datatypes.py

import ctypes

import loopy as lp
import numpy
from petsc4py.PETSc import IntType, RealType, ScalarType

IntType = numpy.dtype(IntType)
RealType = numpy.dtype(RealType)
ScalarType = numpy.dtype(ScalarType)


def as_cstr(dtype):
    """Convert a numpy dtype like object to a C type as a string."""
    return {"bool": "unsigned char",
            "int": "int",
            "int8": "int8_t",
            "int16": "int16_t",
            "int32": "int32_t",
            "int64": "int64_t",
            "uint8": "uint8_t",
            "uint16": "uint16_t",
            "uint32": "uint32_t",
            "uint64": "uint64_t",
            "float32": "float",
            "float64": "double",
            "complex128": "double complex"}[numpy.dtype(dtype).name]


def as_ctypes(dtype):
    """Convert a numpy dtype like object to a ctypes type."""
    return {"bool": ctypes.c_bool,
            "int": ctypes.c_int,
            "int8": ctypes.c_char,
            "int16": ctypes.c_int16,
            "int32": ctypes.c_int32,
            "int64": ctypes.c_int64,
            "uint8": ctypes.c_ubyte,
            "uint16": ctypes.c_uint16,
            "uint32": ctypes.c_uint32,
            "uint64": ctypes.c_uint64,
            "float32": ctypes.c_float,
            "float64": ctypes.c_double}[numpy.dtype(dtype).name]


def as_numpy_dtype(dtype):
    """Convert a dtype-like object into a numpy dtype."""
    if isinstance(dtype, numpy.dtype):
        return dtype
    elif isinstance(dtype, lp.types.NumpyType):
        return dtype.numpy_dtype
    else:
        raise ValueError


def dtype_limits(dtype):
    """Attempt to determine the min and max values of a datatype.

    :arg dtype: A numpy datatype.
    :returns: a 2-tuple of min, max
    :raises ValueError: If numeric limits could not be determined.
    """
    try:
        info = numpy.finfo(dtype)
    except ValueError:
        # maybe an int?
        try:
            info = numpy.iinfo(dtype)
        except ValueError as e:
            raise ValueError("Unable to determine numeric limits from %s" % dtype) from e
    return info.min, info.max


class OpaqueType(lp.types.OpaqueType):
    def __init__(self, name):
        super().__init__(name=name)

    def __repr__(self):
        return self.name