Move :set syntax option implementation to lua

It is no longer possible to change the used syntax by assigning to the
`win.syntax = name` field, instead the function win:set_syntax(name)`
should be called.

The distinction between filetype and syntax lexer to use should probably
be clarified/cleaned up at some point.

3 files changed, 54 insertions, 32 deletions

diff --git a/lua/plugins/filetype.lua b/lua/plugins/filetype.lua
index 3bfda55..4d522e6 100644
--- a/lua/plugins/filetype.lua
+++ b/lua/plugins/filetype.lua
@@ -405,7 +405,7 @@ vis.events.subscribe(vis.events.WIN_OPEN, function(win)
 		for _, cmd in pairs(filetype.cmd or {}) do
 			vis:command(cmd)
 		end
-		win.syntax = syntax
+		win:set_syntax(syntax)
 	end
 
 	local name = win.file.name
@@ -470,6 +470,6 @@ vis.events.subscribe(vis.events.WIN_OPEN, function(win)
 		end
 	end
 
-	win.syntax = nil
+	win:set_syntax(nil)
 end)
 
diff --git a/lua/vis-std.lua b/lua/vis-std.lua
index 4492fcc..845785d 100644
--- a/lua/vis-std.lua
+++ b/lua/vis-std.lua
@@ -17,39 +17,18 @@ vis.events.subscribe(vis.events.THEME_CHANGE, function(name)
 	if vis.lexers then vis.lexers.lexers = {} end
 
 	for win in vis:windows() do
-		win.syntax = win.syntax;
+		win:set_syntax(win.syntax)
 	end
 end)
 
-vis.events.subscribe(vis.events.WIN_SYNTAX, function(win, name)
-	local lexers = vis.lexers
-	if not lexers then return false end
-
-	win:style_define(win.STYLE_DEFAULT, lexers.STYLE_DEFAULT or '')
-	win:style_define(win.STYLE_CURSOR, lexers.STYLE_CURSOR or '')
-	win:style_define(win.STYLE_CURSOR_PRIMARY, lexers.STYLE_CURSOR_PRIMARY or '')
-	win:style_define(win.STYLE_CURSOR_LINE, lexers.STYLE_CURSOR_LINE or '')
-	win:style_define(win.STYLE_SELECTION, lexers.STYLE_SELECTION or '')
-	win:style_define(win.STYLE_LINENUMBER, lexers.STYLE_LINENUMBER or '')
-	win:style_define(win.STYLE_COLOR_COLUMN, lexers.STYLE_COLOR_COLUMN or '')
-	win:style_define(win.STYLE_STATUS, lexers.STYLE_STATUS or '')
-	win:style_define(win.STYLE_STATUS_FOCUSED, lexers.STYLE_STATUS_FOCUSED or '')
-	win:style_define(win.STYLE_SEPARATOR, lexers.STYLE_SEPARATOR or '')
-	win:style_define(win.STYLE_INFO, lexers.STYLE_INFO or '')
-	win:style_define(win.STYLE_EOF, lexers.STYLE_EOF or '')
-
-	if name == nil then return true end
-
-	local lexer = lexers.load(name)
-	if not lexer then return false end
-
-	for token_name, id in pairs(lexer._TOKENSTYLES) do
-		local style = lexers['STYLE_'..string.upper(token_name)] or lexer._EXTRASTYLES[token_name]
-		win:style_define(id, style)
+vis:option_register("syntax", "string", function(name)
+	if not vis.win then return false end
+	if not vis.win:set_syntax(name) then
+		vis:info(string.format("Unknown syntax definition: `%s'", name))
+		return false
 	end
-
 	return true
-end)
+end, "Syntax highlighting lexer to use")
 
 vis.events.subscribe(vis.events.WIN_HIGHLIGHT, function(win, horizon_max)
 	if win.syntax == nil or vis.lexers == nil then return end
diff --git a/lua/vis.lua b/lua/vis.lua
index 286af3d..9b45483 100644
--- a/lua/vis.lua
+++ b/lua/vis.lua
@@ -114,7 +114,6 @@ local events = {
 	WIN_HIGHLIGHT = "Event::WIN_HIGHLIGHT", -- see @{win_highlight}
 	WIN_OPEN = "Event::WIN_OPEN", -- see @{win_open}
 	WIN_STATUS = "Event::WIN_STATUS", -- see @{win_status}
-	WIN_SYNTAX = "Event::WIN_SYNTAX", -- see @{win_syntax}
 }
 
 events.file_close = function(...) events.emit(events.FILE_CLOSE, ...) end
@@ -130,7 +129,6 @@ events.win_close = function(...) events.emit(events.WIN_CLOSE, ...) end
 events.win_highlight = function(...) events.emit(events.WIN_HIGHLIGHT, ...) end
 events.win_open = function(...) events.emit(events.WIN_OPEN, ...) end
 events.win_status = function(...) events.emit(events.WIN_STATUS, ...) end
-events.win_syntax = function(...) return events.emit(events.WIN_SYNTAX, ...) end
 
 local handlers = {}
 
@@ -191,6 +189,51 @@ end
 vis.events = events
 
 ---
+-- @type Window
+
+--- The file type associated with this window.
+-- @tfield string syntax the syntax lexer name or `nil` if unset
+
+--- Change syntax lexer to use for this window
+-- @function set_syntax
+-- @tparam string syntax the syntax lexer name or `nil` to disable syntax highlighting
+-- @treturn bool whether the lexer could be changed
+vis.types.window.set_syntax = function(win, syntax)
+
+	local lexers = vis.lexers
+	if not lexers then return false end
+
+	win:style_define(win.STYLE_DEFAULT, lexers.STYLE_DEFAULT or '')
+	win:style_define(win.STYLE_CURSOR, lexers.STYLE_CURSOR or '')
+	win:style_define(win.STYLE_CURSOR_PRIMARY, lexers.STYLE_CURSOR_PRIMARY or '')
+	win:style_define(win.STYLE_CURSOR_LINE, lexers.STYLE_CURSOR_LINE or '')
+	win:style_define(win.STYLE_SELECTION, lexers.STYLE_SELECTION or '')
+	win:style_define(win.STYLE_LINENUMBER, lexers.STYLE_LINENUMBER or '')
+	win:style_define(win.STYLE_COLOR_COLUMN, lexers.STYLE_COLOR_COLUMN or '')
+	win:style_define(win.STYLE_STATUS, lexers.STYLE_STATUS or '')
+	win:style_define(win.STYLE_STATUS_FOCUSED, lexers.STYLE_STATUS_FOCUSED or '')
+	win:style_define(win.STYLE_SEPARATOR, lexers.STYLE_SEPARATOR or '')
+	win:style_define(win.STYLE_INFO, lexers.STYLE_INFO or '')
+	win:style_define(win.STYLE_EOF, lexers.STYLE_EOF or '')
+
+	if syntax == nil or syntax == 'off' then
+		win.syntax = nil
+		return true
+	end
+
+	local lexer = lexers.load(syntax)
+	if not lexer then return false end
+
+	for token_name, id in pairs(lexer._TOKENSTYLES) do
+		local style = lexers['STYLE_'..string.upper(token_name)] or lexer._EXTRASTYLES[token_name]
+		win:style_define(id, style)
+	end
+
+	win.syntax = syntax
+	return true
+end
+
+---
 -- @type File
 
 --- Check whether LPeg pattern matches at a given file position.