feat: independent code block language padding

## Details

Original PR: #131

The idea of this this change is that there is a slight difference in
behavior for left aligned vs right aligned language for code blocks.

- right: language is put at edge of block, essentially not padded
- left: language is indented along with rest of block, essentially padded

To make the behavior more consistent the language will no longer be
padded for left aligned, unlike before, so it will not be effected by
left_pad like the code block body.

A new field has been added `code.language_pad` which will add padding
specific to the language section. To have the same behavior as before
for left aligned this value should be set to the same value as for
`code.left_pad`.

The padding is applied relative to this position value.

- left: language is left padded, moving it to the right
- right: language is right padded, moving it to the left

This allows more customization for users while allowing for the same
behavior as before if that is preferred. Though not technically fully
backwards compatible as getting the same behavior as before requires
setting an additional option value.

Co-authored-by: Biggybi <[email protected]>

Author: MeanderingProgrammer

Diff for: README.md

@@ -301,6 +301,8 @@ require('render-markdown').setup({
         --  right: right side of code block
         --  left:  left side of code block
         position = 'left',
+        -- Amount of padding to add around the language
+        language_pad = 0,
         -- An array of language names for which background highlighting will be disabled
         -- Likely because that language has background highlights itself
         disable_background = { 'diff' },
@@ -619,6 +621,8 @@ require('render-markdown').setup({
         --  right: right side of code block
         --  left:  left side of code block
         position = 'left',
+        -- Amount of padding to add around the language
+        language_pad = 0,
         -- An array of language names for which background highlighting will be disabled
         -- Likely because that language has background highlights itself
         disable_background = { 'diff' },

Diff for: doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*          For 0.10.0          Last change: 2024 August 20
+*render-markdown.txt*          For 0.10.0          Last change: 2024 August 21
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*
@@ -331,6 +331,8 @@ Full Default Configuration ~
             --  right: right side of code block
             --  left:  left side of code block
             position = 'left',
+            -- Amount of padding to add around the language
+            language_pad = 0,
             -- An array of language names for which background highlighting will be disabled
             -- Likely because that language has background highlights itself
             disable_background = { 'diff' },
@@ -651,6 +653,8 @@ Wiki Page
             --  right: right side of code block
             --  left:  left side of code block
             position = 'left',
+            -- Amount of padding to add around the language
+            language_pad = 0,
             -- An array of language names for which background highlighting will be disabled
             -- Likely because that language has background highlights itself
             disable_background = { 'diff' },

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

@@ -268,6 +268,9 @@ function Handler:code(info)
     if add_background then
         self:code_background(code_block, icon_added)
     end
+    if icon_added then
+        code_block.start_row = code_block.start_row + 1
+    end
     self:code_left_pad(code_block, add_background)
 end
 
@@ -301,15 +304,15 @@ function Handler:language(code_block, add_background)
             -- Code blocks will pick up varying amounts of leading white space depending on the
             -- context they are in. This gets lumped into the delimiter node and as a result,
             -- after concealing, the extmark will be left shifted. Logic below accounts for this.
-            icon_text = str.pad(code_block.leading_spaces, icon_text .. info.text)
+            icon_text = str.pad(code_block.leading_spaces + code.language_pad, icon_text .. info.text)
         end
         return self:add(true, info.start_row, info.start_col, {
             virt_text = { { icon_text, highlight } },
             virt_text_pos = 'inline',
         })
     elseif code.position == 'right' then
         local icon_text = icon .. ' ' .. info.text
-        local win_col = code_block.longest_line
+        local win_col = code_block.longest_line - code.language_pad
         if code.width == 'block' then
             win_col = win_col - str.width(icon_text)
         end

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

@@ -5,7 +5,7 @@ local M = {}
 
 ---@private
 ---@type string
-M.version = '6.1.9'
+M.version = '6.1.10'
 
 function M.check()
     vim.health.start('render-markdown.nvim [version]')

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

@@ -100,6 +100,7 @@ local M = {}
 ---@field public sign? boolean
 ---@field public style? render.md.code.Style
 ---@field public position? render.md.code.Position
+---@field public language_pad? integer
 ---@field public disable_background? string[]
 ---@field public width? render.md.code.Width
 ---@field public left_pad? integer
@@ -334,6 +335,8 @@ M.default_config = {
         --  right: right side of code block
         --  left:  left side of code block
         position = 'left',
+        -- Amount of padding to add around the language
+        language_pad = 0,
         -- An array of language names for which background highlighting will be disabled
         -- Likely because that language has background highlights itself
         disable_background = { 'diff' },

Diff for: lua/render-markdown/parser/code_block.lua

@@ -26,10 +26,15 @@ function M.parse(config, context, info)
     if info.end_row - info.start_row <= 1 then
         return nil
     end
+
+    -- Account for language padding in first row
     local widths = vim.tbl_map(str.width, info:lines())
+    widths[1] = widths[1] + config.language_pad
+    local longest_line, width = M.get_width(config, context, widths)
+
     local code_info = info:child('info_string', info.start_row)
     local language_info = code_info ~= nil and code_info:child('language', info.start_row) or nil
-    local longest_line, width = M.get_width(config, context, widths)
+
     ---@type render.md.parsed.CodeBlock
     return {
         col = info.start_col,

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

@@ -240,6 +240,7 @@ function M.validate()
                 sign = { code.sign, 'boolean', nilable },
                 style = one_of(code.style, { 'full', 'normal', 'language', 'none' }, {}, nilable),
                 position = one_of(code.position, { 'left', 'right' }, {}, nilable),
+                language_pad = { code.language_pad, 'number', nilable },
                 disable_background = string_array(code.disable_background, nilable),
                 width = one_of(code.width, { 'full', 'block' }, {}, nilable),
                 left_pad = { code.left_pad, 'number', nilable },

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

@@ -78,6 +78,7 @@
 ---@field public sign boolean
 ---@field public style render.md.code.Style
 ---@field public position render.md.code.Position
+---@field public language_pad integer
 ---@field public disable_background string[]
 ---@field public width render.md.code.Width
 ---@field public left_pad integer