feat(markdown): Added support for Obsidian-style tags

Closes #491

Author: OXY2DEV

doc/markview.nvim-markdown_inline.txt

@@ -20,6 +20,7 @@
 	---@field inline_codes markview.config.markdown_inline.inline_codes Inline code/code span configuration.
 	---@field internal_links markview.config.markdown_inline.internal_links Internal link configuration.
 	---@field uri_autolinks markview.config.markdown_inline.uri_autolinks URI autolink configuration.
+	---@field tags markview.config.markdown_inline.tags Obsidian-style tags configuration.
 <
 
 --------------------------------------------------------------------------------
@@ -843,6 +844,39 @@ Each uri autolinks type has the following options.
 	---@alias markview.config.markdown_inline.uri_autolinks.opts markview.config.__inline
 <
 
+--------------------------------------------------------------------------------
+tags                                        *markview.nvim-markdown_inline.tags*
+
+>lua
+	--- Configuration for emails.
+	---@class markview.config.markdown_inline.tags
+	---
+	---@field enable boolean Enable rendering of Obsidian-style tags.
+	---
+	---@field default markview.config.markdown_inline.tags.opts Default configuration for tags.
+	---@field [string] markview.config.markdown_inline.tags.opts Configuration for emails whose name(text after `#`) matches `string`.
+<
+
+Changes how `#tags` are shown.
+
+>lua
+	require("markview.config.markdown_inline").tags = {
+	    default = {
+	        hl = "MarkviewPalette7",
+	        padding_left = " ",
+	        padding_right = " "
+	    },
+	    enable = true
+	}
+<
+
+Each tag type has the following options.
+
+>lua
+	--[[ Options for a specific email type. ]]
+	---@alias markview.config.markdown_inline.tags.opts markview.config.__inline
+<
+
 Links ~
 
 1: https://github.com/ikatyang/emoji-cheat-sheet/blob/master/README.md

doc/tags

@@ -95,6 +95,7 @@ markview.nvim-markdown_inline.hyperlinks	markview.nvim-markdown_inline.txt	/*mar
 markview.nvim-markdown_inline.images	markview.nvim-markdown_inline.txt	/*markview.nvim-markdown_inline.images*
 markview.nvim-markdown_inline.inline_codes	markview.nvim-markdown_inline.txt	/*markview.nvim-markdown_inline.inline_codes*
 markview.nvim-markdown_inline.internal_links	markview.nvim-markdown_inline.txt	/*markview.nvim-markdown_inline.internal_links*
+markview.nvim-markdown_inline.tags	markview.nvim-markdown_inline.txt	/*markview.nvim-markdown_inline.tags*
 markview.nvim-markdown_inline.uri_autolinks	markview.nvim-markdown_inline.txt	/*markview.nvim-markdown_inline.uri_autolinks*
 markview.nvim-presets	markview.nvim-presets.txt	/*markview.nvim-presets*
 markview.nvim-preview	markview.nvim-preview.txt	/*markview.nvim-preview*

lua/markview/config/markdown_inline.lua

@@ -515,4 +515,15 @@ return {
 			hl = "MarkviewPalette2Fg"
 		},
 	},
+
+	tags = {
+		enable = true,
+
+		default = {
+			padding_left = " ",
+			padding_right = " ",
+
+			hl = "MarkviewPalette7"
+		}
+	},
 };

lua/markview/parsers/markdown_inline.lua

@@ -1,4 +1,5 @@
 local inline = {};
+local lpeg = vim.lpeg;
 
 --- Queried contents
 ---@type table[]
@@ -486,6 +487,62 @@ inline.shortcut_link = function (buffer, TSNode, text, range)
 	});
 end
 
+---|fS "code: LPeg grammar for matching `tags`"
+
+-- NOTE: A tag must not be followed by a `]]`
+--
+-- This is because `internal links` can have `#^section` parts in them which aren't tags.
+-- Tags also don't have a dedicated `TSNode` and must rely in patterns to match.
+
+-- NOTE: Valid characters are `0-9`, `a-z`, `A-Z`, `_` & `-`.
+--
+-- Special cases such as `#1` are not considered tags in **Obsidian**,
+-- but the extra matching required isn't worth the effort in my opinion.
+local tag_text = lpeg.R("az", "AZ", "09") + lpeg.S("_-");
+local tag = lpeg.C(
+	lpeg.Cp() * -- Start byte
+	lpeg.P("#") * tag_text^1 *
+	lpeg.Cp() -- End byte
+) * -lpeg.P("]]");
+local tag_pattern = lpeg.Ct( ( tag + 1 )^1 );
+
+---|fE
+
+--- Obsidian-style tags
+---@param text string[]
+---@param range markview.parsed.range
+inline.tag = function (_, _, text, range)
+	for l, line in ipairs(text) do
+		local _col_start = l == 1 and range.col_start or 0;
+		local index = 1;
+		local tags = tag_pattern:match(line);
+
+		while index < #tags do
+			local match = tags[index];
+			local col_start = _col_start + tags[index + 1] - 1;
+			local col_end = tags[index + 2] - 1;
+
+			if match and col_start and col_end then
+				inline.insert({
+					class = "inline_tag",
+					label = match:gsub("^#", ""),
+					text = { match },
+
+					range = {
+						row_start = range.row_start + (l - 1),
+						col_start = col_start,
+
+						row_end = range.row_start + (l - 1),
+						col_end = col_end
+					}
+				});
+			end
+
+			index = index + 3;
+		end
+	end
+end
+
 --- Uri autolink parser.
 ---@param TSNode table
 ---@param text string[]
@@ -543,6 +600,9 @@ inline.parse = function (buffer, TSTree, from, to)
 		((inline) @markdown_inline.emoji
 			(#lua-match? @markdown_inline.emoji ":.+:"))
 
