前言
vim有很多著名的grep外掛，我使用過的有ack.vim，ag.vim和ctrlsf.vim，它們應該也是目前使用者最多的幾個了。
- ack.vim
起步比較早，早期後端grep工具是ack，後來也支援ag(the_silver_searcher)，pt(the_platinum_searcher)，rg(ripgrep)等工具了。它是一個比較傳統的grep外掛，不支援非同步，要等到grep結束後才能顯示結果，在大的專案中grep會卡好一陣子。它貌似也不再維護，我N久前提交的pull request還掛在那，它最近的程式碼更新在11個月前。 - ag.vim
它其實是抄襲ack.vim，沒錯，是抄襲。在早期ack.vim還不支援ag時，它的作者在ack.vim程式碼的基礎上稍微改了改，支援了ag。後來被ack.vim的作者給懟了，就放棄了對ag.vim的維護。目前功能上小於ack.vim。 - ctrlsf.vim
這是國人開發的一個外掛, 後端grep工具支援ack/ag/pt/rg，同時也支援非同步，不過需要Vim 8.0.1039+或者NeoVim才支援非同步。這個外掛很好用，在我開發Leaderf rg之前一直使用的是它。
Leaderf rg顧名思義，後端基於rg，由於是LeaderF的子功能，基因上就決定它完美支援非同步。同時LeaderF又是一個非著名的模糊查詢外掛，這使它可以在grep結果的基礎上再通過模糊匹配的方式進行二次過濾，來幫助使用者更快地鎖定目標，這是目前上面提到的外掛所不具備的。
為什麼選擇rg(ripgrep)
快速grep工具目前有ag, rg, pt, sift, ucg等。
我選擇rg有以下幾點原因：
- 速度比較快，rg的README上有作者的對比，我實測也是rg快點。
- Windows上bug少（bug到目前還沒發現），ag和pt都遇到過bug。
- 作者很活躍，提的issue能很快得到回覆。
- rg功能相對多些，可以從
rg --help看出來。
Leaderf rg 使用介紹
Leaderf rg的使用也比較簡單，只要Leaderf[!] + rg命令和選項（同命令列上一樣）就可以了。
具體使用方法可以用:Leaderf rg -h來檢視。
usage: Leaderf[!] rg [-h] [-e <PATTERN>...] [-F] [-i] [-L] [-P] [-S] [-s] [-v]
[-w] [-x] [--hidden] [--no-config] [--no-ignore]
[--no-ignore-global] [--no-ignore-parent]
[--no-ignore-vcs] [--no-pcre2-unicode] [-E <ENCODING>]
[-M <NUM>] [-m <NUM>] [--max-depth <NUM>]
[--max-filesize <NUM+SUFFIX?>]
[--path-separator <SEPARATOR>] [--sort <SORTBY>]
[--sortr <SORTBY>] [-f <PATTERNFILE>...] [-g <GLOB>...]
[--iglob <GLOB>...] [--ignore-file <PATH>...]
[--type-add <TYPE_SPEC>...] [-t <TYPE>...] [-T <TYPE>...]
[--current-buffer | --all-buffers] [--recall] [--append]
[--reverse] [--stayOpen] [--input <INPUT> | --cword]
[--top | --bottom | --left | --right | --belowright | --aboveleft | --fullScreen]
[--nameOnly | --fullPath | --fuzzy | --regexMode] [--nowrap]
[<PATH> [<PATH> ...]]
optional arguments:
-h, --help show this help message and exit
specific arguments:
-e <PATTERN>..., --regexp <PATTERN>...
A pattern to search for. This option can be provided multiple times, where all
patterns given are searched.
-F, --fixed-strings Treat the pattern as a literal string instead of a regular expression.
-i, --ignore-case Searches case insensitively.
-L, --follow Follow symbolic links while traversing directories.
-P, --pcre2 When this flag is present, rg will use the PCRE2 regex engine instead of its
default regex engine.
-S, --smart-case Searches case insensitively if the pattern is all lowercase, case sensitively
otherwise.
-s, --case-sensitive Searches case sensitively.
-v, --invert-match Invert matching. Show lines that do not match the given patterns.
-w, --word-regexp Only show matches surrounded by word boundaries. This is roughly equivalent to
putting \b before and after all of the search patterns.
-x, --line-regexp Only show matches surrounded by line boundaries.
--hidden Search hidden files and directories. By default, hidden files and directories
are skipped.
--no-config Never read configuration files. When this flag is present, rg will not respect
the RIPGREP_CONFIG_PATH environment variable.
--no-ignore Don't respect ignore files (.gitignore, .ignore, etc.). This implies
--no-ignore-parent and --no-ignore-vcs.
--no-ignore-global Don't respect ignore files that come from 'global' sources such as git's
`core.excludesFile` configuration option (which defaults to
`$HOME/.config/git/ignore`).
--no-ignore-parent Don't respect ignore files (.gitignore, .ignore, etc.) in parent directories.
--no-ignore-vcs Don't respect version control ignore files (.gitignore, etc.).
--no-pcre2-unicode When PCRE2 matching is enabled, this flag will disable
Unicode mode, which is otherwise enabled by default.
-E <ENCODING>, --encoding <ENCODING>
Specify the text encoding that rg will use on all files searched.
-M <NUM>, --max-columns <NUM>
Don't print lines longer than this limit in bytes.
-m <NUM>, --max-count <NUM>
Limit the number of matching lines per file searched to NUM.
