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Safe Numerics |
This library should compile and run correctly on any conforming C++14 compiler.
The Safe Numerics library is implemented in terms of some more fundamental software components described here. It is not necessary to know about these components to use the library. This information has been included to help those who want to understand how the library works so they can extend it, correct bugs in it, or understand it's limitations. These components are also interesting in their own right. For all these reasons, they are documented here. In general terms, the library works in the following manner:
All unary/binary expressions where one of the operands is a
"safe" type are Overloaded. These overloads are declared and defined
in the header file "safe_integer.hpp". SFINAE - "Substitution Failure
Is Not An Error and std::enable_if are key features of
C++ used to define these overloads in a correct manner.
Each overloaded operation implements the following:
Retrieve range of values for each operand of type T from
std::numeric_limits<T>::min() and
std::numeric_limits<T>::max().
Given the ranges of the operands, determine the range of the result of the operation using interval arithmetic. This is implemented in the "interval.hpp" header file using constexpr facility of C++14.
if the range of the result type includes the range of the result of the operation, no run time checking of the result is necessary. So the operation reduces to the original built-in C/C++ operation.
Otherwise, the operation is implemented as a "checked integer operation" at run time. This operation returns a variant which will contain either a correct result or an exception enum indicating why a correct result could not be obtained. The variant object is implemented in the header file "checked_result.hpp" and the checked operations are implemented in "checked.hpp".
if a valid result has been obtained, it is passed to the caller.
Otherwise, an exception is invoked.