feat: setext heading

## Details

Adds support for the alternative markdown setext headings.
Uses the same settings from the existing heading configuration.

Some refactoring needed to happen to do this effectively since these
headings can be any number of lines so per row for loops were added
in a few places.

Supports all the same features and behaves in the same way as atx
headings with 2 exceptions:

- borders are not supported: this seems redundant to do since setext
  headings always have a bottom border effectively
- bottom text is concealed: the bottom line of these headings always has
  either equals signs or dashes, to make things look prettier this line
  gets concealed, can be replaced in the future with something else if
  users ask

Author: MeanderingProgrammer

Diff for: README.md

@@ -166,6 +166,7 @@ require('render-markdown').setup({
             (atx_h5_marker)
             (atx_h6_marker)
         ] @heading)
+        (setext_heading) @heading
 
         (thematic_break) @dash
 

Diff for: doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*          For 0.10.0          Last change: 2024 August 28
+*render-markdown.txt*          For 0.10.0          Last change: 2024 August 29
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*
@@ -195,6 +195,7 @@ Full Default Configuration ~
                 (atx_h5_marker)
                 (atx_h6_marker)
             ] @heading)
+            (setext_heading) @heading
 
             (thematic_break) @dash
 

Diff for: lua/render-markdown/core/context.lua

@@ -48,6 +48,15 @@ function Context:compute_bottom(top, offset)
     return bottom
 end
 
+---@param info? render.md.NodeInfo
+---@return integer
+function Context:width(info)
+    if info == nil then
+        return 0
+    end
+    return str.width(info.text) + self:get_offset(info) - self:concealed(info)
+end
+
 ---@param info render.md.NodeInfo
 ---@param amount integer
 function Context:add_offset(info, amount)
@@ -58,6 +67,7 @@ function Context:add_offset(info, amount)
     table.insert(self.links[row], { info.start_col, info.end_col, amount })
 end
 
+---@private
 ---@param info render.md.NodeInfo
 ---@return integer
 function Context:get_offset(info)
@@ -114,10 +124,7 @@ end
 ---@param info? render.md.NodeInfo
 ---@return boolean
 function Context:hidden(info)
-    if info == nil then
-        return true
-    end
-    return str.width(info.text) == self:concealed(info)
+    return info == nil or str.width(info.text) == self:concealed(info)
 end
 
 ---@param info render.md.NodeInfo
@@ -127,8 +134,7 @@ function Context:concealed(info)
     if #ranges == 0 then
         return 0
     end
-    local result = 0
-    local col = info.start_col
+    local result, col = 0, info.start_col
     for _, index in ipairs(vim.fn.str2list(info.text)) do
         local ch = vim.fn.nr2char(index)
         for _, range in ipairs(ranges) do

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

@@ -5,7 +5,7 @@ local M = {}
 
 ---@private
 ---@type string
-M.version = '6.2.11'
+M.version = '6.2.12'
 
 function M.check()
     vim.health.start('render-markdown.nvim [version]')

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

@@ -214,6 +214,7 @@ M.default_config = {
             (atx_h5_marker)
             (atx_h6_marker)
         ] @heading)
+        (setext_heading) @heading
 
         (thematic_break) @dash
 

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

@@ -71,7 +71,7 @@ function Render:render()
     local disabled_language = vim.tbl_contains(self.code.disable_background, self.data.language)
     local add_background = vim.tbl_contains({ 'normal', 'full' }, self.code.style) and not disabled_language
 
-    local icon_added = self:language_hint(add_background)
+    local icon_added = self:language(add_background)
     if add_background then
         self:background(icon_added)
     end
@@ -84,7 +84,7 @@ end
 ---@private
 ---@param add_background boolean
 ---@return boolean
-function Render:language_hint(add_background)
+function Render:language(add_background)
     if not vim.tbl_contains({ 'language', 'full' }, self.code.style) then
         return false
     end

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

@@ -4,12 +4,14 @@ local list = require('render-markdown.core.list')
 local str = require('render-markdown.core.str')
 
 ---@class render.md.data.Heading
+---@field atx boolean
 ---@field level integer
 ---@field icon? string
 ---@field sign? string
 ---@field foreground string
 ---@field background string
 ---@field heading_width render.md.heading.Width
+---@field end_row integer
 
 ---@class render.md.render.Heading: render.md.Renderer
 ---@field private heading render.md.Heading
@@ -33,80 +35,77 @@ function Render:setup()
         return false
     end
 
-    local level = str.width(self.info.text)
+    local atx, level = nil, nil
+    if self.info.type == 'setext_heading' then
+        atx, level = false, self.info:child('setext_h1_underline') ~= nil and 1 or 2
+    else
+        atx, level = true, str.width(self.info.text)
+    end
+
     local heading_width = self.heading.width
     if type(heading_width) == 'table' then
         heading_width = list.clamp(heading_width, level)
     end
+
     self.data = {
+        atx = atx,
         level = level,
         icon = list.cycle(self.heading.icons, level),
         sign = list.cycle(self.heading.signs, level),
         foreground = list.clamp(self.heading.foregrounds, level),
         background = list.clamp(self.heading.backgrounds, level),
         heading_width = heading_width,
+        end_row = self.info.end_row + (atx and 1 or 0),
     }
 
     return true
 end
 
 function Render:render()
-    local icon_width = self:start_icon()
+    local width = self:width(self:icon())
     if self.heading.sign then
         self:sign(self.data.sign, self.data.foreground)
     end
+    self:background(width)
+    self:border(width)
+    self:left_pad()
+    self:conceal_underline()
+end
 
