2fd2c9bfd6
dm-verity may touch some blocks that are not in the care_map due to block device read-ahead. It will fail if such blocks contain non-zeroes. As a workaround, we mark them as extended blocks and zero out explicitly to avoid dm-verity failures. Bug: 20881595 Change-Id: I54e24e70ad822c0d6d7af43301f74d24505f4461
266 lines
7.5 KiB
Python
266 lines
7.5 KiB
Python
# Copyright (C) 2014 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import print_function
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import heapq
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import itertools
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__all__ = ["RangeSet"]
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class RangeSet(object):
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"""A RangeSet represents a set of nonoverlapping ranges on the
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integers (ie, a set of integers, but efficient when the set contains
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lots of runs."""
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def __init__(self, data=None):
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self.monotonic = False
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if isinstance(data, str):
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self._parse_internal(data)
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elif data:
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self.data = tuple(self._remove_pairs(data))
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else:
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self.data = ()
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def __iter__(self):
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for i in range(0, len(self.data), 2):
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yield self.data[i:i+2]
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def __eq__(self, other):
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return self.data == other.data
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def __ne__(self, other):
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return self.data != other.data
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def __nonzero__(self):
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return bool(self.data)
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def __str__(self):
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if not self.data:
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return "empty"
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else:
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return self.to_string()
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def __repr__(self):
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return '<RangeSet("' + self.to_string() + '")>'
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@classmethod
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def parse(cls, text):
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"""Parse a text string consisting of a space-separated list of
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blocks and ranges, eg "10-20 30 35-40". Ranges are interpreted to
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include both their ends (so the above example represents 18
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individual blocks. Returns a RangeSet object.
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If the input has all its blocks in increasing order, then returned
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RangeSet will have an extra attribute 'monotonic' that is set to
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True. For example the input "10-20 30" is monotonic, but the input
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"15-20 30 10-14" is not, even though they represent the same set
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of blocks (and the two RangeSets will compare equal with ==).
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"""
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return cls(text)
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def _parse_internal(self, text):
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data = []
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last = -1
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monotonic = True
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for p in text.split():
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if "-" in p:
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s, e = p.split("-")
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data.append(int(s))
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data.append(int(e)+1)
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if last <= s <= e:
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last = e
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else:
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monotonic = False
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else:
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s = int(p)
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data.append(s)
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data.append(s+1)
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if last <= s:
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last = s+1
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else:
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monotonic = True
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data.sort()
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self.data = tuple(self._remove_pairs(data))
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self.monotonic = monotonic
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@staticmethod
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def _remove_pairs(source):
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last = None
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for i in source:
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if i == last:
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last = None
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else:
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if last is not None:
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yield last
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last = i
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if last is not None:
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yield last
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def to_string(self):
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out = []
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for i in range(0, len(self.data), 2):
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s, e = self.data[i:i+2]
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if e == s+1:
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out.append(str(s))
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else:
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out.append(str(s) + "-" + str(e-1))
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return " ".join(out)
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def to_string_raw(self):
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return str(len(self.data)) + "," + ",".join(str(i) for i in self.data)
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def union(self, other):
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"""Return a new RangeSet representing the union of this RangeSet
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with the argument.
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>>> RangeSet("10-19 30-34").union(RangeSet("18-29"))
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<RangeSet("10-34")>
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>>> RangeSet("10-19 30-34").union(RangeSet("22 32"))
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<RangeSet("10-19 22 30-34")>
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"""
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out = []
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z = 0
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for p, d in heapq.merge(zip(self.data, itertools.cycle((+1, -1))),
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zip(other.data, itertools.cycle((+1, -1)))):
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if (z == 0 and d == 1) or (z == 1 and d == -1):
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out.append(p)
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z += d
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return RangeSet(data=out)
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def intersect(self, other):
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"""Return a new RangeSet representing the intersection of this
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RangeSet with the argument.
