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strict_sequence.hpp
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strict_sequence.hpp
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#pragma once
#include <stdexcept>
#include "strict_elias_fano.hpp"
#include "compact_ranked_bitvector.hpp"
#include "all_ones_sequence.hpp"
#include "global_parameters.hpp"
namespace ds2i {
struct strict_sequence {
enum index_type {
elias_fano = 0,
ranked_bitvector = 1,
all_ones = 2,
index_types = 3
};
static const uint64_t type_bits = 1; // all_ones is implicit
static global_parameters strict_params(global_parameters params)
{
// we do not need to index the zeros
params.ef_log_sampling0 = 63;
params.rb_log_rank1_sampling = 63;
return params;
}
static DS2I_FLATTEN_FUNC uint64_t
bitsize(global_parameters const& params, uint64_t universe, uint64_t n)
{
uint64_t best_cost = all_ones_sequence::bitsize(params, universe, n);
auto sparams = strict_params(params);
uint64_t ef_cost = strict_elias_fano::bitsize(sparams, universe, n) + type_bits;
if (ef_cost < best_cost) {
best_cost = ef_cost;
}
uint64_t rb_cost = compact_ranked_bitvector::bitsize(sparams, universe, n) + type_bits;
if (rb_cost < best_cost) {
best_cost = rb_cost;
}
return best_cost;
}
template <typename Iterator>
static void write(succinct::bit_vector_builder& bvb,
Iterator begin,
uint64_t universe, uint64_t n,
global_parameters const& params)
{
auto sparams = strict_params(params);
uint64_t best_cost = all_ones_sequence::bitsize(params, universe, n);
int best_type = all_ones;
if (best_cost) {
uint64_t ef_cost = strict_elias_fano::bitsize(sparams, universe, n) + type_bits;
if (ef_cost < best_cost) {
best_cost = ef_cost;
best_type = elias_fano;
}
uint64_t rb_cost = compact_ranked_bitvector::bitsize(sparams, universe, n) + type_bits;
if (rb_cost < best_cost) {
best_cost = rb_cost;
best_type = ranked_bitvector;
}
bvb.append_bits(best_type, type_bits);
}
switch (best_type) {
case elias_fano:
strict_elias_fano::write(bvb, begin,
universe, n,
sparams);
break;
case ranked_bitvector:
compact_ranked_bitvector::write(bvb, begin,
universe, n,
sparams);
break;
case all_ones:
all_ones_sequence::write(bvb, begin,
universe, n,
sparams);
break;
default:
assert(false);
}
}
class enumerator {
public:
typedef std::pair<uint64_t, uint64_t> value_type; // (position, value)
enumerator()
{}
enumerator(succinct::bit_vector const& bv, uint64_t offset,
uint64_t universe, uint64_t n,
global_parameters const& params)
{
auto sparams = strict_params(params);
if (all_ones_sequence::bitsize(params, universe, n) == 0) {
m_type = all_ones;
} else {
m_type = index_type(bv.get_word56(offset)
& ((uint64_t(1) << type_bits) - 1));
}
switch (m_type) {
case elias_fano:
m_ef_enumerator = strict_elias_fano::enumerator(bv, offset + type_bits,
universe, n,
sparams);
break;
case ranked_bitvector:
m_rb_enumerator = compact_ranked_bitvector::enumerator(bv, offset + type_bits,
universe, n,
sparams);
break;
case all_ones:
m_ao_enumerator = all_ones_sequence::enumerator(bv, offset + type_bits,
universe, n,
sparams);
break;
default:
throw std::invalid_argument("Unsupported type");
}
}
#define ENUMERATOR_METHOD(RETURN_TYPE, METHOD, FORMALS, ACTUALS) \
RETURN_TYPE DS2I_FLATTEN_FUNC METHOD FORMALS \
{ \
switch (__builtin_expect(m_type, elias_fano)) { \
case elias_fano: \
return m_ef_enumerator.METHOD ACTUALS; \
case ranked_bitvector: \
return m_rb_enumerator.METHOD ACTUALS; \
case all_ones: \
return m_ao_enumerator.METHOD ACTUALS; \
default: \
assert(false); \
__builtin_unreachable(); \
} \
} \
/**/
// semicolons are redundant but they are needed to get emacs to
// align the lines properly
ENUMERATOR_METHOD(value_type, move, (uint64_t position), (position));
ENUMERATOR_METHOD(value_type, next, (), ());
ENUMERATOR_METHOD(uint64_t, size, () const, ());
ENUMERATOR_METHOD(uint64_t, prev_value, () const, ());
#undef ENUMERATOR_METHOD
#undef ENUMERATOR_VOID_METHOD
private:
index_type m_type;
union {
strict_elias_fano::enumerator m_ef_enumerator;
compact_ranked_bitvector::enumerator m_rb_enumerator;
all_ones_sequence::enumerator m_ao_enumerator;
};
};
};
}