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if (bytepos != TEXT_INDEX_INVALID_POSITION)
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return bytepos;
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narrow_charpos_bounds (b, &prev, &next, charpos);
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if (next.charpos - prev.charpos == next.bytepos - prev.bytepos)
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return prev.bytepos + (charpos - prev.charpos); /* ASCII-only! */
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else if (next.charpos == charpos)
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return next.bytepos;
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/* If one of the bounds is already good enough, avoid consulting
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the index since that involves some overhead. */
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if (!is_close_enough_charpos (ti, charpos, prev)
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&& !is_close_enough_charpos (ti, charpos, next))
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if (!is_close_enough_charpos (charpos, prev)
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&& !is_close_enough_charpos (charpos, next))
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{
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ensure_charpos_indexed (b, charpos);
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const ptrdiff_t entry = index_charpos_entry (ti, charpos);
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@ -683,19 +668,23 @@ buf_charpos_to_bytepos (struct buffer *b, const ptrdiff_t charpos)
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narrow_charpos_bounds_1 (index_prev, &prev, &next, charpos);
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const struct text_pos index_next = next_known_text_pos (b, entry);
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narrow_charpos_bounds_1 (index_next, &prev, &next, charpos);
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if (next.charpos - prev.charpos == next.bytepos - prev.bytepos
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/* Beware: NEXT and PREV can be in the middle of multibyte chars! */
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&& CHAR_HEAD_P (BUF_FETCH_BYTE (b, prev.bytepos))
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&& CHAR_HEAD_P (BUF_FETCH_BYTE (b, next.bytepos - 1)))
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return prev.bytepos + (charpos - prev.charpos); /* ASCII-only! */
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}
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/* Don't scan forward if CHARPOS is exactly on the previous know
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position because the index bytepos can be in the middle of a
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character, which is found by scanning backwards. Otherwise, scan
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forward if we believe that's less expensive. */
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if (charpos > prev.charpos
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&& charpos - prev.charpos < next.charpos - charpos)
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bytepos = bytepos_forward_to_charpos (b, prev, charpos);
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else
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bytepos = bytepos_backward_to_charpos (b, next, charpos);
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ptrdiff_t bytepos
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= (charpos > prev.charpos
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&& charpos - prev.charpos < next.charpos - charpos)
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? bytepos_forward_to_charpos (b, prev, charpos)
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: bytepos_backward_to_charpos (b, next, charpos);
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cache (ti, charpos, bytepos);
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return bytepos;
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