fileholders.py at 7c7962b ⋅ nipy/nibabel

# emacs: -*- mode: python-mode; py-indent-offset: 4; indent-tabs-mode: nil -*-
# vi: set ft=python sts=4 ts=4 sw=4 et:
### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
#
#   See COPYING file distributed along with the NiBabel package for the
#   copyright and license terms.
#
### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
""" Fileholder class """

from copy import copy

from .openers import ImageOpener


class FileHolderError(Exception):
    pass


class FileHolder(object):
    """ class to contain filename, fileobj and file position
    """

    def __init__(self,
                 filename=None,
                 fileobj=None,
                 pos=0):
        """ Initialize FileHolder instance

        Parameters
        ----------
        filename : str, optional
           filename.  Default is None
        fileobj : file-like object, optional
           Should implement at least 'seek' (for the purposes for this
           class).  Default is None
        pos : int, optional
           position in filename or fileobject at which to start reading
           or writing data; defaults to 0
        """
        self.filename = filename
        self.fileobj = fileobj
        self.pos = pos

    def get_prepare_fileobj(self, *args, **kwargs):
        """ Return fileobj if present, or return fileobj from filename

        Set position to that given in self.pos

        Parameters
        ----------
        *args : tuple
           positional arguments to file open.  Ignored if there is a
           defined ``self.fileobj``.  These might include the mode, such
           as 'rb'
        **kwargs : dict
           named arguments to file open.  Ignored if there is a
           defined ``self.fileobj``

        Returns
        -------
        fileobj : file-like object
           object has position set (via ``fileobj.seek()``) to
           ``self.pos``
        """
        if self.fileobj is not None:
            obj = ImageOpener(self.fileobj)  # for context manager
            obj.seek(self.pos)
        elif self.filename is not None:
            obj = ImageOpener(self.filename, *args, **kwargs)
            if self.pos != 0:
                obj.seek(self.pos)
        else:
            raise FileHolderError('No filename or fileobj present')
        return obj

    def same_file_as(self, other):
        """ Test if `self` refers to same files / fileobj as `other`

        Parameters
        ----------
        other : object
            object with `filename` and `fileobj` attributes

        Returns
        -------
        tf : bool
            True if `other` has the same filename (or both have None) and the
            same fileobj (or both have None
        """
        return ((self.filename == other.filename) and
                (self.fileobj == other.fileobj))

    @property
    def file_like(self):
        """ Return ``self.fileobj`` if not None, otherwise ``self.filename``
        """
        return self.fileobj if self.fileobj is not None else self.filename


def copy_file_map(file_map):
    r""" Copy mapping of fileholders given by `file_map`

    Parameters
    ----------
    file_map : mapping
       mapping of ``FileHolder`` instances

    Returns
    -------
    fm_copy : dict
       Copy of `file_map`, using shallow copy of ``FileHolder``\s

    """
    fm_copy = {}
    for key, fh in file_map.items():
        fm_copy[key] = copy(fh)
    return fm_copy

Read our documentation on viewing source code .

1		# emacs: -- mode: python-mode; py-indent-offset: 4; indent-tabs-mode: nil --
2		# vi: set ft=python sts=4 ts=4 sw=4 et:
3		### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
4		#
5		# See COPYING file distributed along with the NiBabel package for the
6		# copyright and license terms.
7		#
8		### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
9	33	""" Fileholder class """
10
11	33	from copy import copy
12
13	33	from .openers import ImageOpener
14
15
16	33	class FileHolderError(Exception):
17	33	pass
18
19
20	33	class FileHolder(object):
21		""" class to contain filename, fileobj and file position
22		"""
23
24	33	def __init__(self,
25		filename=None,
26		fileobj=None,
27		pos=0):
28		""" Initialize FileHolder instance
29
30		Parameters
31		----------
32		filename : str, optional
33		filename. Default is None
34		fileobj : file-like object, optional
35		Should implement at least 'seek' (for the purposes for this
36		class). Default is None
37		pos : int, optional
38		position in filename or fileobject at which to start reading
39		or writing data; defaults to 0
40		"""
41	33	self.filename = filename
42	33	self.fileobj = fileobj
43	33	self.pos = pos
44
45	33	def get_prepare_fileobj(self, args, *kwargs):
46		""" Return fileobj if present, or return fileobj from filename
47
48		Set position to that given in self.pos
49
50		Parameters
51		----------
52		*args : tuple
53		positional arguments to file open. Ignored if there is a
54		defined ``self.fileobj``. These might include the mode, such
55		as 'rb'
56		**kwargs : dict
57		named arguments to file open. Ignored if there is a
58		defined ``self.fileobj``
59
60		Returns
61		-------
62		fileobj : file-like object
63		object has position set (via ``fileobj.seek()``) to
64		``self.pos``
65		"""
66	33	if self.fileobj is not None:
67	33	obj = ImageOpener(self.fileobj) # for context manager
68	33	obj.seek(self.pos)
69	33	elif self.filename is not None:
70	33	obj = ImageOpener(self.filename, args, *kwargs)
71	33	if self.pos != 0:
72	0	obj.seek(self.pos)
73		else:
74	33	raise FileHolderError('No filename or fileobj present')
75	33	return obj
76
77	33	def same_file_as(self, other):
78		""" Test if `self` refers to same files / fileobj as `other`
79
80		Parameters
81		----------
82		other : object
83		object with `filename` and `fileobj` attributes
84
85		Returns
86		-------
87		tf : bool
88		True if `other` has the same filename (or both have None) and the
89		same fileobj (or both have None
90		"""
91	33	return ((self.filename == other.filename) and
92		(self.fileobj == other.fileobj))
93
94	33	@property
95	5	def file_like(self):
96		""" Return ``self.fileobj`` if not None, otherwise ``self.filename``
97		"""
98	33	return self.fileobj if self.fileobj is not None else self.filename
99
100
101	33	def copy_file_map(file_map):
102		r""" Copy mapping of fileholders given by `file_map`
103
104		Parameters
105		----------
106		file_map : mapping
107		mapping of ``FileHolder`` instances
108
109		Returns
110		-------
111		fm_copy : dict
112		Copy of `file_map`, using shallow copy of ``FileHolder``\s
113
114		"""
115	33	fm_copy = {}
116	33	for key, fh in file_map.items():
117	33	fm_copy[key] = copy(fh)
118	33	return fm_copy

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