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>>> RangeSet("10-19 30-34").intersect(RangeSet("18-32"))
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<RangeSet("18-19 30-32")>
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>>> RangeSet("10-19 30-34").intersect(RangeSet("22-28"))
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<RangeSet("")>
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"""
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out = []
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z = 0
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for p, d in heapq.merge(zip(self.data, itertools.cycle((+1, -1))),
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zip(other.data, itertools.cycle((+1, -1)))):
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if (z == 1 and d == 1) or (z == 2 and d == -1):
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out.append(p)
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z += d
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return RangeSet(data=out)
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def subtract(self, other):
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"""Return a new RangeSet representing subtracting the argument
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from this RangeSet.
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>>> RangeSet("10-19 30-34").subtract(RangeSet("18-32"))
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<RangeSet("10-17 33-34")>
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>>> RangeSet("10-19 30-34").subtract(RangeSet("22-28"))
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<RangeSet("10-19 30-34")>
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"""
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out = []
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z = 0
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for p, d in heapq.merge(zip(self.data, itertools.cycle((+1, -1))),
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zip(other.data, itertools.cycle((-1, +1)))):
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if (z == 0 and d == 1) or (z == 1 and d == -1):
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out.append(p)
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z += d
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return RangeSet(data=out)
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def overlaps(self, other):
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"""Returns true if the argument has a nonempty overlap with this
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RangeSet.
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>>> RangeSet("10-19 30-34").overlaps(RangeSet("18-32"))
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True
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>>> RangeSet("10-19 30-34").overlaps(RangeSet("22-28"))
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False
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"""
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# This is like intersect, but we can stop as soon as we discover the
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# output is going to be nonempty.
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z = 0
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for _, d in heapq.merge(zip(self.data, itertools.cycle((+1, -1))),
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zip(other.data, itertools.cycle((+1, -1)))):
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if (z == 1 and d == 1) or (z == 2 and d == -1):
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return True
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z += d
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return False
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def size(self):
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"""Returns the total size of the RangeSet (ie, how many integers
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are in the set).
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>>> RangeSet("10-19 30-34").size()
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15
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"""
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total = 0
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for i, p in enumerate(self.data):
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if i % 2:
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total += p
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else:
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total -= p
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return total
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def map_within(self, other):
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"""'other' should be a subset of 'self'. Returns a RangeSet
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representing what 'other' would get translated to if the integers
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of 'self' were translated down to be contiguous starting at zero.
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>>> RangeSet("0-9").map_within(RangeSet("3-4"))
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<RangeSet("3-4")>
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>>> RangeSet("10-19").map_within(RangeSet("13-14"))
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<RangeSet("3-4")>
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>>> RangeSet("10-19 30-39").map_within(RangeSet("17-19 30-32"))
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<RangeSet("7-12")>
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>>> RangeSet("10-19 30-39").map_within(RangeSet("12-13 17-19 30-32"))
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<RangeSet("2-3 7-12")>
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"""
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out = []
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offset = 0
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start = None
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for p, d in heapq.merge(zip(self.data, itertools.cycle((-5, +5))),
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zip(other.data, itertools.cycle((-1, +1)))):
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if d == -5:
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start = p
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elif d == +5:
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offset += p-start
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start = None
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else:
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out.append(offset + p - start)
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return RangeSet(data=out)
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def extend(self, n):
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"""Extend the RangeSet by 'n' blocks.
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The lower bound is guaranteed to be non-negative.
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>>> RangeSet("0-9").extend(1)
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<RangeSet("0-10")>
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>>> RangeSet("10-19").extend(15)
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<RangeSet("0-34")>
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>>> RangeSet("10-19 30-39").extend(4)
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<RangeSet("6-23 26-43")>
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>>> RangeSet("10-19 30-39").extend(10)
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<RangeSet("0-49")>
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"""
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out = self
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for i in range(0, len(self.data), 2):
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s, e = self.data[i:i+2]
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s1 = max(0, s - n)
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e1 = e + n
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out = out.union(RangeSet(str(s1) + "-" + str(e1-1)))
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return out
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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