809 lines
35 KiB
Markdown
809 lines
35 KiB
Markdown
YouCompleteMe: a code-completion engine for Vim
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===============================================
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YouCompleteMe is a fast, as-you-type, fuzzy-search code completion engine for
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[Vim][]. It has two completion engines: an identifier-based engine that works
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with every programming language and a semantic, [Clang][]-based engine that
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provides semantic code completion for C/C++/Objective-C/Objective-C++ (from now
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on referred to as "the C-family languages").
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Here's an explanation of what happens in the short GIF demo above.
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First, realize that **no keyboard shortcuts had to be pressed** to get the list
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of completion candidates at any point in the demo. The user just types and the
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suggestions pop up by themselves. If the user doesn't find the completion
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suggestions relevant and/or just wants to type, he can do so; the completion
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engine will not interfere.
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When the user sees a useful completion string being offered, he presses the TAB
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key to accept it. This inserts the completion string. Repeated presses of the
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TAB key cycle through the offered completions.
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If the offered completions are not relevant enough, the user can continue typing
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to further filter out unwanted completions.
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A critical thing to notice is that the completion **filtering is NOT based on
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the input being a string prefix of the completion** (but that works too). The
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input needs to be a _[subsequence][] match_ of a completion. This is a fancy way
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of saying that any input characters need to be present in a completion string in
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the order in which they appear in the input. So `abc` is a subsequence of
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`xaybgc`, but not of `xbyxaxxc`. After the filter, a complicated sorting system
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ranks the completion strings so that the most relevant ones rise to the top of
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the menu (so you usually need to press TAB just once).
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**All of the above works with any programming language** because of the
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identifier-based completion engine. It collects all of the identifiers in the
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current file and other files you visit and searches them when you type
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(identifiers are put into per-filetype groups).
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The demo also shows the semantic engine in use. The current semantic engine
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supports only C-family languages. When the user presses `.`, `->` or `::` while
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typing in insert mode, the semantic engine is triggered (it can also be
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triggered with a keyboard shortcut; see the rest of the docs).
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The last thing that you can see in the demo is YCM's integration with
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[Syntastic][] (the little red X that shows up in the left gutter) if you are
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editing a file with semantic engine support. As Clang compiles your file and
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detects warnings or errors, they will be piped to Syntastic for display. You
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don't need to save your file or press any keyboard shortcut to trigger this, it
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"just happens" in the background.
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In essence, YCM obsoletes the following Vim plugins because it has all of their
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features plus extra:
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- clang_complete
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- AutoComplPop
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- Supertab
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- neocomplcache
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Mac OS X super-quick installation
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---------------------------------
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Please refer to the full Installation Guide below; the following commands are
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provided on a best-effort basis and may not work for you.
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Install the latest version of [MacVim][]. Yes, MacVim. And yes, the _latest_.
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If you don't use the MacVim GUI, it is recommended to use the Vim binary that is
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inside the MacVim.app package (`MacVim.app/Contents/MacOS/Vim`). To ensure it
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works correctly copy the `mvim` script from the [MacVim][] download to your
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local binary folder (for example `/usr/local/bin/mvim`) and then symlink it:
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ln -s /usr/local/bin/mvim vim
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Install YouCompleteMe with [Vundle][].
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Install CMake. Preferably with [Homebrew][brew], but here's the [stand-alone
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CMake installer][cmake-download].
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_If_ you have installed a Homebrew Python and/or Homebrew MacVim, see the FAQ
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for details.
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_If_ you care about semantic completion for C-family languages, type in the
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following commands in the console. If you don't, **skip this step**.
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cd ~
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mkdir ycm_temp
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cd ycm_temp
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curl -O http://llvm.org/releases/3.2/clang+llvm-3.2-x86_64-apple-darwin11.tar.gz
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tar -zxvf clang+llvm-3.2-x86_64-apple-darwin11.tar.gz
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cp clang+llvm-3.2-x86_64-apple-darwin11/lib/libclang.dylib ~/.vim/bundle/YouCompleteMe/python
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Compiling YCM **with** semantic support for C-family languages (previous step
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required):
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cd ~
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mkdir ycm_build
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cd ycm_build
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cmake -G "Unix Makefiles" -DPATH_TO_LLVM_ROOT=~/ycm_temp/clang+llvm-3.2-x86_64-apple-darwin11 . ~/.vim/bundle/YouCompleteMe/cpp
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make ycm_core
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Compiling YCM **without** semantic support for C-family languages:
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cd ~
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mkdir ycm_build
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cd ycm_build
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cmake -G "Unix Makefiles" . ~/.vim/bundle/YouCompleteMe/cpp
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make ycm_core
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That's it. You're done. Refer to the User Guide section on how to use YCM. Don't
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forget that if you want the C-family semantic completion engine to work, you
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will need to provide the compilation flags for your project to YCM. It's all in
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the User Guide.
