SparseArray¶
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class
SparseArray
¶ This class records a set of integers, where each integer is either present or not present in the set.
It is similar in principle and in interface to a
BitArray
(which can be thought of as a set of integers, one integer corresponding to each different bit position), but the SparseArray is implemented as a list of min/max subrange lists, rather than as a bitmask.This makes it particularly efficient for storing sets which consist of large sections of consecutively included or consecutively excluded elements, with arbitrarily large integers, but particularly inefficient for doing boolean operations such as & or |.
Also, unlike
BitArray
, the SparseArray can store negative integers.Inheritance diagram
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SparseArray
(void)¶
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SparseArray
(SparseArray const&) = default¶
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SparseArray
all_off
(void)¶ Returns a
SparseArray
whose bits are all off.
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SparseArray
all_on
(void)¶ Returns a
SparseArray
with an infinite array of bits, all on.
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SparseArray
bit
(int index)¶ Returns a
SparseArray
with only the indicated bit on.
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void
clear
(void)¶ Sets all the bits in the
SparseArray
off.
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void
clear_bit
(int index)¶ Sets the nth bit off. If n >=
get_num_bits()
, this automatically extends the array.
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void
clear_range
(int low_bit, int size)¶ Sets the indicated range of bits off.
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int
compare_to
(SparseArray const &other) const¶ Returns a number less than zero if this
SparseArray
sorts before the indicated otherSparseArray
, greater than zero if it sorts after, or 0 if they are equivalent. This is based on the same ordering defined by operator <.
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bool
get_bit
(int index) const¶ Returns true if the nth bit is set, false if it is cleared. It is valid for n to increase beyond
get_num_bits()
, but the return valueget_num_bits()
will always be the same.
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static TypeHandle
get_class_type
(void)¶
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bool
get_highest_bits
(void) const¶ Returns true if the infinite set of bits beyond
get_num_bits()
are all on, or false of they are all off.
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int
get_highest_off_bit
(void) const¶ Returns the index of the highest 0 bit in the array. Returns -1 if there are no 0 bits or if there an infinite number of 1 bits.
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int
get_highest_on_bit
(void) const¶ Returns the index of the highest 1 bit in the array. Returns -1 if there are no 1 bits or if there an infinite number of 1 bits.
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int
get_lowest_off_bit
(void) const¶ Returns the index of the lowest 0 bit in the array. Returns -1 if there are no 0 bits or if there are an infinite number of 1 bits.
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int
get_lowest_on_bit
(void) const¶ Returns the index of the lowest 1 bit in the array. Returns -1 if there are no 1 bits or if there are an infinite number of 1 bits.
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int
get_max_num_bits
(void)¶ If get_max_num_bits() returned true, this method may be called to return the maximum number of bits that may be stored in this structure. It is an error to call this if get_max_num_bits() return false.
It is always an error to call this method. The
SparseArray
has no maximum number of bits. This method is defined so generic programming algorithms can use BitMask orSparseArray
interchangeably.
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int
get_next_higher_different_bit
(int low_bit) const¶ Returns the index of the next bit in the array, above low_bit, whose value is different that the value of low_bit. Returns low_bit again if all bits higher than low_bit have the same value.
This can be used to quickly iterate through all of the bits in the array.
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int
get_num_bits
(void) const¶ Returns the current number of possibly different bits in this array. There are actually an infinite number of bits, but every bit higher than this bit will have the same value, either 0 or 1 (see
get_highest_bits()
).This number may grow and/or shrink automatically as needed.
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int
get_num_off_bits
(void) const¶ Returns the number of bits that are set to 0 in the array. Returns -1 if there are an infinite number of 0 bits.
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int
get_num_on_bits
(void) const¶ Returns the number of bits that are set to 1 in the array. Returns -1 if there are an infinite number of 1 bits.
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std::size_t
get_num_subranges
(void) const¶ Returns the number of separate subranges stored in the
SparseArray
. You can use this limit to iterate through the subranges, callingget_subrange_begin()
andget_subrange_end()
for each one.Also see
is_inverse()
.
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int
get_subrange_begin
(std::size_t n) const¶ Returns the first numeric element in the nth subrange.
Also see
is_inverse()
.
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int
get_subrange_end
(std::size_t n) const¶ Returns the last numeric element, plus one, in the nth subrange.
Also see
is_inverse()
.
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bool
has_all_of
(int low_bit, int size) const¶ Returns true if all bits in the indicated range are set, false otherwise.
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bool
has_any_of
(int low_bit, int size) const¶ Returns true if any bit in the indicated range is set, false otherwise.
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bool
has_bits_in_common
(SparseArray const &other) const¶ Returns true if this
SparseArray
has any “one” bits in common with the other one, false otherwise.This is equivalent to (array & other) != 0, but may be faster.
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bool
has_max_num_bits
(void)¶ Returns true if there is a maximum number of bits that may be stored in this structure, false otherwise. If this returns true, the number may be queried in
get_max_num_bits()
.This method always returns false. The
SparseArray
has no maximum number of bits. This method is defined so generic programming algorithms can use BitMask orSparseArray
interchangeably.
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void
invert_in_place
(void)¶ Inverts all the bits in the
SparseArray
. This is equivalent to array = ~array.
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bool
is_all_on
(void) const¶ Returns true if the entire bitmask is one, false otherwise.
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bool
is_inverse
(void) const¶ If this is true, the
SparseArray
is actually defined as a list of subranges of integers that are not in the set. If this is false (the default), then the subranges define the integers that are in the set. This affects the interpretation of the values returned by iterating throughget_num_subranges()
.
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bool
is_zero
(void) const¶ Returns true if the entire bitmask is zero, false otherwise.
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SparseArray
lower_on
(int on_bits)¶ Returns a
SparseArray
whose lower on_bits bits are on.
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void
output
(std::ostream &out) const¶
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SparseArray
range
(int low_bit, int size)¶ Returns a
SparseArray
whose size bits, beginning at low_bit, are on.
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void
set_bit
(int index)¶ Sets the nth bit on. If n >=
get_num_bits()
, this automatically extends the array.
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void
set_bit_to
(int index, bool value)¶ Sets the nth bit either on or off, according to the indicated bool value.
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void
set_range
(int low_bit, int size)¶ Sets the indicated range of bits on.
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void
set_range_to
(bool value, int low_bit, int size)¶ Sets the indicated range of bits to either on or off.
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