text: from __future__ import absolute_import
  import os
  import sys
  
  import numpy
  
  from brian2.core.variables import (DynamicArrayVariable, ArrayVariable,
                                     AuxiliaryVariable, Subexpression)
  from brian2.core.functions import Function
  from brian2.core.preferences import prefs, BrianPreference
  from brian2.utils.logger import get_logger
  from brian2.utils.stringtools import get_identifiers
  
  from ...codeobject import constant_or_scalar, check_compiler_kwds
  from ..numpy_rt import NumpyCodeObject
  from ...templates import Templater
  from ...generators.cython_generator import (CythonCodeGenerator, get_cpp_dtype,
                                              get_numpy_dtype)
  from ...targets import codegen_targets
  from ...cpp_prefs import get_compiler_and_args
  from .extension_manager import cython_extension_manager
  
  __all__ = ['CythonCodeObject']
  
  
  logger = get_logger(__name__)
  
  # Preferences
  prefs.register_preferences(
      'codegen.runtime.cython',
      'Cython runtime codegen preferences',
      multiprocess_safe = BrianPreference(
          default=True,
          docs='''
          Whether to use a lock file to prevent simultaneous write access
          to cython .pyx and .so files.
          '''
          ),
      cache_dir = BrianPreference(
          default=None,
          validator=lambda x: x is None or isinstance(x, str),
          docs='''
          Location of the cache directory for Cython files. By default,
          will be stored in a ``brian_extensions`` subdirectory
          where Cython inline stores its temporary files
          (the result of ``get_cython_cache_dir()``).
          '''
          ),
      delete_source_files = BrianPreference(
          default=True,
          docs='''
          Whether to delete source files after compiling. The Cython
          source files can take a significant amount of disk space, and
          are not used anymore when the compiled library file exists.
          They are therefore deleted by default, but keeping them around
          can be useful for debugging.
          '''
          )
      )
  
  
  class CythonCodeObject(NumpyCodeObject):
      '''
      Execute code using Cython.
      '''
      templater = Templater('brian2.codegen.runtime.cython_rt', '.pyx',
                            env_globals={'cpp_dtype': get_cpp_dtype,
                                         'numpy_dtype': get_numpy_dtype,
                                         'dtype': numpy.dtype,
                                         'constant_or_scalar': constant_or_scalar})
      generator_class = CythonCodeGenerator
      class_name = 'cython'
  
      def __init__(self, owner, code, variables, variable_indices,
                   template_name, template_source, compiler_kwds,
                   name='cython_code_object*'):
          check_compiler_kwds(compiler_kwds, ['libraries', 'include_dirs',
                                              'library_dirs',
                                              'runtime_library_dirs',
                                              'sources'],
                              'Cython')
          super(CythonCodeObject, self).__init__(owner, code, variables,
                                                 variable_indices,
                                                 template_name, template_source,
                                                 compiler_kwds={}, # do not pass the actual args
                                                 name=name)
          self.compiler, self.extra_compile_args = get_compiler_and_args()
          self.define_macros = list(prefs['codegen.cpp.define_macros'])
          self.extra_link_args = list(prefs['codegen.cpp.extra_link_args'])
          self.headers = []  # not actually used
  
          self.include_dirs = (list(prefs['codegen.cpp.include_dirs']) +
                               compiler_kwds.get('include_dirs', []))
          self.include_dirs = list(prefs['codegen.cpp.include_dirs'])
          if sys.platform == 'win32':
              self.include_dirs += [os.path.join(sys.prefix, 'Library', 'include')]
          else:
              self.include_dirs += [os.path.join(sys.prefix, 'include')]
  
          self.library_dirs = (list(prefs['codegen.cpp.library_dirs']) +
                               compiler_kwds.get('library_dirs', []))
          if sys.platform == 'win32':
              self.library_dirs += [os.path.join(sys.prefix, 'Library', 'lib')]
          else:
              self.library_dirs += [os.path.join(sys.prefix, 'lib')]
  
          self.runtime_library_dirs = (list(prefs['codegen.cpp.runtime_library_dirs']),
                                       compiler_kwds.get('runtime_library_dirs', []))
  
          self.libraries = (list(prefs['codegen.cpp.libraries']) +
                            compiler_kwds.get('libraries', []))
          self.sources = compiler_kwds.get('sources', [])
  
