diffs.nvim/lua/diffs/parser.lua
Barrett Ruth 3d640c207b
feat: add neogit support (#117)
## TODO

1. docs (vimdoc + readme) - this is a non-trivial feature
2. push luarocks version

## Problem

diffs.nvim only activates on `fugitive`, `git`, and `gitcommit`
filetypes.
Neogit uses its own custom filetypes (`NeogitStatus`,
`NeogitCommitView`,
`NeogitDiffView`) and doesn't set `b:git_dir`, so the plugin never
attaches
and repo root resolution fails for filetype detection within diff hunks.

## Solution

Two changes:

1. **`lua/diffs/init.lua`** — Add the three Neogit filetypes to the
default
`filetypes` list. The `FileType` autocmd in `plugin/diffs.lua` already
handles them correctly since the `is_fugitive_buffer` guard only applies
   to the `git` filetype.

2. **`lua/diffs/parser.lua`** — Add a CWD-based fallback in
`get_repo_root()`.
After the existing `b:diffs_repo_root` and `b:git_dir` checks, fall back
to
`vim.fn.getcwd()` via `git.get_repo_root()` (already cached). Without
this,
   the parser can't resolve filetypes for files in Neogit buffers.

Neogit's expanded diffs use standard unified diff format, so the parser
handles
them without modification.

