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[WIP] Relax the type constraints for promote_rule(::Type{<:FixedPoint}, ::Type{<:FixedPoint}) #341

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[WIP] Relax the type constraints for promote_rule(::Type{<:FixedPoint}, ::Type{<:FixedPoint}) #341

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21 changes: 14 additions & 7 deletions src/FixedPointNumbers.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,8 @@ reinterpret(::Type{X}, x::T) where {T <: Integer, X <: FixedPoint{T}} = X(x, 0)

# static parameters
nbitsfrac(::Type{X}) where {T, f, X <: FixedPoint{T,f}} = f
rawtype(::Type{X}) where {T, X <: FixedPoint{T}} = T
rawtype(::Type{X}) where {T <: Integer, X <: FixedPoint{T}} = T
rawtype(::Type{<:FixedPoint}) = Union{} # Don't care the constraints for `T`

# traits based on static parameters
signbits(::Type{X}) where {T, X <: FixedPoint{T}} = T <: Unsigned ? 0 : 1
Expand Down Expand Up @@ -531,12 +532,18 @@ promote_rule(::Type{X}, ::Type{Tr}) where {X <: FixedPoint, Tr <: Rational} = Tr

promote_rule(::Type{X}, ::Type{Ti}) where {X <: FixedPoint, Ti <: Integer} = floattype(X)

function promote_rule(::Type{X1}, ::Type{X2}) where {T1, f1, X1 <: FixedPoint{T1,f1},
T2, f2, X2 <: FixedPoint{T2,f2}}
X = wrapper(X1)
X !== wrapper(X2) && return promote_type(floattype(X1), floattype(X2))

f = max(f1, f2) # ensure we have enough precision
function promote_rule(::Type{X1}, ::Type{X2}) where {X1 <: FixedPoint, X2 <: FixedPoint}
X1w, X2w = wrapper.((X1, X2))
if X1w !== X2w
X1w <: X2w && return X2w
X2w <: X1w && return X1w
return promote_type(floattype(X1), floattype(X2))
end
X = X1w
T1, T2 = rawtype.((X1, X2))
isconcretetype(T1) && isconcretetype(T2) || return X{promote_type(T1, T2)}
f1, f2 = nbitsfrac.((X1, X2))
f = max(f1, f2) # ensure we have enough precision
Tp = promote_type(T1, T2)
T = (T1 <: Signed || T2 <: Signed) ? signedtype(Tp) : Tp
# make sure we have enough integer bits
Expand Down
12 changes: 11 additions & 1 deletion test/traits.jl
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
using FixedPointNumbers, Test
using FixedPointNumbers: bitwidth
using FixedPointNumbers: bitwidth, rawtype

struct MyReal <: Real end
struct MyInteger <: Integer end
Expand Down Expand Up @@ -32,3 +32,13 @@ struct MyInteger <: Integer end
@test_throws MethodError floattype(MyReal) # See #177.
@test floattype(MyInteger) === Float64
end

@testset "rawtype" begin
@test rawtype(FixedPoint) === Union{}
@test rawtype(Normed) === Union{}
@test rawtype(Fixed) === Union{}
@test rawtype(Normed{<:Unsigned}) === Union{}
@test rawtype(Fixed{Union{Int8, Int16}}) === Union{Int8, Int16}
@test rawtype(N0f8) === UInt8
@test rawtype(Q0f7) === Int8
end
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