/usr/include/sdsl/bit_vector_il.hpp is in libsdsl-dev 2.0.3-4.
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Copyright (C) 2012 Simon Gog, Matthias Petri
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/ .
*/
/*!\file bit_vector_il.hpp
\brief bit_vector_il.hpp contains the sdsl::bit_vector_il class, and
classes which support rank and select for bit_vector_il.
\author Matthias Petri, Simon Gog
*/
#ifndef SDSL_BIT_VECTOR_IL
#define SDSL_BIT_VECTOR_IL
#include "int_vector.hpp"
#include "util.hpp"
#include "iterators.hpp"
#include <queue>
//! Namespace for the succinct data structure library
namespace sdsl
{
template<uint8_t t_b=1,uint32_t t_bs=512>// forward declaration needed for friend declaration
class rank_support_il; // in bit_vector_il
template<uint8_t t_b=1,uint32_t t_bs=512>// forward declaration needed for friend declaration
class select_support_il; // in bit_vector_il
template<class T>
constexpr bool power_of_two(T x)
{
return std::is_integral<T>::value and x > 1 and
!(x&(x-1));
}
//! A bit vector which interleaves the original bit_vector with rank information.
/*!
* This class is a uncompressed bit vector representation. It copies the original
* bit_vector and interleaves the data every t_bs bits with a cumulative
* sum of set bits before the current position. Each cumulative sum is stored
* in a 64 bit word.
*
* \tparam t_bs Block size in bits. t_bs has to be a power of 2 and t_bs >= 64.
*/
template<uint32_t t_bs=512>
class bit_vector_il
{
static_assert(t_bs >= 64 , "bit_vector_il: blocksize must be be at least 64 bits.");
static_assert(power_of_two(t_bs), "bit_vector_il: blocksize must be a power of two.");
public:
typedef bit_vector::size_type size_type;
typedef size_type value_type;
typedef bit_vector::difference_type difference_type;
typedef random_access_const_iterator<bit_vector_il> iterator;
typedef bv_tag index_category;
friend class rank_support_il<1,t_bs>;
friend class rank_support_il<0,t_bs>;
friend class select_support_il<1,t_bs>;
friend class select_support_il<0,t_bs>;
typedef rank_support_il<1,t_bs> rank_1_type;
typedef rank_support_il<0,t_bs> rank_0_type;
typedef select_support_il<1,t_bs> select_1_type;
typedef select_support_il<0,t_bs> select_0_type;
private:
size_type m_size = 0; //!< Size of the original bitvector
size_type m_block_num = 0; //!< Total size of m_data in uint64_t ss
size_type m_superblocks = 0; //!< Number of superblocks
size_type m_block_shift = 0;
int_vector<64> m_data; //!< Data container
int_vector<64> m_rank_samples;//!< Space for additional rank samples
// precondition: m_rank_samples.size() <= m_superblocks
void init_rank_samples() {
uint32_t blockSize_U64 = bits::hi(t_bs>>6);
size_type idx = 0;
std::queue<size_type> lbs, rbs;
lbs.push(0); rbs.push(m_superblocks);
while (!lbs.empty()) {
size_type lb = lbs.front(); lbs.pop();
size_type rb = rbs.front(); rbs.pop();
if (/*lb < rb and*/ idx < m_rank_samples.size()) {
size_type mid = lb + (rb-lb)/2; // select mid \in [lb..rb)
size_type pos = (mid << blockSize_U64) + mid;
m_rank_samples[ idx++ ] = m_data[pos];
lbs.push(lb); rbs.push(mid);
lbs.push(mid+1); rbs.push(rb);
}
}
}
public:
bit_vector_il() {}
bit_vector_il(const bit_vector_il&) = default;
bit_vector_il(bit_vector_il&&) = default;
bit_vector_il& operator=(const bit_vector_il&) = default;
bit_vector_il& operator=(bit_vector_il&&) = default;
bit_vector_il(const bit_vector& bv) {
m_size = bv.size();
