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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/vespalib/util/typify.h>
#include <vespa/vespalib/stllike/string.h>
#include <limits>
#include <vector>
#include <map>
#include <algorithm>
#include <cmath>
namespace vespalib { class Stash; }
namespace vespalib::eval {
/**
* Enumeration of all different aggregators that are allowed to be
* used in tensor reduce expressions.
**/
enum class Aggr { AVG, COUNT, PROD, SUM, MAX, MEDIAN, MIN };
/**
* Utiliy class used to map between aggregator enum value and symbolic
* name. For example Aggr::AVG <-> "avg".
**/
class AggrNames {
private:
static const AggrNames _instance;
std::map<vespalib::string,Aggr> _name_aggr_map;
std::map<Aggr,vespalib::string> _aggr_name_map;
void add(Aggr aggr, const vespalib::string &name);
AggrNames();
public:
static const vespalib::string *name_of(Aggr aggr);
static const Aggr *from_name(const vespalib::string &name);
};
/**
* Interface defining a general purpose aggregator that can be re-used
* to aggregate multiple groups of values. Each number group is
* aggregated by calling 'first' once, followed by any number of calls
* to 'next', before finally calling 'result' to obtain the
* aggregation result. The 'create' function acts as a factory able to
* create Aggregator instances for all known aggregator enum values
* defined above.
**/
struct Aggregator {
virtual void first(double value) = 0;
virtual void next(double value) = 0;
virtual double result() const = 0;
virtual Aggr enum_value() const = 0;
virtual ~Aggregator();
static Aggregator &create(Aggr aggr, Stash &stash);
static std::vector<Aggr> list();
};
namespace aggr {
// can we start by picking any value from the set to be reduced (or
// the special aggregator-specific null_value) and use the templated
// aggregator 'combine' function in arbitrary order to end up with
// (approximately) the correct result?
constexpr bool is_simple(Aggr aggr) {
return ((aggr == Aggr::PROD) ||
(aggr == Aggr::SUM) ||
(aggr == Aggr::MAX) ||
(aggr == Aggr::MIN));
}
// will a single value reduce to itself?
constexpr bool is_ident(Aggr aggr) {
return ((aggr == Aggr::AVG) ||
(aggr == Aggr::PROD) ||
(aggr == Aggr::SUM) ||
(aggr == Aggr::MAX) ||
(aggr == Aggr::MEDIAN) ||
(aggr == Aggr::MIN));
}
// should we avoid doing clever stuff with this aggregator?
constexpr bool is_complex(Aggr aggr) {
return (aggr == Aggr::MEDIAN);
}
template <typename T> class Avg {
private:
T _sum;
size_t _cnt;
public:
using value_type = T;
constexpr Avg() noexcept : _sum{0}, _cnt{0} {}
constexpr Avg(T value) : _sum{value}, _cnt{1} {}
constexpr void sample(T value) {
_sum += value;
++_cnt;
}
constexpr void merge(const Avg &rhs) {
_sum += rhs._sum;
_cnt += rhs._cnt;
};
constexpr T result() const { return (_sum / _cnt); }
static constexpr Aggr enum_value() { return Aggr::AVG; }
};
template <typename T> class Count {
private:
size_t _cnt;
public:
using value_type = T;
constexpr Count() noexcept : _cnt{0} {}
constexpr Count(T) : _cnt{1} {}
constexpr void sample(T) { ++_cnt; }
constexpr void merge(const Count &rhs) { _cnt += rhs._cnt; }
constexpr T result() const { return _cnt; }
static constexpr Aggr enum_value() { return Aggr::COUNT; }
};
template <typename T> class Prod {
private:
T _prod;
public:
using value_type = T;
constexpr Prod() noexcept : _prod{null_value()} {}
constexpr Prod(T value) : _prod{value} {}
constexpr void sample(T value) { _prod = combine(_prod, value); }
