#echomsg $'ApplyTextEdits: start_line = {start_line}, finish_line = {finish_line}'
#echomsg $'lines = {string(lines)}'
- # Delete all the lines that need to be modified
- bnr->deletebufline(start_line + 1, finish_line + 1)
-
# if the buffer is empty, appending lines before the first line adds an
# extra empty line at the end. Delete the empty line after appending the
# lines.
dellastline = true
endif
- # Append the updated lines
- appendbufline(bnr, start_line, lines)
+ # Now we apply the textedits to the actual buffer.
+ # In theory we could just delete all old lines and append the new lines.
+ # This would however cause the cursor to change position: It will always be
+ # on the last line added.
+ #
+ # Luckily there is an even simpler solution, that has no cursor sideeffects.
+ #
+ # Logically this method is split into the following three cases:
+ #
+ # 1. The number of new lines is equal to the number of old lines:
+ # Just replace the lines inline with setbufline()
+ #
+ # 2. The number of new lines is greater than the old ones:
+ # First append the missing lines at the **end** of the range, then use
+ # setbufline() again. This does not cause the cursor to change position.
+ #
+ # 3. The number of new lines is less than before:
+ # First use setbufline() to replace the lines that we can replace.
+ # Then remove superfluous lines.
+ #
+ # Luckily, the three different cases exist only logically, we can reduce
+ # them to a single case practically, because appendbufline() does not append
+ # anything if an empty list is passed just like deletebufline() does not
+ # delete anything, if the last line of the range is before the first line.
+ # We just need to be careful with all indices.
+ appendbufline(bnr, finish_line + 1, lines[finish_line - start_line + 1 : -1])
+ setbufline(bnr, start_line + 1, lines)
+ deletebufline(bnr, start_line + 1 + lines->len(), finish_line + 1)
if dellastline
bnr->deletebufline(bnr->getbufinfo()[0].linecount)