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YCM comes with sane defaults for its options, but you still may want to take a
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look at what's available for configuration. There are a few interesting options
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that are conservatively turned off by default that you may want to turn on.
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Ubuntu Linux x64 super-quick installation
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-----------------------------------------
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Please refer to the full Installation Guide below; the following commands are
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provided on a best-effort basis and may not work for you.
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Make sure you have Vim 7.3.584 with python2 support. At the time of writing, the
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version of Vim shipping with Ubuntu is too old. You may need to [compile Vim
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from source][vim-build] (don't worry, it's easy).
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Install YouCompleteMe with [Vundle][].
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Install CMake. `sudo apt-get install cmake`
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Make sure you have Python headers installed: `sudo apt-get install python-dev`.
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_If_ you care about semantic completion for C-family languages, type in the
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following commands in the console. If you don't, **skip this step**.
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cd ~
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mkdir ycm_temp
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cd ycm_temp
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curl -O http://llvm.org/releases/3.2/clang+llvm-3.2-x86_64-linux-ubuntu-12.04.tar.gz
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tar -zxvf clang+llvm-3.2-x86_64-linux-ubuntu-12.04.tar.gz
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cp clang+llvm-3.2-x86_64-linux-ubuntu-12.04/lib/libclang.so ~/.vim/bundle/YouCompleteMe/python
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Compiling YCM **with** semantic support for C-family languages (previous step
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required):
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cd ~
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mkdir ycm_build
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cd ycm_build
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cmake -G "Unix Makefiles" -DPATH_TO_LLVM_ROOT=~/ycm_temp/clang+llvm-3.2-x86_64-linux-ubuntu-12.04 . ~/.vim/bundle/YouCompleteMe/cpp
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make ycm_core
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Compiling YCM **without** semantic support for C-family languages:
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cd ~
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mkdir ycm_build
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cd ycm_build
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cmake -G "Unix Makefiles" . ~/.vim/bundle/YouCompleteMe/cpp
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make ycm_core
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That's it. You're done. Refer to the User Guide section on how to use YCM. Don't
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forget that if you want the C-family semantic completion engine to work, you
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will need to provide the compilation flags for your project to YCM. It's all in
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the User Guide.
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YCM comes with sane defaults for its options, but you still may want to take a
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look at what's available for configuration. There are a few interesting options
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that are conservatively turned off by default that you may want to turn on.
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Full Installation Guide
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-----------------------
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These are the steps necessary to get YCM working on a Unix OS like Linux or
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Mac OS X. My apologies to Windows users, but I don't have a guide for them. The
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code is platform agnostic, so if everything is configured correctly, YCM
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_should_ work on Windows without issues (but as of writing, it's untested on
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that platform).
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See the FAQ if you have any issues.
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**Please follow the instructions carefully. Read EVERY WORD.**
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1. **Ensure that your version of Vim is _at least_ 7.3.584 _and_ that it has
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support for python2 scripting**.
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Inside Vim, type `:version`. Look at the first two to three lines of output;
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it should say `Vi IMproved 7.3` and then below that, `Included patches:
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1-X`, where X will be some number. That number needs to be 584 or higher.
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If your version of Vim is not recent enough, you may need to [compile Vim
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from source][vim-build] (don't worry, it's easy).
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After you have made sure that you have Vim 7.3.584+, type the following in
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Vim: `:echo has('python')`. The output should be 1. If it's 0, then get a
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version of Vim with Python support.
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2. **Install YCM** with [Vundle][] (or [Pathogen][], but Vundle is a better
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idea). With Vundle, this would mean adding a `Bundle
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'Valloric/YouCompleteMe'` line to your [vimrc][].
