pyximport.py

"""
Import hooks; when installed with the install() function, these hooks 
allow importing .pyx files as if they were Python modules.

If you want the hook installed every time you run Python
you can add it to your Python version by adding these lines to
sitecustomize.py (which you can create from scratch in site-packages 
if it doesn't exist there or somewhere else on your python path)::

    import pyximport
    pyximport.install()

For instance on the Mac with a non-system Python 2.3, you could create
sitecustomize.py with only those two lines at
/usr/local/lib/python2.3/site-packages/sitecustomize.py .

A custom distutils.core.Extension instance and setup() args
(Distribution) for for the build can be defined by a <modulename>.pyxbld
file like:

# examplemod.pyxbld
def make_ext(modname, pyxfilename):
    from distutils.extension import Extension
    return Extension(name = modname,
                     sources=[pyxfilename, 'hello.c'],
                     include_dirs=['/myinclude'] )
def make_setup_args():
    return dict(script_args=["--compiler=mingw32"])

Extra dependencies can be defined by a <modulename>.pyxdep .
See README.

Since Cython 0.11, the :mod:`pyximport` module also has experimental
compilation support for normal Python modules.  This allows you to
automatically run Cython on every .pyx and .py module that Python
imports, including parts of the standard library and installed
packages.  Cython will still fail to compile a lot of Python modules,
in which case the import mechanism will fall back to loading the
Python source modules instead.  The .py import mechanism is installed
like this::

    pyximport.install(pyimport = True)

Running this module as a top-level script will run a test and then print
the documentation.

This code is based on the Py2.3+ import protocol as described in PEP 302.
"""

import sys
import os
import glob
import imp

mod_name = "pyximport"

assert sys.hexversion >= 0x2030000, "need Python 2.3 or later"

PYX_EXT = ".pyx"
PYXDEP_EXT = ".pyxdep"
PYXBLD_EXT = ".pyxbld"

DEBUG_IMPORT = False


def _print(message, args):
    if args:
        message = message % args
    print(message)


def _debug(message, *args):
    if DEBUG_IMPORT:
        _print(message, args)


def _info(message, *args):
    _print(message, args)


# Performance problem: for every PYX file that is imported, we will
# invoke the whole distutils infrastructure even if the module is 
# already built. It might be more efficient to only do it when the 
# mod time of the .pyx is newer than the mod time of the .so but
# the question is how to get distutils to tell me the name of the .so
# before it builds it. Maybe it is easy...but maybe the peformance
# issue isn't real.
def _load_pyrex(name, filename):
    "Load a pyrex file given a name and filename."


def get_distutils_extension(modname, pyxfilename, language_level=None):
#    try:
#        import hashlib
#    except ImportError:
#        import md5 as hashlib
#    extra = "_" + hashlib.md5(open(pyxfilename).read()).hexdigest()  
#    modname = modname + extra
    extension_mod,setup_args = handle_special_build(modname, pyxfilename)
    if not extension_mod:
        if not isinstance(pyxfilename, str):
            # distutils is stupid in Py2 and requires exactly 'str'
            # => encode accidentally coerced unicode strings back to str
            pyxfilename = pyxfilename.encode(sys.getfilesystemencoding())
        from distutils.extension import Extension
        extension_mod = Extension(name = modname, sources=[pyxfilename])
        if language_level is not None:
            extension_mod.cython_directives = {'language_level': language_level}
    return extension_mod,setup_args


def handle_special_build(modname, pyxfilename):
    special_build = os.path.splitext(pyxfilename)[0] + PYXBLD_EXT
    ext = None
    setup_args={}
    if os.path.exists(special_build): 
        # globls = {}
        # locs = {}
        # execfile(special_build, globls, locs)
        # ext = locs["make_ext"](modname, pyxfilename)
        mod = imp.load_source("XXXX", special_build, open(special_build))
        make_ext = getattr(mod,'make_ext',None)
        if make_ext:
            ext = make_ext(modname, pyxfilename)
            assert ext and ext.sources, "make_ext in %s did not return Extension" % special_build
        make_setup_args = getattr(mod, 'make_setup_args',None)
        if make_setup_args:
            setup_args = make_setup_args()
            assert isinstance(setup_args,dict), ("make_setup_args in %s did not return a dict" 
                                         % special_build)
        assert set or setup_args, ("neither make_ext nor make_setup_args %s" 
                                         % special_build)
        ext.sources = [os.path.join(os.path.dirname(special_build), source) 
                       for source in ext.sources]
    return ext, setup_args


