From 83218cf4c34c3593b4d58bd68d1f280cb3e6634b Mon Sep 17 00:00:00 2001 From: Eli Zaretskii Date: Sun, 9 Jul 2017 17:37:23 +0300 Subject: [PATCH] Speed up display of line numbers for very large buffers * src/xdisp.c (maybe_produce_line_number): Speed up line counting using values cached by mode-line display of line numbers. (Bug#27622) --- src/xdisp.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/src/xdisp.c b/src/xdisp.c index 5df2dd18311..28ed7685236 100644 --- a/src/xdisp.c +++ b/src/xdisp.c @@ -20823,7 +20823,6 @@ maybe_produce_line_number (struct it *it) ptrdiff_t start_from, bytepos; ptrdiff_t this_line; bool first_time = false; - ptrdiff_t beg = display_line_numbers_widen ? BEG : BEGV; ptrdiff_t beg_byte = display_line_numbers_widen ? BEG_BYTE : BEGV_BYTE; ptrdiff_t z_byte = display_line_numbers_widen ? Z_BYTE : ZV_BYTE; void *itdata = bidi_shelve_cache (); @@ -20834,8 +20833,21 @@ maybe_produce_line_number (struct it *it) { if (!last_line) { - /* FIXME: Maybe reuse the data in it->w->base_line_number. */ - start_from = beg; + /* If possible, reuse data cached by line-number-mode. */ + if (it->w->base_line_number > 0 + && it->w->base_line_pos > 0 + && it->w->base_line_pos <= IT_CHARPOS (*it) + /* line-number-mode always displays narrowed line + numbers, so we cannot use its data if the user wants + line numbers that disregard narrowing. */ + && !(display_line_numbers_widen + && (BEG_BYTE != BEGV_BYTE || Z_BYTE != ZV_BYTE))) + { + start_from = CHAR_TO_BYTE (it->w->base_line_pos); + last_line = it->w->base_line_number - 1; + } + else + start_from = beg_byte; if (!it->lnum_bytepos) first_time = true; } @@ -20845,7 +20857,7 @@ maybe_produce_line_number (struct it *it) /* Paranoia: what if someone changes the narrowing since the last time display_line was called? Shouldn't really happen, but who knows what some crazy Lisp invoked by :eval could do? */ - if (!(beg_byte <= start_from && start_from < z_byte)) + if (!(beg_byte <= start_from && start_from <= z_byte)) { last_line = 0; start_from = beg_byte; -- 2.39.2