50_google_navc

README

navc is a daemon to index and navigate your C code. It watches for all file changes and automatically update the index. It provides a RPC API to ask for definition, declaration, calls, and uses of some symbol. This API can be used by any editor plugin to point to the correct location of the looked up symbol. navc uses clang to parse the file. Having the abstract syntax tree of the code can be very powerful as it can know with greater exactitude the location of the declaration or definition being looked up. The project is limited to C only.

List of Query Capabilities

• Uses of a symbol
• Definition of a function
• All declarations of a symbol: functions, variables, structs, typedef, enums, defines.

Installation

You need to have the development headers for clang 3.6. In Ubuntu this is the package libclang-3.6-dev and in mac's homebrew homebrew/versions/llvm36. Once this is installed, you need to simply run:

	CGO_LDFLAGS="-L`llvm-config-3.6 --libdir`" \
	go get github.com/google/navc

The binary will be located in $GOPATH/bin/navc. Make sure to have $GOPATH/bin in your PATH.

VIM plugin

The vim plugin is very basic but usable. For the vim plugin to work, you need vim with python support. I added an installer to make the use of the plugin easier. It assumes that your vim uses ~/.vim as config directory. You can install the plugin by running:

	$ cd $GOPATH/src/github.com/google/navc/editor/vim/
	$ ./install.sh

To uninstall the plugin, just run ./install.sh -u.

Using navc

You should simply cd into your project directory and start the daemon:

	$ cd $HOME/my/project/
	$ navc

If you have a non-standard set of compilation flags (usual on large projects), you probably want to use clang's compile_commands.json database. This can be generated with bear or with cmake if available. Assuming that a project is compiled with make (e.g. Linux kernel) you simply need to run:

	$ bear make

Once navc index your project, from vim you simply place the cursor on top of the symbol to query and issue one of the following commands:

Shortcut	Action
C-z d	Go to definition
C-z e	Go to declaration
C-z u	List uses
C-z b	Go to previous symbol

Caveats

1. Since go version 1.6, the go clang library is having issues with pointers. To bypass this problem for now, navc has to be run disabling the pointer checks:

	$ GODEBUG=cgocheck=0 navc

1. Currently, to update the compile_commands.json file in memory, the daemon has to be restarted.
2. For large projects on Mac, the daemon fail due to too many open files. This is because every file watched counts as an open file. This could maybe be fixed with recursive watching.

TODO

• Have better logging and not log everything. In particular, it would be nice to have a progress bar while indexing code at start up.
• Currently, symbols used in macros are ignored. We need to fix this problem.
• Some array initialization are not been reported by clang (or go-clang). Hence, we are missing some symbol uses.
• Watch all the compile_commands.json files and update the database in memory with any change.

DISCLAIMER

This is not a official Google project and it is not supported by Google Inc.