Vim: use tags file to extend the automatic code completion function of YCM for the third-party library of C language

Preface

In many Vim Editor's auto completion plug-in ,YouCompleteMe(YCM) It is definitely one of the best plug-ins , But the configuration process is often prohibitive for beginners . After years of tossing by the author , So far, it has basically reached the level of daily use .

If the reader is right YouCompleteMe This plug-in is unfamiliar , It is suggested to first refer to the author's blog Vim: To configure Python and C++ Common plug-ins .

For a better understanding of this article , Readers are advised to read my last blog first Vim: Expand YCM Yes C Semantic analysis function of third-party library of family language . In this blog , We solved YCM Error in semantic analysis of , But the improvement of automatic completion function is limited .

In the use of Vim+YCM when ,YCM It is usually not possible to directly access third-party software libraries （ If in c++ Mode of OpenCV） Automatically complete the functions and definitions in . So , This article mainly introduces how to use ctags Generate tags file , Further improve on the basis of the previous blog YCM Automatic completion kinetic energy in third-party software library .

The configuration process

This article takes opencv For example , Describes how to generate tags File to expand YCM Automatic completion function of .

Tags File generation

1 install ctags

sudo apt-get install ctags

Be careful , according to YCM The requirements of , To be installed exuberant-ctags Can only be ${}^{[1]}$. Fortunately, , The above command will be installed by default exuberant-ctags. You can verify with the following command ctags Version of :

ctags --version

My output here is as follows ：

Exuberant Ctags 5.9~svn20110310, Copyright (C) 1996-2009 Darren Hiebert
Addresses: <[email protected]>, http://ctags.sourceforge.net
Optional compiled features: +wildcards, +regex

2 Generate Tags file

This article takes opencv For example , First download opencv Source code , And then in moudles Execute the following command under the path ：

#  Be careful =+l Middle is lowercase L, instead of 1.
ctags -R --fields=+l *

Be careful ,'–fields=+l’c++ Required parameters , If you need to use c Language , I need to add --langmap=c:.c.h Parameters

Then a... Will appear under the current folder tags file , Let's take a look Tags Part of the document , as follows ：

imread	imgcodecs/src/loadsave.cpp	/^Mat imread( const String& filename, int flags )$/;"	f	language:C++	namespace:cv
imread_	imgcodecs/src/loadsave.cpp	/^imread_( const String& filename, int flags, Mat& mat )$/;"	f	language:C++	namespace:cv
imreadmulti	imgcodecs/src/loadsave.cpp	/^bool imreadmulti(const String& filename, std::vector<Mat>& mats, int flags)$/;"	f	language:C++	namespace:cv
imreadmulti	imgcodecs/src/loadsave.cpp	/^bool imreadmulti(const String& filename, std::vector<Mat>& mats, int start, int count, int flags)$/;"	f	language:C++	namespace:cv
imreadmulti_	imgcodecs/src/loadsave.cpp	/^imreadmulti_(const String& filename, int flags, std::vector<Mat>& mats, int start, int count)$/;"	f	language:C++	namespace:cv
imshow	highgui/misc/java/src/java/highgui+HighGui.java	/^    public static void imshow(String winname, Mat img) {$/;"	m	language:Java	class:HighGui
imshow	highgui/src/window.cpp	/^void cv::imshow( const String& winname, InputArray _img )$/;"	f	language:C++	class:cv
imshow	highgui/src/window.cpp	/^void cv::imshow(const String& winname, const ogl::Texture2D& _tex)$/;"	f	language:C++	class:cv
imshow	videoio/src/cap_winrt_bridge.cpp	/^void VideoioBridge::imshow()$/;"	f	language:C++	class:VideoioBridge
imwrite	imgcodecs/src/loadsave.cpp	/^bool imwrite( const String& filename, InputArray _img,$/;"	f	language:C++	namespace:cv
imwrite_	imgcodecs/src/loadsave.cpp	/^static bool imwrite_( const String& filename, const std::vector<Mat>& img_vec,$/;"	f	language:C++	namespace:cv
imwritemulti	imgcodecs/include/opencv2/imgcodecs.hpp	/^bool imwritemulti(const String& filename, InputArrayOfArrays img,$/;"	f	language:C++	namespace:cv

You can see ,tags The file contains function names and basic definitions , And in which file ,YCM They can be well parsed .

3. To configure tags File path

This step , Only required :

1. take tags Move the file to a customized location

2. stay vimrc Point to it in the file

for example , I will just generate tags The file has changed its name , And put it in the following position : ~/.vim/tagfiles/opencv.tags, And then in vimrc Add the following settings :

#  Choose one of the following 
set tags=opencv.tags # The relative position , Need to put tags Put the document under the current project 
set tags+=~/.vim/tagfiles/opencv.tags # Absolute position ,tags The files are right there `~/.vim/tagfiles` Inside 

YCM To configure

To configure

stay vimrc Add the following configuration :

let g:ycm_collect_identifiers_from_tags_files = 1

such ,YCM It will look up automatically vimrc As defined in tags file , And analyze it . Can be in vim Run the following command to view YCM Which is loaded in the current buffer tags file ：

:echo tagfiles()

My computer runs as follows ：

['/home/xuyangcao/.vim/tagfiles/opencv.tags']

matters needing attention

according to YCM Documents , It is found that clangd completer Than libclang completer Be smarter , analysis tags The document is more comprehensive .Clangd completer See resources for specific advantages [3], There is not much here .

therefore , Compiling YCM In the process , It is recommended to use --clanged-completer Parameters .

summary

This article takes opencv For example , Describes how to generate tags File to expand YCM Automatic completion function and syntax highlighting function .

Reference material

1 YCM does not read identifiers from my tags files

2 Vim Configure multiple associations tags file

3 C-family Semantic Completion