Add FernHighlight/FernSyntax autocmd and document

Author: lambdalisue

autoload/fern/internal/viewer.vim

@@ -67,12 +67,18 @@ function! s:init() abort
     call fern#internal#drawer#init()
     call fern#internal#spinner#start()
     call helper.fern.renderer.highlight()
+    " Notify plugins
     call fern#hook#emit('renderer:highlight', helper)
+    " Notify users
+    doautocmd <nomodeline> User FernHighlight
 
     " now the buffer is ready so set filetype to emit FileType
     setlocal filetype=fern
     call helper.fern.renderer.syntax()
+    " Notify plugins
     call fern#hook#emit('renderer:syntax', helper)
+    " Notify users
+    doautocmd <nomodeline> User FernSyntax
     call fern#internal#action#init()
 
     let reveal = split(fri.fragment, '/')
@@ -108,7 +114,10 @@ function! s:BufReadCmd() abort
   let helper = fern#helper#new()
   setlocal filetype=fern
   call helper.fern.renderer.syntax()
+  " Notify plugins
   call fern#hook#emit('renderer:syntax', helper)
+  " Notify users
+  doautocmd <nomodeline> User FernSyntax
   let root = helper.sync.get_root_node()
   let cursor = get(b:, 'fern_cursor', getcurpos())
   call s:Promise.resolve()
@@ -123,5 +132,14 @@ endfunction
 function! s:ColorScheme() abort
   let helper = fern#helper#new()
   call helper.fern.renderer.highlight()
+  " Notify plugins
   call fern#hook#emit('renderer:highlight', helper)
+  " Notify users
+  doautocmd <nomodeline> User FernHighlight
 endfunction
+
+augroup fern-internal-viewer-internal
+  autocmd!
+  autocmd User FernSyntax :
+  autocmd User FernHighlight :
+augroup END

doc/fern.txt

@@ -17,6 +17,8 @@ INTERFACE				|fern-interface|
   VARIABLE				|fern-variable|
   COMMAND				|fern-command|
   FUNCTION				|fern-function|
+  AUTOCMD				|fern-autocmd|
+  HIGHLIGHT				|fern-highlight|
 CHANGELOG				|fern-changelog|
 
 
@@ -272,6 +274,8 @@ Users can customize above appearance by the following variables.
 	OBSOLETE(v1.6.0)~
 	No alternative feature is provided.
 
+See |FernHighlight| and |fern-highlight| to change pre-defeined |highlight|.
+
 Or create user custom renderer to change the appearance completely.
 See |fern-develop-renderer| for more details.
 
@@ -548,7 +552,74 @@ fern#smart#scheme({default}, {schemes})
 	      \     'bookmark': "\<C-^>",
 	      \   },
 	      \ )
+
+-----------------------------------------------------------------------------
+AUTOCMD							*fern-autocmd*
+
+						*FernHighlight*
+FernHighlight
+	Invoked after a fern renderer and 3rd party plugins defined highlight.
+	Use this autocmd to overwrite existing |highlight| like:
+>
+	function! s:on_highlight() abort
+	  " Use brighter highlight on root node
+	  highlight link FernRootSymbol Title
+	  highlight link FernRootText   Title
+	endfunction
+
+	augroup my-fern-highlight
+	  autocmd!
+	  autocmd User FernHighlight call s:on_highlight()
+	augroup END
 <
+	See |fern-highlight| for pre-defined |highlight|.
+
+						*FernSyntax*
+FernSyntax
+	Invoked after a fern renderer and 3rd party plugins defined syntax.
+	Use this |autocmd| to overwrite existing |syntax|.
+	Note that if you'd like to change color/highlight, use |FernHighlight|
+	autocmd instead. This autocmd exists for more complex (heavy) use.
+
+-----------------------------------------------------------------------------
+HIGHLIGHT						*fern-highlight*
+
+FernMarkedLine					*hl-FernMarkedLine*
+	A |highlight| group used as a line highlight of mark |sign|.
+
+FernMarkedText					*hl-FernMarkedText*
+	A |highlight| group used as a text highlight of mark |sign|.
+
+FernRootSymbol					*hl-FernRootSymbol*
+	A |highlight| group of renderer used for root node symbol.
+	An actual appearance will be determined by the |fern-renderer| thus 
+	this highlight might not be referred.
+	
+FernRootText					*hl-FernRootText*
+	A |highlight| group of renderer used for root node text.
+	An actual appearance will be determined by the |fern-renderer| thus 
+	this highlight might not be referred.
+
+FernLeafSymbol					*hl-FernLeafSymbol*
+	A |highlight| group of renderer used for leaf node symbol.
+	An actual appearance will be determined by the |fern-renderer| thus 
+	this highlight might not be referred.
+	
+FernLeafText					*hl-FernLeafText*
+	A |highlight| group of renderer used for leaf node text.
+	An actual appearance will be determined by the |fern-renderer| thus 
+	this highlight might not be referred.
+
+FernBranchSymbol				*hl-FernBranchSymbol*
+	A |highlight| group of renderer used for branch node symbol.
+	An actual appearance will be determined by the |fern-renderer| thus 
+	this highlight might not be referred.
+	
+FernBranchText				*hl-FernBranchText*
+	A |highlight| group of renderer used for branch node text.
+	An actual appearance will be determined by the |fern-renderer| thus 
+	this highlight might not be referred.
+
 
 =============================================================================
 CHANGELOG						*fern-changelog*