lltypes
A type system for Python backed by llvm and ctypes
This project is a wrapping for spelling and translating between ctypes, LLVM types and Numpy dtype.
Example: Structs
In C99 we might define the following structure:
struct {
bool a;
int b;
float c;
} mystruct;We can map this structure in Python:
from lltypes import *
mystruct = Struct(
'mystruct',
Bool('a'),
Int32('b'),
Float32('c'),
)Which can be converted to ctypes using to_ctypes:
mycstruct = mystruct.to_ctypes()
inst = mycstruct(
True,
3,
3.14
)
>>> inst.a
True
>>> inst.b
3
>>> inst.c
3.140000104904175And to LLVM using to_llvm:
llstruct = mystruct.to_llvm()
>>> print llstruct
%mystruct = type { i1, i32, float }And to dtype using to_dtype:
dtstruct = mystruct.to_dtype()
>>> print dtstruct
dtype([('a', '?'), ('b', 'i32'), ('c', '<f4')])Example: Arrays
Blaze defines a family of parameterized types for its array objects. These are first class polytypes in lltypes with the following schema:
nd := 1 | 2 | 3 | 4 | 5
mono := Byte | Int8 | Int32 | ...
poly := Array_C <mono> <nd>
| Array_F <mono> <nd>
| Array_S <mono> <nd>In C these are structures of array kinds parameterized by eltype
and nd.
// Contiguous or Fortran
struct {
eltype *data;
intp shape[nd];
} Array_C;
struct {
eltype *data;
diminfo shape[nd];
} Array_F;
struct {
eltype *data;
intp shape[nd];
intp stride[nd];
} Array_S;In lltypes these are expanded out into lower types by a simple function.
def Array_C(name, ty, nd):
return Struct('Array_C',
Pointer(ty('data')),
Sequence(UNInt8('shape'), nd),
)
def Array_F(name, ty, nd):
return Struct('Array_F',
Pointer(ty('data')),
Sequence(UNInt8('shape'), nd),
)
def Array_S(name, ty, nd):
return Struct('Array_S',
Pointer(ty('data')),
Sequence(UNInt8('shape'), nd),
Sequence(UNInt8('stride'), nd),
)>>> c = Array_C('foo', UNInt8, 3)
>>> f = Array_F('foo', UNInt8, 3)
>>> s = Array_S('foo', UNInt8, 3)
>>> print c.to_llvm()
%Array_C = type { i8*, [3 x i8] }
>>> print f.to_llvm()
%Array_F = type { i8*, [3 x i8] }
>>> print s.to_llvm()
%Array_S = type { i8*, [3 x i8], [3 x i8] }Tests
Test suite can be run with either of the following:
python -m unittest discoveror:
from lltypes import test
test()
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