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AK/Format: Compute TypeErasedParameter type and size at compile-time

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Problem:
- Type and size information is known at compile-time, but computations
  are being performed using run-time parameters.

Solution:
- Move function arguments to be template arguments.
- Convert to `consteval` where possible.
- Decorate functions with `constexpr` which are used in both run-time
  and compile-time contexts.
This commit is contained in:
Lenny Maiorani 2021-04-21 13:47:03 -06:00 • committed by Andreas Kling
parent 6cbf88ad4c
commit e117756d9f
2 changed files with 44 additions and 45 deletions
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53
AK/Format.h
View file

@ -65,25 +65,26 @@ struct TypeErasedParameter {
Custom
};
static Type get_type_from_size(size_t size, bool is_unsigned)
template<size_t size, bool is_unsigned>
static consteval Type get_type_from_size()
{
if (is_unsigned) {
if (size == 1)
if constexpr (is_unsigned) {
if constexpr (size == 1)
return Type::UInt8;
if (size == 2)
if constexpr (size == 2)
return Type::UInt16;
if (size == 4)
if constexpr (size == 4)
return Type::UInt32;
if (size == 8)
if constexpr (size == 8)
return Type::UInt64;
} else {
if (size == 1)
if constexpr (size == 1)
return Type::Int8;
if (size == 2)
if constexpr (size == 2)
return Type::Int16;
if (size == 4)
if constexpr (size == 4)
return Type::Int32;
if (size == 8)
if constexpr (size == 8)
return Type::Int64;
}
@ -91,15 +92,41 @@ struct TypeErasedParameter {
}
template<typename T>
static Type get_type()
static consteval Type get_type()
{
if constexpr (IsIntegral<T>)
return get_type_from_size(sizeof(T), IsUnsigned<T>);
return get_type_from_size<sizeof(T), IsUnsigned<T>>();
else
return Type::Custom;
}
size_t to_size() const;
constexpr size_t to_size() const
{
i64 svalue;
if (type == TypeErasedParameter::Type::UInt8)
svalue = *static_cast<const u8*>(value);
else if (type == TypeErasedParameter::Type::UInt16)
svalue = *static_cast<const u16*>(value);
else if (type == TypeErasedParameter::Type::UInt32)
svalue = *static_cast<const u32*>(value);
else if (type == TypeErasedParameter::Type::UInt64)
svalue = *static_cast<const u64*>(value);
else if (type == TypeErasedParameter::Type::Int8)
svalue = *static_cast<const i8*>(value);
else if (type == TypeErasedParameter::Type::Int16)
svalue = *static_cast<const i16*>(value);
else if (type == TypeErasedParameter::Type::Int32)
svalue = *static_cast<const i32*>(value);
else if (type == TypeErasedParameter::Type::Int64)
svalue = *static_cast<const i64*>(value);
else
VERIFY_NOT_REACHED();
VERIFY(svalue >= 0);
return static_cast<size_t>(svalue);
}
// FIXME: Getters and setters.