Vim代码补全插件youcompleteme

目标：使YouCompleteMe能作用于C、Java、JavaScript。

根据YouCompleteMe插件的要求，我们需要Vim 7.4.1578 with Python 2 or Python 3 support。你可以通过vim --version命令来查看你的Vim是否符合上述要求。如果不符合，则可以通过第1、2步源码编译重装Vim；如果符合，则可跳至第3步

0 简介
1 安装 Python
2 安装 Vim
3 通过安装 vim-plug 安装 YouCompleteMe
4 安装并配置 YouCompleteMe
5 使用
- 5.1 通用
- 5.2 C语言
6 参考链接

0 简介

YouCompleteMe is a fast, as-you-type, fuzzy-search code completion engine for Vim. It has several completion engines:

an identifier-based engine that works with every programming language,

a Clang-based engine that provides native semantic code completion for C/C++/Objective-C/Objective-C++/CUDA (from now on referred to as “the C-family languages”),

a Jedi-based completion engine for Python 2 and 3,

an OmniSharp-based completion engine for C#,

a combination of Gocode and Godef semantic engines for Go,

a TSServer-based completion engine for JavaScript and TypeScript,

a racer-based completion engine for Rust,

a jdt.ls-based experimental completion engine for Java.

and an omnifunc-based completer that uses data from Vim’s omnicomplete system to provide semantic completions for many other languages (Ruby, PHP etc.).

总之，YouCompleteMe 是目前（2018-11-26）最强大的代码补全插件（但同时也是最难安装的插件）

1 安装 Python

使用 pyenv(Simple Python version management)进行安装

安装pyenv

git clone https://github.com/pyenv/pyenv.git ~/.pyenv
echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n  eval "$(pyenv init -)"\nfi' >> ~/.bashrc
. ~/.bashrc

安装编译CPython（即最流行的Python）需要使用的依赖，因为pyenv要用:

yum install gcc zlib-devel bzip2 bzip2-devel readline-devel sqlite sqlite-devel openssl-devel tk-devel libffi-devel

使之后Python的编译拥有动态库（dynamic library），因为后面需要:

echo 'export PYTHON_CONFIGURE_OPTS="--enable-shared"' >> ~/.bashrc

安装一个Python版本（如2.7.15）：

pyenv install 2.7.15

2 安装 Vim

安装编译Vim需要的依赖：

sudo yum install -y ruby ruby-devel lua lua-devel luajit \
luajit-devel ctags git \
tcl-devel perl perl-devel perl-ExtUtils-ParseXS \
perl-ExtUtils-XSpp perl-ExtUtils-CBuilder \
perl-ExtUtils-Embed

移除已经安装的Vim：

apt remove vim vim-runtime gvim

安装Vim：

cd ~
git clone https://github.com/vim/vim.git
cd vim/src
./configure --with-features=huge \
            --enable-multibyte \
	    --enable-pythoninterp=yes \
	    --with-python-config-dir=/root/.pyenv/versions/2.7.15/lib/python2.7/config/ \ #通过 `find ~/.pyenv -name "config"` 获取该目录
	    --enable-luainterp=yes \
            --enable-cscope \
	   --prefix=/usr/local
   
make VIMRUNTIMEDIR=/usr/local/share/vim/vim81
make install

验证安装，确认Vim已带有python支持：
```
1
vim --version
```

注：如果失败了可以使用make uninstall卸载找到原因后重来（我重来了好几次，因为系统自带的Python2.7.5好像不行，所以我才使用Python的版本管理工具pyenv安装了Python2.7.15，之所以没直接卸载系统自带的Python2.7.5是因为我卸载不掉，它说它被很多其他软件依赖）

3 通过安装 vim-plug 安装 YouCompleteMe

往~/.vimrc中添加如下配置：

if empty(glob('~/.vim/autoload/plug.vim'))
  silent !curl -fLo ~/.vim/autoload/plug.vim --create-dirs
    \ https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim
  autocmd VimEnter * PlugInstall --sync | source $MYVIMRC
endif
   
call plug#begin('~/.vim/bundle')
Plug 'junegunn/vim-plug'
Plug 'Raimondi/delimitMate'
" Plug 'yianwillis/vimcdoc'
" Plug 'vim-scripts/VimIM'
Plug 'mzlogin/vim-markdown-toc'
Plug 'dhruvasagar/vim-table-mode'
Plug 'ervandew/supertab'
Plug 'mattn/emmet-vim'
Plug 'Valloric/YouCompleteMe' # { 'do': './install.py --clang-completer --java-completer' }
call plug#end()

进入Vim后输入:PlugInstall安装各种插件（包括YouCompleteMe）。其实这个时候并没有成功安装YouCompleteMe，只是把YouCompleteMe的git源克隆到了~/.vim/bundle目录

