feat: add the entire plugin

README.md

@@ -4,7 +4,9 @@ Treesitter syntax highlighting for vim-fugitive diff views.
 
 ## Problem
 
-vim-fugitive uses regex-based `syntax/diff.vim` for highlighting expanded diffs in the status buffer. This means code inside diffs has no language-aware highlighting:
+vim-fugitive uses regex-based `syntax/diff.vim` for highlighting expanded diffs
+in the status buffer. This means code inside diffs has no language-aware
+highlighting:
 
 ```
 Unstaged (1)
@@ -17,7 +19,9 @@ M lua/mymodule.lua
 
 ## Solution
 
-Hook into fugitive's buffer, detect diff hunks, extract the language from filenames, and apply treesitter highlights as extmarks on top of fugitive's existing highlighting.
+Hook into fugitive's buffer, detect diff hunks, extract the language from
+filenames, and apply treesitter highlights as extmarks on top of fugitive's
+existing highlighting.
 
 ```
 Unstaged (1)
@@ -66,6 +70,7 @@ Staged (N)
 ```
 
 Pattern to detect:
+
 - Filename: `^[MADRC?] .+%.(%w+)$` → captures extension
 - Hunk header: `^@@ .+ @@`
 - Code lines: after hunk header, lines starting with ` `, `+`, or `-`
@@ -154,7 +159,8 @@ end
 
 ### 6. Re-highlight on Buffer Change
 
-Fugitive modifies the buffer when user expands/collapses diffs. Need to re-parse:
+Fugitive modifies the buffer when user expands/collapses diffs. Need to
+re-parse:
 
 ```lua
 vim.api.nvim_create_autocmd({"TextChanged", "TextChangedI"}, {
@@ -226,5 +232,5 @@ require("fugitive-ts").setup({
 
 - [Neovim Treesitter API](https://neovim.io/doc/user/treesitter.html)
 - [vim-fugitive User events](https://github.com/tpope/vim-fugitive/blob/master/doc/fugitive.txt)
-- [nvim_buf_set_extmark](https://neovim.io/doc/user/api.html#nvim_buf_set_extmark())
-- [vim.treesitter.get_string_parser](https://neovim.io/doc/user/treesitter.html#vim.treesitter.get_string_parser())
+- [nvim_buf_set_extmark](<https://neovim.io/doc/user/api.html#nvim_buf_set_extmark()>)
+- [vim.treesitter.get_string_parser](<https://neovim.io/doc/user/treesitter.html#vim.treesitter.get_string_parser()>)

doc/fugitive-ts.nvim.txt

@@ -0,0 +1,69 @@
+*fugitive-ts.nvim.txt*        Treesitter highlighting for vim-fugitive diffs
+
+Author:  Barrett Ruth <br.barrettruth@gmail.com>
+License: MIT
+
+==============================================================================
+INTRODUCTION                                                   *fugitive-ts.nvim*
+
+fugitive-ts.nvim adds treesitter-based syntax highlighting to vim-fugitive
+diff views. It overlays language-aware highlights on top of fugitive's
+default regex-based diff highlighting.
+
+==============================================================================
+REQUIREMENTS                                          *fugitive-ts-requirements*
+
+- Neovim 0.9.0+
+- vim-fugitive
+- Treesitter parsers for languages you want highlighted
+
+==============================================================================
+SETUP                                                        *fugitive-ts-setup*
+
+>lua
+    require('fugitive-ts').setup({
+      -- Enable/disable highlighting (default: true)
+      enabled = true,
+
+      -- Custom filename -> language mappings (optional)
+      languages = {},
+
+      -- Debounce delay in ms (default: 50)
+      debounce_ms = 50,
+    })
+<
+
+==============================================================================
+COMMANDS                                                  *fugitive-ts-commands*
+
+This plugin works automatically when you open a fugitive buffer. No commands
+are required.
+
+==============================================================================
+API                                                            *fugitive-ts-api*
+
+                                                    *fugitive-ts.setup()*
+setup({opts})
+    Configure the plugin. See |fugitive-ts-setup| for options.
+
+                                                   *fugitive-ts.attach()*
+attach({bufnr})
+    Manually attach highlighting to a buffer. Called automatically for
+    fugitive buffers.
+
+                                                  *fugitive-ts.refresh()*
+refresh({bufnr})
+    Manually refresh highlighting for a buffer.
+
+==============================================================================
+ROADMAP                                                    *fugitive-ts-roadmap*
+
+Planned features and improvements:
+
+- Vim syntax fallback: For languages without treesitter parsers, fall back
+  to vim's built-in syntax highlighting via scratch buffers. This would
+  provide highlighting coverage for more languages at the cost of
+  implementation complexity.
+
+==============================================================================
+ vim:tw=78:ts=8:ft=help:norl:

