原文出处：http://blog.jobbole.com/58978/

第一次听说这个插件还是在偶然的情况下看到别人的博客，听说了这个插件的大名。本来打算在实训期间来完成安装的，无奈网实在不给力，也就拖到了回家的时候。在开始准备工作的时候就了解到这个插件不是很容易安装，安装的时候果然名不虚传。(关于这方面的内容，请查看另一篇文章)不过，有付出总有回报，安装之后用上这个插件，真心为这个插件的强大所折服。

那这个插件有何不同？

YouCompleteMe的特别之处

基于语义补全

总所周知，Vim是一款文本编辑器。也就是说，其最基础的工作就是编辑文本，而不管该文本的内容是什么。在Vim被程序员所使用后，其慢慢的被肩负了与IDE一样的工作，文本自动补全(ie.acp,omnicppcompleter)，代码检查(Syntastic)等等工作。

针对文本自动补全这个功能来说，主要有两种实现方式。

基于文本

我们常用的omnicppcompleter,acp,vim自带的c-x, c-n的实现方式就是基于文本。更通俗的说法，其实就是一个字：

猜

其通过文本进行一些正则表达式的匹配，再根据生成的tags(利用ctags生成)来实现自动补全的效果。

基于语义

顾名思义，其是通过分析源文件，经过语法分析以后进行补全。由于对源文件进行分析，基于语义的补全可以做到很精确。但是这显然是vim所不可能支持的。而且经过这么多年发展，由于语法分析有很高的难度，也一直没有合适的工具出现。直到，由apple支持的clang/llvm横空出世。YouCompleteMe也正是在clang/llvm的基础上进行构建的。

整合实现了多种插件

clang_complete

AutoComplPop

Supertab

neocomplcache

Syntastic(类似功能,仅仅针对c/c++/obj-c代码)

支持语言

c

c++

obj-c

c#

python

对于其他的语言，会调用vim设置的omnifunc来匹配，因此同样支持php,ruby等语言。

已知的有 * javascript —-tern_for_vim * ruby/java —-eclim

使用效果图

使用感受

和IDE一样，自动补全，

根据include的文件进行补全

不用再蹩脚的生成tags

补全非常精准，而且速度很快，不会有延迟(以前在大项目上，acp用起来实在是很卡)

支持类似tags的跳转，跳到定义处以及使用处

出错提示很智能，并且用起来真的是如丝般柔滑，不用输入:w进行强制检测

安装

说完了那么多好处，就要说到安装了。不同于以往其他vim插件，YCM是一款编译型的插件。在下载完后，需要手动编译后才能使用。对应其他的插件来说，仅仅就是把.vim的文件丢到相应文件夹下就可以。而这也加大了使用YCM的难度。

安装准备

最新版的Vim(7.3.584+)，编译时添加+python标志(已经安装的可以通过vim --version查看)

cmake(mac可以通过homebrew安装，brew install cmake,ubuntu可以通过sudo apt-get install cmake)

安装vundle插件，用于安装管理vim的插件

mac下快速安装

在.vimrc中添加下列代码

Shell

Bundle 'Valloric/YouCompleteMe'

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Bundle'Valloric/YouCompleteMe'

保存退出后打开vim，在正常模式下输入

Shell

:BundleInstall

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:BundleInstall

等待vundle将YouCompleteMe安装完成

而后进行编译安装：

Shell

cd ~/.vim/bundle/YouCompleteMe

./install --clang-completer

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cd~/.vim/bundle/YouCompleteMe

./install--clang-completer

如果不需要c-family的补全，可以去掉--clang-completer。如果需要c#的补全，请加上--omnisharp-completer。

正常来说,YCM会去下载clang的包，如果已经有，也可以用系统--system-libclang。

就这样，安装结束。打开vim，如果没有提示YCM未编译，则说明安装已经成功了。

手动编译安装

安装的脚本并不是什么时候都好用，至少对我来说是这样的。安装完之后出现了问题，参考issue#809。

在用:BundleInstall安装完成或者使用

Shell

git clone --recursive https://github.com/Valloric/YouCompleteMe.git

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git clone--recursive https://github.com/Valloric/YouCompleteMe.git

获取最新的仓库，而后使用git submodule update --init --recursive确认仓库的完整性后，开始安装流程。

下载最新的clang二进制文件 YCM要求clang版本 > 3.2，一般来说都是下载最新的。

安装python-dev.(ubuntu下使用sudo apt-get install python-dev,mac下默认提供，否则请安装command line tools)

编译

Shell

cd ~

mkdir ycm_build

cd ycm_build

cmake -G “Unix Makefiles” -DPATH_TO_LLVM_ROOT=~/ycm_temp/llvm_root_dir . ~/.vim/bundle/YouCompleteMe/cpp make ycm_support_libs

