# BitArray¶

class BitArray

A dynamic array with an unlimited number of bits.

This is similar to a BitMask, except it appears to contain an infinite number of bits. You can use it very much as you would use a BitMask.

Inheritance diagram

BitArray(void)
BitArray(BitArray::WordType init_value)
BitArray(SparseArray const &from)
BitArray(BitArray const&) = default
BitArray all_off(void)

Returns a BitArray whose bits are all off.

BitArray all_on(void)

Returns a BitArray with an infinite array of bits, all on.

BitArray bit(int index)

Returns a BitArray with only the indicated bit on.

void clear(void)

Sets all the bits in the BitArray off.

void clear_bit(int index)

Sets the nth bit off. If n >= get_num_bits(), this automatically extends the array.

void clear_range(int low_bit, int size)

Sets the indicated range of bits off.

int compare_to(BitArray const &other) const

Returns a number less than zero if this BitArray sorts before the indicated other BitArray, greater than zero if it sorts after, or 0 if they are equivalent. This is based on the same ordering defined by operator <.

WordType extract(int low_bit, int size) const

Returns a word that represents only the indicated range of bits within this BitArray, shifted to the least-significant position. size must be <= get_num_bits_per_word().

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 value get_num_bits() will always be the same.

static TypeHandle get_class_type(void)
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.

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.

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.

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.

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.

static constexpr int get_max_num_bits(void)
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.

std::size_t 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.

static constexpr int get_num_bits_per_word(void)
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.

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.

std::size_t get_num_words(void) const

Returns the number of possibly-unique words stored in the array.

MaskType get_word(std::size_t n) const

Returns the nth word in the array. It is valid for n to be greater than get_num_words(), but the return value beyond get_num_words() will always be the same.

bool has_all_of(int low_bit, int size) const

Returns true if all bits in the indicated range are set, false otherwise.

bool has_any_of(int low_bit, int size) const

Returns true if any bit in the indicated range is set, false otherwise.

bool has_bits_in_common(BitArray const &other) const

Returns true if this BitArray has any “one” bits in common with the other one, false otherwise.

This is equivalent to (array & other) != 0, but may be faster.

static constexpr bool has_max_num_bits(void)
void invert_in_place(void)

Inverts all the bits in the BitArray. This is equivalent to array = ~array.

bool is_all_on(void) const

Returns true if the entire bitmask is one, false otherwise.

bool is_zero(void) const

Returns true if the entire bitmask is zero, false otherwise.

BitArray lower_on(int on_bits)

Returns a BitArray whose lower on_bits bits are on.

void output(std::ostream &out) const

Writes the BitArray out as a hex number. For a BitArray, this is always the same as output_hex(); it’s too confusing for the output format to change back and forth at runtime.

void output_binary(std::ostream &out, int spaces_every = 4) const

Writes the BitArray out as a binary number, with spaces every four bits.

void output_hex(std::ostream &out, int spaces_every = 4) const

Writes the BitArray out as a hexadecimal number, with spaces every four digits.

BitArray range(int low_bit, int size)

Returns a BitArray whose size bits, beginning at low_bit, are on.

void set_bit(int index)

Sets the nth bit on. If n >= get_num_bits(), this automatically extends the array.

void set_bit_to(int index, bool value)

Sets the nth bit either on or off, according to the indicated bool value.

void set_range(int low_bit, int size)

Sets the indicated range of bits on.

void set_range_to(bool value, int low_bit, int size)

Sets the indicated range of bits to either on or off.

void set_word(std::size_t n, WordType value)

Replaces the nth word in the array. If n >= get_num_words(), this automatically extends the array.

void store(BitArray::WordType value, int low_bit, int size)

Stores the indicated word into the indicated range of bits with this BitArray.

void write(std::ostream &out, int indent_level = 0) const

Writes the BitArray out as a binary or a hex number, according to the number of bits.