path: root/astroid/manager.py

# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of astroid.
#
# astroid is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 2.1 of the License, or (at your
# option) any later version.
#
# astroid is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
# for more details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with astroid. If not, see <http://www.gnu.org/licenses/>.
"""astroid manager: avoid multiple astroid build of a same module when
possible by providing a class responsible to get astroid representation
from various source and using a cache of built modules)
"""

import imp
import os
import sys
import zipimport

import six

from astroid import exceptions
from astroid import modutils
from astroid import transforms
from astroid import util


def safe_repr(obj):
    try:
        return repr(obj)
    except Exception: # pylint: disable=broad-except
        return '???'


class AstroidManager(object):
    """the astroid manager, responsible to build astroid from files
     or modules.

    Use the Borg pattern.
    """

    name = 'astroid loader'
    brain = {}

    def __init__(self):
        self.__dict__ = AstroidManager.brain
        if not self.__dict__:
            # NOTE: cache entries are added by the [re]builder
            self.astroid_cache = {}
            self._mod_file_cache = {}
            self._failed_import_hooks = []
            self.always_load_extensions = False
            self.optimize_ast = False
            self.extension_package_whitelist = set()
            self._transform = transforms.TransformVisitor()

            # Export these APIs for convenience
            self.register_transform = self._transform.register_transform
            self.unregister_transform = self._transform.unregister_transform

    def visit_transforms(self, node):
        """Visit the transforms and apply them to the given *node*."""
        return self._transform.visit(node)

    def ast_from_file(self, filepath, modname=None, fallback=True, source=False):
        """given a module name, return the astroid object"""
        try:
            filepath = modutils.get_source_file(filepath, include_no_ext=True)
            source = True
        except modutils.NoSourceFile:
            pass
        if modname is None:
            try:
                modname = '.'.join(modutils.modpath_from_file(filepath))
            except ImportError:
                modname = filepath
        if modname in self.astroid_cache and self.astroid_cache[modname].file == filepath:
            return self.astroid_cache[modname]
        if source:
            from astroid.builder import AstroidBuilder
            return AstroidBuilder(self).file_build(filepath, modname)
        elif fallback and modname:
            return self.ast_from_module_name(modname)
        raise exceptions.AstroidBuildingException(
            'Unable to build an AST for {path}.', path=filepath)

    def _build_stub_module(self, modname):
        from astroid.builder import AstroidBuilder
        return AstroidBuilder(self).string_build('', modname)

    def _can_load_extension(self, modname):
        if self.always_load_extensions:
            return True
        if modutils.is_standard_module(modname):
            return True
        parts = modname.split('.')
        return any(
            '.'.join(parts[:x]) in self.extension_package_whitelist
            for x in range(1, len(parts) + 1))

    def ast_from_module_name(self, modname, context_file=None):
        """given a module name, return the astroid object"""
        if modname in self.astroid_cache:
            return self.astroid_cache[modname]
        if modname == '__main__':
            return self._build_stub_module(modname)
        old_cwd = os.getcwd()
        if context_file:
            os.chdir(os.path.dirname(context_file))
        try:
            filepath, mp_type = self.file_from_module_name(modname, context_file)
            if mp_type == modutils.PY_ZIPMODULE:
                module = self.zip_import_data(filepath)
                if module is not None:
                    return module
            elif mp_type in (imp.C_BUILTIN, imp.C_EXTENSION):
                if mp_type == imp.C_EXTENSION and not self._can_load_extension(modname):
                    return self._build_stub_module(modname)
                try:
                    module = modutils.load_module_from_name(modname)
                except Exception as ex: # pylint: disable=broad-except
                    util.reraise(exceptions.AstroidBuildingException(
                        'Loading {modname} failed with:\n{error}',
                        modname=modname, path=filepath, error=ex))
                return self.ast_from_module(module, modname)
            elif mp_type == imp.PY_COMPILED:
                raise exceptions.AstroidBuildingException(
                    "Unable to load compiled module {modname}.",
                    modname=modname, path=filepath)
            if filepath is None:
                raise exceptions.AstroidBuildingException(
                    "Can't find a file for module {modname}.",
                    modname=modname)
            return self.ast_from_file(filepath, modname, fallback=False)
        except exceptions.AstroidBuildingException as e:
            for hook in self._failed_import_hooks:
                try:
                    return hook(modname)
                except exceptions.AstroidBuildingException:
                    pass
            raise e
        finally:
            os.chdir(old_cwd)