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cd~

mkdirycm_build

cdycm_build

cmake-G“Unix Makefiles”-DPATH_TO_LLVM_ROOT=~/ycm_temp/llvm_root_dir.~/.vim/bundle/YouCompleteMe/cpp makeycm_support_libs

这里需要注意的是，~/ycm_temp/llvm_root_dir中包含的是根据第一步下载的压缩包解压出来的内容(包括include, bin等等文件)。

这样就完成了,开始感受YCM提供的完全不逊色于大型IDE所提供的自动补全功能吧。

配置

不同于很多vim插件，YCM首先需要编译，另外还需要有配置。在vim启动后，YCM会找寻当前路径以及上层路径的.ycm_extra_conf.py.在~/.vim/bundle/YouCompleteMe/cpp/ycm/.ycm_extra_conf.py中提供了默认的模板。也可以参考我的(就在模板上改改而已)。不过这个解决了标准库提示找不到的问题。

一般来说,我会在~目录下放一个默认的模板，而后再根据不同的项目在当前目录下再拷贝个.ycm_extra_conf.py。

Shell

# This file is NOT licensed under the GPLv3, which is the license for the rest

# of YouCompleteMe.

#

# Here's the license text for this file:

#

# This is free and unencumbered software released into the public domain.

#

# Anyone is free to copy, modify, publish, use, compile, sell, or

# distribute this software, either in source code form or as a compiled

# binary, for any purpose, commercial or non-commercial, and by any

# means.

#

# In jurisdictions that recognize copyright laws, the author or authors

# of this software dedicate any and all copyright interest in the

# software to the public domain. We make this dedication for the benefit

# of the public at large and to the detriment of our heirs and

# successors. We intend this dedication to be an overt act of

# relinquishment in perpetuity of all present and future rights to this

# software under copyright law.

#

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR

# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,

# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

# OTHER DEALINGS IN THE SOFTWARE.

#

# For more information, please refer to

import os

import ycm_core

# These are the compilation flags that will be used in case there's no

# compilation database set (by default, one is not set).

# CHANGE THIS LIST OF FLAGS. YES, THIS IS THE DROID YOU HAVE BEEN LOOKING FOR.

flags = [

'-Wall',

'-Wextra',

#'-Werror',

#'-Wc++98-compat',

'-Wno-long-long',

'-Wno-variadic-macros',

'-fexceptions',

'-stdlib=libc++',

# THIS IS IMPORTANT! Without a "-std=" flag, clang won't know which

# language to use when compiling headers. So it will guess. Badly. So C++

# headers will be compiled as C headers. You don't want that so ALWAYS specify

# a "-std=".

# For a C project, you would set this to something like 'c99' instead of

# 'c++11'.

'-std=c++11',

# ...and the same thing goes for the magic -x option which specifies the

# language that the files to be compiled are written in. This is mostly

# relevant for c++ headers.

# For a C project, you would set this to 'c' instead of 'c++'.

'-x',

'c++',

'-I',

'.',

'-isystem',

'/usr/include',

'-isystem',

'/usr/local/include',

'-isystem',

'/Library/Developer/CommandLineTools/usr/include',

'-isystem',

'/Library/Developer/CommandLineTools/usr/bin/../lib/c++/v1',

]

# Set this to the absolute path to the folder (NOT the file!) containing the

# compile_commands.json file to use that instead of 'flags'. See here for

# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html

#

# Most projects will NOT need to set this to anything; you can just change the

# 'flags' list of compilation flags. Notice that YCM itself uses that approach.

compilation_database_folder = ''

if os.path.exists( compilation_database_folder ):

database = ycm_core.CompilationDatabase( compilation_database_folder )

else:

database = None

SOURCE_EXTENSIONS = [ '.cpp', '.cxx', '.cc', '.c', '.m', '.mm' ]

def DirectoryOfThisScript():

return os.path.dirname( os.path.abspath( __file__ ) )

def MakeRelativePathsInFlagsAbsolute( flags, working_directory ):

if not working_directory:

return list( flags )

new_flags = []

make_next_absolute = False

path_flags = [ '-isystem', '-I', '-iquote', '--sysroot=' ]

for flag in flags:

new_flag = flag

if make_next_absolute:

make_next_absolute = False

if not flag.startswith( '/' ):

new_flag = os.path.join( working_directory, flag )

for path_flag in path_flags:

if flag == path_flag:

make_next_absolute = True

break

if flag.startswith( path_flag ):

path = flag[ len( path_flag ): ]

new_flag = path_flag + os.path.join( working_directory, path )

break

if new_flag:

new_flags.append( new_flag )

return new_flags

def IsHeaderFile( filename ):

extension = os.path.splitext( filename )[ 1 ]

return extension in [ '.h', '.hxx', '.hpp', '.hh' ]

def GetCompilationInfoForFile( filename ):

