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#pragma once
#include "function_traits.hpp"
#include <memory>
#include <functional>
namespace func {
template<class T>
class AbstractPredicate {
public:
typedef T checked_type;
virtual bool Check(T t) const = 0;
bool operator()(T t) const { return Check(t); }
virtual ~AbstractPredicate() {}
};
template<typename T>
class TypedPredicate {
struct TypedPredicateConcept {
virtual ~TypedPredicateConcept() { };
virtual bool operator()(T x) const = 0;
};
template<class P>
struct TypedPredicateModel : TypedPredicateConcept {
TypedPredicateModel(P p)
: data_(std::move(p)) { }
virtual bool operator()(T x) const override {
return (bool) data_(x);
}
P data_;
};
std::shared_ptr<const TypedPredicateConcept> self_;
public:
typedef T checked_type;
template<typename P>
TypedPredicate(P p)
: self_(std::make_shared<TypedPredicateModel<P>>(std::move(p))) { }
bool operator()(T x) const {
return self_->operator()(x);
}
};
template<typename T>
class AlwaysTrueOperator {
public:
typedef T checked_type;
bool operator()(T) const {
return true;
}
};
template<typename T>
class AlwaysFalseOperator {
typedef T checked_type;
public:
bool operator()(T) const {
return false;
}
};
template<typename T>
class AndOperator {
public:
typedef T checked_type;
AndOperator(TypedPredicate<T> lhs, TypedPredicate<T> rhs)
: lhs_(std::move(lhs)),
rhs_(std::move(rhs)) { }
bool operator()(T x) const {
return lhs_(x) && rhs_(x);
}
private:
const TypedPredicate<T> lhs_, rhs_;
};
template<typename T>
class OrOperator {
public:
typedef T checked_type;
OrOperator(TypedPredicate<T> lhs, TypedPredicate<T> rhs)
: lhs_(std::move(lhs)), rhs_(std::move(rhs)) { }
bool operator()(T x) const {
return lhs_(x) || rhs_(x);
}
private:
const TypedPredicate<T> lhs_, rhs_;
};
template<typename T>
class NotOperator {
public:
typedef T checked_type;
NotOperator(const TypedPredicate<T> p)
: p_(std::move(p)) { }
bool operator()(T x) const {
return !p_(x);
}
private:
const TypedPredicate<T> p_;
};
template<class P,
bool = function_traits<P>::arity == 1 &&
std::is_same<typename function_traits<P>::return_type, bool>::value>
struct is_predicate : public std::true_type {
};
template<class P>
struct is_predicate<P, false> : public std::false_type {
};
template<class TP1, class TP2,
typename _T1 = typename function_traits<TP1>::template arg<0>::type,
typename _T2 = typename function_traits<TP2>::template arg<0>::type,
typename =
typename std::enable_if<std::is_same<_T1, _T2>::value &&
is_predicate<TP1>::value && is_predicate<TP2>::value
>::type>
TypedPredicate<_T1> And(TP1 lhs, TP2 rhs) {
return AndOperator<_T1>(lhs, rhs);
}
template<class TP1, class TP2,
typename _T1 = typename function_traits<TP1>::template arg<0>::type,
typename _T2 = typename function_traits<TP2>::template arg<0>::type,
typename =
typename std::enable_if<std::is_same<_T1, _T2>::value &&
is_predicate<TP1>::value && is_predicate<TP2>::value
>::type>
TypedPredicate<_T1> Or(TP1 lhs, TP2 rhs) {
return OrOperator<_T1>(lhs, rhs);
}
template<class TP,
typename _T = typename function_traits<TP>::template arg<0>::type,
typename =
typename std::enable_if<is_predicate<TP>::value>::type>
TypedPredicate<_T> Not(TP p) {
return NotOperator<_T>(p);
}
template<class T>
TypedPredicate<T> AlwaysTrue() {
return AlwaysTrueOperator<T>();
}
template<class T>
TypedPredicate<T> AlwaysFalse() {
return AlwaysFalseOperator<T>();
}
} // namespace func
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