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import os
import string
import random
import mmap
import sys
DATATYPES = dict(
ascii_letters=string.ascii_letters.encode(),
ascii_lowercase=string.ascii_lowercase.encode(),
ascii_uppercase=string.ascii_uppercase.encode(),
digits=string.digits.encode(),
hexdigits=string.hexdigits.encode(),
octdigits=string.octdigits.encode(),
punctuation=string.punctuation.encode(),
whitespace=string.whitespace.encode(),
ascii=string.printable.encode(),
bytes=bytes(range(256))
)
class TransformGenerator:
"""
Perform a byte-by-byte transform another generator - that is, for each
input byte, the transformation must produce one output byte.
gen: A generator to wrap
transform: A function (offset, data) -> transformed
"""
def __init__(self, gen, transform):
self.gen = gen
self.transform = transform
def __len__(self):
return len(self.gen)
def __getitem__(self, x):
d = self.gen.__getitem__(x)
if isinstance(x, slice):
return self.transform(x.start, d)
return self.transform(x, d)
def __repr__(self):
return "'transform(%s)'" % self.gen
def rand_byte(chars):
"""
Return a random character as byte from a charset.
"""
# bytearray has consistent behaviour on both Python 2 and 3
# while bytes does not
return bytes([random.choice(chars)])
class RandomGenerator:
def __init__(self, dtype, length):
self.dtype = dtype
self.length = length
def __len__(self):
return self.length
def __getitem__(self, x):
chars = DATATYPES[self.dtype]
if isinstance(x, slice):
return b"".join(rand_byte(chars) for _ in range(*x.indices(min(self.length, sys.maxsize))))
return rand_byte(chars)
def __repr__(self):
return "%s random from %s" % (self.length, self.dtype)
class FileGenerator:
def __init__(self, path):
self.path = os.path.expanduser(path)
def __len__(self):
return os.path.getsize(self.path)
def __getitem__(self, x):
with open(self.path, mode="rb") as f:
if isinstance(x, slice):
with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mapped:
return mapped.__getitem__(x)
else:
f.seek(x)
return f.read(1)
def __repr__(self):
return "<%s" % self.path
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