def handle_dependencies(pyxfilename):
    testing = '_test_files' in globals()
    dependfile = os.path.splitext(pyxfilename)[0] + PYXDEP_EXT

    # by default let distutils decide whether to rebuild on its own
    # (it has a better idea of what the output file will be)

    # but we know more about dependencies so force a rebuild if 
    # some of the dependencies are newer than the pyxfile.
    if os.path.exists(dependfile):
        depends = open(dependfile).readlines()
        depends = [depend.strip() for depend in depends]

        # gather dependencies in the "files" variable
        # the dependency file is itself a dependency
        files = [dependfile]
        for depend in depends:
            fullpath = os.path.join(os.path.dirname(dependfile),
                                    depend) 
            files.extend(glob.glob(fullpath))

        # only for unit testing to see we did the right thing
        if testing:
            _test_files[:] = []  #$pycheck_no

        # if any file that the pyxfile depends upon is newer than
        # the pyx file, 'touch' the pyx file so that distutils will
        # be tricked into rebuilding it.
        for file in files:
            from distutils.dep_util import newer
            if newer(file, pyxfilename):
                _debug("Rebuilding %s because of %s", pyxfilename, file)
                filetime = os.path.getmtime(file)
                os.utime(pyxfilename, (filetime, filetime))
                if testing:
                    _test_files.append(file)


def build_module(name, pyxfilename, pyxbuild_dir=None, inplace=False, language_level=None):
    assert os.path.exists(pyxfilename), "Path does not exist: %s" % pyxfilename
    handle_dependencies(pyxfilename)

    extension_mod, setup_args = get_distutils_extension(name, pyxfilename, language_level)
    build_in_temp = pyxargs.build_in_temp
    sargs = pyxargs.setup_args.copy()
    sargs.update(setup_args)
    build_in_temp = sargs.pop('build_in_temp',build_in_temp)

    from . import pyxbuild
    so_path = pyxbuild.pyx_to_dll(pyxfilename, extension_mod,
                                  build_in_temp=build_in_temp,
                                  pyxbuild_dir=pyxbuild_dir,
                                  setup_args=sargs,
                                  inplace=inplace,
                                  reload_support=pyxargs.reload_support)
    assert os.path.exists(so_path), "Cannot find: %s" % so_path
    
    junkpath = os.path.join(os.path.dirname(so_path), name+"_*") #very dangerous with --inplace ? yes, indeed, trying to eat my files ;)
    junkstuff = glob.glob(junkpath)
    for path in junkstuff:
        if path != so_path:
            try:
                os.remove(path)
            except IOError:
                _info("Couldn't remove %s", path)

    return so_path


def load_module(name, pyxfilename, pyxbuild_dir=None, is_package=False,
                build_inplace=False, language_level=None, so_path=None):
    try:
        if so_path is None:
            if is_package:
                module_name = name + '.__init__'
            else:
                module_name = name
            so_path = build_module(module_name, pyxfilename, pyxbuild_dir,
                                   inplace=build_inplace, language_level=language_level)
        mod = imp.load_dynamic(name, so_path)
        if is_package and not hasattr(mod, '__path__'):
            mod.__path__ = [os.path.dirname(so_path)]
        assert mod.__file__ == so_path, (mod.__file__, so_path)
    except Exception:
        if pyxargs.load_py_module_on_import_failure and pyxfilename.endswith('.py'):
            # try to fall back to normal import
            mod = imp.load_source(name, pyxfilename)
            assert mod.__file__ in (pyxfilename, pyxfilename+'c', pyxfilename+'o'), (mod.__file__, pyxfilename)
        else:
            tb = sys.exc_info()[2]
            import traceback
            exc = ImportError("Building module %s failed: %s" % (
                name, traceback.format_exception_only(*sys.exc_info()[:2])))
            if sys.version_info[0] >= 3:
                raise exc.with_traceback(tb)
            else:
                exec("raise exc, None, tb", {'exc': exc, 'tb': tb})
    return mod