4 安装并配置 YouCompleteMe

4.1 安装 YouCompleteMe

编译并安装YouCompleteMe（建议先让终端科学上网后再编译安装，否则极有可能会出现下述问题中的第二个问题，且其解决方案似乎已经失效，2018-11-28）:

cd ~/.vim/bundle/YouCompleteMe/
python install.py --clang-completer --java-completer 
#可在此添加加的语言支持有C(--clang-completer), C#(--cs-completer), Go(--go-completer), Rust(--rust-completer), Java(--java-completer)

以上步骤的可能遇到的问题

如果在git submodule update --init --recursive这一步（隐含在python install.py --clang-completer --java-completer中）中发现下载很慢，则可以参考我的另一篇博客Kali Linux科学上网配置好git部分后再下载。

如果在：

-- Downloading libclang 7.0.0 from https://dl.bintray.com/micbou/libclang/libclang-7.0.0-x86_64-unknown-linux-gnu.tar.bz2

这一步中卡住了

或者等待很长时间后错误如下（--clang-completer参数导致的问题）：

CMake Error at ycm/CMakeLists.txt:103 (file):
file DOWNLOAD HASH mismatch
for file: [/home/up_ding/.vim/bundle/YouCompleteMe/third_party/ycmd/cpp/../clang_archives/clang+llvm-3.7.0-x86_64-linux-gnu-ubuntu-14.04.tar.xz]
  expected hash: [093a94ff8982ae78461f0d2604c98f6b454c15e2ef768d34c235c6676c336460]
    actual hash: [a12a54f4e937e521a5e9ff790db0bf7a358f6dbc6febebcddab62c798ffc4d51]

则可以手动下载 Clang archive(复制那个下载链接即可，记得要科学上网后再下载), 然后将它移动至~/.vim/bundle/YouCompleteMe/third_party/ycmd/clang_archives目录下，然后重新安装YouCompleteMe（即运行上面那个python intall.py……命令），具体可参考https://github.com/Valloric/YouCompleteMe/issues/1711

编译YCM需要的ycm_core库:

mkdir ~/.ycm_build
cd ~/.ycm_build
cmake -G "Unix Makefiles" -DEXTERNAL_LIBCLANG_PATH=/root/.vim/bundle/YouCompleteMe/third_party/ycmd/libclang.so.6.0 . ~/.vim/bundle/YouCompleteMe/third_party/ycmd/cpp
cmake --build . --target ycm_core

详情见YouCompleteMe#full-installation-guide

（可选）为改善Unicode支持和更好的正则表达式性能构建正则表达式模块:

cd ~
mkdir .regex_build
cd .regex_build
cmake -G "Unix Makefiles" . ~/.vim/bundle/YouCompleteMe/third_party/ycmd/third_party/cregex
cmake --build . --target _regex --config Release

Vim配置（仅供参考）：

" for ycm"
let g:ycm_min_num_identifier_candidate_chars = 4
let g:ycm_min_num_of_chars_for_completion = 2 "set 99 to turn off identifiers completer"
let g:ycm_max_num_identifier_candidates = 10 "identifier completion"
let g:ycm_max_num_candidates = 30 "semantic completion"
let g:ycm_auto_trigger = 1
let g:ycm_key_list_stop_completion = ['<C-y>']
let g:ycm_server_python_interpreter='/root/.pyenv/shims/python'
let g:ycm_global_ycm_extra_conf='~/.vim/.ycm_extra_conf.py' "used for c-family language"
let g:ycm_error_symbol = '>>'
let g:ycm_warning_symbol = '>*'
let g:ycm_key_invoke_completion = '<c-l>'
nnoremap <leader>gl :YcmCompleter GoToDeclaration<CR>
nnoremap <leader>gf :YcmCompleter GoToDefinition<CR>
nnoremap <leader>gg :YcmCompleter GoToDefinitionElseDeclaration<CR>
nmap <F4> :YcmDiags<CR>

4.2 配置 C 支持

复制并修改 .ycm_extra_conf.py文件：

cp ~/.vim/bundle/YouCompleteMe/third_party/ycmd/examples/.ycm_extra_conf.py ~/.vim/

然后在~/.vimrc中设置g:ycm_global_ycm_extra_conf变量：

let g:ycm_global_ycm_extra_conf='~/.vim/.ycm_extra_conf.py' "used for c-family language"

