Document OpenMP in %%cython magic

IPython/extensions/cythonmagic.py

@@ -1,279 +1,285
 # -*- coding: utf-8 -*-
 """
 Cython related magics.
 
 Author:
 * Brian Granger
 
 Parts of this code were taken from Cython.inline.
 """
 #-----------------------------------------------------------------------------
 # Copyright (C) 2010-2011, IPython Development Team.
 #
 # Distributed under the terms of the Modified BSD License.
 #
 # The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 from __future__ import print_function
 
 import imp
 import io
 import os
 import re
 import sys
 import time
 
 try:
     import hashlib
 except ImportError:
     import md5 as hashlib
 
 from distutils.core import Distribution, Extension
 from distutils.command.build_ext import build_ext
 
 from IPython.core import display
 from IPython.core import magic_arguments
 from IPython.core.magic import Magics, magics_class, cell_magic
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import py3compat
 
 import Cython
 from Cython.Compiler.Errors import CompileError
 from Cython.Build.Dependencies import cythonize
 
 
 @magics_class
 class CythonMagics(Magics):
 
     def __init__(self, shell):
         super(CythonMagics,self).__init__(shell)
         self._reloads = {}
         self._code_cache = {}
 
     def _import_all(self, module):
         for k,v in module.__dict__.items():
             if not k.startswith('__'):
                 self.shell.push({k:v})
 
     @cell_magic
     def cython_inline(self, line, cell):
         """Compile and run a Cython code cell using Cython.inline.
 
         This magic simply passes the body of the cell to Cython.inline
         and returns the result. If the variables `a` and `b` are defined
         in the user's namespace, here is a simple example that returns
         their sum::
 
             %%cython_inline
             return a+b
 
         For most purposes, we recommend the usage of the `%%cython` magic.
         """
         locs = self.shell.user_global_ns
         globs = self.shell.user_ns
         return Cython.inline(cell, locals=locs, globals=globs)
 
     @cell_magic
     def cython_pyximport(self, line, cell):
         """Compile and import a Cython code cell using pyximport.
 
         The contents of the cell are written to a `.pyx` file in the current
         working directory, which is then imported using `pyximport`. This
         magic requires a module name to be passed::
 
             %%cython_pyximport modulename
             def f(x):
                 return 2.0*x
 
         The compiled module is then imported and all of its symbols are
         injected into the user's namespace. For most purposes, we recommend
         the usage of the `%%cython` magic.
         """
         module_name = line.strip()
         if not module_name:
             raise ValueError('module name must be given')
         fname = module_name + '.pyx'
         with io.open(fname, 'w', encoding='utf-8') as f:
             f.write(cell)
         if 'pyximport' not in sys.modules:
             import pyximport
             pyximport.install(reload_support=True)
         if module_name in self._reloads:
             module = self._reloads[module_name]
             reload(module)
         else:
             __import__(module_name)
             module = sys.modules[module_name]
             self._reloads[module_name] = module
         self._import_all(module)
 
     @magic_arguments.magic_arguments()
     @magic_arguments.argument(
         '-c', '--compile-args', action='append', default=[],
         help="Extra flags to pass to compiler via the `extra_compile_args` "
              "Extension flag (can be specified  multiple times)."
     )
     @magic_arguments.argument(
         '-la', '--link-args', action='append', default=[],
         help="Extra flags to pass to linker via the `extra_link_args` "
              "Extension flag (can be specified  multiple times)."
     )
     @magic_arguments.argument(
         '-l', '--lib', action='append', default=[],
         help="Add a library to link the extension against (can be specified "
              "multiple times)."
     )
     @magic_arguments.argument(
         '-L', dest='library_dirs', metavar='dir', action='append', default=[],
         help="Add a path to the list of libary directories (can be specified "
              "multiple times)."
     )
     @magic_arguments.argument(
         '-I', '--include', action='append', default=[],
         help="Add a path to the list of include directories (can be specified "
              "multiple times)."
     )
     @magic_arguments.argument(
         '-+', '--cplus', action='store_true', default=False,
         help="Output a C++ rather than C file."
     )
     @magic_arguments.argument(
         '-f', '--force', action='store_true', default=False,
         help="Force the compilation of a new module, even if the source has been "
              "previously compiled."
     )
     @magic_arguments.argument(
         '-a', '--annotate', action='store_true', default=False,
         help="Produce a colorized HTML version of the source."
     )
     @cell_magic
     def cython(self, line, cell):
         """Compile and import everything from a Cython code cell.
 
