mapbox / cncc

Customizable Naming Convention Checker - uses Clang, developed with C++ in mind

Customizable Naming Convention Checker

CNCC is a customizable naming conventions checker for C++. In using the Clang frontend CNCC works directly on the language's abstract syntax tree (AST). This is quite similar to what clang-format does but way more simple and for naming conventions only.

In short, CNCC supports user-defined pattern validation based on AST nodes: you can specify patterns for variables, class names, namespace names, and so on.

Note: recent this patch introduces the concept to clang-tidy.

Example

You provide a style file containing regular expressions for validating AST nodes, such as: camel-case for class names, members should have an underscore appended, and so on.

class_decl: '^([A-Z][a-z]+)+$'
field_decl: '^[a-z]+_$'
var_decl: '^[a-z][a-z0-9]*$'
namespace: '^[a-z]?$'

CNCC then checks the AST's nodes against the provided rules, issuing warnings to stderr and returning with a appropriate status code for easy integration:

test.cc:4:11: "myNamespace" does not conform to pattern "^[a-z]?$" associated with namespace
test.cc:6:7: "myClass" does not conform to pattern "^([A-Z][a-z]+)+$" associated with class_decl
test.cc:11:9: "myMember" does not conform to pattern "^[a-z]+_$" associated with field_decl
test.cc:19:24: "myMember" does not conform to pattern "^[a-z]+_$" associated with field_decl

For all available nodes see the official libclang documentation or the Python wrapper documentation and look for CursorKind.

Requirements

• python2
• python-clang
• python-yaml

Usage

For standalone files, with default compiler invocation:

cncc --style=examples/small.style examples/test.cc

CNCC defaults to reading a .cncc.style file in your home directory if no style file was given.

cncc examples/test.cc

Sometimes compilation gets more involved. Use CMake or Bear in order to create a compile_command.json compilation database. In it compiler invocation flags and arguments are stored for each file involved in the build process. This does not require you to build your program.

mkdir build
cd build
ccmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=1
cncc --style=~/.cncc.style --dbdir . ../main.cc

License

Copyright © 2015 Daniel J. Hofmann

Distributed under the MIT License (MIT).

cncc's Issues

Implement test cases

Test directory with test case C++ programs and style files to validate against.

Search local / global (home directory) style files instead of using commandline switch

Be more similar to clang-format in that regard.

Is this project dead?

Hi,

This looks awesome and just like something I could use perfectly and built upon. Do you guys support it and accept PRs and stuff?

Cheers

KeyError on node kind that is not available: provide user-friendly error message

cncc does not check the ruledb for the kinds the user provides in the styles file --- it's just a subscript-operator dict lookup that fails with a KeyError in case a node kind with such a name is not available.

Example style file:

funX_decl: '.*'

Examples for CursorKind

Examples directory for various / all CursorKinds and how the kinds map to C++ classes, variables, and so on.

Maybe provide a single big C++ file and annotate it based on the AST.

Make easily installable with tracked dependencies

Does this mean pip installable nowadays? Investigate this!

AttributeError: 'CompileCommand' object has no attribute 'encode'

Hi I found this project while looking for a regex-based check to clang-tidy for checking a highly non-standard naming convention and I thought I'd give it a go.

I installed:
python 3.8 (win python distribution - i'm running windows)
clang 11.0 (https://pypi.org/project/clang/)
pyyaml 5.3.1 (https://pypi.org/project/PyYAML/)

I have clang 10.0.0 installed aswell and added the libclang.dll to my PATH. Prior to running cncc I also generated a compiler database.

When I run python.exe cncc --style examples\basic.style --dbdir d:\path\to\folder\with\compile\database d:\some\file.c d:\some\other\file.c I get the following error:

Traceback (most recent call last):
File "cncc", line 44, in
unit = index.parse(f, args=commands)
File "C:\Users\username\Desktop\WPy64-3850\python-3.8.5.amd64\lib\site-packages\clang\cindex.py", line 2721, in parse
return TranslationUnit.from_source(path, args, unsaved_files, options,
File "C:\Users\username\Desktop\WPy64-3850\python-3.8.5.amd64\lib\site-packages\clang\cindex.py", line 2816, in from_source
args_array = (c_char_p * len(args))([b(x) for x in args])
File "C:\Users\username\Desktop\WPy64-3850\python-3.8.5.amd64\lib\site-packages\clang\cindex.py", line 2816, in
args_array = (c_char_p * len(args))([b(x) for x in args])
File "C:\Users\username\Desktop\WPy64-3850\python-3.8.5.amd64\lib\site-packages\clang\cindex.py", line 109, in b
return x.encode('utf8')
AttributeError: 'CompileCommand' object has no attribute 'encode'

I was hoping maybe you could shed a little light on this? The compilation database works fine when using just clang-tidy, so I don't suppose it's corrupt in any way.

Error when running: "libclang.so: cannot open shared object file: No such file or directory"

First, I ran sudo apt-get install python-yaml and sudo pip install clang. Success.

Then I tried:

[dev@ubuntu:~/cncc (master)] $ ls
cncc  examples  LICENSE  MyClass.cpp  MyClass.h  README.md  util
[dev@ubuntu:~/cncc (master)] $ git log -1
commit 4529cb3536c7cec20ea0bb850d0f95e80cded733
Author: Daniel J. Hofmann <[email protected]>
Date:   Wed Aug 19 14:55:48 2015 +0200

    Respect global style file, closes #5

    Local style files do not seem to make a lot sense. What we could do is
    walk all parent directories like `clang-format` does, though.
[dev@ubuntu:~/cncc (master)] $ cat MyClass.h 
class MyClass{
public:
    void init(int a, int b);
    int loopAlot();
private:
    int var1, var2;
};

[dev@ubuntu:~/cncc (master)] $ cat MyClass.cpp 
#include "MyClass.h"

void MyClass::init(int a, int b){
    var1 = a;
    var2 = b;
}

int MyClass::loopAlot(){
    int res = this->var1 + var2;
    for(int i=0; i<this->var1; ++i){
        res = res + this->var2;
    }
    return res;
}
[dev@ubuntu:~/cncc (master)] $ ./cncc --style=examples/basic.style MyClass.cpp
Traceback (most recent call last):
  File "./cncc", line 22, in <module>
    index = I.create()
  File "/usr/local/lib/python2.7/dist-packages/clang/cindex.py", line 2119, in create
    return Index(conf.lib.clang_createIndex(excludeDecls, 0))
  File "/usr/local/lib/python2.7/dist-packages/clang/cindex.py", line 141, in __get__
    value = self.wrapped(instance)
  File "/usr/local/lib/python2.7/dist-packages/clang/cindex.py", line 3429, in lib
    lib = self.get_cindex_library()
  File "/usr/local/lib/python2.7/dist-packages/clang/cindex.py", line 3460, in get_cindex_library
    raise LibclangError(msg)
clang.cindex.LibclangError: libclang.so: cannot open shared object file: No such file or directory. To provide a path to libclang use Config.set_library_path() or Config.set_library_file().

Any idea what I'm doing wrong?