+		((inline) @markdown_inline.tag
+			(#lua-match? @markdown_inline.tag "#[a-zA-Z0-9_-]+"))
+
 		((email_autolink) @markdown_inline.email)
 
 		((image) @markdown_inline.image)

lua/markview/renderers/markdown_inline.lua

@@ -1035,6 +1035,74 @@ inline.link_uri_autolink = function (buffer, item)
 	});
 end
 
+--- Render ==tag==.
+---@param buffer integer
+---@param item markview.parsed.markdown_inline.tags
+inline.tag = function (buffer, item)
+	---@type markview.config.markdown_inline.tags?
+	local main_config = spec.get({ "markdown_inline", "tags" }, { fallback = nil });
+	local range = item.range;
+
+	if not main_config then
+		return;
+	end
+
+	---@type markview.config.__inline?
+	local config = utils.match(
+		main_config,
+		item.label,
+		{
+			eval_args = { buffer, item }
+		}
+	);
+
+	if config == nil then
+		return;
+	end
+
+	--[[
+		NOTE: `hl_mode` shouldn't be "combine".
+
+		As tags don't have delimiter surrounding it,
+		using "combine" prevents adding `paddings`/`margins`
+		to the right side.
+	]]
+
+	vim.api.nvim_buf_set_extmark(buffer, inline.ns, range.row_start, range.col_start, {
+		undo_restore = false, invalidate = true,
+		end_col = range.col_start + 1,
+		conceal = "",
+
+		virt_text_pos = "inline",
+		virt_text = {
+			{ config.corner_left or "", utils.set_hl(config.corner_left_hl or config.hl) },
+			{ config.padding_left or "", utils.set_hl(config.padding_left_hl or config.hl) },
+
+			{ config.icon or "", utils.set_hl(config.icon_hl or config.hl) }
+		},
+
+		-- hl_mode = "combine"
+	});
+
+	vim.api.nvim_buf_set_extmark(buffer, inline.ns, range.row_start, range.col_start + 1, {
+		undo_restore = false, invalidate = true,
+		end_col = range.col_end,
+		hl_group = utils.set_hl(config.hl)
+	});
+
+	vim.api.nvim_buf_set_extmark(buffer, inline.ns, range.row_start, range.col_end, {
+		undo_restore = false, invalidate = true,
+
+		virt_text_pos = "inline",
+		virt_text = {
+			{ config.corner_right or "", utils.set_hl(config.corner_right_hl or config.hl) },
+			{ config.padding_right or "", utils.set_hl(config.padding_right_hl or config.hl) }
+		},
+
+		-- hl_mode = "combine"
+	});
+end
+
 --- Renders inline markdown.
 ---@param buffer integer
 ---@param content markview.parsed.markdown_inline[]

lua/markview/types/parsers/markdown_inline.lua

@@ -208,6 +208,17 @@
 
 ------------------------------------------------------------------------------
 
+---@class markview.parsed.markdown_inline.tags
+---
+---@field class "inline_tag"
+---
+---@field label string Tag label(text after `#`).
+---
+---@field text string[]
+---@field range markview.parsed.range
+
+------------------------------------------------------------------------------
+
 ---@class markview.parsed.markdown_inline.uri_autolinks
 ---
 ---@field class "inline_link_uri_autolinks"

lua/markview/types/renderers/markdown_inline.lua

@@ -19,6 +19,7 @@
 ---@field inline_codes markview.config.markdown_inline.inline_codes Inline code/code span configuration.
 ---@field internal_links markview.config.markdown_inline.internal_links Internal link configuration.
 ---@field uri_autolinks markview.config.markdown_inline.uri_autolinks URI autolink configuration.
+---@field tags markview.config.markdown_inline.tags Obsidian-style tags configuration.
 
 ------------------------------------------------------------------------------
 
@@ -190,3 +191,17 @@
 --[[ Options for a specific URI autolink type. ]]
 ---@alias markview.config.markdown_inline.uri_autolinks.opts markview.config.__inline
 
+------------------------------------------------------------------------------
+
+--- Configuration for emails.
+---@class markview.config.markdown_inline.tags
+---
+---@field enable boolean Enable rendering of Obsidian-style tags.
+---
+---@field default markview.config.markdown_inline.tags.opts Default configuration for tags.
+---@field [string] markview.config.markdown_inline.tags.opts Configuration for emails whose name(text after `#`) matches `string`.
+
+
+--[[ Options for a specific email type. ]]
+---@alias markview.config.markdown_inline.tags.opts markview.config.__inline
+