Closes #110.
2026-02-14 17:12:01 -05:00

310 lines
8.4 KiB
Lua

---@class diffs.Hunk
---@field filename string
---@field ft string?
---@field lang string?
---@field start_line integer
---@field header_context string?
---@field header_context_col integer?
---@field lines string[]
---@field header_start_line integer?
---@field header_lines string[]?
---@field file_old_start integer?
---@field file_old_count integer?
---@field file_new_start integer?
---@field file_new_count integer?
---@field prefix_width integer
---@field repo_root string?
local M = {}
local dbg = require('diffs.log').dbg
---@type table<string, {ft: string?, lang: string?}>
local ft_lang_cache = {}
---@param filepath string
---@param n integer
---@return string[]?
local function read_first_lines(filepath, n)
local f = io.open(filepath, 'r')
if not f then
return nil
end
local lines = {}
for _ = 1, n do
local line = f:read('*l')
if not line then
break
end
table.insert(lines, line)
end
f:close()
return #lines > 0 and lines or nil
end
---@param filename string
---@param repo_root string?
---@return string?
local function get_ft_from_filename(filename, repo_root)
if repo_root then
local full_path = vim.fs.joinpath(repo_root, filename)
local buf = vim.fn.bufnr(full_path)
if buf ~= -1 then
local ft = vim.api.nvim_get_option_value('filetype', { buf = buf })
if ft and ft ~= '' then
dbg('filetype from existing buffer %d: %s', buf, ft)
return ft
end
end
end
local ft = vim.filetype.match({ filename = filename })
if ft then
dbg('filetype from filename: %s', ft)
return ft
end
if repo_root then
local full_path = vim.fs.joinpath(repo_root, filename)
local contents = read_first_lines(full_path, 10)
if contents then
ft = vim.filetype.match({ filename = filename, contents = contents })
if ft then
dbg('filetype from file content: %s', ft)
return ft
end
end
end
dbg('no filetype for: %s', filename)
return nil
end
---@param ft string
---@return string?
local function get_lang_from_ft(ft)
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
dbg('no parser for lang: %s (ft: %s)', lang, ft)
else
dbg('no ts lang for filetype: %s', ft)
end
return nil
end
---@param bufnr integer
---@return string?
local function get_repo_root(bufnr)
local ok, repo_root = pcall(vim.api.nvim_buf_get_var, bufnr, 'diffs_repo_root')
if ok and repo_root then
return repo_root
end
local ok2, git_dir = pcall(vim.api.nvim_buf_get_var, bufnr, 'git_dir')
if ok2 and git_dir then
return vim.fn.fnamemodify(git_dir, ':h')
end
local cwd = vim.fn.getcwd()
local git = require('diffs.git')
return git.get_repo_root(cwd .. '/.')
end
---@param bufnr integer
---@return diffs.Hunk[]
function M.parse_buffer(bufnr)
local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
local repo_root = get_repo_root(bufnr)
---@type diffs.Hunk[]
local hunks = {}
---@type string?
local current_filename = nil
---@type string?
local current_ft = nil
---@type string?
local current_lang = nil
---@type integer?
local hunk_start = nil
---@type string?
local hunk_header_context = nil
---@type integer?
local hunk_header_context_col = nil
---@type string[]
local hunk_lines = {}
---@type integer?
local hunk_count = nil
---@type integer
local hunk_prefix_width = 1
---@type integer?
local header_start = nil
---@type string[]
local header_lines = {}
---@type integer?
local file_old_start = nil
---@type integer?
local file_old_count = nil
---@type integer?
local file_new_start = nil
---@type integer?
local file_new_count = nil
---@type integer?
local old_remaining = nil
---@type integer?
local new_remaining = nil
local is_unified_diff = false
local function flush_hunk()
if hunk_start and #hunk_lines > 0 then
local hunk = {
filename = current_filename,
ft = current_ft,
lang = current_lang,
start_line = hunk_start,
header_context = hunk_header_context,
header_context_col = hunk_header_context_col,
lines = hunk_lines,
prefix_width = hunk_prefix_width,
file_old_start = file_old_start,
file_old_count = file_old_count,
file_new_start = file_new_start,
file_new_count = file_new_count,
repo_root = repo_root,
}
if hunk_count == 1 and header_start and #header_lines > 0 then
hunk.header_start_line = header_start
hunk.header_lines = header_lines
end
table.insert(hunks, hunk)
end
hunk_start = nil
hunk_header_context = nil
hunk_header_context_col = nil
hunk_lines = {}
file_old_start = nil
file_old_count = nil
file_new_start = nil
file_new_count = nil
old_remaining = nil
new_remaining = nil
end
for i, line in ipairs(lines) do
local diff_git_file = line:match('^diff %-%-git a/.+ b/(.+)$')
local neogit_file = line:match('^modified%s+(.+)$')
or line:match('^new file%s+(.+)$')
or line:match('^deleted%s+(.+)$')
or line:match('^renamed%s+(.+)$')
or line:match('^copied%s+(.+)$')
local bare_file = not hunk_start and line:match('^([^%s]+%.[^%s]+)$')
local filename = line:match('^[MADRCU%?!]%s+(.+)$') or diff_git_file or neogit_file or bare_file
if filename then
is_unified_diff = diff_git_file ~= nil
flush_hunk()
current_filename = filename
local cache_key = (repo_root or '') .. '\0' .. filename
local cached = ft_lang_cache[cache_key]
if cached then
current_ft = cached.ft
current_lang = cached.lang
else
current_ft = get_ft_from_filename(filename, repo_root)
current_lang = current_ft and get_lang_from_ft(current_ft) or nil
if current_ft or vim.fn.did_filetype() == 0 then
ft_lang_cache[cache_key] = { ft = current_ft, lang = current_lang }
end
end
if current_lang then
dbg('file: %s -> lang: %s', filename, current_lang)
elseif current_ft then
dbg('file: %s -> ft: %s (no ts parser)', filename, current_ft)
end
hunk_count = 0
hunk_prefix_width = 1
header_start = i
header_lines = {}
elseif line:match('^@@+') then
flush_hunk()
hunk_start = i
local at_prefix = line:match('^(@@+)')
hunk_prefix_width = #at_prefix - 1
if #at_prefix == 2 then
local hs, hc, hs2, hc2 = line:match('^@@ %-(%d+),?(%d*) %+(%d+),?(%d*) @@')
if hs then
file_old_start = tonumber(hs)
file_old_count = tonumber(hc) or 1
file_new_start = tonumber(hs2)
file_new_count = tonumber(hc2) or 1
old_remaining = file_old_count
new_remaining = file_new_count
end
else
local hs2, hc2 = line:match('%+(%d+),?(%d*) @@')
if hs2 then
file_new_start = tonumber(hs2)
file_new_count = tonumber(hc2) or 1
end
end
local at_end, context = line:match('^(@@+.-@@+%s*)(.*)')
if context and context ~= '' then
hunk_header_context = context
hunk_header_context_col = #at_end
end
if hunk_count then
hunk_count = hunk_count + 1
end
elseif hunk_start then
local prefix = line:sub(1, 1)
if prefix == ' ' or prefix == '+' or prefix == '-' then
table.insert(hunk_lines, line)
if old_remaining and (prefix == ' ' or prefix == '-') then
old_remaining = old_remaining - 1
end
if new_remaining and (prefix == ' ' or prefix == '+') then
new_remaining = new_remaining - 1
end
elseif
line == ''
and is_unified_diff
and old_remaining
and old_remaining > 0
and new_remaining
and new_remaining > 0
then
table.insert(hunk_lines, ' ')
old_remaining = old_remaining - 1
new_remaining = new_remaining - 1
elseif
line == ''
or line:match('^[MADRC%?!]%s+')
or line:match('^diff ')
or line:match('^index ')
or line:match('^Binary ')
then
flush_hunk()
current_filename = nil
current_ft = nil
current_lang = nil
header_start = nil
end
end
if header_start and not hunk_start then
table.insert(header_lines, line)
end
end
flush_hunk()
return hunks
end
M._test = {
ft_lang_cache = ft_lang_cache,
}
return M