# import hooks

class PyxImporter(object):
    """A meta-path importer for .pyx files.
    """
    def __init__(self, extension=PYX_EXT, pyxbuild_dir=None, inplace=False,
                 language_level=None):
        self.extension = extension
        self.pyxbuild_dir = pyxbuild_dir
        self.inplace = inplace
        self.language_level = language_level

    def find_module(self, fullname, package_path=None):
        if fullname in sys.modules  and  not pyxargs.reload_support:
            return None  # only here when reload() 
        try:
            fp, pathname, (ext,mode,ty) = imp.find_module(fullname,package_path)
            if fp: fp.close()  # Python should offer a Default-Loader to avoid this double find/open!
            if pathname and ty == imp.PKG_DIRECTORY:
                pkg_file = os.path.join(pathname, '__init__'+self.extension)
                if os.path.isfile(pkg_file):
                    return PyxLoader(fullname, pathname,
                        init_path=pkg_file,
                        pyxbuild_dir=self.pyxbuild_dir,
                        inplace=self.inplace,
                        language_level=self.language_level)
            if pathname and pathname.endswith(self.extension):
                return PyxLoader(fullname, pathname,
                                 pyxbuild_dir=self.pyxbuild_dir,
                                 inplace=self.inplace,
                                 language_level=self.language_level)
            if ty != imp.C_EXTENSION: # only when an extension, check if we have a .pyx next!
                return None

            # find .pyx fast, when .so/.pyd exist --inplace
            pyxpath = os.path.splitext(pathname)[0]+self.extension
            if os.path.isfile(pyxpath):
                return PyxLoader(fullname, pyxpath,
                                 pyxbuild_dir=self.pyxbuild_dir,
                                 inplace=self.inplace,
                                 language_level=self.language_level)

            # .so/.pyd's on PATH should not be remote from .pyx's
            # think no need to implement PyxArgs.importer_search_remote here?

        except ImportError:
            pass

        # searching sys.path ...

        #if DEBUG_IMPORT:  print "SEARCHING", fullname, package_path
        if '.' in fullname: # only when package_path anyway?
            mod_parts = fullname.split('.')
            module_name = mod_parts[-1]
        else:
            module_name = fullname
        pyx_module_name = module_name + self.extension
        # this may work, but it returns the file content, not its path
        #import pkgutil
        #pyx_source = pkgutil.get_data(package, pyx_module_name)

        if package_path:
            paths = package_path
        else:
            paths = sys.path
        join_path = os.path.join
        is_file = os.path.isfile
        is_abs = os.path.isabs
        abspath = os.path.abspath
        #is_dir = os.path.isdir
        sep = os.path.sep
        for path in paths:
            if not path:
                path = os.getcwd()
            elif not is_abs(path):
                path = abspath(path)
            if is_file(path+sep+pyx_module_name):
                return PyxLoader(fullname, join_path(path, pyx_module_name),
                                 pyxbuild_dir=self.pyxbuild_dir,
                                 inplace=self.inplace,
                                 language_level=self.language_level)