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3. [Complete this step ONLY if you care about semantic completion support for
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C-family languages. Otherwise it's not neccessary.]
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**Download the latest version of `libclang`**. Clang is an open-source
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compiler that can compile C/C++/Objective-C/Objective-C++. The `libclang`
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library it provides is used to power the YCM semantic completion engine for
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those languages. YCM needs libclang version 3.2 or higher.
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You can use the system libclang _only if you are sure it is version 3.2 or
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higher_, otherwise don't. Even if it is, I recommend using the [official
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binaries from llvm.org][clang-download] if at all possible. Make sure you
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download the correct archive file for your OS.
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4. **Compile the `ycm_core` plugin plugin** (ha!) that YCM needs. This is the
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C++ engine that YCM uses to get fast completions.
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You will need to have `cmake` installed in order to generate the required
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makefiles. Linux users can install cmake with their package manager (`sudo
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apt-get install cmake` for Ubuntu) whereas other users can [download and
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install][cmake-download] cmake from its project site. Mac users can also get
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it through [Homebrew][brew] with `brew install cmake`.
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You also need to make sure you have Python headers installed. On a
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Debian-like Linux distro, this would be `sudo apt-get install python-dev`.
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On Mac they should already be present.
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Here we'll assume you installed YCM with Vundle. That means that the
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top-level YCM directory is in `~/.vim/bundle/YouCompleteMe`.
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We'll create a new folder where build files will be placed. Run the
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following:
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cd ~
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mkdir ycm_build
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cd ycm_build
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Now we need to generate the makefiles. If you DON'T care about semantic
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support for C-family languages, run the following command in the `ycm_build`
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directory: `cmake -G "Unix Makefiles" . ~/.vim/bundle/YouCompleteMe/cpp`
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If you DO care about semantic support for C-family languages, then your
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`cmake` call will be a bit more complicated. We'll assume you downloaded a
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binary distribution of LLVM+Clang from llvm.org in step 3 and that you
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extracted the archive file to folder `~/ycm_temp/llvm_root_dir` (with `bin`,
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`lib`, `include` etc. folders right inside that folder). With that in mind,
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run the following command in the `ycm_build` directory: `cmake -G "Unix Makefiles" -DPATH_TO_LLVM_ROOT=~/ycm_temp/llvm_root_dir . ~/.vim/bundle/YouCompleteMe/cpp`
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Now that makefiles have been generated, simply run `make ycm_core`.
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For those who want to use the system version of libclang, you would pass
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`-DUSE_SYSTEM_LIBCLANG=ON` to cmake _instead of_ the
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`-DPATH_TO_LLVM_ROOT=...` flag.
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You could also force the use of a custom libclang library with
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`-DEXTERNAL_LIBCLANG_PATH=/path/to/libclang.so` flag (the library would end
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with `.dylib` on a Mac). Again, this flag would be used _instead of_ the
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other flags.
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5. [Complete this step ONLY if you care about semantic completion support for
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C-family languages. Otherwise it's not neccessary.]
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**Copy the libclang library file into the `YouCompleteMe/python` folder.**
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The library file is `libclang.so` on Linux and `libclang.dylib` on Mac.
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We'll assume you downloaded a binary distribution of LLVM+Clang from
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llvm.org in step 3 and that you extracted the archive file to folder
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`~/ycm_temp/llvm_root_dir` (with `bin`, `lib`, `include` etc. folders right
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inside that folder).
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We'll also assume you installed YCM with Vundle. That means that the
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top-level YCM directory is in `~/.vim/bundle/YouCompleteMe`.
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On Linux, run: `cp ~/ycm_temp/llvm_root_dir/lib/libclang.so ~/.vim/bundle/YouCompleteMe/python`
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On Mac, run: `cp ~/ycm_temp/llvm_root_dir/lib/libclang.dylib ~/.vim/bundle/YouCompleteMe/python`
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**DO NOT FORGET THIS STEP**. If you forget to copy over `libclang.so`
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version 3.2 into the `YouCompleteMe/python` folder then YCM _will not work_
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if you selected C-family support during YCM compilation.
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That's it. You're done. Refer to the User Guide section on how to use YCM. Don't
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forget that if you want the C-family semantic completion engine to work, you
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will need to provide the compilation flags for your project to YCM. It's all in
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the User Guide.
