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|
#===- common.py - Python LLVM Bindings -----------------------*- python -*--===#
#
# The LLVM Compiler Infrastructure
#
# This file is distributed under the University of Illinois Open Source
# License. See LICENSE.TXT for details.
#
#===------------------------------------------------------------------------===#
from ctypes import POINTER
from ctypes import c_void_p
from ctypes import cdll
import ctypes.util
__all__ = [
'c_object_p',
'find_library',
'get_library',
]
c_object_p = POINTER(c_void_p)
class LLVMObject(object):
"""Base class for objects that are backed by an LLVM data structure.
This class should never be instantiated outside of this package.
"""
def __init__(self, ptr, ownable=True, disposer=None):
assert isinstance(ptr, c_object_p)
self._ptr = self._as_parameter_ = ptr
self._self_owned = True
self._ownable = ownable
self._disposer = disposer
self._owned_objects = []
def take_ownership(self, obj):
"""Take ownership of another object.
When you take ownership of another object, you are responsible for
destroying that object. In addition, a reference to that object is
placed inside this object so the Python garbage collector will not
collect the object while it is still alive in libLLVM.
This method should likely only be called from within modules inside
this package.
"""
assert isinstance(obj, LLVMObject)
self._owned_objects.append(obj)
obj._self_owned = False
def from_param(self):
"""ctypes function that converts this object to a function parameter."""
return self._as_parameter_
def __del__(self):
if not hasattr(self, '_self_owned') or not hasattr(self, '_disposer'):
return
if self._self_owned and self._disposer:
self._disposer(self)
class CachedProperty(object):
"""Decorator that caches the result of a property lookup.
This is a useful replacement for @property. It is recommended to use this
decorator on properties that invoke C API calls for which the result of the
call will be idempotent.
"""
def __init__(self, wrapped):
self.wrapped = wrapped
try:
self.__doc__ = wrapped.__doc__
except: # pragma: no cover
pass
def __get__(self, instance, instance_type=None):
if instance is None:
return self
value = self.wrapped(instance)
setattr(instance, self.wrapped.__name__, value)
return value
def find_library():
# FIXME should probably have build system define absolute path of shared
# library at install time.
for lib in ['LLVM-3.1svn', 'libLLVM-3.1svn', 'LLVM', 'libLLVM']:
result = ctypes.util.find_library(lib)
if result:
return result
return None
def get_library():
"""Obtain a reference to the llvm library."""
lib = find_library()
if not lib:
raise Exception('LLVM shared library not found!')
return cdll.LoadLibrary(lib)
|
