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Bonsai

Bonsai is an attempt to provide a miniature and refined representation for the
often cumbersome syntax trees and program models.
This idea, of providing a smaller tree that is more or less the same thing,
is where the name comes from.
This work started as part of an analysis tool that I am developing for my own
research. I am interested in analysing ROS
robotics applications, which are often written in C++.
Since free C++ analysis tools are rather scarce, I tried
to come up with my own, using the Python bindings of the clang compiler.
At the moment of this writing, I am aware that these bindings are incomplete
in terms of AST information they provide.
As this analysis tool developed, I realized that the C++ analysis features
are independent of ROS or any other framework, and that this kind of tool
might be useful for someone else, either as is, or as a starting point for
something else.

Features

Bonsai provides an interface to represent, analyse or manipulate programs.
The model it uses is abstract enough to serve as a basis for specific language
implementations, although it focuses more on imperative/object-oriented
languages for now.

What to expect from bonsai:

  • classes for the different entities of a program (e.g. variables, functions, etc.);
  • extended classes for specific programming languages (only C++ for now);
  • parser implementations, able to take a file and produce a model (e.g. clang for C++);
  • extensible interface to manipulate and query the resulting model (e.g. find calls for a function);
  • a console script to use as a standalone application.

Installation

Here are some instructions to help you get bonsai.
Bonsai has been tested with Linux Ubuntu and Python 2.7,
but the platform should not make much of a difference.
Dependencies are minimal, and depend on what you want to analyse.
Since at the moment there is only a single implementation for C++
using clang 3.8, you will need to install libclang and the
(pip install clang) to parse C++ files. Skip this if you want to use
the library in any other way.

Method 1: Running Without Installation

Open a terminal, and move to a directory where you want to clone this
repository.
git clone https://github.com/git-afsantos/bonsai.git
There is an executable script in the root of this repository to help you get started.
It allows you to run bonsai without installing it. Make sure that your terminal is at
the root of the repository.
cd bonsai
python bonsai-runner.py <args>

You can also run it with the executable package syntax.

python -m bonsai <args>

Method 2: Installing Bonsai on Your Machine

Bonsai is now available on PyPi.
You can install it from source or from a wheel.
[sudo] pip install bonsai-code
The above command will install bonsai for you. Alternatively, download and extract its
source, move to the project’s root directory, and then execute the following.
python setup.py install
After installation, you should be able to run the command bonsai in your terminal
from anywhere.

Examples

The cpp_example.py script at the root of this repository is a small example on
how to parse a C++ file and then find all references to a variable a in that file.
In it, you can see parser creation
parser = CppAstParser(workspace = "examples/cpp")
access to the global (top level, or root) scope of the program, and obtaining
a pretty string representation of everything that goes in it
parser.global_scope.pretty_str()
getting a list of all references to variable a, starting the search from
the top of the program (global scope)
CodeQuery(parser.global_scope).all_references.where_name("a").get()
and accessing diverse properties from the returned CodeReference objects,
such as file line and column (cppobj.line, cppobj.column), the type of the
object (cppobj.result), what is it a reference of (cppobj.reference,
in this case a CodeVariable) and an attempt to interpret the program and
resolve the reference to a concrete value (resolve_reference(cppobj)).
Do note that resolving expressions and references is still experimental,
and more often that not will not be able to produce anything useful.
This is the pretty string output for a program that defines a class C
and a couple of functions.
class C:
  C():
    [declaration]

  void m(int a):
    [declaration]

  int x_ = None

C():
  x_ = 0

void m(int a):
  a = (a + 2) * 3
  this.x_ = a

int main(int argc, char ** argv):
  C c = new C()
  c.m(42)
  C * c1 = new C()
  C * c2 = new C()
  new C()
  delete(c1)
  delete(c2)
  return 0
The pretty string representation, as seen, is a sort of pseudo-language, inspired
in the Python syntax, even though the parsed program is originally in C++.
For more details on what you can get from the various program entities, check out
the source for the abstract model and then the language-specific
implementation of your choice.