88 lines
2.9 KiB
C++
88 lines
2.9 KiB
C++
#pragma once
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#include <fc/exception/exception.hpp>
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#include <fc/reflect/reflect.hpp>
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#include <limits>
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namespace fc {
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/**
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* This type is designed to provide automatic checks for
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* integer overflow and default initialization. It will
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* throw an exception on overflow conditions.
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*
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* It can only be used on built-in types. In particular,
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* safe<uint128_t> is buggy and should not be used.
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*/
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template<typename T>
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struct safe
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{
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template<typename O>
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safe( O o ):value(o){}
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safe(){}
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safe( const safe& o ):value(o.value){}
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safe& operator += ( const safe& b )
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{
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if( b.value > 0 && value > (std::numeric_limits<T>::max() - b.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (*this)(b) );
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if( b.value < 0 && value < (std::numeric_limits<T>::min() - b.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (*this)(b) );
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value += b.value;
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return *this;
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}
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friend safe operator + ( const safe& a, const safe& b )
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{
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if( b.value > 0 && a.value > std::numeric_limits<T>::max() - b.value ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
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if( b.value < 0 && a.value < std::numeric_limits<T>::min() - b.value ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
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return safe(a.value+b.value);
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}
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safe& operator *= ( safe v ) { value *= v.value; return *this; }
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safe& operator /= ( safe v ) { FC_ASSERT(v.value != 0); value /= v.value; return *this; }
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safe& operator -= ( const safe& b ) { return *this += safe(-b.value); }
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safe operator -()const
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{
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if( value == std::numeric_limits<T>::min() )
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FC_CAPTURE_AND_THROW( overflow_exception, (value) );
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return safe(-value);
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}
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safe operator++(int) { safe bak = *this; *this += 1; return bak; }
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safe& operator++() { return *this += 1; }
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safe operator--(int) { safe bak = *this; *this -= 1; return bak; }
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safe& operator--() { return *this -= 1; }
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friend safe operator - ( const safe& a, const safe& b )
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{
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safe tmp(a); tmp -= b; return tmp;
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}
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friend bool operator == ( const safe& a, const safe& b )
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{
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return a.value == b.value;
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}
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friend bool operator != ( const safe& a, const safe& b )
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{
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return a.value != b.value;
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}
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friend bool operator < ( const safe& a, const safe& b )
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{
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return a.value < b.value;
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}
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friend bool operator > ( const safe& a, const safe& b )
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{
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return a.value > b.value;
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}
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friend bool operator >= ( const safe& a, const safe& b )
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{
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return a.value >= b.value;
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}
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friend bool operator <= ( const safe& a, const safe& b )
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{
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return a.value <= b.value;
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}
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T value = 0;
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};
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}
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FC_REFLECT_TEMPLATE( (typename T), safe<T>, (value) )
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