Cleanup structure of highlighting backend

lua/highlite.lua

@@ -1,41 +1,39 @@
 --[[ NOTHING INSIDE THIS FILE NEEDS TO BE EDITED BY THE USER. ]]
-local highlite = {}
+
+--[[
+	/*
+	 * IMPORTS
+	 */
+--]]
+
 local vim = vim
+local cmd = vim.api.nvim_command
 
--- Clear the highlighting.
+--[[
-vim.cmd('hi clear')
+	/*
-
+	 * VARS
--- Disable automatic coloring for the IndentGuides plugin.
+	 */
-vim.g.indent_guides_auto_colors = 0
+--]]
-
--- If the syntax has been enabled, reset it.
-if vim.fn.exists('syntax_on') then vim.cmd('syntax reset') end
-
--- Determine which set of colors to use.
-highlite.using_hex_or_256 = tonumber(vim.o.t_Co) >= 256
-	or vim.o.termguicolors
-	or vim.fn.has('gui_running')
-	or string.find(vim.fn.expand('$TERM'), '256')
-
--- If we aren't using the hex and 256 colorset, then set the &t_Co variable to 16.
-if not highlite.using_hex_or_256 then vim.o.t_Co = 16 end
 
 -- These are constants for the indexes in the colors that were defined before.
-local PALETTE_ANSI = 3
+local _NONE = 'NONE'
-local PALETTE_256  = 2
+local _PALETTE_256  = 2
-local PALETTE_HEX  = 1
+local _PALETTE_ANSI = 3
-local NONE = "NONE"
+local _PALETTE_HEX  = 1
+local _TYPE_STRING = 'string'
+local _TYPE_TABLE  = 'table'
 
--- Get the color value of a color variable, or "NONE" as a default.
+-- Determine which set of colors to use.
-local function get(color, index) -- {{{ †
+local _USING_HEX_OR_256 = tonumber(vim.o.t_Co) >= 256
-	if type(color) == 'table' and color[index] then
+	or vim.o.termguicolors
-		return color[index]
+	or vim.fn.has('gui_running')
-	elseif type(color) == 'string' then
+	or string.find(vim.env.TERM, '256')
-		return color
+
-	else
+--[[
-		return NONE
+	/*
-	end
+	 * HELPER FUNCTIONS
-end --}}} ‡
+	 */
+--]]
 
 -- Add the 'blend' parameter to some highlight command, if there is one.
 local function blend(command, attributes) -- {{{ †
@@ -44,33 +42,65 @@ local function blend(command, attributes) -- {{{ †
 	end
 end --}}} ‡
 
+-- Get the color value of a color variable, or "NONE" as a default.
+local function get(color, index) -- {{{ †
+	if type(color) == _TYPE_TABLE and color[index] then
+		return color[index]
+	elseif type(color) == _TYPE_STRING then
+		return color
+	else
+		return _NONE
+	end
+end --}}} ‡
+
 --[[ If using hex and 256-bit colors, then populate the gui* and cterm* args.
 	If using 16-bit colors, just populate the cterm* args. ]]
-local colorize = highlite.using_hex_or_256 and function(command, attributes) -- {{{ †
+local colorize = _USING_HEX_OR_256 and function(command, attributes) -- {{{ †
 	command[#command + 1] =
-		' ctermbg='..get(attributes.bg, PALETTE_256)
+		' ctermbg='..get(attributes.bg, _PALETTE_256)
-		..' ctermfg='..get(attributes.fg, PALETTE_256)
+		..' ctermfg='..get(attributes.fg, _PALETTE_256)
-		..' guibg='..get(attributes.bg, PALETTE_HEX)
+		..' guibg='..get(attributes.bg, _PALETTE_HEX)
-		..' guifg='..get(attributes.fg, PALETTE_HEX)
+		..' guifg='..get(attributes.fg, _PALETTE_HEX)
 	blend(command, attributes)
 end or function(command, attributes)
 	command[#command + 1] =
-		' ctermbg='..get(attributes.bg, PALETTE_ANSI)
+		' ctermbg='..get(attributes.bg, _PALETTE_ANSI)
-		..' ctermfg='..get(attributes.fg, PALETTE_ANSI)
+		..' ctermfg='..get(attributes.fg, _PALETTE_ANSI)
 	blend(command, attributes)
 end --}}} ‡
 