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YCM comes with sane defaults for its options, but you still may want to take a
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look at what's available for configuration. There are a few interesting options
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that are conservatively turned off by default that you may want to turn on.
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User Guide
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----------
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### General Usage
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- If the offered completions are too broad, keep typing characters; YCM will
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continue refining the offered completions based on your input.
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- Use the TAB key to accept a completion and continue pressing TAB to cycle
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through the completions. Use Shift-TAB to cycle backwards. Note that if you're
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using console Vim (that is, not Gvim or MacVim) then it's likely that the
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Shift-TAB binding will not work because the console will not pass it to Vim.
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You can remap the keys; see the options section below.
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### Completion string ranking
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The subsequence filter removes any completions that do not match the input, but
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then the sorting system kicks in. It's actually very complicated and uses lots
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of factors, but suffice it to say that "word boundary" (WB) subsequence
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character matches are "worth" more than non-WB matches. In effect, this means
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given an input of "gua", the completion "getUserAccount" would be ranked higher
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in the list than the "Fooguxa" completion (both of which are subsequence
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matches). A word-boundary character are all capital characters, characters
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preceded by an underscore and the first letter character in the completion
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string.
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### Semantic Completion Engine Usage
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- You can use Ctrl+Space to trigger the completion suggestions anywhere, even
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without a string prefix. This is useful to see which top-level functions are
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available for use.
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- You _really_ also want to install the latest version of the [Syntastic][] Vim
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plugin. It has support for YCM and together they will provide you with compile
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errors/warnings practically instantly and without saving the file.
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YCM looks for a `.ycm_extra_conf.py` file in the directory of the opened file
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or in any directory above it in the hierarchy (recursively); when the file is
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found, it is loaded (only once!) as a Python module. YCM calls a `FlagsForFile`
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method in that module which should provide it with the information necessary to
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compile the current file. (You can also provide a path to a global
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`.ycm_extra_conf.py` file and override this searching behavior. See the Options
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section for more details.)
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This system was designed this way so that the user can perform any arbitrary
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sequence of operations to produce a list of compilation flags YCM should hand
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to Clang.
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[See YCM's own `.ycm_extra_conf.py`][flags_example] for details on how this
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works. You should be able to use it as a starting point. Hint: just replace the
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strings in the `flags` variable with compilation flags necessary for your
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project. That should be enough for 99% of projects.
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Yes, [Clang's `CompilationDatabase` system][compdb] is also supported. Again, see the
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above linked example file.
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If Clang encounters errors when compiling the header files that your file
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includes, then it's probably going to take a long time to get completions. When
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the completion menu finally appears, it's going to have a large number of
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unrelated completion strings (type/function names that are not actually
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members). This is because Clang fails to build a precompiled preamble for your
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file if there are any errors in the included headers and that preamble is key to
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getting fast completions.
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Call the `:YcmDiags` command to see if any errors or warnings were detected in
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your file. Even better, use Syntastic.
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### Syntastic integration
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YCM has explicit support for [Syntastic][] (and vice-versa) if you compiled YCM
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with Clang support; this means that any diagnostics (errors or warnings) that
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Clang encounters while compiling your file will be fed back to Syntastic for
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display.
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YCM will recompile your file in the background `updatetime` (see `:h updatetime`
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in Vim) milliseconds after you stop typing (to be specific, on `CursorHold` and
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`CursorHoldI` Vim events). YCM will change your `updatetime` value to be `2000`
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milliseconds (there's an option to tell it not to do this if you wish).
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The new diagnostics (if any) will be fed back to Syntastic the next time you
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press any key on the keyboard. So if you stop typing and just wait for the new
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diagnostics to come in, that _will not work_. You need to press some key for the
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GUI to update.
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Having to press a key to get the updates is unfortunate, but cannot be changed
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due to the way Vim internals operate; there is no way that a background task can
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update Vim's GUI after it has finished running. You _have to_ press a key. This
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will make YCM check for any pending diagnostics updates.
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You _can_ force a full, blocking compilation cycle with the
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`:YcmForceCompileAndDiagnostics` command (you may want to map that command to a
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key; try putting `nnoremap <F5> :YcmForceCompileAndDiagnostics<CR>` in your
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vimrc). Calling this command will force YCM to immediately recompile your file
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and display any new diagnostics it encounters. Do note that recompilation with
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this command may take a while and during this time the Vim GUI _will_ be
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blocked.
