#ifndef BOOST_NUMERIC_SAFE_BASE_HPP
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#define BOOST_NUMERIC_SAFE_BASE_HPP
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// Copyright (c) 2012 Robert Ramey
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <limits>
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#include <type_traits> // is_integral, enable_if, conditional is_convertible
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#include <boost/config.hpp> // BOOST_CLANG
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#include "concept/exception_policy.hpp"
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#include "concept/promotion_policy.hpp"
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#include "safe_common.hpp"
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#include "exception_policies.hpp"
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#include "boost/concept/assert.hpp"
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namespace boost {
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namespace safe_numerics {
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/////////////////////////////////////////////////////////////////
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// forward declarations to support friend function declarations
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// in safe_base
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template<
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class Stored,
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Stored Min,
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Stored Max,
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class P, // promotion polic
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class E // exception policy
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>
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class safe_base;
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template<
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class T,
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T Min,
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T Max,
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class P,
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class E
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>
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struct is_safe<safe_base<T, Min, Max, P, E> > : public std::true_type
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{};
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template<
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class T,
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T Min,
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T Max,
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class P,
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class E
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>
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struct get_promotion_policy<safe_base<T, Min, Max, P, E> > {
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using type = P;
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};
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template<
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class T,
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T Min,
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T Max,
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class P,
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class E
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>
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struct get_exception_policy<safe_base<T, Min, Max, P, E> > {
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using type = E;
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};
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template<
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class T,
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T Min,
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T Max,
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class P,
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class E
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>
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struct base_type<safe_base<T, Min, Max, P, E> > {
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using type = T;
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};
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template<
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class T,
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T Min,
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T Max,
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class P,
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class E
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>
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constexpr T base_value(
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const safe_base<T, Min, Max, P, E> & st
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) {
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return static_cast<T>(st);
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}
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template<
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typename T,
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T N,
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class P, // promotion policy
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class E // exception policy
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>
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class safe_literal_impl;
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// works for both GCC and clang
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#if BOOST_CLANG==1
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wmismatched-tags"
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#endif
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/////////////////////////////////////////////////////////////////
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// Main implementation
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template<
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class Stored,
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Stored Min,
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Stored Max,
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class P, // promotion polic
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class E // exception policy
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>
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class safe_base {
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private:
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BOOST_CONCEPT_ASSERT((PromotionPolicy<P>));
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BOOST_CONCEPT_ASSERT((ExceptionPolicy<E>));
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Stored m_t;
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template<
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class StoredX,
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StoredX MinX,
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StoredX MaxX,
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class PX, // promotion polic
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class EX // exception policy
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>
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friend class safe_base;
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friend class std::numeric_limits<safe_base>;
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template<class T>
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constexpr Stored validated_cast(const T & t) const;
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// stream support
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template<class CharT, class Traits>
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void output(std::basic_ostream<CharT, Traits> & os) const;
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// note usage of friend declaration to mark function as
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// a global function rather than a member function. If
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// this is not done, the compiler will confuse this with
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// a member operator overload on the << operator. Weird
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// I know. But it's documented here
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// http://en.cppreference.com/w/cpp/language/friend
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// under the heading "Template friend operators"
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template<class CharT, class Traits>
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friend std::basic_ostream<CharT, Traits> &
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operator<<(
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std::basic_ostream<CharT, Traits> & os,
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const safe_base & t
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){
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t.output(os);
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return os;
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}
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template<class CharT, class Traits>
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void input(std::basic_istream<CharT, Traits> & is);
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// see above
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template<class CharT, class Traits>
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friend inline std::basic_istream<CharT, Traits> &
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operator>>(
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std::basic_istream<CharT, Traits> & is,
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safe_base & t
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){
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t.input(is);
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return is;
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}
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public:
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////////////////////////////////////////////////////////////
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// constructors
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constexpr safe_base();
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struct skip_validation{};
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constexpr explicit safe_base(const Stored & rhs, skip_validation);
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// construct an instance of a safe type from an instance of a convertible underlying type.