# The compilation_commands.json file generated by CMake does not have entries

# for header files. So we do our best by asking the db for flags for a

# corresponding source file, if any. If one exists, the flags for that file

# should be good enough.

if IsHeaderFile( filename ):

basename = os.path.splitext( filename )[ 0 ]

for extension in SOURCE_EXTENSIONS:

replacement_file = basename + extension

if os.path.exists( replacement_file ):

compilation_info = database.GetCompilationInfoForFile(

replacement_file )

if compilation_info.compiler_flags_:

return compilation_info

return None

return database.GetCompilationInfoForFile( filename )

def FlagsForFile( filename, **kwargs ):

if database:

# Bear in mind that compilation_info.compiler_flags_ does NOT return a

# python list, but a "list-like" StringVec object

compilation_info = GetCompilationInfoForFile( filename )

if not compilation_info:

return None

final_flags = MakeRelativePathsInFlagsAbsolute(

compilation_info.compiler_flags_,

compilation_info.compiler_working_dir_ )

# NOTE: This is just for YouCompleteMe; it's highly likely that your project

# does NOT need to remove the stdlib flag. DO NOT USE THIS IN YOUR

# ycm_extra_conf IF YOU'RE NOT 100% SURE YOU NEED IT.

#try:

# final_flags.remove( '-stdlib=libc++' )

#except ValueError:

# pass

else:

relative_to = DirectoryOfThisScript()

final_flags = MakeRelativePathsInFlagsAbsolute( flags, relative_to )

return {

'flags': final_flags,

'do_cache': True

}

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# This file is NOT licensed under the GPLv3, which is the license for the rest

# of YouCompleteMe.

#

# Here's the license text for this file:

#

# This is free and unencumbered software released into the public domain.

#

# Anyone is free to copy, modify, publish, use, compile, sell, or

# distribute this software, either in source code form or as a compiled

# binary, for any purpose, commercial or non-commercial, and by any

# means.

#

# In jurisdictions that recognize copyright laws, the author or authors

# of this software dedicate any and all copyright interest in the

# software to the public domain. We make this dedication for the benefit

# of the public at large and to the detriment of our heirs and

# successors. We intend this dedication to be an overt act of

# relinquishment in perpetuity of all present and future rights to this

# software under copyright law.

#

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR

# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,

# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

# OTHER DEALINGS IN THE SOFTWARE.

#

# For more information, please refer to

import os

import ycm_core

# These are the compilation flags that will be used in case there's no

# compilation database set (by default, one is not set).

# CHANGE THIS LIST OF FLAGS. YES, THIS IS THE DROID YOU HAVE BEEN LOOKING FOR.

flags=[

'-Wall',

'-Wextra',

#'-Werror',

#'-Wc++98-compat',

'-Wno-long-long',

'-Wno-variadic-macros',

'-fexceptions',

'-stdlib=libc++',

# THIS IS IMPORTANT! Without a "-std=" flag, clang won't know which

# language to use when compiling headers. So it will guess. Badly. So C++

# headers will be compiled as C headers. You don't want that so ALWAYS specify

# a "-std=".

# For a C project, you would set this to something like 'c99' instead of

# 'c++11'.

'-std=c++11',

# ...and the same thing goes for the magic -x option which specifies the

# language that the files to be compiled are written in. This is mostly

# relevant for c++ headers.

# For a C project, you would set this to 'c' instead of 'c++'.

'-x',

'c++',

'-I',

'.',

'-isystem',

'/usr/include',

'-isystem',

'/usr/local/include',

'-isystem',

'/Library/Developer/CommandLineTools/usr/include',

'-isystem',

'/Library/Developer/CommandLineTools/usr/bin/../lib/c++/v1',

]

# Set this to the absolute path to the folder (NOT the file!) containing the

# compile_commands.json file to use that instead of 'flags'. See here for

# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html

#

# Most projects will NOT need to set this to anything; you can just change the

# 'flags' list of compilation flags. Notice that YCM itself uses that approach.

compilation_database_folder=''

ifos.path.exists(compilation_database_folder):

database=ycm_core.CompilationDatabase(compilation_database_folder)

else:

database=None

SOURCE_EXTENSIONS=['.cpp','.cxx','.cc','.c','.m','.mm']

def DirectoryOfThisScript():

returnos.path.dirname(os.path.abspath(__file__))

def MakeRelativePathsInFlagsAbsolute(flags,working_directory):

ifnotworking_directory:

returnlist(flags)

new_flags=[]

make_next_absolute=False

path_flags=['-isystem','-I','-iquote','--sysroot=']

forflag inflags:

new_flag=flag

ifmake_next_absolute:

make_next_absolute=False

ifnotflag.startswith('/'):

new_flag=os.path.join(working_directory,flag)

forpath_flag inpath_flags:

ifflag==path_flag:

make_next_absolute=True

break

ifflag.startswith(path_flag):

path=flag[len(path_flag):]

new_flag=path_flag+os.path.join(working_directory,path)

break

ifnew_flag:

new_flags.append(new_flag)

returnnew_flags

def IsHeaderFile(filename):

extension=os.path.splitext(filename)[1]

returnextension in['.h','.hxx','.hpp','.hh']

def GetCompilationInfoForFile(filename):