constexpr void merge(const Prod &rhs) { _prod = combine(_prod, rhs._prod); }
constexpr T result() const { return _prod; }
static constexpr Aggr enum_value() { return Aggr::PROD; }
static constexpr T null_value() { return 1; }
static constexpr T combine(T a, T b) { return (a * b); }
};
template <typename T> class Sum {
private:
T _sum;
public:
using value_type = T;
constexpr Sum() noexcept : _sum{null_value()} {}
constexpr Sum(T value) : _sum{value} {}
constexpr void sample(T value) { _sum = combine(_sum, value); }
constexpr void merge(const Sum &rhs) { _sum = combine(_sum, rhs._sum); }
constexpr T result() const { return _sum; }
static constexpr Aggr enum_value() { return Aggr::SUM; }
static constexpr T null_value() { return 0; }
static constexpr T combine(T a, T b) { return (a + b); }
};
template <typename T> class Max {
private:
T _max;
public:
using value_type = T;
constexpr Max() noexcept : _max{null_value()} {}
constexpr Max(T value) : _max{value} {}
constexpr void sample(T value) { _max = combine(_max, value); }
constexpr void merge(const Max &rhs) { _max = combine(_max, rhs._max); }
constexpr T result() const { return _max; }
static constexpr Aggr enum_value() { return Aggr::MAX; }
static constexpr T null_value() { return -std::numeric_limits<T>::infinity(); }
static constexpr T combine(T a, T b) { return std::max(a,b); }
};
template <typename T> class Median {
private:
std::vector<T> _seen;
public:
using value_type = T;
constexpr Median() noexcept : _seen() {}
constexpr Median(T value) : _seen({value}) {}
constexpr void sample(T value) { _seen.push_back(value); }
constexpr void merge(const Median &rhs) {
for (T value: rhs._seen) {
_seen.push_back(value);
}
};
T result() const {
if (_seen.empty()) {
return std::numeric_limits<T>::quiet_NaN();
}
std::vector<T> tmp;
tmp.reserve(_seen.size());
for (T value: _seen) {
if (!std::isnan(value)) {
tmp.push_back(value);
} else {
return std::numeric_limits<T>::quiet_NaN();
}
}
size_t n = (tmp.size() / 2);
std::nth_element(tmp.begin(), tmp.begin() + n, tmp.end());
T result = tmp[n]; // the nth element
if ((tmp.size() % 2) == 0) {
result += *std::max_element(tmp.begin(), tmp.begin() + n);
result /= T{2};
}
return result;
}
static constexpr Aggr enum_value() { return Aggr::MEDIAN; }
};
template <typename T> class Min {
private:
T _min;
public:
using value_type = T;
constexpr Min() noexcept : _min{null_value()} {}
constexpr Min(T value) : _min{value} {}
constexpr void sample(T value) { _min = combine(_min, value); }
constexpr void merge(const Min &rhs) { _min = combine(_min, rhs._min); }
constexpr T result() const { return _min; }
static constexpr Aggr enum_value() { return Aggr::MIN; }
static constexpr T null_value() { return std::numeric_limits<T>::infinity(); }
static constexpr T combine(T a, T b) { return std::min(a,b); }
};
} // namespace vespalib::eval::aggr
struct TypifyAggr {
template <template<typename> typename TT> using Result = TypifyResultSimpleTemplate<TT>;
template <typename F> static decltype(auto) resolve(Aggr aggr, F &&f) {
switch (aggr) {
case Aggr::AVG: return f(Result<aggr::Avg>());
case Aggr::COUNT: return f(Result<aggr::Count>());
case Aggr::PROD: return f(Result<aggr::Prod>());
case Aggr::SUM: return f(Result<aggr::Sum>());
case Aggr::MAX: return f(Result<aggr::Max>());
case Aggr::MEDIAN: return f(Result<aggr::Median>());
case Aggr::MIN: return f(Result<aggr::Min>());
}
abort();
}
};
} // namespace vespalib::eval
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