Source code for zict.file

import os
from urllib.parse import quote, unquote

from .common import ZictBase


def _safe_key(key):
    """
    Escape key so as to be usable on all filesystems.
    """
    # Even directory separators are unsafe.
    return quote(key, safe="")


def _unsafe_key(key):
    """
    Undo the escaping done by _safe_key().
    """
    return unquote(key)


[docs]class File(ZictBase): """Mutable Mapping interface to a directory Keys must be strings, values must be bytes Note this shouldn't be used for interprocess persistence, as keys are cached in memory. Parameters ---------- directory: string mode: string, ('r', 'w', 'a'), defaults to 'a' Examples -------- >>> z = File('myfile') # doctest: +SKIP >>> z['x'] = b'123' # doctest: +SKIP >>> z['x'] # doctest: +SKIP b'123' Also supports writing lists of bytes objects >>> z['y'] = [b'123', b'4567'] # doctest: +SKIP >>> z['y'] # doctest: +SKIP b'1234567' Or anything that can be used with file.write, like a memoryview >>> z['data'] = np.ones(5).data # doctest: +SKIP """ def __init__(self, directory, mode="a"): self.directory = directory self.mode = mode self._keys = set() if not os.path.exists(self.directory): os.makedirs(self.directory, exist_ok=True) else: for n in os.listdir(self.directory): self._keys.add(_unsafe_key(n)) def __str__(self): return '<File: %s, mode="%s", %d elements>' % ( self.directory, self.mode, len(self), ) __repr__ = __str__ def __getitem__(self, key): if key not in self._keys: raise KeyError(key) with open(os.path.join(self.directory, _safe_key(key)), "rb") as f: return f.read() def __setitem__(self, key, value): with open(os.path.join(self.directory, _safe_key(key)), "wb") as f: if isinstance(value, (tuple, list)): for v in value: f.write(v) else: f.write(value) self._keys.add(key) def __contains__(self, key): return key in self._keys
[docs] def keys(self): return iter(self._keys)
__iter__ = keys def __delitem__(self, key): if key not in self._keys: raise KeyError(key) os.remove(os.path.join(self.directory, _safe_key(key))) self._keys.remove(key) def __len__(self): return len(self._keys)