前言

vim 有很多著名的 grep 插件，我使用过的有 ack.vim，ag.vim 和 ctrlsf.vim，它们应该也是目前用户最多的几个了。

1. ack.vim
   起步比较早，早期后端 grep 工具是 ack，后来也支持 ag(the_silver_searcher)，pt(the_platinum_searcher)，rg(ripgrep) 等工具了。它是一个比较传统的 grep 插件，不支持异步，要等到 grep 结束后才能显示结果，在大的项目中 grep 会卡好一阵子。它貌似也不再维护，我 N 久前提交的 pull request 还挂在那，它最近的代码更新在 11 个月前。
2. ag.vim
   它其实是抄袭 ack.vim，没错，是抄袭。在早期 ack.vim 还不支持 ag 时，它的作者在 ack.vim 代码的基础上稍微改了改，支持了 ag。后来被 ack.vim 的作者给怼了，就放弃了对 ag.vim 的维护。目前功能上小于 ack.vim。
3. ctrlsf.vim
   这是国人开发的一个插件，后端 grep 工具支持 ack/ag/pt/rg，同时也支持异步，不过需要 Vim 8.0.1039+ 或者 NeoVim 才支持异步。这个插件很好用，在我开发Leaderf rg之前一直使用的是它。

Leaderf rg顾名思义，后端基于 rg，由于是LeaderF的子功能，基因上就决定它完美支持异步。同时 LeaderF 又是一个非著名的模糊查找插件，这使它可以在 grep 结果的基础上再通过模糊匹配的方式进行二次过滤，来帮助用户更快地锁定目标，这是目前上面提到的插件所不具备的。

为什么选择 rg(ripgrep)

快速 grep 工具目前有 ag, rg, pt, sift, ucg 等。
我选择 rg 有以下几点原因：

1. 速度比较快，rg 的 README 上有作者的对比，我实测也是 rg 快点。
2. Windows 上 bug 少（bug 到目前还没发现），ag 和 pt 都遇到过 bug。
3. 作者很活跃，提的 issue 能很快得到回复。
4. rg 功能相对多些，可以从rg --help 看出来。

Leaderf rg 使用介绍

Leaderf rg的使用也比较简单，只要Leaderf[!] + rg命令和选项（同命令行上一样）就可以了。 具体使用方法可以用:Leaderf rg -h来查看。

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.

注意：如果:Leaderf后面有感叹号，会直接进入 normal 模式；如果没有感叹号，则是输入模式，此时可以输入字符来进行模糊匹配过滤。可以用 tab 键在两个模式间来回切换。

Leaderf rg基本支持 rg 所有的必要选项，用户如果对 rg 命令比较熟悉，可以在 vim 命令行内输入:Leaderf, 然后手敲 rg 命令，命令选项还可以通过 tab 来补全。 当然，更聪明的做法是定义一些快捷键。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>

参考：rg 的glob 语法。

顺便说一下，直接在 vim 命令行敲:Leaderf rg，就会有传说中的"grep on the fly"的功能哦，同时支持 fuzzy 和 regex 两种模式。

会不会支持 ag 等其他 grep 工具

不会。
首先，ripgrep 已经足够强大，基本不存在别的工具有而 ripgrep 没有的功能。其次，ripgrep 有编译好的 Windows、Linux 和 MacOS 上的binary，可以在这些平台上很容易安装。再者，由于作者比较懒，不想再实现重复的功能。