mirror of
https://github.com/boostorg/safe_numerics.git
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403 lines
11 KiB
C++
403 lines
11 KiB
C++
#ifndef BOOST_NUMERIC_SAFE_BASE_HPP
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#define BOOST_NUMERIC_SAFE_BASE_HPP
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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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
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#include <boost/mpl/if.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/identity.hpp>
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#include <boost/mpl/and.hpp>
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// don't use constexpr so we can debug
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#define SAFE_NUMERIC_CONSTEXPR constexpr
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#include "safe_compare.hpp"
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namespace boost {
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namespace numeric {
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template<
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class Stored,
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class Derived,
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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_base {
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SAFE_NUMERIC_CONSTEXPR const Derived &
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derived() const {
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return static_cast<const Derived &>(*this);
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}
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Stored m_t;
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protected:
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// note: Rule of Three. Don't specify custom move, copy etc.
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////////////////////////////////////////////////////////////
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// constructors
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// default constructor
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SAFE_NUMERIC_CONSTEXPR safe_base() {}
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// copy constructor
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SAFE_NUMERIC_CONSTEXPR safe_base(const safe_base & t) :
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m_t(t.m_t)
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{}
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template<class T>
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SAFE_NUMERIC_CONSTEXPR safe_base(T & t) :
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m_t(t)
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{
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// verify that this is convertible to the storable type
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static_assert(
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std::is_convertible<T, Stored>::value,
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"Constructor argument is convertible to the storable type"
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);
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if(! derived().validate(t)){
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E::range_error(
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"Invalid value"
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);
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}
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}
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bool validate() const {
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if(! derived().validate(m_t)){
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E::range_error(
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"Invalid value"
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);
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}
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}
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public:
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// used to implement stream i/o operators
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Stored & get_stored_value() {
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return m_t;
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}
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SAFE_NUMERIC_CONSTEXPR const Stored & get_stored_value() const {
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return m_t;
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}
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/////////////////////////////////////////////////////////////////
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// modification binary operators
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template<class T>
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Derived & operator=(const T & rhs){
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if(! derived().validate(rhs)){
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E::range_error(
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"Invalid value passed on assignment"
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);
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}
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m_t = rhs;
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return derived();
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}
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template<class T>
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Derived & operator+=(const T & rhs){
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// validate?
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m_t = derived() + rhs;
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return derived();
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}
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template<class T>
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Derived & operator-=(const T & rhs){
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*this = *this - rhs;
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return derived();
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}
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template<class T>
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Derived & operator*=(const T & rhs){
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*this = *this * rhs;
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return derived();
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}
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template<class T>
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Derived & operator/=(const T & rhs){
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*this = *this / rhs;
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return derived();
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}
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template<class T>
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Derived & operator%=(const T & rhs){
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*this = *this % rhs;
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return derived();
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}
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template<class T>
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Derived & operator|=(const T & rhs){
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*this = *this | rhs;
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return derived();
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}
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template<class T>
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Derived & operator&=(const T & rhs){
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*this = *this & rhs;
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return derived();
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}
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template<class T>
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Derived & operator^=(const T & rhs){
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*this = *this * rhs;
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return derived();
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}
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template<class T>
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Derived & operator>>=(const T & rhs){
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*this = *this >> rhs;
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return derived();
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}
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template<class T>
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Derived & operator<<=(const T & rhs){
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*this = *this << rhs;
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return derived();
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}
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// unary operators
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Derived operator++(){
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// this checks for overflow
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*this = *this + 1;
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return derived();
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}
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Derived operator--(){
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// this checks for overflow
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*this = *this - 1;
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return derived();
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}
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Derived operator++(int){ // post increment
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Stored t = m_t;
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if(! derived().validate(*this + 1)){
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E::overflow_error(
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"Overflow on increment"
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);
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}
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++t;
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return derived();
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}
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Derived & operator--(int){ // post decrement
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Stored t = m_t;
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if(! derived().validate(*this - 1)){
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E::overflow_error(
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"Overflow on increment"
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);
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}
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--t;
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return derived();
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}
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Derived operator-() const { // unary minus
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static_assert(
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std::numeric_limits<Stored>::is_signed,
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"Application of unary minus to unsigned value is an error"
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);
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*this = 0 - *this; // this will check for overflow
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return derived();
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}
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Derived operator~() const {
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static_assert(
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std::numeric_limits<Stored>::is_signed,
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"Bitwise inversion of unsigned value is an error"
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);
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if(! derived().validate(~m_t)){
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E::overflow_error(
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"Overflow on increment"
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);
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}
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return derived();
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}
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/////////////////////////////////////////////////////////////////
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// binary comparison operators
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template<class U>
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bool operator<(const U & rhs) const {
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return boost::numeric::safe_compare::less_than(m_t, rhs);
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}
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template<class U>
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bool operator>(const U & rhs) const {
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return boost::numeric::safe_compare::greater_than(m_t, rhs);
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}