/* calculate the number of superblocks */
// each block of size > 0 gets suberblock in which we store the cumulative sum up to this block
m_superblocks = (m_size+t_bs) / t_bs;
m_block_shift = bits::hi(t_bs);
/* allocate new data */
size_type blocks = (m_size+64)/64;
size_type mem = blocks + m_superblocks + 1;
// ^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^ ^
// bit vector data | cum. sum data | sum after last block
m_data = int_vector<64>(mem);
m_block_num = mem;
/* assign data and calculate super block values */
const uint64_t* bvp = bv.data();
size_type j = 0; // 64-bit word counter in the m_data
size_type cum_sum = 0;
size_type sample_rate = t_bs/64;
for (size_type i=0, sample_cnt=sample_rate; i < blocks; ++i, ++sample_cnt) {
if (sample_cnt == sample_rate) {
m_data[j] = cum_sum;
sample_cnt = 0;
j++;
}
m_data[j] = bvp[i];
cum_sum += bits::cnt(m_data[j]);
j++;
}
m_data[j] = cum_sum; /* last superblock so we can always
get num_ones fast */
if (m_block_num > 1024*64) {
// we store at most m_superblocks+1 rank_samples:
// we do a cache efficient binary search for the select on X=1024
// or X=the smallest power of two smaller than m_superblock
m_rank_samples.resize(std::min(1024ULL, 1ULL << bits::hi(m_superblocks)));
}
init_rank_samples();
}
//! Accessing the i-th element of the original bit_vector
/*! \param i An index i with \f$ 0 \leq i < size() \f$.
* \return The i-th bit of the original bit_vector
* \par Time complexity
* \f$ \Order{1} \f$
*/
value_type operator[](size_type i)const {
assert(i < m_size);
size_type bs = i >> m_block_shift;
size_type block = bs + (i>>6) + 1;
return ((m_data[block] >> (i&63)) & 1ULL);
}
//! Get the integer value of the binary string of length len starting at position idx.
/*! \param idx Starting index of the binary representation of the integer.
* \param len Length of the binary representation of the integer. Default value is 64.
* \returns The integer value of the binary string of length len starting at position idx.
*
* \pre idx+len-1 in [0..size()-1]
* \pre len in [1..64]
*/
uint64_t get_int(size_type idx, uint8_t len=64)const {
assert(idx+len-1 < m_size);
size_type bs = idx >> m_block_shift;
size_type b_block = bs + (idx>>6) + 1;
bs = (idx+len-1) >> m_block_shift;
size_type e_block = bs + ((idx+len-1)>>6) + 1;
if (b_block == e_block) { // spans on block
return (m_data[b_block] >> (idx&63)) & bits::lo_set[len];
} else { // spans two blocks
uint8_t b_len = 64-(idx&63);
return (m_data[b_block] >> (idx&63))
| (m_data[e_block] & bits::lo_set[len-b_len]) << b_len;
}
}
//! Returns the size of the original bit vector.
size_type size()const {
return m_size;
}
//! Serializes the data structure into the given ostream
size_type serialize(std::ostream& out, structure_tree_node* v=nullptr, std::string name="")const {
structure_tree_node* child = structure_tree::add_child(v, name, util::class_name(*this));
size_type written_bytes = 0;
written_bytes += write_member(m_size, out, child, "size");
written_bytes += write_member(m_block_num, out, child, "block_num");
written_bytes += write_member(m_superblocks, out, child, "superblocks");
written_bytes += write_member(m_block_shift, out, child, "block_shift");
written_bytes += m_data.serialize(out, child, "data");
written_bytes += m_rank_samples.serialize(out, child, "rank_samples");
structure_tree::add_size(child, written_bytes);
return written_bytes;
}
//! Loads the data structure from the given istream.