lua/fugitive-ts/health.lua

@@ -0,0 +1,41 @@
+local M = {}
+
+function M.check()
+  vim.health.start('fugitive-ts.nvim')
+
+  if vim.fn.has('nvim-0.9.0') == 1 then
+    vim.health.ok('Neovim 0.9.0+ detected')
+  else
+    vim.health.error('fugitive-ts.nvim requires Neovim 0.9.0+')
+  end
+
+  local fugitive_loaded = vim.fn.exists(':Git') == 2
+  if fugitive_loaded then
+    vim.health.ok('vim-fugitive detected')
+  else
+    vim.health.warn('vim-fugitive not detected (required for this plugin to be useful)')
+  end
+
+  local common_langs = { 'lua', 'python', 'javascript', 'typescript', 'rust', 'go', 'c', 'cpp' }
+  local available = {}
+  local missing = {}
+
+  for _, lang in ipairs(common_langs) do
+    local ok = pcall(vim.treesitter.language.inspect, lang)
+    if ok then
+      table.insert(available, lang)
+    else
+      table.insert(missing, lang)
+    end
+  end
+
+  if #available > 0 then
+    vim.health.ok('Treesitter parsers available: ' .. table.concat(available, ', '))
+  end
+
+  if #missing > 0 then
+    vim.health.info('Treesitter parsers not installed: ' .. table.concat(missing, ', '))
+  end
+end
+
+return M

lua/fugitive-ts/highlight.lua

@@ -0,0 +1,52 @@
+local M = {}
+
+function M.highlight_hunk(bufnr, ns, hunk)
+  local lang = hunk.lang
+  if not lang then
+    return
+  end
+
+  local code_lines = {}
+  for _, line in ipairs(hunk.lines) do
+    table.insert(code_lines, line:sub(2))
+  end
+
+  local code = table.concat(code_lines, '\n')
+  if code == '' then
+    return
+  end
+
+  local ok, parser_obj = pcall(vim.treesitter.get_string_parser, code, lang)
+  if not ok or not parser_obj then
+    return
+  end
+
+  local trees = parser_obj:parse()
+  if not trees or #trees == 0 then
+    return
+  end
+
+  local query = vim.treesitter.query.get(lang, 'highlights')
+  if not query then
+    return
+  end
+
+  for id, node, _ in query:iter_captures(trees[1]:root(), code) do
+    local capture_name = '@' .. query.captures[id]
+    local sr, sc, er, ec = node:range()
+
+    local buf_sr = hunk.start_line + sr
+    local buf_er = hunk.start_line + er
+    local buf_sc = sc + 1
+    local buf_ec = ec + 1
+
+    pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_sr, buf_sc, {
+      end_row = buf_er,
+      end_col = buf_ec,
+      hl_group = capture_name,
+      priority = 200,
+    })
+  end
+end
+
+return M