4.3 配置 JavaScript 支持

安装 TSServer 引擎（通过安装TypeScript SDK）：

安装nvm（node version manager，安装它后再安装各种版本的node.js就非常简单了，因为后面要用到npm）：

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.11/install.sh | bash

根据提示将如下内容添加至~/.bashrc：

# node version manager
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion

退出并重进终端（或者使用source ~/.bashrc命令），然后使用nvm --help以确认是否安装成功

安装最新稳定版的node.js（会自动安装npm）：

nvm install stable

安装TypeScript SDK：

npm install -g typescript

（可选）为了获得语法检查的功能，可以在工程目录中的jsconfig.json文件里设置checkJs选项：
```
 {
     "compilerOptions": {
         "checkJs": true
     }
 }
 
```

5 使用

参见:h youcompleteme-commands及:h youcompleteme-ycmcompleter-subcommands

5.1 通用

Commands youcompleteme-commands
1. The :YcmRestartServer command
2. The :YcmForceCompileAndDiagnostics command
3. The :YcmDiags command
4. The :YcmShowDetailedDiagnostic command
5. The :YcmDebugInfo command
6. The :YcmToggleLogs command
7. The :YcmCompleter command
YcmCompleter Subcommands youcompleteme-ycmcompleter-subcommands
1. GoTo Commands youcompleteme-goto-commands
  1. The GoToInclude subcommand
  2. The GoToDeclaration subcommand
  3. The GoToDefinition subcommand
  4. The GoTo subcommand
  5. The GoToImprecise subcommand
  6. The GoToReferences subcommand
  7. The GoToImplementation subcommand
  8. The GoToImplementationElseDeclaration subcommand
  9. The GoToType subcommand
2. Semantic Information Commands youcompleteme-semantic-information-commands
  1. The GetType subcommand
  2. The GetTypeImprecise subcommand
  3. The GetParent subcommand
  4. The GetDoc subcommand
  5. The GetDocImprecise subcommand
3. Refactoring Commands youcompleteme-refactoring-commands
  1. The FixIt subcommand
  2. The ‘RefactorRename ' subcommand `RefactorRename-new-name`
  3. Multi-file Refactor youcompleteme-multi-file-refactor
  4. The Format subcommand
  5. The OrganizeImports subcommand
4. Miscellaneous Commands youcompleteme-miscellaneous-commands
  1. The RestartServer subcommand
  2. The ClearCompilationFlagCache subcommand
  3. The ReloadSolution subcommand

关于它们的用法请参见:h :<命令名>，如:h :YcmRestartServer

输入字符超过2个，即会出现补全菜单，主要支持本文档内的补全（注释中的不会用于补全，如想补全注释中的内容，可以使用Ctrl+N和Ctrl+P）、语义补全（根据编程语言自动解析补全，精准度很高）、代码片断补全（和 vim-snippets 配合使用）

Ctrl+N和Ctrl+P：出现补全菜单后，使用Ctrl+N向下选择（也可以使用Tab），使用Ctrl+P向上选择
\gd(GetDoc)：获取光标所在单词的帮助文档（主要是它的API）
\gr(GoToReferences)：获取引用光标所在单词的所有位置
\gg(GoTo): 先尝试跳转至声明处，若失败，则跳转至定义处
Ctrl+L: 强制补全
Ctrl+Y：在补全菜单出现时可以使用该快捷键关闭补全菜单（有时很有用）

5.2 C语言

normal	cmdline(`:YcmCompleter <subcmd>`)	Description	备注
`\gi`	`GoToInclude`	Looks up the current line for a header and jumps to it.	和 Vim 自带的`gf`命令类似
`\gc`	`GoToDeclaration`	Looks up the symbol under the cursor and jumps to its declaration.	和 Vim 自带的`gd`命令类似
`\gf`	`GoToDefinition`	Looks up the symbol under the cursor and jumps to its definition.
`\gg`	`GoTo`	Auto select from above
`\gt`	`GetType`	Echos the type of the variable or method under the cursor
`\gp`	`GetParent`	Echos the semantic parent of the point under the cursor.
`\gd`	`GetDoc`	Displays the preview window populated with quick info about the identifier under the cursor.	可以使用`K`或`\K`命令查看`man`手册，详情参见`:h :Man`

注意，上述命令需要配置文件~/.vimrc如下：

nnoremap <leader>gi :YcmCompleter GoToInclude<CR>
nnoremap <leader>gc :YcmCompleter GoToDeclaration<CR>
nnoremap <leader>gf :YcmCompleter GoToDefinition<CR>
nnoremap <leader>gg :YcmCompleter GoTo<CR>
nnoremap <leader>gt :YcmCompleter GetType<CR>
nnoremap <leader>gp :YcmCompleter GetParent<CR>
nnoremap <leader>gd :YcmCompleter GetDoc<CR>

且其中的<leader>没有被修改过，即为默认的\。详情参见:h <leader>