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Diffstat (limited to 'util.lua')
| -rw-r--r-- | util.lua | 25 |
1 files changed, 25 insertions, 0 deletions
@@ -279,4 +279,29 @@ function util.vis_pos_to_sel(win, pos) return sel end +--- Count the visual characters in a line +-- This is useful to detect wrapped lines including tabs which may add a +-- unspecified amount of white space to a line depending on their position and +-- the used tabwidth. +-- @param win the window containing the line +-- @param line the line to count +-- @param nchars the number of characters in the line +-- @return the number of visual characters +util.visual_chars_in_line = function(win, line, nchars) + -- fast string iteration inspired by: + -- https://stackoverflow.com/a/49222705 + local l = {string.byte(line, 1, nchars)} + local line_len = 0 + for i = 1, nchars do + local c = l[i] -- Note: produces char codes instead of chars. + if c == 9 then -- '\t' + local chars_to_tab_stop = win.options.tabwidth - (line_len % win.options.tabwidth) + line_len = line_len + chars_to_tab_stop + else + line_len = line_len + 1 + end + end + return line_len +end + return util |