-    self.marks:add(true, self.info.start_row, 0, {
-        end_row = self.info.end_row + 1,
-        end_col = 0,
-        hl_group = self.data.background,
-        hl_eol = true,
-    })
-
-    local width = self:width(icon_width)
-    if self.data.heading_width == 'block' then
-        -- Overwrite anything beyond width with Normal
-        self.marks:add(true, self.info.start_row, 0, {
-            priority = 0,
-            virt_text = { { str.spaces(vim.o.columns * 2), 'Normal' } },
-            virt_text_win_col = width,
-        })
-    end
-
-    if self.heading.border then
-        self:border(width)
-    end
-
-    if self.heading.left_pad > 0 then
-        self.marks:add(false, self.info.start_row, 0, {
-            priority = 0,
-            virt_text = { { str.spaces(self.heading.left_pad), self.data.background } },
+---@private
+---@return integer
+function Render:icon()
+    if not self.data.atx then
+        if self.data.icon == nil then
+            return 0
+        end
+        local added = self.marks:add(true, self.info.start_row, self.info.start_col, {
+            end_row = self.info.end_row,
+            end_col = self.info.end_col,
+            virt_text = { { self.data.icon, { self.data.foreground, self.data.background } } },
             virt_text_pos = 'inline',
         })
+        return added and str.width(self.data.icon) or 0
     end
-end
 
----@private
----@return integer
-function Render:start_icon()
-    -- Available width is level + 1 - concealed, where level = number of `#` characters, one
-    -- is added to account for the space after the last `#` but before the heading title,
-    -- and concealed text is subtracted since that space is not usable
+    -- For atx headings available width is level + 1 - concealed, where level = number of
+    -- `#` characters, one is added to account for the space after the last `#` but before
+    -- the  heading title, and concealed text is subtracted since that space is not usable
     local width = self.data.level + 1 - self.context:concealed(self.info)
     if self.data.icon == nil then
         return width
     end
 
     local padding = width - str.width(self.data.icon)
     if self.heading.position == 'inline' or padding < 0 then
-        self.marks:add(true, self.info.start_row, self.info.start_col, {
+        local added = self.marks:add(true, self.info.start_row, self.info.start_col, {
             end_row = self.info.end_row,
             end_col = self.info.end_col,
             virt_text = { { self.data.icon, { self.data.foreground, self.data.background } } },
             virt_text_pos = 'inline',
             conceal = '',
         })
-        return str.width(self.data.icon)
+        return added and str.width(self.data.icon) or width
     else
         self.marks:add(true, self.info.start_row, self.info.start_col, {
             end_row = self.info.end_row,
@@ -123,20 +122,50 @@ end
 ---@return integer
 function Render:width(icon_width)
     if self.data.heading_width == 'block' then
-        local width = self.heading.left_pad + icon_width + self.heading.right_pad
-        local content = self.info:sibling('inline')
-        if content ~= nil then
-            width = width + str.width(content.text) + self.context:get_offset(content) - self.context:concealed(content)
+        local width = nil
+        if self.data.atx then
+            width = icon_width + self.context:width(self.info:sibling('inline'))
+        else
+            -- Account for icon in first row
+            local widths = vim.tbl_map(str.width, self.info:lines())
+            widths[1] = widths[1] + icon_width
+            width = vim.fn.max(widths)
         end
+        width = self.heading.left_pad + width + self.heading.right_pad
         return math.max(width, self.heading.min_width)
     else
         return self.context:get_width()
     end
 end
 
+---@private
+---@param width integer
+function Render:background(width)
+    for row = self.info.start_row, self.data.end_row - 1 do
+        self.marks:add(true, row, 0, {
+            end_row = row + 1,
+            hl_group = self.data.background,
+            hl_eol = true,
+        })
+        if self.data.heading_width == 'block' then
+            -- Overwrite anything beyond width with Normal
+            self.marks:add(true, row, 0, {
+                priority = 0,
+                virt_text = { { str.spaces(vim.o.columns * 2), 'Normal' } },
+                virt_text_win_col = width,
+            })
+        end
+    end
+end
+
 ---@private
 ---@param width integer
 function Render:border(width)
+    -- Only atx headings support borders
+    if not self.heading.border or not self.data.atx then
+        return
+    end
+
     local background = colors.inverse(self.data.background)
     local prefix = self.heading.border_prefix and self.data.level or 0
 
@@ -175,4 +204,34 @@ function Render:border(width)
     end
 end
 
+---@private
+function Render:left_pad()
+    if self.heading.left_pad <= 0 then
+        return
+    end
+    for row = self.info.start_row, self.data.end_row - 1 do
+        self.marks:add(false, row, 0, {
+            priority = 0,
+            virt_text = { { str.spaces(self.heading.left_pad), self.data.background } },
+            virt_text_pos = 'inline',
+        })
+    end
+end
+
+---@private
+function Render:conceal_underline()
+    if self.data.atx then
+        return
+    end
+    local info = self.info:child(string.format('setext_h%d_underline', self.data.level))
+    if info == nil then
+        return
+    end
+    self.marks:add(true, info.start_row, info.start_col, {
+        end_row = info.end_row,
+        end_col = info.end_col,
+        conceal = '',
+    })
+end
+
 return Render

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

@@ -136,10 +136,8 @@ function Render:parse_row(row, num_columns)
     local columns = {}
     for i = 1, #cells do
         local cell, width = cells[i], pipes[i + 1].start_col - pipes[i].end_col
-        -- Account for double width glyphs by replacing cell spacing with text width
-        width = width - (cell.end_col - cell.start_col) + str.width(cell.text)
-        -- Remove concealed and add inlined text
-        width = width - self.context:concealed(cell) + self.context:get_offset(cell)
+        -- Account for double width glyphs by replacing cell spacing with width
+        width = width - (cell.end_col - cell.start_col) + self.context:width(cell)
         if width < 0 then
             return nil
         end