Support highlighting callout quote markers

resolves: #24

# Details

Figuring out which callout, if any, is in a `block_quote` is non trivial
using treesitter as the links in a `block_quote` are markdown_inline while
the markers themselves are standard markdown.

Passing information between these 2 parsers is not really possible, i.e.
we cannot take a markdown `TSNode` and query for markdown_inline elements.

Re-parsing the contents of the node is likely possible though I imagine there
would need to be some handling of (start/end) (row/col).

To get around this compexity we take an approach that's really similar to
how we compute list levels to pick a bullet point.

When handling a `quote_marker` find the closest parent `block_quote` element.
From there we get the text of the `block_quote` node and do a naive
string contains check to determine if the `block_quote` is a callout and,
if so, which kind it is. Based on this select an appropriate highlight.

This likely has edge cases just based on how adhoc the logic is, though,
at the moment, I cannot think of any. Release this into the wild and
hopefully any bugs will be reported so I can iron out the kinks.

Author: MeanderingProgrammer

demo/callout.gif

@@ -1,5 +1,4 @@
 init := "tests/minimal.lua"
-default_cols := "55"
 
 test:
   nvim --headless --noplugin -u {{init}} \
@@ -8,17 +7,27 @@ test:
 health:
   nvim -c "checkhealth render-markdown" -- .
 
-demo-all cols=default_cols:
-  just demo {{cols}} "30" "heading_code" "## Heading 2"
-  just demo {{cols}} "30" "list_table" ""
-  just demo {{cols}} "15" "box_dash_quote" ""
-  just demo {{cols}} "15" "latex" ""
-  just demo {{cols}} "30" "callout" ""
+demo-all: demo-heading demo-list demo-box demo-latex demo-callout
 
-demo cols rows file content:
+demo-heading:
+  just demo "heading_code" "30" "## Heading 2"
+
+demo-list:
+  just demo "list_table" "30" ""
+
+demo-box:
+  just demo "box_dash_quote" "15" ""
+
+demo-latex:
+  just demo "latex" "15" ""
+
+demo-callout:
+  just demo "callout" "30" ""
+
+demo file rows content:
   rm -f demo/{{file}}.gif
   python demo/record.py \
-    --cols {{cols}} \
+    --cols "55" \
     --rows {{rows}} \
     --file demo/{{file}}.md \
     --cast {{file}}.cast \

justfile

@@ -0,0 +1,28 @@
+local callout_to_key = {
+    ['[!NOTE]'] = 'note',
+    ['[!TIP]'] = 'tip',
+    ['[!IMPORTANT]'] = 'important',
+    ['[!WARNING]'] = 'warning',
+    ['[!CAUTION]'] = 'caution',
+}
+
+local M = {}
+
+---@param value string
+---@return string?
+M.get_key_exact = function(value)
+    return callout_to_key[value]
+end
+
+---@param value string
+---@return string?
+M.get_key_contains = function(value)
+    for callout, key in pairs(callout_to_key) do
+        if value:find(callout, 1, true) then
+            return key
+        end
+    end
+    return nil
+end
+
+return M

lua/render-markdown/callout.lua

@@ -1,3 +1,4 @@
+local callout = require('render-markdown.callout')
 local list = require('render-markdown.list')
 local logger = require('render-markdown.logger')
 local state = require('render-markdown.state')
@@ -75,7 +76,17 @@ M.render = function(namespace, root, buf)
                 })
             end
         elseif capture == 'quote_marker' then
-            local virt_text = { value:gsub('>', state.config.quote), highlights.quote }
+            local highlight = highlights.quote
+            local quote = M.get_quote(node)
+            if quote ~= nil then
+                local quote_value = vim.treesitter.get_node_text(quote, buf)
+                local key = callout.get_key_contains(quote_value)
+                if key ~= nil then
+                    highlight = highlights.callout[key]
+                end
+            end
+
+            local virt_text = { value:gsub('>', state.config.quote), highlight }
             vim.api.nvim_buf_set_extmark(buf, namespace, start_row, start_col, {
                 end_row = end_row,
                 end_col = end_col,
@@ -167,7 +178,6 @@ M.is_sibling_checkbox = function(node)
 end
 