      @classmethod
      def is_available(cls):
          try:
              compiler, extra_compile_args = get_compiler_and_args()
              code = '''
              #cython: language_level=3
              def main():
                  cdef int x
                  x = 0'''
              compiled = cython_extension_manager.create_extension(code,
                                                                   compiler=compiler,
                                                                   extra_compile_args=extra_compile_args,
                                                                   extra_link_args=prefs['codegen.cpp.extra_link_args'],
                                                                   include_dirs=prefs['codegen.cpp.include_dirs'],
                                                                   library_dirs=prefs['codegen.cpp.library_dirs'])
              compiled.main()
              return True
          except Exception as ex:
              logger.warn(('Cannot use Cython, a test compilation '
                           'failed: %s (%s)' % (str(ex),
                                                ex.__class__.__name__)) ,
                          'failed_compile_test')
              return False
  
      def compile(self):
          self.compiled_code = cython_extension_manager.create_extension(
              self.code,
              define_macros=self.define_macros,
              libraries=self.libraries,
              extra_compile_args=self.extra_compile_args,
              extra_link_args=self.extra_link_args,
              include_dirs=self.include_dirs,
              library_dirs=self.library_dirs,
              compiler=self.compiler,
              owner_name=self.owner.name+'_'+self.template_name,
              sources=self.sources
              )
          
      def run(self):
          return self.compiled_code.main(self.namespace)
  
      # the following are copied from WeaveCodeObject
  
      def _insert_func_namespace(self, func):
          impl = func.implementations[self]
          func_namespace = impl.get_namespace(self.owner)
          if func_namespace is not None:
              self.namespace.update(func_namespace)
          if impl.dependencies is not None:
              for dep in impl.dependencies.values():
                  self._insert_func_namespace(dep)
  
      def variables_to_namespace(self):
  
          # Variables can refer to values that are either constant (e.g. dt)
          # or change every timestep (e.g. t). We add the values of the
          # constant variables here and add the names of non-constant variables
          # to a list
  
          # A list containing tuples of name and a function giving the value
          self.nonconstant_values = []
  
          for name, var in self.variables.items():
              if isinstance(var, Function):
                  self._insert_func_namespace(var)
              if isinstance(var, (AuxiliaryVariable, Subexpression)):
                  continue
              try:
                  value = var.get_value()
              except (TypeError, AttributeError):
                  # A dummy Variable without value or a function
                  self.namespace[name] = var
                  continue
  
              if isinstance(var, ArrayVariable):
                  self.namespace[self.device.get_array_name(var,
                                                              self.variables)] = value
                  self.namespace['_num'+name] = var.get_len()
                  if var.scalar and var.constant:
                      self.namespace[name] = value.item()
              else:
                  self.namespace[name] = value
  
              if isinstance(var, DynamicArrayVariable):
                  dyn_array_name = self.generator_class.get_array_name(var,
                                                                      access_data=False)
                  self.namespace[dyn_array_name] = self.device.get_value(var,
                                                                         access_data=False)
  
              # Also provide the Variable object itself in the namespace (can be
              # necessary for resize operations, for example)
              self.namespace['_var_'+name] = var
  
          # Get all identifiers in the code -- note that this is not a smart
          # function, it will get identifiers from strings, comments, etc. This
          # is not a problem here, since we only use this list to filter out
          # things. If we include something incorrectly, this only means that we
          # will pass something into the namespace unnecessarily.
          all_identifiers = get_identifiers(self.code)
          # Filter out all unneeded objects
          self.namespace = {k: v for k, v in self.namespace.items()
                            if k in all_identifiers}
  
          # There is one type of objects that we have to inject into the
          # namespace with their current value at each time step: dynamic
          # arrays that change in size during runs, where the size change is not
          # initiated by the template itself
          for name, var in self.variables.items():
              if (isinstance(var, DynamicArrayVariable) and
                      var.needs_reference_update):
                  array_name = self.device.get_array_name(var, self.variables)
                  if array_name in self.namespace:
                      self.nonconstant_values.append((array_name, var.get_value))
                  if '_num'+name in self.namespace:
                      self.nonconstant_values.append(('_num'+name, var.get_len))
  
      def update_namespace(self):
          # update the values of the non-constant values in the namespace
          for name, func in self.nonconstant_values:
              self.namespace[name] = func()
  
  
  codegen_targets.add(CythonCodeObject)
  