143 lines
4.3 KiB
Python
143 lines
4.3 KiB
Python
# Copyright 2007 Matt Chaput. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY MATT CHAPUT ``AS IS'' AND ANY EXPRESS OR
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# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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# EVENT SHALL MATT CHAPUT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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# OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and documentation are
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# those of the authors and should not be interpreted as representing official
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# policies, either expressed or implied, of Matt Chaput.
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from __future__ import with_statement
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import random, sys, time
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from bisect import insort, bisect_left
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from functools import wraps
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from whoosh.compat import xrange
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# These must be valid separate characters in CASE-INSENSTIVE filenames
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IDCHARS = "0123456789abcdefghijklmnopqrstuvwxyz"
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if hasattr(time, "perf_counter"):
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now = time.perf_counter
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elif sys.platform == 'win32':
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now = time.clock
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else:
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now = time.time
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def random_name(size=28):
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return "".join(random.choice(IDCHARS) for _ in xrange(size))
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def random_bytes(size=28):
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gen = (random.randint(0, 255) for _ in xrange(size))
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if sys.version_info[0] >= 3:
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return bytes(gen)
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else:
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return array("B", gen).tostring()
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def make_binary_tree(fn, args, **kwargs):
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"""Takes a function/class that takes two positional arguments and a list of
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arguments and returns a binary tree of results/instances.
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>>> make_binary_tree(UnionMatcher, [matcher1, matcher2, matcher3])
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UnionMatcher(matcher1, UnionMatcher(matcher2, matcher3))
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Any keyword arguments given to this function are passed to the class
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initializer.
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"""
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count = len(args)
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if not count:
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raise ValueError("Called make_binary_tree with empty list")
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elif count == 1:
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return args[0]
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half = count // 2
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return fn(make_binary_tree(fn, args[:half], **kwargs),
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make_binary_tree(fn, args[half:], **kwargs), **kwargs)
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def make_weighted_tree(fn, ls, **kwargs):
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"""Takes a function/class that takes two positional arguments and a list of
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(weight, argument) tuples and returns a huffman-like weighted tree of
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results/instances.
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"""
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if not ls:
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raise ValueError("Called make_weighted_tree with empty list")
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ls.sort()
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while len(ls) > 1:
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a = ls.pop(0)
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b = ls.pop(0)
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insort(ls, (a[0] + b[0], fn(a[1], b[1])))
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return ls[0][1]
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# Fibonacci function
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_fib_cache = {}
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def fib(n):
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"""Returns the nth value in the Fibonacci sequence.
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"""
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if n <= 2:
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return n
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if n in _fib_cache:
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return _fib_cache[n]
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result = fib(n - 1) + fib(n - 2)
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_fib_cache[n] = result
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return result
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# Decorators
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def synchronized(func):
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"""Decorator for storage-access methods, which synchronizes on a threading
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lock. The parent object must have 'is_closed' and '_sync_lock' attributes.
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"""
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@wraps(func)
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def synchronized_wrapper(self, *args, **kwargs):
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with self._sync_lock:
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return func(self, *args, **kwargs)
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return synchronized_wrapper
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def unclosed(method):
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"""
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Decorator to check if the object is closed.
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"""
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@wraps(method)
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def unclosed_wrapper(self, *args, **kwargs):
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if self.closed:
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raise ValueError("Operation on a closed object")
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return method(self, *args, **kwargs)
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return unclosed_wrapper
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