1 # Copyright 2013 The Chromium Authors. All rights reserved.
2 # Use of this source code is governed by a BSD-style license that can be
3 # found in the LICENSE file.
8 _BASE_PATH
= os
.path
.dirname(os
.path
.dirname(os
.path
.abspath(__file__
)))
9 _BINTREES_PATH
= os
.path
.join(
10 _BASE_PATH
, os
.pardir
, os
.pardir
, 'third_party', 'bintrees')
11 sys
.path
.insert(0, _BINTREES_PATH
)
13 from bintrees
import FastRBTree
# pylint: disable=F0401
16 class ExclusiveRangeDict(object):
17 """A class like dict whose key is a range [begin, end) of integers.
19 It has an attribute for each range of integers, for example:
20 [10, 20) => Attribute(0),
21 [20, 40) => Attribute(1),
22 [40, 50) => Attribute(2),
25 An instance of this class is accessed only via iter_range(begin, end).
26 The instance is accessed as follows:
28 1) If the given range [begin, end) is not covered by the instance,
29 the range is newly created and iterated.
31 2) If the given range [begin, end) exactly covers ranges in the instance,
32 the ranges are iterated.
33 (See test_set() in tests/range_dict_tests.py.)
35 3) If the given range [begin, end) starts at and/or ends at a mid-point of
36 an existing range, the existing range is split by the given range, and
37 ranges in the given range are iterated. For example, consider a case that
38 [25, 45) is given to an instance of [20, 30), [30, 40), [40, 50). In this
39 case, [20, 30) is split into [20, 25) and [25, 30), and [40, 50) into
40 [40, 45) and [45, 50). Then, [25, 30), [30, 40), [40, 45) are iterated.
41 (See test_split() in tests/range_dict_tests.py.)
43 4) If the given range [begin, end) includes non-existing ranges in an
44 instance, the gaps are filled with new ranges, and all ranges are iterated.
45 For example, consider a case that [25, 50) is given to an instance of
46 [30, 35) and [40, 45). In this case, [25, 30), [35, 40) and [45, 50) are
47 created in the instance, and then [25, 30), [30, 35), [35, 40), [40, 45)
48 and [45, 50) are iterated.
49 (See test_fill() in tests/range_dict_tests.py.)
51 class RangeAttribute(object):
56 return '<RangeAttribute>'
59 return '<RangeAttribute>'
61 def copy(self
): # pylint: disable=R0201
62 return ExclusiveRangeDict
.RangeAttribute()
64 def __init__(self
, attr
=RangeAttribute
):
65 self
._tree
= FastRBTree()
68 def iter_range(self
, begin
=None, end
=None):
70 begin
= self
._tree
.min_key()
72 end
= self
._tree
.max_item()[1][0]
74 # Assume that self._tree has at least one element.
75 if self
._tree
.is_empty():
76 self
._tree
[begin
] = (end
, self
._attr
())
78 # Create a beginning range (border)
80 bound_begin
, bound_value
= self
._tree
.floor_item(begin
)
81 bound_end
= bound_value
[0]
82 if begin
>= bound_end
:
83 # Create a blank range.
85 new_end
, _
= self
._tree
.succ_item(bound_begin
)
88 self
._tree
[begin
] = (min(end
, new_end
), self
._attr
())
89 elif bound_begin
< begin
and begin
< bound_end
:
90 # Split the existing range.
91 new_end
= bound_value
[0]
92 new_value
= bound_value
[1]
93 self
._tree
[bound_begin
] = (begin
, new_value
.copy())
94 self
._tree
[begin
] = (new_end
, new_value
.copy())
95 else: # bound_begin == begin
96 # Do nothing (just saying it clearly since this part is confusing)
98 except KeyError: # begin is less than the smallest element.
99 # Create a blank range.
100 # Note that we can assume self._tree has at least one element.
101 self
._tree
[begin
] = (min(end
, self
._tree
.min_key()), self
._attr
())
103 # Create an ending range (border)
105 bound_begin
, bound_value
= self
._tree
.floor_item(end
)
106 bound_end
= bound_value
[0]
108 # Create a blank range.
109 new_begin
= bound_end
110 self
._tree
[new_begin
] = (end
, self
._attr
())
111 elif bound_begin
< end
and end
< bound_end
:
112 # Split the existing range.
113 new_end
= bound_value
[0]
114 new_value
= bound_value
[1]
115 self
._tree
[bound_begin
] = (end
, new_value
.copy())
116 self
._tree
[end
] = (new_end
, new_value
.copy())
117 else: # bound_begin == begin
118 # Do nothing (just saying it clearly since this part is confusing)
120 except KeyError: # end is less than the smallest element.
121 # It must not happen. A blank range [begin,end) has already been created
122 # even if [begin,end) is less than the smallest range.
123 # Do nothing (just saying it clearly since this part is confusing)
129 for range_begin
, range_value
in self
._tree
.itemslice(begin
, end
):
130 range_end
= range_value
[0]
131 # Note that we can assume that we have a range beginning with |begin|
132 # and a range ending with |end| (they may be the same range).
133 if prev_end
and prev_end
!= range_begin
:
134 missing_ranges
.append((prev_end
, range_begin
))
137 for missing_begin
, missing_end
in missing_ranges
:
138 self
._tree
[missing_begin
] = (missing_end
, self
._attr
())
140 for range_begin
, range_value
in self
._tree
.itemslice(begin
, end
):
141 yield range_begin
, range_value
[0], range_value
[1]
144 return str(self
._tree
)