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After the errors are displayed by Syntastic, it will display a short diagnostic
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message when you move your cursor to the line with the error. You can get a
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detailed diagnostic message with the `<leader>d` key mapping (can be changed in
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the options) YCM provides when your cursor is on the line with the diagnostic.
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You can also see the full diagnostic message for all the diagnostics in the
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current file in Vim's `locationlist`, which can be opened with the `:lopen` and
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`:lclose` commands. A good way to toggle the display of the `locationlist` with
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a single key mapping is provided by another (very small) Vim plugin called
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[ListToggle][] (which also makes it possible to change the height of the
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`locationlist` window), also written by yours truly.
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TODO: extending the semantic engine for other langs
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Commands
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--------
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### The `YcmForceCompileAndDiagnostics` command
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Calling this command will force YCM to immediately recompile your file
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and display any new diagnostics it encounters. Do note that recompilation with
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this command may take a while and during this time the Vim GUI _will_ be
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blocked.
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You may want to map this command to a key; try putting `nnoremap <F5>
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:YcmForceCompileAndDiagnostics<CR>` in your vimrc.
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### The `YcmDiags` command
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Calling this command will fill Vim's `locationlist` with errors or warnings if
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any were detected in your file and then open it.
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A better option would be to use Syntastic which will keep your `locationlist`
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up to date automatically and will also show error/warning notifications in Vim's
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gutter.
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### The `YcmShowDetailedDiagnostic` command
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This command shows the full diagnostic text when the user's cursor is on the
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line with the diagnostic.
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### The `YcmDebugInfo` command
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This will print out various debug information for the current file. Useful to
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see what compile commands will be used for the file if you're using the semantic
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completion engine.
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Options
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-------
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All options have reasonable defaults so if the plug-in works after installation
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you don't need to change any options. These options can be configured in your
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[vimrc script][vimrc] by including a line like this:
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let g:ycm_min_num_of_chars_for_completion = 1
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Note that after changing an option in your [vimrc script] [vimrc] you have to
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restart Vim for the changes to take effect.
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### The `g:ycm_min_num_of_chars_for_completion` option
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This option controls the number of characters the user needs to type before
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completion suggestions are triggered. For example, if the option is set to `2`,
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then when the user types a second alphanumeric character after a whitespace
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character, completion suggestions will be triggered.
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Default: `2`
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let g:ycm_min_num_of_chars_for_completion = 2
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### The `g:ycm_filetypes_to_completely_ignore` option
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This option controls for which Vim filetypes (see `:h filetype`) should YCM be
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turned off. The option value should be a Vim dictionary with keys being filetype
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strings (like `python`, `cpp` etc) and values being unimportant (the dictionary
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is used like a hash set, meaning that only the keys matter). The listed
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filetypes will be completely ignored by YCM, meaning that neither the
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identifier-based completion engine nor the semantic engine will operate in files
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of those filetypes.
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You can get the filetype of the current file in Vim with `:set ft?`.
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Default: `{notes: 1, markdown: 1, text: 1}`
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let g:ycm_filetypes_to_completely_ignore = {
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\ 'notes' : 1,
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\ 'markdown' : 1,
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\ 'text' : 1,
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\}
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### The `g:ycm_filetype_specific_completion_to_disable` option
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This option controls for which Vim filetypes (see `:h filetype`) should the YCM
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semantic completion engine be turned off. The option value should be a Vim
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dictionary with keys being filetype strings (like `python`, `cpp` etc) and
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values being unimportant (the dictionary is used like a hash set, meaning that
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only the keys matter). The listed filetypes will be ignored by the YCM semantic
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completion engine, but the identifier-based completion engine will still trigger
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in files of those filetypes.
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Note that even if semantic completion is not turned off for a specific filetype,
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you will not get semantic completion if the semantic engine does not support
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that filetype. Currently, the semantic engine only supports the `c`, `cpp`,
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`objc` and `objcpp` filetypes.
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You can get the filetype of the current file in Vim with `:set ft?`.
