import SCons
from SCons.Action import Action

cythonAction = Action("$CYTHONCOM")

def create_builder(env):
  try:
    cython = env['BUILDERS']['Cython']
  except KeyError:
    cython = SCons.Builder.Builder(
               action = cythonAction,
               emitter = {},
               suffix = cython_suffix_emitter,
               single_source = 1
             )
    env['BUILDERS']['Cython'] = cython
  return cython

def cython_suffix_emitter(env, source):
  return "$CYTHONCFILESUFFIX"

def generate(env):
  env["CYTHON"] = "cythonize"
  env["CYTHONCOM"] = "$CYTHON $CYTHONFLAGS $SOURCE"
  env["CYTHONCFILESUFFIX"] = ".cpp"

  c_file, _ = SCons.Tool.createCFileBuilders(env)

  c_file.suffix['.pyx'] = cython_suffix_emitter
  c_file.add_action('.pyx', cythonAction)

  c_file.suffix['.py'] = cython_suffix_emitter
  c_file.add_action('.py', cythonAction)

  create_builder(env)

def exists(env):
  return True