feat: support heading border per level

## Details

Discussion: #240

This allows the `heading.border` config to be a list of booleans. This
works in exactly the same way as padding and margin settings which use a
clamp to index into the list if multiple values are specified.

Author: MeanderingProgrammer

Diff for: README.md

@@ -245,6 +245,7 @@ require('render-markdown').setup({
         -- Can also be a list of integers in which case the 'level' is used to index into the list using a clamp
         min_width = 0,
         -- Determines if a border is added above and below headings
+        -- Can also be a list of booleans in which case the 'level' is used to index into the list using a clamp
         border = false,
         -- Always use virtual lines for heading borders instead of attempting to use empty lines
         border_virtual = false,
@@ -651,6 +652,7 @@ require('render-markdown').setup({
         -- Can also be a list of integers in which case the 'level' is used to index into the list using a clamp
         min_width = 0,
         -- Determines if a border is added above and below headings
+        -- Can also be a list of booleans in which case the 'level' is used to index into the list using a clamp
         border = false,
         -- Always use virtual lines for heading borders instead of attempting to use empty lines
         border_virtual = false,

Diff for: doc/render-markdown.txt

@@ -292,6 +292,7 @@ Default Configuration ~
             -- Can also be a list of integers in which case the 'level' is used to index into the list using a clamp
             min_width = 0,
             -- Determines if a border is added above and below headings
+            -- Can also be a list of booleans in which case the 'level' is used to index into the list using a clamp
             border = false,
             -- Always use virtual lines for heading borders instead of attempting to use empty lines
             border_virtual = false,
@@ -696,6 +697,7 @@ Heading Configuration ~
             -- Can also be a list of integers in which case the 'level' is used to index into the list using a clamp
             min_width = 0,
             -- Determines if a border is added above and below headings
+            -- Can also be a list of booleans in which case the 'level' is used to index into the list using a clamp
             border = false,
             -- Always use virtual lines for heading borders instead of attempting to use empty lines
             border_virtual = false,

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

@@ -4,7 +4,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '7.5.10'
+M.version = '7.5.11'
 
 function M.check()
     M.start('version')

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

@@ -170,7 +170,7 @@ local M = {}
 ---@field public left_pad? number|number[]
 ---@field public right_pad? number|number[]
 ---@field public min_width? integer|integer[]
----@field public border? boolean
+---@field public border? boolean|boolean[]
 ---@field public border_virtual? boolean
 ---@field public border_prefix? boolean
 ---@field public above? string
@@ -363,6 +363,7 @@ M.default_config = {
         -- Can also be a list of integers in which case the 'level' is used to index into the list using a clamp
         min_width = 0,
         -- Determines if a border is added above and below headings
+        -- Can also be a list of booleans in which case the 'level' is used to index into the list using a clamp
         border = false,
         -- Always use virtual lines for heading borders instead of attempting to use empty lines
         border_virtual = false,

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

@@ -16,6 +16,7 @@ local colors = require('render-markdown.colors')
 ---@field left_pad number
 ---@field right_pad number
 ---@field min_width integer
+---@field border boolean
 ---@field end_row integer
 
 ---@class render.md.width.Heading
@@ -55,6 +56,7 @@ function Render:setup()
         left_pad = List.clamp(self.heading.left_pad, level) or 0,
         right_pad = List.clamp(self.heading.right_pad, level) or 0,
         min_width = List.clamp(self.heading.min_width, level) or 0,
+        border = List.clamp(self.heading.border, level) or false,
         end_row = self.node.end_row + (atx and 1 or 0),
     }
 
@@ -178,7 +180,7 @@ end
 ---@param width render.md.width.Heading
 function Render:border(width)
     -- Only atx headings support borders
-    if not self.heading.border or not self.data.atx then
+    if not self.data.border or not self.data.atx then
         return
     end
 

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

@@ -153,8 +153,9 @@ function M.validate()
             end)
             :nested('heading', function(heading)
                 heading
-                    :type({ 'enabled', 'sign', 'border', 'border_virtual', 'border_prefix' }, 'boolean')
+                    :type({ 'enabled', 'sign', 'border_virtual', 'border_prefix' }, 'boolean')
                     :type({ 'above', 'below' }, 'string')
+                    :list('border', 'boolean', 'boolean')
                     :list({ 'left_margin', 'left_pad', 'right_pad', 'min_width' }, 'number', 'number')
                     :list({ 'icons', 'signs', 'backgrounds', 'foregrounds' }, 'string')
                     :one_of('position', { 'overlay', 'inline' })

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

@@ -143,7 +143,7 @@
 ---@field public left_pad number|number[]
 ---@field public right_pad number|number[]
 ---@field public min_width integer|integer[]
----@field public border boolean
+---@field public border boolean|boolean[]
 ---@field public border_virtual boolean
 ---@field public border_prefix boolean
 ---@field public above string