Feature: add language icon above code blocks

# Details

Idea from: https://github.com/OXY2DEV/markview.nvim

Adds support for overlaying a language icon above code blocks
using nvim-web-devicons.

Make the nvim-web-devicons dependency optional and gracefully
handle the case when it is not installed using a pcall.

Add a code_style option to allow users to disable this if they
prefer not to have it.

Author: MeanderingProgrammer

README.md

@@ -38,6 +38,8 @@ Plugin to improve viewing Markdown files in Neovim
     Used to parse `markdown` files
   - [latex](https://github.com/latex-lsp/tree-sitter-latex) (Optional):
     Used to get `LaTeX` blocks from `markdown` files
+- [nvim-web-devicons](https://github.com/nvim-tree/nvim-web-devicons) (Optional):
+  Used for icon above code blocks
 - System dependencies:
   - [pylatexenc](https://pypi.org/project/pylatexenc/) (Optional):
     Used to transform `LaTeX` strings to appropriate unicode using `latex2text`
@@ -50,7 +52,10 @@ Plugin to improve viewing Markdown files in Neovim
 {
     'MeanderingProgrammer/markdown.nvim',
     name = 'render-markdown', -- Only needed if you have another plugin named markdown.nvim
-    dependencies = { 'nvim-treesitter/nvim-treesitter' },
+    dependencies = {
+        'nvim-treesitter/nvim-treesitter', -- Mandatory
+        'nvim-tree/nvim-web-devicons', -- Optional but recommended
+    },
     config = function()
         require('render-markdown').setup({})
     end,
@@ -63,7 +68,8 @@ Plugin to improve viewing Markdown files in Neovim
 use({
     'MeanderingProgrammer/markdown.nvim',
     as = 'render-markdown', -- Only needed if you have another plugin named markdown.nvim
-    after = { 'nvim-treesitter' },
+    after = { 'nvim-treesitter' }, -- Mandatory
+    requires = { 'nvim-tree/nvim-web-devicons', opt = true }, -- Optional but recommended
     config = function()
         require('render-markdown').setup({})
     end,
@@ -173,10 +179,15 @@ require('render-markdown').setup({
             rendered = 'nvic',
         },
     },
+    -- Determines how code blocks are rendered
+    --  full: adds language icon above code block if possible + normal behavior
+    --  normal: renders a background
+    --  none: disables rendering
+    code_style = 'full',
     -- Determines how tables are rendered
     --  full: adds a line above and below tables + normal behavior
     --  normal: renders the rows of tables
-    --  none: disables rendering, use this if you prefer having cell highlights
+    --  none: disables rendering
     table_style = 'full',
     -- Determines how table cells are rendered
     --  overlay: writes over the top of cells removing conealing and highlighting

demo/heading_code.gif

@@ -1,4 +1,4 @@
-*render-markdown.txt*           For 0.10.0           Last change: 2024 June 24
+*render-markdown.txt*           For 0.10.0           Last change: 2024 June 26
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*
@@ -69,6 +69,8 @@ Plugin to improve viewing Markdown files in Neovim
         Used to parse `markdown` files
     - latex <https://github.com/latex-lsp/tree-sitter-latex> (Optional):
         Used to get `LaTeX` blocks from `markdown` files
+- nvim-web-devicons <https://github.com/nvim-tree/nvim-web-devicons> (Optional):
+    Used for icon above code blocks
 - System dependencies:
     - pylatexenc <https://pypi.org/project/pylatexenc/> (Optional):
         Used to transform `LaTeX` strings to appropriate unicode using `latex2text`
@@ -84,7 +86,10 @@ LAZY.NVIM                                  *render-markdown-install-lazy.nvim*
     {
         'MeanderingProgrammer/markdown.nvim',
         name = 'render-markdown', -- Only needed if you have another plugin named markdown.nvim
-        dependencies = { 'nvim-treesitter/nvim-treesitter' },
+        dependencies = {
+            'nvim-treesitter/nvim-treesitter', -- Mandatory
+            'nvim-tree/nvim-web-devicons', -- Optional but recommended
+        },
         config = function()
             require('render-markdown').setup({})
         end,
@@ -98,7 +103,8 @@ PACKER.NVIM                              *render-markdown-install-packer.nvim*
     use({
         'MeanderingProgrammer/markdown.nvim',
         as = 'render-markdown', -- Only needed if you have another plugin named markdown.nvim
-        after = { 'nvim-treesitter' },
+        after = { 'nvim-treesitter' }, -- Mandatory
+        requires = { 'nvim-tree/nvim-web-devicons', opt = true }, -- Optional but recommended
         config = function()
             require('render-markdown').setup({})
         end,
@@ -210,10 +216,15 @@ modified by the user.
                 rendered = 'nvic',
             },
         },
+        -- Determines how code blocks are rendered
+        --  full: adds language icon above code block if possible + normal behavior
+        --  normal: renders a background
+        --  none: disables rendering
+        code_style = 'full',
         -- Determines how tables are rendered
         --  full: adds a line above and below tables + normal behavior
         --  normal: renders the rows of tables
-        --  none: disables rendering, use this if you prefer having cell highlights
+        --  none: disables rendering
         table_style = 'full',
         -- Determines how table cells are rendered
         --  overlay: writes over the top of cells removing conealing and highlighting