        # not found, normal package, not a .pyx file, none of our business
        _debug("%s not found" % fullname)
        return None


class PyImporter(PyxImporter):
    """A meta-path importer for normal .py files.
    """
    def __init__(self, pyxbuild_dir=None, inplace=False, language_level=None):
        if language_level is None:
            language_level = sys.version_info[0]
        self.super = super(PyImporter, self)
        self.super.__init__(extension='.py', pyxbuild_dir=pyxbuild_dir, inplace=inplace,
                            language_level=language_level)
        self.uncompilable_modules = {}
        self.blocked_modules = ['Cython', 'pyxbuild', 'pyximport.pyxbuild',
                                'distutils.extension', 'distutils.sysconfig']

    def find_module(self, fullname, package_path=None):
        if fullname in sys.modules:
            return None
        if fullname.startswith('Cython.'):
            return None
        if fullname in self.blocked_modules:
            # prevent infinite recursion
            return None
        if _lib_loader.knows(fullname):
            return _lib_loader
        _debug("trying import of module '%s'", fullname)
        if fullname in self.uncompilable_modules:
            path, last_modified = self.uncompilable_modules[fullname]
            try:
                new_last_modified = os.stat(path).st_mtime
                if new_last_modified > last_modified:
                    # import would fail again
                    return None
            except OSError:
                # module is no longer where we found it, retry the import
                pass

        self.blocked_modules.append(fullname)
        try:
            importer = self.super.find_module(fullname, package_path)
            if importer is not None:
                if importer.init_path:
                    path = importer.init_path
                    real_name = fullname + '.__init__'
                else:
                    path = importer.path
                    real_name = fullname
                _debug("importer found path %s for module %s", path, real_name)
                try:
                    so_path = build_module(
                        real_name, path,
                        pyxbuild_dir=self.pyxbuild_dir,
                        language_level=self.language_level,
                        inplace=self.inplace)
                    _lib_loader.add_lib(fullname, path, so_path,
                                        is_package=bool(importer.init_path))
                    return _lib_loader
                except Exception:
                    if DEBUG_IMPORT:
                        import traceback
                        traceback.print_exc()
                    # build failed, not a compilable Python module
                    try:
                        last_modified = os.stat(path).st_mtime
                    except OSError:
                        last_modified = 0
                    self.uncompilable_modules[fullname] = (path, last_modified)
                    importer = None
        finally:
            self.blocked_modules.pop()
        return importer


class LibLoader(object):
    def __init__(self):
        self._libs = {}

    def load_module(self, fullname):
        try:
            source_path, so_path, is_package = self._libs[fullname]
        except KeyError:
            raise ValueError("invalid module %s" % fullname)
        _debug("Loading shared library module '%s' from %s", fullname, so_path)
        return load_module(fullname, source_path, so_path=so_path, is_package=is_package)

    def add_lib(self, fullname, path, so_path, is_package):
        self._libs[fullname] = (path, so_path, is_package)

    def knows(self, fullname):
        return fullname in self._libs

_lib_loader = LibLoader()


class PyxLoader(object):
    def __init__(self, fullname, path, init_path=None, pyxbuild_dir=None,
                 inplace=False, language_level=None):
        _debug("PyxLoader created for loading %s from %s (init path: %s)",
               fullname, path, init_path)
        self.fullname = fullname
        self.path, self.init_path = path, init_path
        self.pyxbuild_dir = pyxbuild_dir
        self.inplace = inplace
        self.language_level = language_level

    def load_module(self, fullname):
        assert self.fullname == fullname, (
            "invalid module, expected %s, got %s" % (
            self.fullname, fullname))
        if self.init_path:
            # package
            #print "PACKAGE", fullname
            module = load_module(fullname, self.init_path,
                                 self.pyxbuild_dir, is_package=True,
                                 build_inplace=self.inplace,
                                 language_level=self.language_level)
            module.__path__ = [self.path]
        else:
            #print "MODULE", fullname
            module = load_module(fullname, self.path,
                                 self.pyxbuild_dir,
                                 build_inplace=self.inplace,
                                 language_level=self.language_level)
        return module


#install args
class PyxArgs(object):
    build_dir=True
    build_in_temp=True
    setup_args={}   #None

##pyxargs=None


def _have_importers():
    has_py_importer = False
    has_pyx_importer = False
    for importer in sys.meta_path:
        if isinstance(importer, PyxImporter):
            if isinstance(importer, PyImporter):
                has_py_importer = True
            else:
                has_pyx_importer = True

    return has_py_importer, has_pyx_importer


def install(pyximport=True, pyimport=False, build_dir=None, build_in_temp=True,
            setup_args=None, reload_support=False,
            load_py_module_on_import_failure=False, inplace=False,
            language_level=None):
    """Main entry point. Call this to install the .pyx import hook in
    your meta-path for a single Python process.  If you want it to be
    installed whenever you use Python, add it to your sitecustomize
    (as described above).