lua/fugitive-ts/init.lua

@@ -0,0 +1,109 @@
+---@class fugitive-ts.Config
+---@field enabled boolean
+---@field languages table<string, string>
+---@field debounce_ms integer
+
+---@class fugitive-ts
+---@field attach fun(bufnr?: integer)
+---@field refresh fun(bufnr?: integer)
+---@field setup fun(opts?: fugitive-ts.Config)
+local M = {}
+
+local highlight = require('fugitive-ts.highlight')
+local parser = require('fugitive-ts.parser')
+
+local ns = vim.api.nvim_create_namespace('fugitive_ts')
+
+---@type fugitive-ts.Config
+local default_config = {
+  enabled = true,
+  languages = {},
+  debounce_ms = 50,
+}
+
+---@type fugitive-ts.Config
+local config = vim.deepcopy(default_config)
+
+---@type table<integer, boolean>
+local attached_buffers = {}
+
+---@param bufnr integer
+local function highlight_buffer(bufnr)
+  if not config.enabled then
+    return
+  end
+
+  if not vim.api.nvim_buf_is_valid(bufnr) then
+    return
+  end
+
+  vim.api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
+
+  local hunks = parser.parse_buffer(bufnr, config.languages)
+  for _, hunk in ipairs(hunks) do
+    highlight.highlight_hunk(bufnr, ns, hunk)
+  end
+end
+
+---@param bufnr integer
+---@return fun()
+local function create_debounced_highlight(bufnr)
+  ---@type uv_timer_t?
+  local timer = nil
+  return function()
+    if timer then
+      timer:stop()
+      timer:close()
+    end
+    timer = vim.uv.new_timer()
+    timer:start(
+      config.debounce_ms,
+      0,
+      vim.schedule_wrap(function()
+        timer:close()
+        timer = nil
+        highlight_buffer(bufnr)
+      end)
+    )
+  end
+end
+
+---@param bufnr? integer
+function M.attach(bufnr)
+  bufnr = bufnr or vim.api.nvim_get_current_buf()
+
+  if attached_buffers[bufnr] then
+    return
+  end
+  attached_buffers[bufnr] = true
+
+  local debounced = create_debounced_highlight(bufnr)
+
+  highlight_buffer(bufnr)
+
+  vim.api.nvim_create_autocmd({ 'TextChanged', 'TextChangedI' }, {
+    buffer = bufnr,
+    callback = debounced,
+  })
+
+  vim.api.nvim_create_autocmd('BufWipeout', {
+    buffer = bufnr,
+    callback = function()
+      attached_buffers[bufnr] = nil
+    end,
+  })
+end
+
+---@param bufnr? integer
+function M.refresh(bufnr)
+  bufnr = bufnr or vim.api.nvim_get_current_buf()
+  highlight_buffer(bufnr)
+end
+
+---@param opts? fugitive-ts.Config
+function M.setup(opts)
+  opts = opts or {}
+  config = vim.tbl_deep_extend('force', default_config, opts)
+end
+
+return M

lua/fugitive-ts/parser.lua

@@ -0,0 +1,89 @@
+---@class fugitive-ts.Hunk
+---@field filename string
+---@field lang string
+---@field start_line integer
+---@field lines string[]
+
+local M = {}
+
+---@param filename string
+---@param custom_langs? table<string, string>
+---@return string?
+local function get_lang_from_filename(filename, custom_langs)
+  if custom_langs and custom_langs[filename] then
+    return custom_langs[filename]
+  end
+
+  local ft = vim.filetype.match({ filename = filename })
+  if not ft then
+    return nil
+  end
+
+  local lang = vim.treesitter.language.get_lang(ft)
+  if lang then
+    local ok = pcall(vim.treesitter.language.inspect, lang)
+    if ok then
+      return lang
+    end
+  end
+
+  return nil
+end
+
+---@param bufnr integer
+---@param custom_langs? table<string, string>
+---@return fugitive-ts.Hunk[]
+function M.parse_buffer(bufnr, custom_langs)
+  local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
+  ---@type fugitive-ts.Hunk[]
+  local hunks = {}
+
+  ---@type string?
+  local current_filename = nil
+  ---@type string?
+  local current_lang = nil
+  ---@type integer?
+  local hunk_start = nil
+  ---@type string[]
+  local hunk_lines = {}
+
+  local function flush_hunk()
+    if hunk_start and #hunk_lines > 0 and current_lang then
+      table.insert(hunks, {
+        filename = current_filename,
+        lang = current_lang,
+        start_line = hunk_start,
+        lines = hunk_lines,
+      })
+    end
+    hunk_start = nil
+    hunk_lines = {}
+  end
+
+  for i, line in ipairs(lines) do
+    local filename = line:match('^[MADRC%?!]%s+(.+)$')
+    if filename then
+      flush_hunk()
+      current_filename = filename
+      current_lang = get_lang_from_filename(filename, custom_langs)
+    elseif line:match('^@@.-@@') then
+      flush_hunk()
+      hunk_start = i
+    elseif hunk_start then
+      local prefix = line:sub(1, 1)
+      if prefix == ' ' or prefix == '+' or prefix == '-' then
+        table.insert(hunk_lines, line)
+      elseif line == '' or line:match('^[MADRC%?!]%s+') or line:match('^%a') then
+        flush_hunk()
+        current_filename = nil
+        current_lang = nil
+      end
+    end
+  end
+
+  flush_hunk()
+
+  return hunks
+end
+
+return M

plugin/fugitive-ts.lua

@@ -0,0 +1,11 @@
+if vim.g.loaded_fugitive_ts then
+  return
+end
+vim.g.loaded_fugitive_ts = 1
+
+vim.api.nvim_create_autocmd('FileType', {
+  pattern = 'fugitive',
+  callback = function(args)
+    require('fugitive-ts').attach(args.buf)
+  end,
+})