Vim自动补全神器：YouCompleteMe

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

Bundle 'Valloric/YouCompleteMe'

保存退出后打开vim,在正常模式下输入

:BundleInstall

等待vundle将YouCompleteMe安装完成

而后进行编译安装:

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

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.

1. 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.
2. 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)

3. 编译

   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

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.

# 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 <http://unlicense.org/>import osimport 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=<something>" 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=<something>".# 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 = NoneSOURCE_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_flagsdef 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  }

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.

nnoremap <leader>gl :YcmCompleter GoToDeclaration<CR>nnoremap <leader>gf :YcmCompleter GoToDefinition<CR>nnoremap <leader>gg :YcmCompleter GoToDefinitionElseDeclaration<CR>

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

let g:ycm_error_symbol = '>>'let g: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:

" for ycmlet g:ycm_error_symbol = '>>'let g:ycm_warning_symbol = '>*'nnoremap <leader>gl :YcmCompleter GoToDeclaration<CR>nnoremap <leader>gf :YcmCompleter GoToDefinition<CR>nnoremap <leader>gg :YcmCompleter GoToDefinitionElseDeclaration<CR>nmap <F4> :YcmDiags<CR>

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.