--max-depth <NUM> Limit the depth of directory traversal to NUM levels beyond the paths given.
--max-filesize <NUM+SUFFIX?>
Ignore files larger than NUM in size. This does not apply to directories.
--path-separator <SEPARATOR>
Set the path separator to use when printing file paths.
--sort <SORTBY> This flag enables sorting of results in ascending order.
--sortr <SORTBY> This flag enables sorting of results in descending order.
-f <PATTERNFILE>..., --file <PATTERNFILE>...
Search for patterns from the given file, with one pattern per line.
(This option can be provided multiple times.)
-g <GLOB>..., --glob <GLOB>...
Include or exclude files and directories for searching that match the given
glob.(This option can be provided multiple times.)
--iglob <GLOB>... Include or exclude files and directories for searching that match the given glob.
Globs are matched case insensitively.(This option can be provided multiple times.)
--ignore-file <PATH>...
Specifies a path to one or more .gitignore format rules files.
--type-add <TYPE_SPEC>...
Add a new glob for a particular file type.
-t <TYPE>..., --type <TYPE>...
Only search files matching TYPE. Multiple type flags may be provided.
-T <TYPE>..., --type-not <TYPE>...
Do not search files matching TYPE. Multiple type-not flags may be provided.
<PATH> A file or directory to search. Directories are searched recursively. Paths
specified on the command line override glob and ignore rules.
--current-buffer Searches in current buffer.
--all-buffers Searches in all listed buffers.
--recall Recall last search. If the result window is closed, reopen it.
--append Append to the previous search results.
common arguments:
--reverse show results in bottom-up order
--stayOpen don't quit LeaderF after accepting an entry
--input <INPUT> specifies INPUT as the pattern inputted in advance
--cword current word under cursor is inputted in advance
--top the LeaderF window is at the top of the screen
--bottom the LeaderF window is at the bottom of the screen
--left the LeaderF window is at the left of the screen
--right the LeaderF window is at the right of the screen
--belowright the LeaderF window is at the belowright of the screen
--aboveleft the LeaderF window is at the aboveleft of the screen
--fullScreen the LeaderF window takes up the full screen
--nameOnly LeaderF is in NameOnly mode by default
--fullPath LeaderF is in FullPath mode by default
--fuzzy LeaderF is in Fuzzy mode by default
--regexMode LeaderF is in Regex mode by default
--nowrap long lines in the LeaderF window won't wrap
If [!] is given, enter normal mode directly.
複製程式碼注意：如果:Leaderf後面有感嘆號，會直接進入normal模式；如果沒有感嘆號，則是輸入模式，此時可以輸入字元來進行模糊匹配過濾。可以用tab鍵在兩個模式間來回切換。
Leaderf rg基本支援rg所有的必要選項，使用者如果對rg命令比較熟悉，可以在vim命令列內輸入:Leaderf, 然後手敲rg命令，命令選項還可以通過tab來補全。
當然，更聰明的做法是定義一些快捷鍵。例如：
" search word under cursor, the pattern is treated as regex, and enter normal mode directly
noremap <C-F> :<C-U><C-R>=printf("Leaderf! rg -e %s ", expand("<cword>"))<CR>
" search word under cursor, the pattern is treated as regex,
" append the result to previous search results.
noremap <C-G> :<C-U><C-R>=printf("Leaderf! rg --append -e %s ", expand("<cword>"))<CR>
" search word under cursor literally only in current buffer
noremap <C-B> :<C-U><C-R>=printf("Leaderf! rg -F --current-buffer -e %s ", expand("<cword>"))<CR>
" search word under cursor literally in all listed buffers
noremap <C-D> :<C-U><C-R>=printf("Leaderf! rg -F --all-buffers -e %s ", expand("<cword>"))<CR>
" search visually selected text literally, don't quit LeaderF after accepting an entry
xnoremap gf :<C-U><C-R>=printf("Leaderf! rg -F --stayOpen -e %s ", leaderf#Rg#visual())<CR>
" recall last search. If the result window is closed, reopen it.
noremap go :<C-U>Leaderf! rg --recall<CR>
" search word under cursor in *.h and *.cpp files.
noremap <Leader>a :<C-U><C-R>=printf("Leaderf! rg -e %s -g *.h -g *.cpp", expand("<cword>"))<CR>
" the same as above
noremap <Leader>a :<C-U><C-R>=printf("Leaderf! rg -e %s -g *.{h,cpp}", expand("<cword>"))<CR>
" search word under cursor in cpp and java files.
noremap <Leader>b :<C-U><C-R>=printf("Leaderf! rg -e %s -t cpp -t java", expand("<cword>"))<CR>
" search word under cursor in cpp files, exclude the *.hpp files
noremap <Leader>c :<C-U><C-R>=printf("Leaderf! rg -e %s -t cpp -g !*.hpp", expand("<cword>"))<CR>
複製程式碼參考：rg的glob語法。
順便說一下，直接在vim命令列敲:Leaderf rg，就會有傳說中的"grep on the fly"的功能哦，同時支援fuzzy和regex兩種模式。
會不會支援ag等其他grep工具
不會。
首先，ripgrep已經足夠強大，基本不存在別的工具有而ripgrep沒有的功能。其次，ripgrep有編譯好的Windows、Linux和MacOS上的binary，可以在這些平臺上很容易安裝。再者，由於作者比較懶，不想再實現重複的功能。