    You can pass ``pyimport=True`` to also install the .py import hook
    in your meta-path.  Note, however, that it is highly experimental,
    will not work for most .py files, and will therefore only slow
    down your imports.  Use at your own risk.

    By default, compiled modules will end up in a ``.pyxbld``
    directory in the user's home directory.  Passing a different path
    as ``build_dir`` will override this.

    ``build_in_temp=False`` will produce the C files locally. Working
    with complex dependencies and debugging becomes more easy. This
    can principally interfere with existing files of the same name.
    build_in_temp can be overriden by <modulename>.pyxbld/make_setup_args()
    by a dict item of 'build_in_temp'

    ``setup_args``: dict of arguments for Distribution - see
    distutils.core.setup() . They are extended/overriden by those of
    <modulename>.pyxbld/make_setup_args()

    ``reload_support``:  Enables support for dynamic
    reload(<pyxmodulename>), e.g. after a change in the Cython code.
    Additional files <so_path>.reloadNN may arise on that account, when
    the previously loaded module file cannot be overwritten.

    ``load_py_module_on_import_failure``: If the compilation of a .py
    file succeeds, but the subsequent import fails for some reason,
    retry the import with the normal .py module instead of the
    compiled module.  Note that this may lead to unpredictable results
    for modules that change the system state during their import, as
    the second import will rerun these modifications in whatever state
    the system was left after the import of the compiled module
    failed.

    ``inplace``: Install the compiled module next to the source file.

    ``language_level``: The source language level to use: 2 or 3.
    The default is to use the language level of the current Python
    runtime for .py files and Py2 for .pyx files.
    """
    if setup_args is None:
        setup_args = {}
    if not build_dir:
        build_dir = os.path.join(os.path.expanduser('~'), '.pyxbld')
        
    global pyxargs
    pyxargs = PyxArgs()  #$pycheck_no
    pyxargs.build_dir = build_dir
    pyxargs.build_in_temp = build_in_temp
    pyxargs.setup_args = (setup_args or {}).copy()
    pyxargs.reload_support = reload_support
    pyxargs.load_py_module_on_import_failure = load_py_module_on_import_failure

    has_py_importer, has_pyx_importer = _have_importers()
    py_importer, pyx_importer = None, None

    if pyimport and not has_py_importer:
        py_importer = PyImporter(pyxbuild_dir=build_dir, inplace=inplace,
                                 language_level=language_level)
        # make sure we import Cython before we install the import hook
        import Cython.Compiler.Main, Cython.Compiler.Pipeline, Cython.Compiler.Optimize
        sys.meta_path.insert(0, py_importer)

    if pyximport and not has_pyx_importer:
        pyx_importer = PyxImporter(pyxbuild_dir=build_dir, inplace=inplace,
                                   language_level=language_level)
        sys.meta_path.append(pyx_importer)

    return py_importer, pyx_importer


def uninstall(py_importer, pyx_importer):
    """
    Uninstall an import hook.
    """
    try:
        sys.meta_path.remove(py_importer)
    except ValueError:
        pass

    try:
        sys.meta_path.remove(pyx_importer)
    except ValueError:
        pass


# MAIN

def show_docs():
    import __main__
    __main__.__name__ = mod_name
    for name in dir(__main__):
        item = getattr(__main__, name)
        try:
            setattr(item, "__module__", mod_name)
        except (AttributeError, TypeError):
            pass
    help(__main__)


if __name__ == '__main__':
    show_docs()