Fix language selector to pull language from info_string

resolves: #44

# Details

Previously when getting the langauge for a fenced code block we simply
pulled the info_string in full. However `markdown` supports additional
information in this component so would not resolve correctly. Instead
we need to pull the language node from the info_string node to handle
these cases.

To do this add a separate query / capture to handle getting the language
of a fenced code block.

Since the language can now be in different places, including nested in
curly braces generating the right virtual text becomes harder. To avoid
dealing with these cases use an inline extmark to shift things for us.
This does mean that the icon feature is now restricted to neovim
versions >= 0.10.0. Add a version check to avoid failing for early
versions.

Author: MeanderingProgrammer

Diff for: README.md

@@ -12,18 +12,22 @@ Plugin to improve viewing Markdown files in Neovim
 
 - Functions entirely inside of Neovim with no external windows
 - Changes between `rendered` view in normal mode and `raw` view in all other modes
-- Changes `conceallevel` between `rendered` and `raw` view based on configuration
+- Changes window options between `rendered` and `raw` view based on configuration
+  - Effects `conceallevel` & `concealcursor` by default
 - Supports rendering `markdown` injected into other file types
-- Highlights headings with different groups depending on level and replaces `#`
-- Updates horizontal breaks with full-width lines
-- Highlights code blocks and inline code to better stand out
-- Replaces bullet points with provided character based on level
-- Replaces checkboxes with provided characters based on whether they are checked
-- Replaces block quote leading `>` with provided character
-- Updates table borders with better border characters, does NOT automatically align
-- Basic support for `LaTeX` if `latex` parser and `pylatexenc` are installed
+- Renders the following `markdown` components:
+  - Headings: highlight depending on level and replaces `#` with icon
+  - Horizontal breaks: replace with full-width lines
+  - Code blocks: highlight to better stand out
+    - Adds language icon, requires `nvim-web-devicons` and neovim >= `0.10.0`
+  - Inline code: highlight to better stand out
+  - List bullet points: replace with provided icon based on level
+  - Checkboxes: replace with provided icon based on whether they are checked
+  - Block quotes: replace leading `>` with provided icon
+  - Tables: replace border characters, does NOT automatically align
+  - [Callouts](https://github.com/orgs/community/discussions/16925)
+  - `LaTeX` blocks: renders formulas if `latex` parser and `pylatexenc` are installed
 - Disable rendering when file is larger than provided value
-- Support for [callouts](https://github.com/orgs/community/discussions/16925)
 - Support custom handlers which are ran identically to builtin handlers
 
 # Dependencies
@@ -99,6 +103,7 @@ require('render-markdown').setup({
         (thematic_break) @dash
 
         (fenced_code_block) @code
+        (fenced_code_block (info_string (language) @language))
 
         [
             (list_marker_plus)

Diff for: demo/heading_code.gif

@@ -8,7 +8,7 @@
 
 ###### Heading 6
 
-```python
+```python {filename="demo.py"}
 def main() -> None:
     sum = 0
     for i in range(10):

Diff for: demo/heading_code.md

@@ -1,4 +1,4 @@
-*render-markdown.txt*           For 0.10.0           Last change: 2024 June 28
+*render-markdown.txt*           For 0.10.0           Last change: 2024 June 30
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*
@@ -32,18 +32,22 @@ Plugin to improve viewing Markdown files in Neovim
 
 - Functions entirely inside of Neovim with no external windows
 - Changes between `rendered` view in normal mode and `raw` view in all other modes
-- Changes `conceallevel` between `rendered` and `raw` view based on configuration
+- Changes window options between `rendered` and `raw` view based on configuration
+    - Effects `conceallevel` & `concealcursor` by default
 - Supports rendering `markdown` injected into other file types
-- Highlights headings with different groups depending on level and replaces `#`
-- Updates horizontal breaks with full-width lines
-- Highlights code blocks and inline code to better stand out
-- Replaces bullet points with provided character based on level
-- Replaces checkboxes with provided characters based on whether they are checked
-- Replaces block quote leading `>` with provided character
-- Updates table borders with better border characters, does NOT automatically align
-- Basic support for `LaTeX` if `latex` parser and `pylatexenc` are installed
+- Renders the following `markdown` components:
+    - Headings: highlight depending on level and replaces `#` with icon
+    - Horizontal breaks: replace with full-width lines
+    - Code blocks: highlight to better stand out
+        - Adds language icon, requires `nvim-web-devicons` and neovim >= `0.10.0`
+    - Inline code: highlight to better stand out
+    - List bullet points: replace with provided icon based on level
+    - Checkboxes: replace with provided icon based on whether they are checked
+    - Block quotes: replace leading `>` with provided icon
+    - Tables: replace border characters, does NOT automatically align
+    - Callouts <https://github.com/orgs/community/discussions/16925>
+    - `LaTeX` blocks: renders formulas if `latex` parser and `pylatexenc` are installed
 - Disable rendering when file is larger than provided value
-- Support for callouts <https://github.com/orgs/community/discussions/16925>
 - Support custom handlers which are ran identically to builtin handlers
 
 
@@ -127,6 +131,7 @@ modified by the user.
             (thematic_break) @dash
 
             (fenced_code_block) @code
+            (fenced_code_block (info_string (language) @language))
 
             [
                 (list_marker_plus)

Diff for: doc/render-markdown.txt

@@ -66,28 +66,24 @@ M.render_node = function(namespace, buf, capture, node)
             hl_group = highlights.code,
             hl_eol = true,
         })
-
+    elseif capture == 'language' then
         if state.config.code_style ~= 'full' then
             return
         end
-
-        local info = ts.child(node, 'info_string')
-        if info == nil then
+        -- Requires inline extmarks
+        if vim.fn.has('nvim-0.10') == 0 then
             return
         end
-        local language = vim.treesitter.get_node_text(info, buf)
-        local icon, icon_highlight = icons.get(language)
+
+        local icon, icon_highlight = icons.get(value)
         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 } }
+
+        local icon_text = { icon .. ' ' .. value, { icon_highlight, highlights.code } }
         vim.api.nvim_buf_set_extmark(buf, namespace, start_row, start_col, {
-            virt_text = { icon_text, language_text },
-            virt_text_pos = 'overlay',
+            virt_text = { icon_text },
+            virt_text_pos = 'inline',
         })
     elseif capture == 'list_marker' then
         if ts.sibling(node, { 'task_list_marker_unchecked', 'task_list_marker_checked' }) ~= nil then

Diff for: lua/render-markdown/handler/markdown.lua

@@ -92,6 +92,7 @@ M.default_config = {
         (thematic_break) @dash
 
         (fenced_code_block) @code
+        (fenced_code_block (info_string (language) @language))
 
         [
             (list_marker_plus)

Diff for: lua/render-markdown/init.lua

@@ -61,12 +61,9 @@ async_tests.describe('heading_code.md', function()
             },
             {
                 row = { 10 },
-                col = { 0 },
-                virt_text = {
-                    { ' ', { 'DevIconPy', 'ColorColumn' } },
-                    { 'python ', { 'Normal', 'ColorColumn' } },
-                },
-                virt_text_pos = 'overlay',
+                col = { 3 },
+                virt_text = { { ' python', { 'DevIconPy', 'ColorColumn' } } },
+                virt_text_pos = 'inline',
             },
         })