feat(extmarks,ts,spell): full support for spelling

- Added 'spell' option to extmarks:

  Extmarks with this set will have the region spellchecked.

- Added 'noplainbuffer' option to 'spelloptions':

  This is used to tell Neovim not to spellcheck the buffer. The old
  behaviour was to spell check the whole buffer unless :syntax was set.

- Added spelling support to the treesitter highlighter:

  @spell captures in highlights.scm are used to define regions which
  should be spell checked.

- Added support for navigating spell errors for extmarks:

  Works for both ephemeral and static extmarks

- Added '_on_spell_nav' callback for decoration providers:

  Since ephemeral callbacks are only drawn for the visible screen,
  providers must implement this callback to instruct Neovim which
  regions in the buffer need can be spell checked.

  The callback takes a start position and an end position.

  Note: this callback is subject to change hence the _ prefix.

- Added spell captures for built-in support languages

Co-authored-by: Lewis Russell <lewis6991@gmail.com>
Co-authored-by: Björn Linse <bjorn.linse@gmail.com>

2 files changed, 9 insertions, 3 deletions

diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index ea562e60b6..00a3759936 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -2646,6 +2646,8 @@ nvim_buf_set_extmark({buffer}, {ns_id}, {line}, {col}, {*opts})
                     When a character is supplied it is used as |:syn-cchar|.
                     "hl_group" is used as highlight for the cchar if provided,
                     otherwise it defaults to |hl-Conceal|.
+                  • spell: boolean indicating that spell checking should be
+                    performed within this extmark
                   • ui_watched: boolean that indicates the mark should be
                     drawn by a UI. When set, the UI will receive win_extmark
                     events. Note: the mark is positioned by virt_text
@@ -2677,7 +2679,7 @@ nvim_get_namespaces()                                  *nvim_get_namespaces()*
         dict that maps from names to namespace ids.
 
                                               *nvim_set_decoration_provider()*
-nvim_set_decoration_provider({ns_id}, {opts})
+nvim_set_decoration_provider({ns_id}, {*opts})
     Set or change decoration provider for a namespace
 
     This is a very general purpose interface for having lua callbacks being
@@ -2709,7 +2711,7 @@ nvim_set_decoration_provider({ns_id}, {opts})
 
     Parameters: ~
         {ns_id}  Namespace id from |nvim_create_namespace()|
-        {opts}   Callbacks invoked during redraw:
+        {opts}   Table of callbacks:
                  • on_start: called first on each screen redraw ["start",
                    tick]
                  • on_buf: called for each buffer being redrawn (before window
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 316b7ae3f1..b84a41eabc 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -5871,10 +5871,14 @@ A jump table for the options with a short description can be found at |Q_op|.
 'spelloptions' 'spo'	string	(default "")
 			local to buffer
 	A comma-separated list of options for spell checking:
-	   camel	When a word is CamelCased, assume "Cased" is a
+	camel		When a word is CamelCased, assume "Cased" is a
 			separate word: every upper-case character in a word
 			that comes after a lower case character indicates the
 			start of a new word.
+	noplainbuffer	Only spellcheck a buffer when 'syntax' is enabled, or
+			or when extmarks are set within the buffer. Only
+			designated regions of the buffer are spellchecked in
+			this case.
 
 						*'spellsuggest'* *'sps'*
 'spellsuggest' 'sps'	string	(default "best")