    def zip_import_data(self, filepath):
        if zipimport is None:
            return None
        from astroid.builder import AstroidBuilder
        builder = AstroidBuilder(self)
        for ext in ('.zip', '.egg'):
            try:
                eggpath, resource = filepath.rsplit(ext + os.path.sep, 1)
            except ValueError:
                continue
            try:
                importer = zipimport.zipimporter(eggpath + ext)
                zmodname = resource.replace(os.path.sep, '.')
                if importer.is_package(resource):
                    zmodname = zmodname + '.__init__'
                module = builder.string_build(importer.get_source(resource),
                                              zmodname, filepath)
                return module
            except Exception: # pylint: disable=broad-except
                continue
        return None

    def file_from_module_name(self, modname, contextfile):
        try:
            value = self._mod_file_cache[(modname, contextfile)]
            traceback = sys.exc_info()[2]
        except KeyError:
            try:
                value = modutils.file_info_from_modpath(
                    modname.split('.'), context_file=contextfile)
                traceback = sys.exc_info()[2]
            except ImportError as ex:
                value = exceptions.AstroidBuildingException(
                    'Failed to import module {modname} with error:\n{error}.',
                    modname=modname, error=ex)
                traceback = sys.exc_info()[2]
            self._mod_file_cache[(modname, contextfile)] = value
        if isinstance(value, exceptions.AstroidBuildingException):
            six.reraise(exceptions.AstroidBuildingException,
                        value, traceback)
        return value

    def ast_from_module(self, module, modname=None):
        """given an imported module, return the astroid object"""
        modname = modname or module.__name__
        if modname in self.astroid_cache:
            return self.astroid_cache[modname]
        try:
            # some builtin modules don't have __file__ attribute
            filepath = module.__file__
            if modutils.is_python_source(filepath):
                return self.ast_from_file(filepath, modname)
        except AttributeError:
            pass
        from astroid.builder import AstroidBuilder
        return AstroidBuilder(self).module_build(module, modname)

    def ast_from_class(self, klass, modname=None):
        """get astroid for the given class"""
        if modname is None:
            try:
                modname = klass.__module__
            except AttributeError:
                util.reraise(exceptions.AstroidBuildingException(
                    'Unable to get module for class {class_name}.',
                    cls=klass, class_repr=safe_repr(klass), modname=modname))
        modastroid = self.ast_from_module_name(modname)
        return modastroid.getattr(klass.__name__)[0] # XXX

    def infer_ast_from_something(self, obj, context=None):
        """infer astroid for the given class"""
        if hasattr(obj, '__class__') and not isinstance(obj, type):
            klass = obj.__class__
        else:
            klass = obj
        try:
            modname = klass.__module__
        except AttributeError:
            util.reraise(exceptions.AstroidBuildingException(
                'Unable to get module for {class_repr}.',
                cls=klass, class_repr=safe_repr(klass)))
        except Exception as ex: # pylint: disable=broad-except
            util.reraise(exceptions.AstroidBuildingException(
                'Unexpected error while retrieving module for {class_repr}:\n'
                '{error}', cls=klass, class_repr=safe_repr(klass), error=ex))
        try:
            name = klass.__name__
        except AttributeError:
            util.reraise(exceptions.AstroidBuildingException(
                'Unable to get name for {class_repr}:\n',
                cls=klass, class_repr=safe_repr(klass)))
        except Exception as ex: # pylint: disable=broad-except
            util.reraise(exceptions.AstroidBuildingException(
                'Unexpected error while retrieving name for {class_repr}:\n'
                '{error}', cls=klass, class_repr=safe_repr(klass), error=ex))
        # take care, on living object __module__ is regularly wrong :(
        modastroid = self.ast_from_module_name(modname)
        if klass is obj:
            for inferred in modastroid.igetattr(name, context):
                yield inferred
        else:
            for inferred in modastroid.igetattr(name, context):
                yield inferred.instantiate_class()

    def register_failed_import_hook(self, hook):
        """Registers a hook to resolve imports that cannot be found otherwise.

        `hook` must be a function that accepts a single argument `modname` which
        contains the name of the module or package that could not be imported.
        If `hook` can resolve the import, must return a node of type `astroid.Module`,
        otherwise, it must raise `AstroidBuildingException`.
        """
        self._failed_import_hooks.append(hook)

    def cache_module(self, module):
        """Cache a module if no module with the same name is known yet."""
        self.astroid_cache.setdefault(module.name, module)

    def clear_cache(self, astroid_builtin=None):
        # XXX clear transforms
        self.astroid_cache.clear()
        # force bootstrap again, else we may ends up with cache inconsistency
        # between the manager and CONST_PROXY, making
        # unittest_lookup.LookupTC.test_builtin_lookup fail depending on the
        # test order
        import astroid.raw_building
        astroid.raw_building._astroid_bootstrapping(
            astroid_builtin=astroid_builtin)