doc/render-markdown.txt

@@ -1,4 +1,5 @@
 local callout = require('render-markdown.callout')
+local icons = require('render-markdown.icons')
 local list = require('render-markdown.list')
 local logger = require('render-markdown.logger')
 local state = require('render-markdown.state')
@@ -55,12 +56,39 @@ M.render_node = function(namespace, buf, capture, node)
             virt_text_pos = 'overlay',
         })
     elseif capture == 'code' then
+        if state.config.code_style == 'none' then
+            return
+        end
+
         vim.api.nvim_buf_set_extmark(buf, namespace, start_row, 0, {
             end_row = end_row,
             end_col = 0,
             hl_group = highlights.code,
             hl_eol = true,
         })
+
+        if state.config.code_style ~= 'full' then
+            return
+        end
+
+        local info = ts.child(node, 'info_string')
+        if info == nil then
+            return
+        end
+        local language = vim.treesitter.get_node_text(info, buf)
+        local icon, icon_highlight = icons.get(language)
+        if icon == nil or icon_highlight == nil then
+            return
+        end
+        local icon_text = { icon .. ' ', { icon_highlight, highlights.code } }
+        -- language takes care of info_string so padding needs to take care of code block start, i.e. ```
+        -- subtract space taken up by icon and pad the remainder
+        local padding = string.rep(' ', 3 - vim.fn.strdisplaywidth(icon_text[1]))
+        local language_text = { language .. padding, { 'Normal', highlights.code } }
+        vim.api.nvim_buf_set_extmark(buf, namespace, start_row, start_col, {
+            virt_text = { icon_text, language_text },
+            virt_text_pos = 'overlay',
+        })
     elseif capture == 'list_marker' then
         if ts.sibling(node, { 'task_list_marker_unchecked', 'task_list_marker_checked' }) ~= nil then
             -- Hide the list marker for checkboxes rather than replacing with a bullet point
@@ -145,7 +173,7 @@ M.render_node = function(namespace, buf, capture, node)
         local delim_value = vim.treesitter.get_node_text(delim, buf)
         local delim_width = get_table_row_width(delim_row, delim_value)
 
-        local lines = vim.api.nvim_buf_get_lines(buf, start_row, end_row, false)
+        local lines = vim.api.nvim_buf_get_lines(buf, start_row, end_row, true)
         local start_width = get_table_row_width(start_row, list.first(lines))
         local end_width = get_table_row_width(end_row - 1, list.last(lines))
 

lua/render-markdown/handler/markdown.lua

@@ -0,0 +1,16 @@
+local ok, devicons = pcall(require, 'nvim-web-devicons')
+
+local M = {}
+
+---@param language string
+---@return string?
+---@return string?
+M.get = function(language)
+    if ok then
+        return devicons.get_icon_by_filetype(language)
+    else
+        return nil, nil
+    end
+end
+
+return M

lua/render-markdown/icons.lua

@@ -63,6 +63,7 @@ local M = {}
 ---@field public quote? string
 ---@field public callout? render.md.UserCallout
 ---@field public win_options? table<string, render.md.WindowOption>
+---@field public code_style? 'full'|'normal'|'none'
 ---@field public table_style? 'full'|'normal'|'none'
 ---@field public cell_style? 'overlay'|'raw'
 ---@field public custom_handlers? table<string, render.md.Handler>
@@ -166,10 +167,15 @@ M.default_config = {
             rendered = 'nvic',
         },
     },
+    -- Determines how code blocks are rendered
+    --  full: adds language icon above code block if possible + normal behavior
+    --  normal: renders a background
+    --  none: disables rendering
+    code_style = 'full',
     -- Determines how tables are rendered
     --  full: adds a line above and below tables + normal behavior
     --  normal: renders the rows of tables
-    --  none: disables rendering, use this if you prefer having cell highlights
+    --  none: disables rendering
     table_style = 'full',
     -- Determines how table cells are rendered
     --  overlay: writes over the top of cells removing conealing and highlighting

lua/render-markdown/init.lua

@@ -49,6 +49,7 @@
 ---@field public quote string
 ---@field public callout render.md.Callout
 ---@field public win_options table<string, render.md.WindowOption>
+---@field public code_style 'full'|'normal'|'none'
 ---@field public table_style 'full'|'normal'|'none'
 ---@field public cell_style 'overlay'|'raw'
 ---@field public custom_handlers table<string, render.md.Handler>

lua/render-markdown/types.lua

@@ -59,6 +59,15 @@ async_tests.describe('heading_code.md', function()
                 hl_eol = true,
                 hl_group = 'ColorColumn',
             },
+            {
+                row = { 10 },
+                col = { 0 },
+                virt_text = {
+                    { ' ', { 'DevIconPy', 'ColorColumn' } },
+                    { 'python ', { 'Normal', 'ColorColumn' } },
+                },
+                virt_text_pos = 'overlay',
+            },
         })
 
         local actual = util.get_actual_marks()

tests/heading_code_spec.lua

@@ -22,6 +22,7 @@ end
 vim.opt.rtp:prepend('.')
 source_plugin('plenary.nvim', 'plenary.vim')
 source_plugin('nvim-treesitter', 'nvim-treesitter.lua')
+source_plugin('nvim-web-devicons', 'nvim-web-devicons.vim')
 
 -- https://github.com/ThePrimeagen/refactoring.nvim/blob/master/scripts/minimal.vim
 ensure_installed({ 'markdown', 'markdown_inline', 'latex' })

tests/minimal.lua

@@ -53,7 +53,7 @@ M.marks_are_equal = function(expected, actual)
     for i = 1, math.min(#expected, #actual) do
         eq(expected[i], actual[i], string.format('Marks at index %d mismatch', i))
     end
-    eq(#expected, #actual)
+    eq(#expected, #actual, 'Different number of marks found')
 end
 
 return M