 --- Walk through all parent nodes and count the number of nodes with type list
---- to calculate the level of the given node
 ---@param node TSNode
 ---@return integer
 M.calculate_list_level = function(node)
@@ -176,8 +186,7 @@ M.calculate_list_level = function(node)
     while parent ~= nil do
         local parent_type = parent:type()
         if vim.tbl_contains({ 'section', 'document' }, parent_type) then
-            -- when reaching a section or the document we are clearly at the
-            -- top of the list
+            -- reaching a section or document means we are clearly at the top of the list
             break
         elseif parent_type == 'list' then
             -- found a list increase the level and continue
@@ -188,4 +197,22 @@ M.calculate_list_level = function(node)
     return level
 end
 
+--- Walk through parent nodes until block_quote, return first found
+---@param node TSNode
+---@return TSNode?
+M.get_quote = function(node)
+    local parent = node:parent()
+    while parent ~= nil do
+        local parent_type = parent:type()
+        if vim.tbl_contains({ 'section', 'document' }, parent_type) then
+            -- reaching a section or document means we are clearly outside of a quote
+            break
+        elseif parent_type == 'block_quote' then
+            return parent
+        end
+        parent = parent:parent()
+    end
+    return nil
+end
+
 return M

lua/render-markdown/handler/markdown.lua

@@ -1,3 +1,4 @@
+local callout = require('render-markdown.callout')
 local logger = require('render-markdown.logger')
 local state = require('render-markdown.state')
 
@@ -21,14 +22,7 @@ M.render = function(namespace, root, buf)
                 hl_group = highlights.code,
             })
         elseif capture == 'callout' then
-            local value_to_key = {
-                ['[!NOTE]'] = 'note',
-                ['[!TIP]'] = 'tip',
-                ['[!IMPORTANT]'] = 'important',
-                ['[!WARNING]'] = 'warning',
-                ['[!CAUTION]'] = 'caution',
-            }
-            local key = value_to_key[value]
+            local key = callout.get_key_exact(value)
             if key ~= nil then
                 local virt_text = { state.config.callout[key], highlights.callout[key] }
                 vim.api.nvim_buf_set_extmark(buf, namespace, start_row, start_col, {

lua/render-markdown/handler/markdown_inline.lua

@@ -409,7 +409,7 @@ async_tests.describe('init', function()
             {
                 row = { 2, 2 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticInfo' } },
                 virt_text_pos = 'overlay',
             },
             -- Callout text
@@ -423,7 +423,7 @@ async_tests.describe('init', function()
             {
                 row = { 3, 3 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticInfo' } },
                 virt_text_pos = 'overlay',
             },
         })
@@ -443,7 +443,7 @@ async_tests.describe('init', function()
             {
                 row = { 7, 7 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticOk' } },
                 virt_text_pos = 'overlay',
             },
             -- Callout text
@@ -457,7 +457,7 @@ async_tests.describe('init', function()
             {
                 row = { 8, 8 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticOk' } },
                 virt_text_pos = 'overlay',
             },
         })
@@ -477,7 +477,7 @@ async_tests.describe('init', function()
             {
                 row = { 12, 12 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticHint' } },
                 virt_text_pos = 'overlay',
             },
             -- Callout text
@@ -491,7 +491,7 @@ async_tests.describe('init', function()
             {
                 row = { 13, 13 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticHint' } },
                 virt_text_pos = 'overlay',
             },
         })
@@ -511,7 +511,7 @@ async_tests.describe('init', function()
             {
                 row = { 17, 17 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticWarn' } },
                 virt_text_pos = 'overlay',
             },
             -- Callout text
@@ -525,7 +525,7 @@ async_tests.describe('init', function()
             {
                 row = { 18, 18 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticWarn' } },
                 virt_text_pos = 'overlay',
             },
         })
@@ -545,7 +545,7 @@ async_tests.describe('init', function()
             {
                 row = { 22, 22 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticError' } },
                 virt_text_pos = 'overlay',
             },
             -- Callout text
@@ -559,7 +559,7 @@ async_tests.describe('init', function()
             {
                 row = { 23, 23 },
                 col = { 0, 2 },
-                virt_text = { { '┃ ', '@markup.quote' } },
+                virt_text = { { '┃ ', 'DiagnosticError' } },
                 virt_text_pos = 'overlay',
             },
         })