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template<
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class T,
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typename std::enable_if<
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std::is_convertible<T, Stored>::value,
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bool
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>::type = 0
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>
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constexpr /*explicit*/ safe_base(const T & t);
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// construct an instance of a safe type from a literal value
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template<typename T, T N, class Px, class Ex>
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constexpr /*explicit*/ safe_base(const safe_literal_impl<T, N, Px, Ex> & t);
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// note: Rule of Five. Supply all or none of the following
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// a) user-defined destructor
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~safe_base() = default;
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// b) copy-constructor
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constexpr safe_base(const safe_base &) = default;
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// c) copy-assignment
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constexpr safe_base & operator=(const safe_base &) = default;
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// d) move constructor
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constexpr safe_base(safe_base &&) = default;
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// e) move assignment operator
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constexpr safe_base & operator=(safe_base &&) = default;
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/////////////////////////////////////////////////////////////////
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// casting operators for intrinsic integers
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// convert to any type which is not safe. safe types need to be
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// excluded to prevent ambiguous function selection which
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// would otherwise occur. validity of safe types is checked in
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// the constructor of safe types
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template<
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class R,
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typename std::enable_if<
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! boost::safe_numerics::is_safe<R>::value,
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int
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>::type = 0
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>
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constexpr /*explicit*/ operator R () const;
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/////////////////////////////////////////////////////////////////
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// modification binary operators
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template<class T>
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constexpr safe_base &
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operator=(const T & rhs){
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m_t = validated_cast(rhs);
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return *this;
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}
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// mutating unary operators
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safe_base & operator++(){ // pre increment
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return *this = *this + 1;
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}
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safe_base & operator--(){ // pre decrement
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return *this = *this - 1;
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}
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safe_base operator++(int){ // post increment
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safe_base old_t = *this;
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++(*this);
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return old_t;
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}
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safe_base operator--(int){ // post decrement
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safe_base old_t = *this;
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--(*this);
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return old_t;
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}
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// non mutating unary operators
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constexpr auto operator+() const { // unary plus
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return *this;
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}
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// after much consideration, I've permited the resulting value of a unary
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// - to change the type. The C++ standard does invoke integral promotions
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// so it's changing the type as well.
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/* section 5.3.1 &8 of the C++ standard
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The operand of the unary - operator shall have arithmetic or unscoped
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enumeration type and the result is the negation of its operand. Integral
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promotion is performed on integral or enumeration operands. The negative
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of an unsigned quantity is computed by subtracting its value from 2n,
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where n is the number of bits in the promoted operand. The type of the
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result is the type of the promoted operand.
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*/
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constexpr auto operator-() const { // unary minus
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// if this is a unsigned type and the promotion policy is native
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// the result will be unsigned. But then the operation will fail
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// according to the requirements of arithmetic correctness.
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// if this is an unsigned type and the promotion policy is automatic.
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// the result will be signed.
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return 0 - *this;
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}
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/* section 5.3.1 &10 of the C++ standard
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The operand of ~ shall have integral or unscoped enumeration type;
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the result is the ones’ complement of its operand. Integral promotions
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are performed. The type of the result is the type of the promoted operand.
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*/
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constexpr auto operator~() const { // complement
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return ~Stored(0u) ^ *this;
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}
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};
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} // safe_numerics
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} // boost
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/////////////////////////////////////////////////////////////////
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// numeric limits for safe<int> etc.
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#include <limits>
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namespace std {
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template<
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class T,
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T Min,
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T Max,
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class P,
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class E
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>
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class numeric_limits<boost::safe_numerics::safe_base<T, Min, Max, P, E> >
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: public std::numeric_limits<T>
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{
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using SB = boost::safe_numerics::safe_base<T, Min, Max, P, E>;
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public:
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constexpr static SB lowest() noexcept {
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return SB(Min, typename SB::skip_validation());
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}
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constexpr static SB min() noexcept {
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return SB(Min, typename SB::skip_validation());
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}
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constexpr static SB max() noexcept {
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return SB(Max, typename SB::skip_validation());
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}
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};
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} // std
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#if BOOST_CLANG==1
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#pragma GCC diagnostic pop
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#endif
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#endif // BOOST_NUMERIC_SAFE_BASE_HPP
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