Add abstract operations #450
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We add special types for the kinds of operations that can occur in unit conversions. Later on, we'll create traits that judge the risks of these operations for overflow and truncation, and can even determine which individual values will be lossy in these ways. For now, the operations are: - `StaticCast<T, U>` represents a static cast from type `T` to `U`. - `MultiplyTypeBy<T, M>` represents multiplying a value of `T` by the magnitude `M`. - `DivideTypeByInteger<T, M>` represents dividing a value of `T` by the magnitude `M`, which must be an integer. - `OpSequence<Ops...>` chains any sequence of operations, and is automatically flattened to a single layer. We also provide the `OpInput<Op>` and `OpOutput<Op>` traits. For `OpSequence`, we also explicitly check that the output type of one operation equals the input type of the next. This has helped prevent a few errors already. Helps #349.
hoffbrinkle
approved these changes
Jul 10, 2025
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| TEST(DivideTypeByInteger, IntegerTypeDividedByIntegerTooBigToRepresentGivesZero) { | ||
| EXPECT_THAT((DivideTypeByInteger<uint8_t, decltype(mag<256>())>::apply_to(uint8_t{1})), | ||
| SameTypeAndValue(uint8_t{0})); | ||
| } |
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Would it make sense for an additional case that tests dividing to a result of 0 without overflowing the result type?
TEST(DivideTypeByInteger, IntegerTypeDividedByIntegerMagGreaterThanDividend) {
EXPECT_THAT((DivideTypeByInteger<uint8_t, decltype(mag<2>())>::apply_to(uint8_t{1})),
SameTypeAndValue(uint8_t{0}));
}
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We add special types for the kinds of operations that can occur in unit
conversions. Later on, we'll create traits that judge the risks of
these operations for overflow and truncation, and can even determine
which individual values will be lossy in these ways.
For now, the operations are:
StaticCast<T, U>represents a static cast from typeTtoU.MultiplyTypeBy<T, M>represents multiplying a value ofTby themagnitude
M.DivideTypeByInteger<T, M>represents dividing a value ofTby themagnitude
M, which must be an integer.OpSequence<Ops...>chains any sequence of operations, and isautomatically flattened to a single layer.
We also provide the
OpInput<Op>andOpOutput<Op>traits. ForOpSequence, we also explicitly check that the output type of oneoperation equals the input type of the next. This has helped prevent a
few errors already.
Helps #349.