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#ifndef BITVECTOR_H
#define BITVECTOR_H
#include <cstdint>
#include <vector>
#include <terraces/trees.hpp>
#include "bits.hpp"
#include "stack_allocator.hpp"
namespace terraces {
template <typename Bitvector>
class bitvector_iterator;
template <typename Allocator>
class basic_bitvector {
public:
using value_type = index;
using iterator = bitvector_iterator<Allocator>;
static index alloc_size(index size) { return size / bits::word_bits + 1; }
protected:
index m_size;
std::vector<value_type, Allocator> m_blocks;
void add_sentinel() {
// add sentinel bit for iteration
m_blocks[bits::block_index(m_size)] |= bits::set_mask(m_size);
}
public:
/** Initializes a bitvector with given size. */
basic_bitvector(index size, Allocator alloc)
: m_size{size}, m_blocks(alloc_size(size), 0, alloc) {
add_sentinel();
}
/** Sets a bit in the bitvector. */
void set(index i) {
assert(i < m_size);
m_blocks[bits::block_index(i)] |= bits::set_mask(i);
}
/** Clears a bit in the bitvector. */
void clr(index i) {
assert(i < m_size);
m_blocks[bits::block_index(i)] &= bits::clear_mask(i);
}
/** Flips a bit in the bitvector. */
void flip(index i) {
assert(i < m_size);
m_blocks[bits::block_index(i)] ^= bits::set_mask(i);
}
/** Returns a bit from the bitvector. */
bool get(index i) const {
assert(i < m_size);
return ((m_blocks[bits::block_index(i)] >> bits::shift_index(i)) & 1) != 0u;
}
/** Returns the size of the bitvector. */
index size() const { return m_size; }
/** Returns true if and only if no bit is set. */
bool empty() const;
/** Clears all bits in the bitvector. */
void blank();
/** Inverts all bits in the bitvector. */
void invert();
/** Applies element-wise xor from another bitvector. */
void bitwise_xor(const basic_bitvector<Allocator>& other);
/** Sets the values of this bitvector to the bitwise or of two bitvectors. */
void set_bitwise_or(const basic_bitvector<Allocator>& fst,
const basic_bitvector<Allocator>& snd);
/** Returns the index of the first set bit or size() if no bit is set. */
index first_set() const;
/** Returns the index of the next set bit after the index or size() if no bit is set. */
index next_set(index i) const;
/** Returns the index one past the last element. */
index last_set() const { return m_size; }
iterator begin() const;
iterator end() const;
Allocator get_allocator() const { return m_blocks.get_allocator(); }
bool operator<(const basic_bitvector<Allocator>& other) const {
assert(size() == other.size());
return m_blocks < other.m_blocks;
}
bool operator==(const basic_bitvector<Allocator>& other) const {
assert(size() == other.size());
return m_blocks == other.m_blocks;
}
bool operator!=(const basic_bitvector<Allocator>& other) const { return !(*this == other); }
};
using bitvector = basic_bitvector<utils::stack_allocator<index>>;
using simple_bitvector = basic_bitvector<std::allocator<bitvector::value_type>>;
template <typename Alloc>
class bitvector_iterator {
public:
using value_type = typename Alloc::value_type;
private:
const basic_bitvector<Alloc>& m_set;
index m_index;
public:
bitvector_iterator(const basic_bitvector<Alloc>& set, index i) : m_set{set}, m_index{i} {}
bitvector_iterator& operator++() {
m_index = m_set.next_set(m_index);
return *this;
}
bool operator==(const bitvector_iterator& other) const { return m_index == other.m_index; }
bool operator!=(const bitvector_iterator& other) const { return !(*this == other); }
const index& operator*() const { return m_index; }
};
template <typename Alloc>
auto basic_bitvector<Alloc>::begin() const -> iterator {
return {*this, first_set()};
}
template <typename Alloc>
auto basic_bitvector<Alloc>::end() const -> iterator {
return {*this, last_set()};
}
template <typename Alloc>
bool basic_bitvector<Alloc>::empty() const {
for (index b = 0; b < m_blocks.size() - 1; ++b) {
if (m_blocks[b]) {
return false;
}
}
return !(m_blocks[m_blocks.size() - 1] & bits::prefix_mask(bits::shift_index(m_size)));
}
template <typename Alloc>
void basic_bitvector<Alloc>::blank() {
for (auto& el : m_blocks) {
el = 0;
}
add_sentinel();
}
template <typename Alloc>
void basic_bitvector<Alloc>::bitwise_xor(const basic_bitvector<Alloc>& other) {
assert(size() == other.size());
for (index b = 0; b < m_blocks.size(); ++b) {
m_blocks[b] ^= other.m_blocks[b];
}
add_sentinel();
}
template <typename Alloc>
void basic_bitvector<Alloc>::invert() {
for (index b = 0; b < m_blocks.size() - 1; ++b) {
m_blocks[b] = ~m_blocks[b];
}
m_blocks[m_blocks.size() - 1] ^= bits::prefix_mask(bits::shift_index(m_size));
}
template <typename Alloc>
void basic_bitvector<Alloc>::set_bitwise_or(const basic_bitvector<Alloc>& fst,
const basic_bitvector<Alloc>& snd) {
assert(size() == fst.size() && size() == snd.size());
for (index b = 0; b < m_blocks.size(); ++b) {
m_blocks[b] = fst.m_blocks[b] | snd.m_blocks[b];
}
}
template <typename Alloc>
index basic_bitvector<Alloc>::first_set() const {
index b = 0;
while (!bits::has_next_bit0(m_blocks[b])) {
++b;
}
return bits::next_bit0(m_blocks[b], bits::base_index(b));
}
template <typename Alloc>
index basic_bitvector<Alloc>::next_set(index i) const {
++i;
index b = bits::block_index(i);
if (bits::has_next_bit(m_blocks[b], i)) {
// the next bit is in the current block
return bits::next_bit(m_blocks[b], i);
}
// the next bit is in a far-away block
do {
++b;
} while (!bits::has_next_bit0(m_blocks[b]));
return bits::next_bit0(m_blocks[b], bits::base_index(b));
}
/** Returns a bitvector containing size elements. */
template <typename Alloc>
basic_bitvector<Alloc> full_set(index size, Alloc a) {
basic_bitvector<Alloc> set{size, a};
set.invert();
return set;
}
} // namespace terraces
#endif // BITVECTOR_H
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