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Default: `{}`
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let g:ycm_filetype_specific_completion_to_disable = {}
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### The `g:ycm_allow_changing_updatetime` option
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When this option is set to `1`, YCM will change the `updatetime` Vim option to
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`2000` (see `:h updatetime`). This may conflict with some other plugins you have
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(but it's unlikely). The `updatetime` option is the number of milliseconds that
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have to pass before Vim's `CursorHold` (see `:h CursorHold`) event fires. YCM
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runs the completion engines' "file comprehension" systems in the background on
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every such event; the identifier-based engine collects the identifiers whereas
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the semantic engine compiles the file to build an AST.
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The Vim default of `4000` for `updatetime` is a bit long, so YCM reduces
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this. Set this option to `0` to force YCM to leave your `updatetime` setting
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alone.
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Default: `1`
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let g:ycm_allow_changing_updatetime = 1
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### The `g:ycm_add_preview_to_completeopt` option
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When this option is set to `1`, YCM will add the `preview` string to Vim's
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`completeopt` option (see `:h completeopt`). If your `completeopt` option
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already has `preview` set, there will be no effect. You can see the current
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state of your `completeopt` setting with `:set completeopt?` (yes, the question
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mark is important).
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When `preview` is present in `completeopt`, YCM will use the `preview` window at
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the top of the file to store detailed information about the current completion
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candidate (but only if the candidate came from the semantic engine). For
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instance, it would show the full function prototype and all the function
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overloads in the window if the current completion is a function name.
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Default: `0`
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let g:ycm_add_preview_to_completeopt = 0
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### The `g:ycm_autoclose_preview_window_after_completion` option
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When this option is set to `1`, YCM will auto-close the `preview` window after
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the user accepts the offered completion string. If there is no `preview` window
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triggered because there is no `preview` string in `completeopt`, this option is
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irrelevant. See the `g:ycm_add_preview_to_completeopt` option for more details.
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Default: `0`
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let g:ycm_autoclose_preview_window_after_completion = 0
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### The `g:ycm_max_diagnostics_to_display` option
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This option controls the maximum number of diagnostics shown to the user when
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errors or warnings are detected in the file. This option is only relevant if you
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are using the semantic completion engine and have installed the version of the
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Syntastic plugin that supports YCM.
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Default: `30`
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let g:ycm_max_diagnostics_to_display = 30
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### The `g:ycm_key_select_completion` option
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This option controls the key mapping used to select the first completion string.
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Invoking it repeatedly cycles forward through the completion list.
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Default: `<TAB>`
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let g:ycm_key_select_completion = '<TAB>'
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### The `g:ycm_key_previous_completion` option
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This option controls the key mapping used to select the previous completion
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string. Invoking it repeatedly cycles backwards through the completion list.
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Note that the default of `<S-TAB>` means Shift-TAB. Also note that the default
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mapping will probably only work in GUI Vim (Gvim or MacVim) and not in plain
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console Vim because the terminal usually does not forward modifier key
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combinations to Vim.
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Default: `<S-TAB>`
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let g:ycm_key_previous_completion = '<S-TAB>'
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### The `g:ycm_key_invoke_completion` option
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This option controls the key mapping used to invoke the completion menu for
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semantic completion. By default, semantic completion is trigged automatically
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after typing `.`, `->` and `::` in insert mode (if semantic completion support
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has been compiled in). This key mapping can be used to trigger semantic
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completion anywhere. Useful for searching for top-level functions and classes.
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Note that the default of `<C-Space>` means Ctrl-Space. Also note that the
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default mapping will probably only work in GUI Vim (Gvim or MacVim) and not in
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plain console Vim because the terminal usually does not forward modifier key
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combinations to Vim.
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Setting this option to an empty string will make sure no mapping is created.
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Default: `<C-Space>`
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let g:ycm_key_invoke_completion = '<C-Space>'
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### The `g:ycm_key_detailed_diagnostics` option
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This option controls the key mapping used to show the full diagnostic text when
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the user's cursor is on the line with the diagnostic. It basically calls
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`:YcmShowDetailedDiagnostic`.
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Setting this option to an empty string will make sure no mapping is created.
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Default: `<leader>d`
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let g:ycm_key_detailed_diagnostics = '<leader>d'
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### The `g:ycm_global_ycm_extra_conf` option
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Normally, YCM searches for a `.ycm_extra_conf.py` file for compilation flags
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(see the User Guide for more details on how this works). You can use this option
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to override this searching behavior by providing a full, absolute path to a
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global `.ycm_extra_conf.py` file (although you can call the global file whatever
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you want).
