vim-patch:9.1.1341: cannot define completion triggers

Problem:  Cannot define completion triggers and act upon it
Solution: add the new option 'isexpand' and add the complete_match()
          function to return the completion matches according to the
          'isexpand' setting (glepnir)

Currently, completion trigger position is determined solely by the
'iskeyword' pattern (\k\+$), which causes issues when users need
different completion behaviors - such as triggering after '/' for
comments or '.' for methods. Modifying 'iskeyword' to include these
characters has undesirable side effects on other Vim functionality that
relies on keyword definitions.

Introduce a new buffer-local option 'isexpand' that allows specifying
different completion triggers and add the complete_match() function that
finds the appropriate start column for completion based on these
triggers, scanning backwards from cursor position.

This separation of concerns allows customized completion behavior
without affecting iskeyword-dependent features. The option's
buffer-local nature enables per-filetype completion triggers.

closes: vim/vim#16716

https://github.com/vim/vim/commit/bcd5995b40a1c26e735bc326feb2e3ac4b05426b

Co-authored-by: glepnir <glephunter@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index 1e0e40a3a3..13dec50231 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -3429,6 +3429,24 @@ vim.o.inf = vim.o.infercase
 vim.bo.infercase = vim.o.infercase
 vim.bo.inf = vim.bo.infercase
 
+--- Defines characters and patterns for completion in insert mode. Used by
+--- the `complete_match()` function to determine the starting position for
+--- completion. This is a comma-separated list of triggers. Each trigger
+--- can be:
+--- - A single character like "." or "/"
+--- - A sequence of characters like "->", "/*", or "/**"
+---
+--- Note: Use "\\," to add a literal comma as trigger character, see
+--- `option-backslash`.
+---
+--- @type string
+vim.o.isexpand = ""
+vim.o.ise = vim.o.isexpand
+vim.bo.isexpand = vim.o.isexpand
+vim.bo.ise = vim.bo.isexpand
+vim.go.isexpand = vim.o.isexpand
+vim.go.ise = vim.go.isexpand
+
 --- The characters specified by this option are included in file names and
 --- path names.  Filenames are used for commands like "gf", "[i" and in
 --- the tags file.  It is also used for "\f" in a `pattern`.