void load(std::istream& in) {
read_member(m_size, in);
read_member(m_block_num, in);
read_member(m_superblocks, in);
read_member(m_block_shift, in);
m_data.load(in);
m_rank_samples.load(in);
}
void swap(bit_vector_il& bv) {
if (this != &bv) {
std::swap(m_size, bv.m_size);
std::swap(m_block_num, bv.m_block_num);
std::swap(m_superblocks, bv.m_superblocks);
std::swap(m_block_shift, bv.m_block_shift);
m_data.swap(bv.m_data);
m_rank_samples.swap(bv.m_rank_samples);
}
}
iterator begin() const {
return iterator(this, 0);
}
iterator end() const {
return iterator(this, size());
}
};
template<uint8_t t_b, uint32_t t_bs>
class rank_support_il
{
static_assert(t_b == 1 or t_b == 0 , "rank_support_il only supports bitpatterns 0 or 1.");
public:
typedef bit_vector::size_type size_type;
typedef bit_vector_il<t_bs> bit_vector_type;
enum { bit_pat = t_b };
private:
const bit_vector_type* m_v;
size_type m_block_shift;
size_type m_block_mask;
size_type m_block_size_U64; //! Size of superblocks in 64-bit words
inline size_type rank1(size_type i) const {
size_type SBlockNum = i >> m_block_shift;
size_type SBlockPos = (SBlockNum << m_block_size_U64) + SBlockNum;
uint64_t resp = m_v->m_data[SBlockPos];
const uint64_t* B = (m_v->m_data.data() + (SBlockPos+1));
uint64_t rem = i&63;
uint64_t bits = (i&m_block_mask) - rem;
while (bits) {
resp += bits::cnt(*B++);
bits -= 64;
}
resp += bits::cnt(*B & bits::lo_set[rem]);
return resp;
}
inline size_type rank0(size_type i) const {
size_type SBlockNum = i >> m_block_shift;
size_type SBlockPos = (SBlockNum << m_block_size_U64) + SBlockNum;
uint64_t resp = (SBlockNum << m_block_shift) - m_v->m_data[SBlockPos];
const uint64_t* B = (m_v->m_data.data() + (SBlockPos+1));
uint64_t rem = i&63;
uint64_t bits = (i&m_block_mask) - rem;
while (bits) {
resp += bits::cnt(~(*B)); B++;
bits -= 64;
}
resp += bits::cnt((~(*B)) & bits::lo_set[rem]);
return resp;
}
public:
rank_support_il(const bit_vector_type* v=nullptr) {
set_vector(v);
m_block_shift = bits::hi(t_bs);
m_block_mask = t_bs - 1;
m_block_size_U64 = bits::hi(t_bs>>6);
}
//! Returns the position of the i-th occurrence in the bit vector.
size_type rank(size_type i) const {
if (t_b) return rank1(i);
return rank0(i);
}
size_type operator()(size_type i)const {
return rank(i);
}
size_type size()const {
return m_v->size();
}
void set_vector(const bit_vector_type* v=nullptr) {
m_v = v;
}
rank_support_il& operator=(const rank_support_il& rs) {
if (this != &rs) {
set_vector(rs.m_v);
}
return *this;
}
void swap(rank_support_il&) { }
void load(std::istream&, const bit_vector_type* v=nullptr) {
set_vector(v);
}
size_type serialize(std::ostream& out, structure_tree_node* v=nullptr, std::string name="")const {
return serialize_empty_object(out, v, name, this);
}
};
template<uint8_t t_b, uint32_t t_bs>
class select_support_il
{
static_assert(t_b == 1 or t_b == 0 , "select_support_il only supports bitpatterns 0 or 1.");
public:
typedef bit_vector::size_type size_type;
typedef bit_vector_il<t_bs> bit_vector_type;
enum { bit_pat = t_b };
private:
const bit_vector_type* m_v;
size_type m_superblocks;
size_type m_block_shift;
size_type m_block_size_U64;
//! Returns the position of the i-th occurrence in the bit vector.