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You can place such a global file anywhere in your filesystem.
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Default: ``
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let g:ycm_global_ycm_extra_conf = ''
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FAQ
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---
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### I get a linker warning regarding `libpython` on Mac when compiling YCM
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If the warning is `ld: warning: path '/usr/lib/libpython2.7.dylib' following -L
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not a directory`, then feel free to ignore it; it's caused by a limitation of
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CMake and is not an issue. Everything should still work fine.
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### I get a weird window at the top of my file when I use the semantic engine
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This is Vim's `preview` window. Vim uses it to show you extra information about
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something if such information is available. YCM provides Vim with such extra
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information. For instance, when you select a function in the completion list,
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the `preview` window will hold that function's prototype and the prototypes of
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any overloads of the function. It will stay there after you select the
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completion so that you can use the information about the parameters and their
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types to write the function call.
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If you would like this window to auto-close after you select a completion
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string, set the `g:ycm_autoclose_preview_window_after_completion` option to `1`
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in your `vimrc` file.
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If you don't want this window to ever show up, add `set completeopt-=preview` to
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your `vimrc`. Also make sure that the `g:ycm_add_preview_to_completeopt` option
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is set to `0`.
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### It appears that YCM is not working
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In Vim, run `:messages` and carefully read the output. YCM will echo messages to
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the message log if it encounters problems. It's likely you misconfigured
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something and YCM is complaining about it.
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Also, you may want to run the `:YcmDebugInfo` command; it will make YCM spew out
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various debugging information, including the compile flags for the file if the
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file is a C-family language file and you have compiled in Clang support.
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### I cannot get the Syntastic integration to work
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Try to update your version of Syntastic. At the time of writing (Jan 2013), the
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YCM integration is very recent and it's likely that your version of Syntastic
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does not have it.
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### Sometimes it takes much longer to get semantic completions than normal
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This means that libclang (which YCM uses for C-family semantic completion)
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failed to pre-compile your file's preamble. In other words, there was an error
|
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compiling some of the source code you pulled in through your header files. I
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suggest calling the `:YcmDiags` command to see what they were (even better, have
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Syntastic installed and call `:lopen`).
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Bottom line, if libclang can't pre-compile your file's preamble because there
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were errors in it, you're going to get slow completions because there's no AST
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cache.
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### YCM auto-inserts completion strings I don't want!
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This means you probably have some mappings that interfere with YCM's internal
|
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ones. Make sure you don't have something mapped to `<C-p>`, `<C-x>` or `<C-u>`
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(in insert mode).
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YCM _never_ selects something for you; it just shows you a menu and the user has
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to explicitly select something. If something is being selected automatically,
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this means there's a bug or a misconfiguration somewhere.
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### I get a `E227: mapping already exists for <blah>` error when I start Vim
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This means that YCM tried to set up a key mapping but failed because you already
|
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had something mapped to that key combination. The `<blah>` part of the message
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will tell you what was the key combination that failed.
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Look in the options section and see if which of the default mappings conflict
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with your own. Then change that option value to something else so that the
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conflict goes away.
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### I'm trying to use a Homebrew Vim with YCM and I'm getting segfaults
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Something (I don't know what) is wrong with the way that Homebrew configures and
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builds Vim. I recommend using [MacVim][]. Even if you don't like the MacVim GUI,
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you can use the Vim binary that is inside the MacVim.app package (it's
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`MacVim.app/Contents/MacOS/Vim`) and get the Vim console experience.
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### I have a Homebrew Python and/or MacVim; can't compile/SIGABRT when starting
|
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You should probably run `brew rm python; brew install python` to get the latest
|
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fixes that should make YCM work with such a configuration. Also rebuild Macvim
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then. If you still get problems with this, see [issue #18][issue18] for
|
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suggestions.
