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#pragma once
#include <cstdlib>
#include <vector>
#include <algorithm>
#include "ts/builder.h"
template <typename K, typename V, size_t E=1024>
class BSMTrieSpline {
private:
typedef std::pair<K, V> R;
public:
struct RangeQueryParameters {
K lower_bound;
K upper_bound;
};
public:
static BSMTrieSpline *build(std::vector<R> &records) {
std::sort(records.begin(), records.end());
return new BSMTrieSpline(records);
}
static BSMTrieSpline *build_presorted(std::vector<R> &records) {
return new BSMTrieSpline(records);
}
std::vector<R> unbuild() {
return std::move(m_data);
}
std::vector<R> query(void *q) {
std::vector<R> rs;
/* return an empty result set if q is invalid */
if (q == nullptr) {
rs.push_back({0, 0});
return rs;
}
auto parms = (BSMTrieSpline::RangeQueryParameters*) q;
size_t idx = lower_bound(parms->lower_bound);
size_t cnt = 0;
while (idx < m_data.size() && m_data[idx].first < parms->upper_bound) {
cnt++;
}
rs.push_back({cnt, 0});
return std::move(rs);
}
std::vector<R> query_merge(std::vector<R> &rsa, std::vector<R> &rsb, void *parms) {
rsa[0].first += rsb[0].first;
return std::move(rsa);
}
size_t record_count() {
return m_data.size();
}
~BSMTrieSpline() = default;
private:
std::vector<R> m_data;
K m_max_key;
K m_min_key;
ts::TrieSpline<K> m_ts;
BSMTrieSpline(std::vector<R> &records) {
m_data = std::move(records);
m_min_key = m_data[0].first;
m_max_key = m_data[m_data.size() - 1].first;
auto bldr = ts::Builder<K>(m_min_key, m_max_key, E);
for (size_t i=0; i<m_data.size(); i++) {
bldr.AddKey(m_data[i].first);
}
if (m_data.size() > 1) {
m_ts = bldr.Finalize();
}
}
size_t lower_bound(K key) {
if (m_data.size() == 0) {
return 1;
} else if (m_data.size() == 1) {
if (m_data[0].first < key) {
return 1;
} else {
return 0;
}
}
auto bound = m_ts.GetSearchBound(key);
size_t idx = bound.begin;
if (idx >= m_data.size()) {
return m_data.size();
}
// If the region to search is less than some pre-specified
// amount, perform a linear scan to locate the record.
if (bound.end - bound.begin < 256) {
while (idx < bound.end && m_data[idx].first < key) {
idx++;
}
} else {
// Otherwise, perform a binary search
idx = bound.begin;
size_t max = bound.end;
while (idx < max) {
size_t mid = (idx + max) / 2;
if (key > m_data[mid].first) {
idx = mid + 1;
} else {
max = mid;
}
}
}
if (idx == m_data.size()) {
return m_data.size();
}
if (m_data[idx].first > key && idx > 0 && m_data[idx-1].first <= key) {
return idx-1;
}
return idx;
}
};
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