         The contents of the cell are written to a `.pyx` file in the
         directory `IPYTHONDIR/cython` using a filename with the hash of the
         code. This file is then cythonized and compiled. The resulting module
         is imported and all of its symbols are injected into the user's
         namespace. The usage is similar to that of `%%cython_pyximport` but
         you don't have to pass a module name::
 
-        %%cython
-        def f(x):
-            return 2.0*x
+            %%cython
+            def f(x):
+                return 2.0*x
+
+        To compile OpenMP codes, pass the required  `--compile-args`
+        and `--link-args`.  For example with gcc::
+
+            %%cython --compile-args=-fopenmp --link-args=-fopenmp
+            ...
         """
         args = magic_arguments.parse_argstring(self.cython, line)
         code = cell if cell.endswith('\n') else cell+'\n'
         lib_dir = os.path.join(self.shell.ipython_dir, 'cython')
         quiet = True
         key = code, sys.version_info, sys.executable, Cython.__version__
 
         if not os.path.exists(lib_dir):
             os.makedirs(lib_dir)
 
         if args.force:
             # Force a new module name by adding the current time to the
             # key which is hashed to determine the module name.
             key += time.time(),
 
         module_name = "_cython_magic_" + hashlib.md5(str(key).encode('utf-8')).hexdigest()
         module_path = os.path.join(lib_dir, module_name + self.so_ext)
 
         have_module = os.path.isfile(module_path)
         need_cythonize = not have_module
 
         if args.annotate:
             html_file = os.path.join(lib_dir, module_name + '.html')
             if not os.path.isfile(html_file):
                 need_cythonize = True
 
         if need_cythonize:
             c_include_dirs = args.include
             if 'numpy' in code:
                 import numpy
                 c_include_dirs.append(numpy.get_include())
             pyx_file = os.path.join(lib_dir, module_name + '.pyx')
             pyx_file = py3compat.cast_bytes_py2(pyx_file, encoding=sys.getfilesystemencoding())
             with io.open(pyx_file, 'w', encoding='utf-8') as f:
                 f.write(code)
             extension = Extension(
                 name = module_name,
                 sources = [pyx_file],
                 include_dirs = c_include_dirs,
                 library_dirs = args.library_dirs,
                 extra_compile_args = args.compile_args,
                 extra_link_args = args.link_args,
                 libraries = args.lib,
                 language = 'c++' if args.cplus else 'c',
             )
             build_extension = self._get_build_extension()
             try:
                 opts = dict(
                     quiet=quiet,
                     annotate = args.annotate,
                     force = True,
                     )
                 build_extension.extensions = cythonize([extension], **opts)
             except CompileError:
                 return
 
         if not have_module:
             build_extension.build_temp = os.path.dirname(pyx_file)
             build_extension.build_lib  = lib_dir
             build_extension.run()
             self._code_cache[key] = module_name
 
         module = imp.load_dynamic(module_name, module_path)
         self._import_all(module)
 
         if args.annotate:
             try:
                 with io.open(html_file, encoding='utf-8') as f:
                     annotated_html = f.read()
             except IOError as e:
                 # File could not be opened. Most likely the user has a version
                 # of Cython before 0.15.1 (when `cythonize` learned the
                 # `force` keyword argument) and has already compiled this
                 # exact source without annotation.
                 print('Cython completed successfully but the annotated '
                       'source could not be read.', file=sys.stderr)
                 print(e, file=sys.stderr)
             else:
                 return display.HTML(self.clean_annotated_html(annotated_html))
 
     @property
     def so_ext(self):
         """The extension suffix for compiled modules."""
         try:
             return self._so_ext
         except AttributeError:
             self._so_ext = self._get_build_extension().get_ext_filename('')
             return self._so_ext
 
     def _get_build_extension(self):
         dist = Distribution()
         config_files = dist.find_config_files()
         try:
             config_files.remove('setup.cfg')
         except ValueError:
             pass
         dist.parse_config_files(config_files)
         build_extension = build_ext(dist)
         build_extension.finalize_options()
         return build_extension
 
     @staticmethod
     def clean_annotated_html(html):
         """Clean up the annotated HTML source.
 
         Strips the link to the generated C or C++ file, which we do not
         present to the user.
         """
         r = re.compile('<p>Raw output: <a href="(.*)">(.*)</a>')
         html = '\n'.join(l for l in html.splitlines() if not r.match(l))
         return html
 
 
 def load_ipython_extension(ip):
     """Load the extension in IPython."""
     ip.register_magics(CythonMagics)