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### I get `LONG_BIT definition appears wrong for platform` when compiling
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|
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Look at the output of your CMake call. There should be a line in it like the
|
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following (with `.dylib` in place of `.so` on a Mac):
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```
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-- Found PythonLibs: /usr/lib/libpython2.7.so (Required is at least version "2.5")
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```
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That would be the **correct** output. An example of **incorrect** output would
|
|
be the following:
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|
```
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-- Found PythonLibs: /usr/lib/libpython2.7.so (found suitable version "2.5.1", minimum required is "2.5")
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```
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Notice how there's an extra bit of output there, the `found suitable version
|
|
"<version>"` part, where `<version>` is not the same as the version of the
|
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dynamic library. In the example shown, the library is version 2.7 but the second
|
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string is version `2.5.1`.
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|
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This means that CMake found one version of Python headers and a different
|
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version for the library. This is wrong. It can happen when you have multiple
|
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versions of Python installed on your machine.
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You should probably add the following flags to your cmake call (again, `dylib`
|
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instead of `so` on a Mac):
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```
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-DPYTHON_INCLUDE_DIR=/usr/include/python2.7 -DPYTHON_LIBRARY=/usr/lib/libpython2.7.so
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```
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This will force the paths to the Python include directory and the Python library
|
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to use. You may need to set these flags to something else, but you need to make
|
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sure you use the same version of Python that your Vim binary is built against,
|
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which is highly likely to be the system's default Python.
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|
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### Why isn't YCM just written in plain VimScript, FFS?
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Because of the identifier completion engine and subsequence-based filtering.
|
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Let's say you have _many_ dozens of files open in a single Vim instance (I often
|
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do); the identifier-based engine then needs to store thousands (if not tens of
|
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thousands) of identifiers in its internal data-structures. When the user types,
|
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YCM needs to perform subsequence-based filtering on _all_ of those identifiers
|
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(every single one!) in less than 10 milliseconds.
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I'm sorry, but that level of performance is just plain impossible to achieve
|
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with VimScript. I've tried, and the language is just too slow. No, you can't get
|
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acceptable performance even if you limit yourself to just the identifiers in the
|
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current file and simple prefix-based fitering.
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### Why does YCM demand such a recent version of Vim?
|
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During YCM's development several show-stopper bugs where encountered in Vim.
|
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Those needed to be fixed upstream (and were). A few months after those bugs were
|
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fixed, Vim trunk landed the `pyeval()` function which improved YCM performance
|
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even more since less time was spent serializing and deserializing data between
|
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Vim and the embedded Python interpreter. A few critical bugfixes for `pyeval()`
|
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landed in Vim 7.3.584 (and a few commits before that).
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Contact
|
|
-------
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If you have questions, bug reports, suggestions, etc. please use the [issue
|
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tracker][tracker]. The latest version is available at
|
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<http://valloric.github.com/YouCompleteMe/>.
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The author's homepage is <http://val.markovic.io>.
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|
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License
|
|
-------
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This software is licensed under the [GPL v3 license][gpl].
|
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© 2012 Strahinja Val Markovic <<val@markovic.io>>.
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|
|
|
|
[Clang]: http://clang.llvm.org/
|
|
[vundle]: https://github.com/gmarik/vundle#about
|
|
[pathogen]: https://github.com/tpope/vim-pathogen#pathogenvim
|
|
[clang-download]: http://llvm.org/releases/download.html#3.2
|
|
[brew]: http://mxcl.github.com/homebrew/
|
|
[cmake-download]: http://www.cmake.org/cmake/resources/software.html
|
|
[macvim]: http://code.google.com/p/macvim/#Download
|
|
[vimrc]: http://vimhelp.appspot.com/starting.txt.html#vimrc
|
|
[gpl]: http://www.gnu.org/copyleft/gpl.html
|
|
[vim]: http://www.vim.org/
|
|
[syntastic]: https://github.com/scrooloose/syntastic
|
|
[flags_example]: https://github.com/Valloric/YouCompleteMe/blob/master/cpp/ycm/.ycm_extra_conf.py
|
|
[compdb]: http://clang.llvm.org/docs/JSONCompilationDatabase.html
|
|
[subsequence]: http://en.wikipedia.org/wiki/Subsequence
|
|
[listtoggle]: https://github.com/Valloric/ListToggle
|
|
[vim-build]: https://github.com/Valloric/YouCompleteMe/wiki/Building-Vim-from-source
|
|
[tracker]: https://github.com/Valloric/YouCompleteMe/issues?state=open
|
|
[issue18]: https://github.com/Valloric/YouCompleteMe/issues/18
|