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template<class U>
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bool operator==(const U & rhs) const {
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return boost::numeric::safe_compare::equal(m_t, rhs);
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}
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template<class U>
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bool inline operator!=(const U & rhs) const {
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return ! boost::numeric::safe_compare::equal(m_t,rhs);
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}
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template<class U>
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bool inline operator>=(const U & rhs) const {
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return ! boost::numeric::safe_compare::less_than(m_t, rhs);
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}
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template<class U>
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bool inline operator<=(const U & rhs) const {
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return ! boost::numeric::safe_compare::greater_than(m_t, rhs);
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}
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/*
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/////////////////////////////////////////////////////////////////
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// subtraction
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template<class T, class U>
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struct no_subtraction_overflow_possible : public
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boost::mpl::and_<
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typename boost::mpl::greater<
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typename boost::mpl::sizeof_< decltype(Stored() - U()) >,
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typename boost::mpl::max<
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boost::mpl::sizeof_<U>,
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boost::mpl::sizeof_<Stored>
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>::type
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>,
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boost::numeric::is_signed<decltype(Stored() - U())>
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>
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{};
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template<class T, class U>
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struct no_subtraction_overflow_possible;
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// case 1 - no overflow possible
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template<class U>
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typename boost::enable_if<
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no_subtraction_overflow_possible<Stored, U>,
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decltype(Stored() - U())
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>::type
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inline operator-(const U & rhs) const {
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return m_t - rhs;
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}
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template<class U>
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typename boost::disable_if<
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no_subtraction_overflow_possible<Stored, U>,
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decltype(Stored() - U())
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>::type
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inline operator-(const U & rhs) const {
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return detail::check_subtraction_overflow<
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boost::numeric::is_signed<Stored>::value,
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boost::numeric::is_signed<U>::value
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>::subtract(m_t, boost::numeric::safe_cast<decltype(Stored() - U())>(rhs));
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}
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/////////////////////////////////////////////////////////////////
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// multiplication
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template<class U>
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decltype(U() * Stored())
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inline operator*(const U & rhs) const {
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return detail::check_multiplication_overflow(m_t, rhs);
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}
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/////////////////////////////////////////////////////////////////
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// division
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template<class U>
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decltype(U() / Stored())
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inline operator/(const U & rhs) const {
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return detail::check_division_overflow(m_t, rhs);
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}
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/////////////////////////////////////////////////////////////////
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// modulus
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template<class U>
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decltype(Stored() % U())
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inline operator%(const U & rhs) const {
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if(0 == rhs)
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throw std::domain_error("Divide by zero");
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return detail::check_modulus_overflow(m_t, rhs);
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}
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/////////////////////////////////////////////////////////////////
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// logical operators
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template<class U>
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decltype(Stored() | U())
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inline operator|(const U & rhs) const {
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// verify that U is an integer type
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static_assert(
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std::numeric_limits<U>::is_integer,
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"right hand side is not an integer type"
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);
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return m_t | rhs;
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}
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template<class U>
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decltype(Stored() & U())
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inline operator&(const U & rhs) const {
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// verify that U is an integer type
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static_assert(
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std::numeric_limits<U>::is_integer,
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"right hand side is not an integer type"
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);
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return m_t & rhs;
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}
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template<class U>
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decltype(Stored() ^ U())
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inline operator^(const U & rhs) const {
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// verify that U is an integer type
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static_assert(
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std::numeric_limits<U>::is_integer,
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"right hand side is not an integer type"
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);
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return m_t ^ rhs;
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}
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template<class U>
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Stored inline operator>>(const U & rhs) const {
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// verify that U is an integer type
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static_assert(
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std::numeric_limits<U>::is_integer,
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"right hand side is not an integer type"
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);
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if(m_t < 0)
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boost::numeric::overflow("right shift of negative number undefined");
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typedef decltype(Stored() >> U()) result_type;
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if(rhs > boost::numeric::bits<Stored>::value)
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boost::numeric::overflow("conversion of negative value to unsigned");
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return m_t >> rhs;
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}
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template<class U>
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Stored inline operator<<(const U & rhs) const {
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// verify that U is an integer type
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static_assert(
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std::numeric_limits<U>::is_integer,
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"right hand side is not an integer type"
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);
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if(m_t < 0)
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boost::numeric::overflow("right shift of negative number undefined");
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typedef decltype(Stored() >> U()) result_type;
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if(rhs > boost::numeric::bits<Stored>::value)
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boost::numeric::overflow("conversion of negative value to unsigned");
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return m_t << rhs;
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}
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*/
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/////////////////////////////////////////////////////////////////
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// casting operators for intrinsic integers
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explicit SAFE_NUMERIC_CONSTEXPR operator const Stored & () const {
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return m_t;
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}
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};
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} // numeric
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} // boost
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namespace boost {
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namespace numeric {
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// default implementations for required meta-functions
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template<typename T>
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struct is_safe : public std::false_type
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{};
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template<typename T>
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struct base_type {
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typedef T type;
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};
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template<class T>
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SAFE_NUMERIC_CONSTEXPR const typename base_type<T>::type & base_value(const T & t) {
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return static_cast<const typename base_type<T>::type & >(t);
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}
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template<typename T>
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struct get_promotion_policy {
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typedef void type;
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};
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template<typename T>
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struct get_exception_policy {
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typedef void type;
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};
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} // numeric
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} // boost
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#endif // BOOST_NUMERIC_SAFE_BASE_HPP
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