Source code for xonsh.imphooks
# -*- coding: utf-8 -*-
"""Import hooks for importing xonsh source files.
This module registers the hooks it defines when it is imported.
"""
import builtins
import os
import sys
import types
from importlib.machinery import ModuleSpec
from importlib.abc import MetaPathFinder, SourceLoader
from xonsh.execer import Execer
from xonsh.platform import scandir
[docs]class XonshImportHook(MetaPathFinder, SourceLoader):
"""Implements the import hook for xonsh source files."""
def __init__(self, *args, **kwargs):
super(XonshImportHook, self).__init__(*args, **kwargs)
self._filenames = {}
self._execer = None
@property
def execer(self):
if hasattr(builtins, '__xonsh_execer__'):
execer = builtins.__xonsh_execer__
if self._execer is not None:
self._execer = None
elif self._execer is None:
self._execer = execer = Execer(unload=False)
else:
execer = self._execer
return execer
#
# MetaPathFinder methods
#
[docs] def find_spec(self, fullname, path, target=None):
"""Finds the spec for a xonsh module if it exists."""
dot = '.'
spec = None
path = sys.path if path is None else path
if dot not in fullname and dot not in path:
path = [dot] + path
name = fullname.rsplit(dot, 1)[-1]
fname = name + '.xsh'
for p in path:
if not isinstance(p, str):
continue
if not os.path.isdir(p) or not os.access(p, os.R_OK):
continue
if fname not in (x.name for x in scandir(p)):
continue
spec = ModuleSpec(fullname, self)
self._filenames[fullname] = os.path.join(p, fname)
break
return spec
#
# SourceLoader methods
#
[docs] def create_module(self, spec):
"""Create a xonsh module with the appropriate attributes."""
mod = types.ModuleType(spec.name)
mod.__file__ = self.get_filename(spec.name)
mod.__loader__ = self
mod.__package__ = spec.parent or ''
return mod
[docs] def get_filename(self, fullname):
"""Returns the filename for a module's fullname."""
return self._filenames[fullname]
[docs] def get_data(self, path):
"""Gets the bytes for a path."""
raise NotImplementedError
[docs] def get_code(self, fullname):
"""Gets the code object for a xonsh file."""
filename = self.get_filename(fullname)
if filename is None:
msg = "xonsh file {0!r} could not be found".format(fullname)
raise ImportError(msg)
with open(filename, 'r') as f:
src = f.read()
src = src if src.endswith('\n') else src + '\n'
execer = self.execer
execer.filename = filename
ctx = {} # dummy for modules
code = execer.compile(src, glbs=ctx, locs=ctx)
return code
[docs]def install_hook():
"""
Install Xonsh import hook in `sys.metapath` in order for `.xsh` files to be
importable.
Can safely be called many times, will be no-op if a xonsh import hook is
already present.
"""
for hook in sys.meta_path:
if isinstance(hook, XonshImportHook):
break
else:
sys.meta_path.append(XonshImportHook())