size_type select1(size_type i) const {
size_type lb = 0, rb = m_v->m_superblocks; // search interval [lb..rb)
size_type res = 0;
size_type idx = 0; // index in m_rank_samples
/* binary search over super blocks */
// invariant: lb==0 or m_data[ pos(lb-1) ] < i
// m_data[ pos(rb) ] >= i, initial since i < rank(size())
while (lb < rb) {
size_type mid = (lb+rb)/2; // select mid \in [lb..rb)
#ifndef NOSELCACHE
if (idx < m_v->m_rank_samples.size()) {
if (m_v->m_rank_samples[idx] >= i) {
idx = (idx<<1) + 1;
rb = mid;
} else {
idx = (idx<<1) + 2;
lb = mid + 1;
}
} else {
#endif
size_type pos = (mid << m_block_size_U64) + mid;
// ^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^
// data blocks to jump superblock position
if (m_v->m_data[pos] >= i) {
rb = mid;
} else {
lb = mid + 1;
}
#ifndef NOSELCACHE
}
#endif
}
res = (rb-1) << m_block_shift;
/* iterate in 64 bit steps */
const uint64_t* w = m_v->m_data.data() + ((rb-1) << m_block_size_U64) + (rb-1);
i -= *w; // subtract the cumulative sum before the superblock
++w; /* step into the data */
size_type ones = bits::cnt(*w);
while (ones < i) {
i -= ones; ++w;
ones = bits::cnt(*w);
res += 64;
}
/* handle last word */
res += bits::sel(*w, i);
return res;
}
//! Returns the position of the i-th occurrence in the bit vector.
size_type select0(size_type i)const {
size_type lb = 0, rb = m_v->m_superblocks; // search interval [lb..rb)
size_type res = 0;
size_type idx = 0; // index in m_rank_samples
/* binary search over super blocks */
// invariant: lb==0 or m_data[ pos(lb-1) ] < i
// m_data[ pos(rb) ] >= i, initial since i < rank(size())
while (lb < rb) {
size_type mid = (lb+rb)/2; // select mid \in [lb..rb)
#ifndef NOSELCACHE
if (idx < m_v->m_rank_samples.size()) {
if (((mid << m_block_shift) - m_v->m_rank_samples[idx]) >= i) {
idx = (idx<<1) + 1;
rb = mid;
} else {
idx = (idx<<1) + 2;
lb = mid + 1;
}
} else {
#endif
size_type pos = (mid << m_block_size_U64) + mid;
// ^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^
// data blocks to jump superblock position
if (((mid << m_block_shift) - m_v->m_data[pos]) >= i) {
rb = mid;
} else {
lb = mid + 1;
}
#ifndef NOSELCACHE
}
#endif
}
res = (rb-1) << m_block_shift;
/* iterate in 64 bit steps */
const uint64_t* w = m_v->m_data.data() + ((rb-1) << m_block_size_U64) + (rb-1);
i = i - (res - *w); // substract the cumulative sum before the superblock
++w; /* step into the data */
size_type zeros = bits::cnt(~ *w);
while (zeros < i) {
i -= zeros; ++w;
zeros = bits::cnt(~ *w);
res += 64;
}
/* handle last word */
res += bits::sel(~ *w, i);
return res;
}
public:
select_support_il(const bit_vector_type* v=nullptr) {
set_vector(v);
m_block_shift = bits::hi(t_bs);
m_block_size_U64 = bits::hi(t_bs>>6);
}
//! Returns the position of the i-th occurrence in the bit vector.
size_type select(size_type i) const {
if (t_b) return select1(i);
return select0(i);
}
size_type operator()(size_type i)const {
return select(i);
}
size_type size()const {
return m_v->size();
}
void set_vector(const bit_vector_type* v=nullptr) {
m_v = v;
}
select_support_il& operator=(const select_support_il& rs) {
if (this != &rs) {
set_vector(rs.m_v);
}
return *this;
}
void swap(select_support_il&) { }
void load(std::istream&, const bit_vector_type* v=nullptr) {
set_vector(v);
}
size_type serialize(std::ostream& out, structure_tree_node* v=nullptr, std::string name="")const {
return serialize_empty_object(out, v, name, this);
}
};
} // end namespace sdsl
#endif
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