patch 9.1.0055: formatting long lines is slow
Problem: formatting long lines is slow
(kawaii-Code)
Solution: optimize gq (internal_format) for long
lines (kawaii-Code)
Implemented two workarounds that significantly reduce
the amount of pointless calls. Ideally the algorithm
would be rewritten not to be n^2, but it's too complicated
with too many corner cases.
closes: #13914
Signed-off-by: kawaii-Code <nia.personal.0@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/textformat.c b/src/textformat.c
index 5a52950..500e889 100644
--- a/src/textformat.c
+++ b/src/textformat.c
@@ -90,11 +90,18 @@
colnr_T end_col;
int wcc; // counter for whitespace chars
int did_do_comment = FALSE;
+ int first_pass;
- virtcol = get_nolist_virtcol()
- + char2cells(c != NUL ? c : gchar_cursor());
- if (virtcol <= (colnr_T)textwidth)
- break;
+ // Cursor is currently at the end of line. No need to format
+ // if line length is less than textwidth (8 * textwidth for
+ // utf safety)
+ if (curwin->w_cursor.col < 8 * textwidth)
+ {
+ virtcol = get_nolist_virtcol()
+ + char2cells(c != NUL ? c : gchar_cursor());
+ if (virtcol <= (colnr_T)textwidth)
+ break;
+ }
if (no_leader)
do_comments = FALSE;
@@ -144,9 +151,17 @@
coladvance((colnr_T)textwidth);
wantcol = curwin->w_cursor.col;
- curwin->w_cursor.col = startcol;
+ // If startcol is large (a long line), formatting takes too much
+ // time. The algorithm is O(n^2), it walks from the end of the
+ // line to textwidth border every time for each line break.
+ //
+ // Ceil to 8 * textwidth to optimize.
+ curwin->w_cursor.col = startcol < 8 * textwidth ? startcol :
+ 8 * textwidth;
+
foundcol = 0;
skip_pos = 0;
+ first_pass = TRUE;
// Find position to break at.
// Stop at first entered white when 'formatoptions' has 'v'
@@ -155,8 +170,11 @@
|| curwin->w_cursor.lnum != Insstart.lnum
|| curwin->w_cursor.col >= Insstart.col)
{
- if (curwin->w_cursor.col == startcol && c != NUL)
+ if (first_pass && c != NUL)
+ {
cc = c;
+ first_pass = FALSE;
+ }
else
cc = gchar_cursor();
if (WHITECHAR(cc))