+-- Detect attribute links and link them
+local function link_attributes(attributes)
+	for attribute, val in pairs(attributes) do
+		if type(val) == _TYPE_STRING then print() end
+	end
+end
+
 -- This function appends `selected_attributes` to the end of `highlight_cmd`.
-local stylize = highlite.using_hex_or_256 and function(command, style, color) -- {{{ †
+local stylize = _USING_HEX_OR_256 and function(command, style, color) -- {{{ †
 	command[#command + 1] = ' cterm='..style..' gui='..style
 
 	if color then -- There is an undercurl color.
-		command[#command + 1] = ' guisp='..get(color, PALETTE_HEX)
+		command[#command + 1] = ' guisp='..get(color, _PALETTE_HEX)
 	end
 end or function(command, style)
 	command[#command + 1] = ' cterm='..style
 end --}}} ‡
 
+-- Load specific &bg instructions
+local function use_background_with(attributes)
+	attributes.__index = attributes
+	return setmetatable(attributes[vim.o.background], attributes)
+end
+
+--[[
+	/*
+	 * MODULE
+	 */
+--]]
+
+local highlite = {}
+
 -- Generate a `:highlight` command from a group and some attributes.
 function highlite.highlight(highlight_group, attributes) -- {{{ †
 	-- The base highlight command
@@ -78,22 +108,22 @@ function highlite.highlight(highlight_group, attributes) -- {{{ †
 
 	-- Take care of special instructions for certain background colors.
 	if attributes[vim.o.background] then
-		attributes.__index = attributes
+		attributes = use_background_with(attributes)
-		attributes = setmetatable(attributes[vim.o.background], attributes)
 	end
 
 	-- Determine if there is a highlight link, and if so, assign it.
-	local link = (type(attributes) == 'string') and attributes or attributes.link
+	local link = (type(attributes) == _TYPE_STRING) and attributes or attributes.link
 
 	if link then -- `highlight_group` is a link to another group.
 		highlight_cmd[3] = highlight_cmd[2]..' '
 		highlight_cmd[2] = 'link '
 		highlight_cmd[4] = link
 	else -- The `highlight_group` is uniquely defined.
+		link_attributes(attributes)
 		colorize(highlight_cmd, attributes)
 
-		local style = attributes.style or NONE
+		local style = attributes.style or _NONE
-		if type(style) == 'table' then
+		if type(style) == _TYPE_TABLE then
 			-- Concat all of the entries together with a comma between before styling.
 			stylize(highlight_cmd, table.concat(style, ','), style.color)
 		else -- The style is just a single entry.
@@ -101,17 +131,26 @@ function highlite.highlight(highlight_group, attributes) -- {{{ †
 		end
 	end
 
-	vim.cmd(table.concat(highlight_cmd))
+	cmd(table.concat(highlight_cmd))
 end --}}} ‡
 
 function highlite:highlight_terminal(terminal_ansi_colors)
 	if self.using_hex_or_256 then for index, color in ipairs(terminal_ansi_colors) do
-		vim.g['terminal_color_'..index] = vim.o.termguicolors and color[PALETTE_HEX] or color[PALETTE_256]
+		vim.g['terminal_color_'..index] = vim.o.termguicolors and color[_PALETTE_HEX] or color[_PALETTE_256]
 	end end
 end
 
 return setmetatable(highlite, {
 	['__call'] = function(self, normal, highlights, terminal_ansi_colors)
+		-- Clear the highlighting.
+		cmd('hi clear')
+
+		-- If the syntax has been enabled, reset it.
+		if vim.fn.exists('syntax_on') then cmd('syntax reset') end
+
+		-- If we aren't using hex nor 256 colorsets.
+		if not _USING_HEX_OR_256 then vim.o.t_Co = 16 end
+
 		-- Highlight the baseline.
 		self.highlight('Normal', normal)