# The compilation_commands.json file generated by CMake does not have entries

# for header files. So we do our best by asking the db for flags for a

# corresponding source file, if any. If one exists, the flags for that file

# should be good enough.

ifIsHeaderFile(filename):

basename=os.path.splitext(filename)[0]

forextension inSOURCE_EXTENSIONS:

replacement_file=basename+extension

ifos.path.exists(replacement_file):

compilation_info=database.GetCompilationInfoForFile(

replacement_file)

ifcompilation_info.compiler_flags_:

returncompilation_info

returnNone

returndatabase.GetCompilationInfoForFile(filename)

def FlagsForFile(filename,**kwargs):

ifdatabase:

# Bear in mind that compilation_info.compiler_flags_ does NOT return a

# python list, but a "list-like" StringVec object

compilation_info=GetCompilationInfoForFile(filename)

ifnotcompilation_info:

returnNone

final_flags=MakeRelativePathsInFlagsAbsolute(

compilation_info.compiler_flags_,

compilation_info.compiler_working_dir_)

# NOTE: This is just for YouCompleteMe; it's highly likely that your project

# does NOT need to remove the stdlib flag. DO NOT USE THIS IN YOUR

# ycm_extra_conf IF YOU'RE NOT 100% SURE YOU NEED IT.

#try:

#  final_flags.remove( '-stdlib=libc++' )

#except ValueError:

#  pass

else:

relative_to=DirectoryOfThisScript()

final_flags=MakeRelativePathsInFlagsAbsolute(flags,relative_to)

return{

'flags':final_flags,

'do_cache':True

}

YouCompleteMe提供的其他功能

YCM除了提供了基本的补全功能,自动提示错误的功能外,还提供了类似tags的功能：

跳转到定义GoToDefinition

跳转到声明GoToDeclaration

以及两者的合体GoToDefinitionElseDeclaration

可以在.vimrc中配置相应的快捷键。

Shell

nnoremap gl :YcmCompleter GoToDeclaration

nnoremap gf :YcmCompleter GoToDefinition

nnoremap gg :YcmCompleter GoToDefinitionElseDeclaration

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nnoremapgl:YcmCompleter GoToDeclaration

nnoremapgf:YcmCompleter GoToDefinition

nnoremapgg:YcmCompleter GoToDefinitionElseDeclaration

另外，YCM也提供了丰富的配置选项，同样在.vimrc中配置。具体请参考

Shell

let g:ycm_error_symbol = '>>'

let g:ycm_warning_symbol = '>*'

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letg:ycm_error_symbol='>>'

letg:ycm_warning_symbol='>*'

同时，YCM可以打开location-list来显示警告和错误的信息:YcmDiags。个人关于ycm的配置如下：

Shell

" for ycm

let g:ycm_error_symbol = '>>'

let g:ycm_warning_symbol = '>*'

nnoremap gl :YcmCompleter GoToDeclaration

nnoremap gf :YcmCompleter GoToDefinition

nnoremap gg :YcmCompleter GoToDefinitionElseDeclaration

nmap :YcmDiags

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"forycm

letg:ycm_error_symbol='>>'

letg:ycm_warning_symbol='>*'

nnoremapgl:YcmCompleter GoToDeclaration

nnoremapgf:YcmCompleter GoToDefinition

nnoremapgg:YcmCompleter GoToDefinitionElseDeclaration

nmap:YcmDiags

YCM提供的跳跃功能采用了vim的jumplist，往前跳和往后跳的快捷键为Ctrl+O以及Ctrl+I。

总结

YouCompleteMe是我用过的最爽的一个自动补全的插件了。之前使用acp时，遇到大文件基本上就卡死了，以至于都不怎么敢使用。由于YCM使用的时C/S结构，部分使用vim脚本编写，部分认为原生代码，使得跑起来速度飞快。

抛弃Vim自带的坑爹的补全吧，抛弃ctags吧，抛弃cscope吧，YCM才是终极的补全神器。

在安装过程中,我也遇到了不少的坑。一会会发一篇解决这些坑的文章。

最后祝大家码年顺利，一码平川，码到功成。