#ifndef BOOST_NUMERIC_CPP_HPP
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#define BOOST_NUMERIC_CPP_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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// policy which creates results types equal to that of C++ promotions.
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// Using the policy will permit the program to build and run in release
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// mode which is identical to that in debug mode except for the fact
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// that errors aren't trapped.
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#include <type_traits> // integral constant, remove_cv, conditional
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#include <limits>
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#include <boost/integer.hpp> // integer type selection
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#include "safe_common.hpp"
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#include "checked_result.hpp"
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namespace boost {
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namespace safe_numerics {
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// in C++ the following rules govern integer arithmetic
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// This policy is use to emulate another compiler/machine architecture
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// For example, a Z80 has 8 bit char, 16 bit short, 16 bit int, 32 bit long. So one
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// would use cpp<8, 16, 16, 32, 32> to test programs destined to run on a Z80
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// Follow section 5 of the standard.
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template<
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int CharBits,
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int ShortBits,
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int IntBits,
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int LongBits,
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int LongLongBits
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>
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struct cpp {
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public:
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using local_char_type = typename boost::int_t<CharBits>::exact;
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using local_short_type = typename boost::int_t<ShortBits>::exact;
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using local_int_type = typename boost::int_t<IntBits>::exact;
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using local_long_type = typename boost::int_t<LongBits>::exact;
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using local_long_long_type = typename boost::int_t<LongLongBits>::exact;
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template<class T>
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using rank =
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typename std::conditional<
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std::is_same<local_char_type, typename std::make_signed<T>::type>::value,
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std::integral_constant<int, 1>,
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typename std::conditional<
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std::is_same<local_short_type, typename std::make_signed<T>::type>::value,
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std::integral_constant<int, 2>,
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typename std::conditional<
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std::is_same<local_int_type, typename std::make_signed<T>::type>::value,
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std::integral_constant<int, 3>,
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typename std::conditional<
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std::is_same<local_long_type, typename std::make_signed<T>::type>::value,
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std::integral_constant<int, 4>,
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typename std::conditional<
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std::is_same<local_long_long_type, typename std::make_signed<T>::type>::value,
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std::integral_constant<int, 5>,
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std::integral_constant<int, 6> // catch all - never promote integral
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>::type >::type >::type >::type >::type;
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// section 4.5 integral promotions
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// convert smaller of two types to the size of the larger
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template<class T, class U>
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using higher_ranked_type = typename std::conditional<
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(rank<T>::value < rank<U>::value),
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U,
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T
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>::type;
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template<class T, class U>
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using copy_sign = typename std::conditional<
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std::is_signed<U>::value,
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typename std::make_signed<T>::type,
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typename std::make_unsigned<T>::type
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>::type;
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template<class T>
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using integral_promotion = copy_sign<
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higher_ranked_type<local_int_type, T>,
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T
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>;
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// note presumption that T & U don't have he same sign
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// if that's not true, these won't work
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template<class T, class U>
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using select_signed = typename std::conditional<
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std::numeric_limits<T>::is_signed,
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T,
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U
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>::type;
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template<class T, class U>
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using select_unsigned = typename std::conditional<
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std::numeric_limits<T>::is_signed,
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U,
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T
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>::type;
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// section 5 clause 11 - usual arithmetic conversions
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template<typename T, typename U>
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using usual_arithmetic_conversions =
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// clause 0 - if both operands have the same type
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typename std::conditional<
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std::is_same<T, U>::value,
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// no further conversion is needed
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T,
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// clause 1 - otherwise if both operands have the same sign
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typename std::conditional<
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std::numeric_limits<T>::is_signed
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== std::numeric_limits<U>::is_signed,
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// convert to the higher ranked type
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higher_ranked_type<T, U>,
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// clause 2 - otherwise if the rank of he unsigned type exceeds
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// the rank of the of the signed type
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typename std::conditional<
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rank<select_unsigned<T, U>>::value
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>= rank< select_signed<T, U>>::value,
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// use unsigned type
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select_unsigned<T, U>,
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// clause 3 - otherwise if the type of the signed integer type can
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// represent all the values of the unsigned type
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typename std::conditional<
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std::numeric_limits< select_signed<T, U>>::digits >=
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std::numeric_limits< select_unsigned<T, U>>::digits,
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// use signed type
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select_signed<T, U>,
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// clause 4 - otherwise use unsigned version of the signed type
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std::make_signed< select_signed<T, U>>
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>::type >::type >::type
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>;
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template<typename T, typename U>
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using result_type = typename usual_arithmetic_conversions<
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integral_promotion<typename base_type<T>::type>,
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integral_promotion<typename base_type<U>::type>
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>::type;
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public:
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template<typename T, typename U>
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struct addition_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct subtraction_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct multiplication_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct division_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct modulus_result {
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using type = result_type<T, U>;
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};
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// note: comparison_result (<, >, ...) is special.
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// The return value is always a bool. The type returned here is
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// the intermediate type applied to make the values comparable.
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template<typename T, typename U>
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struct comparison_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct left_shift_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct right_shift_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct bitwise_and_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct bitwise_or_result {
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using type = result_type<T, U>;
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};
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template<typename T, typename U>
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struct bitwise_xor_result {
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using type = result_type<T, U>;
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};
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};
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} // safe_numerics
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} // boost
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#endif // BOOST_NUMERIC_cpp_HPP
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