sealang 3.9.dev258341

Installation

Sealang works by providing a C module (sealang.so) that adds C interfaces for useful operations on the LLVM AST. This C module is then accessed using ctypes to provide Python bindings.

To compile Sealang, you’ll need to:

1. Install LLVM (with clang)

2. Set some environment variables

3. Install Sealang

The exact commands needed will vary between platforms.

$ brew install llvm --with-clang --with-asan

$ export LLVM_HOME=/usr/local/opt/llvm
$ export DYLD_LIBRARY_PATH=$LLVM_HOME/lib

$ pip install sealang

$ sudo apt-get install libclang-3.6 clang-3.6 -y

$ pip install sealang

Usage

Sealang provides a superset of the functionality provided by libclang. Those features are:

• Cursor objects have 4 additional attributes:

  • literal - the value of a literal expression. Available on IntegerLiteral, FloatingLiteral, StringLiteral, CharacterLiteral, and CXXBooleanLiteral nodes.

  • operator - the printable version of an operator. Only available on BinaryOperator, UnaryOperator, and CompoundAssignOperator cursor nodes.

  • binary_operator - an enumeration value describing a BinaryOperator or CompoundAssignOperator node.

  • unary_operator - an enumeration value describing a UnaryOperator node.

• BinaryOperator - An enumeration for the types of binary operators:

  • BinaryOperator.INVALID

  • BinaryOperator.PTRMEMD

  • BinaryOperator.PTRMEMI

  • BinaryOperator.MUL

  • BinaryOperator.DIV

  • BinaryOperator.REM

  • BinaryOperator.ADD

  • BinaryOperator.SUB

  • BinaryOperator.SHL

  • BinaryOperator.SHR

  • BinaryOperator.LT

  • BinaryOperator.GT

  • BinaryOperator.LE

  • BinaryOperator.GE

  • BinaryOperator.EQ

  • BinaryOperator.NE

  • BinaryOperator.AND

  • BinaryOperator.XOR

  • BinaryOperator.OR

  • BinaryOperator.LAND

  • BinaryOperator.LOR

  • BinaryOperator.ASSIGN

  • BinaryOperator.MULASSIGN

  • BinaryOperator.DIVASSIGN

  • BinaryOperator.REMASSIGN

  • BinaryOperator.ADDASSIGN

  • BinaryOperator.SUBASSIGN

  • BinaryOperator.SHLASSIGN

  • BinaryOperator.SHRASSIGN

  • BinaryOperator.ANDASSIGN

  • BinaryOperator.XORASSIGN

  • BinaryOperator.ORASSIGN

  • BinaryOperator.COMMA

  • BinaryOperator.UNKNOWN

• UnaryOperator - An enumeration for the types of binary operators:

  • UnaryOperator.INVALID

  • UnaryOperator.POSTINC

  • UnaryOperator.POSTDEC

  • UnaryOperator.PREINC

  • UnaryOperator.PREDEC

  • UnaryOperator.ADDROF

  • UnaryOperator.DEREF

  • UnaryOperator.PLUS

  • UnaryOperator.MINUS

  • UnaryOperator.NOT

  • UnaryOperator.LNOT

  • UnaryOperator.REAL

  • UnaryOperator.IMAG

  • UnaryOperator.EXTENSION

  • UnaryOperator.UNKNOWN

How it works

Sealang is a bit of a nasty hack. libclang is a set of C bindings to a C++ API; Python ctypes are then used to wrap the C API. However, while the C++ API is quite rich, libclang is less so.

Sealang bridges this gap by providing C wrappers around the C++ calls that provide the useful functionality. This library of C functions is wrapped up as a Python C module for delivery purposes - this C module contains no exposed Python objects or methods, but because it’s a module, the underlying compiled sealang.so file is easy to find. ctypes are then used to expose the sealang wrapper functions;

Internally, Sealang reproduces some minor pieces of the libclang API; these are methods (such as the string creation and manipulation methods) that aren’t exposed as symbols for third-party use.

All this functionality is potentially a candidate to be passed upstream to libclang.

Community

Sealang is part of the BeeWare suite. You can talk to the community through:

• @pybeeware on Twitter

• The BeeWare Users Mailing list, for questions about how to use the BeeWare suite.

• The BeeWare Developers Mailing list, for discussing the development of new features in the BeeWare suite, and ideas for new tools for the suite.

Contributing

If you experience problems with Sealang, log them on GitHub. If you want to contribute code, please fork the code and submit a pull request.