Fully working project with RBAC, ABAC support

[romitkarmakar]

basic policy enforcer, model adapter and built-in csv adapter has been added. Expression parsing is being done using recursive descent parsing tree as a replacement for govaluate package. Google tests has been included.

[romitkarmakar]

@hsluoyz review this pr.

[mnprtpsingh]

@romitkarmakar i personally feel that it will be good, if we don't create seperate a project for tests as mentioned here. It will help to get all the advantages of dynamic linking/loading along with having a good coverage. What do you think about this?

[hsluoyz]

No capital letters in file names.

casbin-test instead of casbin-cpp-test

[leeqvip]

I think this PR is very valuable, but can the directory structure keep the same style of Casbin (golang)?

[romitkarmakar]

@techoner Thanks, I will refactor the code acccording to the go directory structure.

[romitkarmakar]

• Added google test and test cases for basic enforcement of policy.
• Removed dependencies to windows.h, so that it can get compiled in Linux. See issue: window.h in ubuntu gives error. #14
• Enforcer, Model, File adapter, Effector, RBAC, Log built See Issue Enforcer, Model, Adapter, File Adapter should be built first. #2
• Project has been structured according to the core go lang engine.
• A custom recursive descent parser has been built to work as an alternative to the govaluate package, and the api has been kept similar with the govaluate package.

@hsluoyz , @techoner can you review this PR ?

[romitkarmakar]

@mnprtpsingh Sorry for the late reply, I think we can also test non-exported functions in DLL by statically linking .obj files to the test project. Having a separate test folder gives us better integration testing.

[divy9881]

Nice to know, you have completed the project, but I would like to point out some missing core elements without which a user cannot use this project to the fullest.

1. AddFunction() API
2. Watcher

[divy9881]

I am afraid that your expression evaluator cannot take generic functions with different return types and different arguments. You can refer to more generic evaluators here : issue #3

[romitkarmakar]

Thanks, @divypatel9881. This is a MVP. I will be adding the watcher and synced enforcer in the next commit. Currently, I am working on the expression evaluator and it is still in development phase, and I will surely try to integrate generic templates and reflection into it.