Use type inference instead of test_value (cont. #34) (#43)

Co-authored-by: MasonProtter <[email protected]>
Co-authored-by: Johnny Chen <[email protected]>

Author: 3 people

Project.toml

@@ -1,6 +1,6 @@
 name = "MappedArrays"
 uuid = "dbb5928d-eab1-5f90-85c2-b9b0edb7c900"
-version = "0.3.0"
+version = "0.4.0"
 
 [compat]
 FixedPointNumbers = "0.6.1, 0.7, 0.8"

src/MappedArrays.jl

@@ -58,7 +58,7 @@ not set them).
 When multiple input arrays are supplied, `M[i] = f(A[i], B[i], C[i]...)`.
 """
 function mappedarray(f, data::AbstractArray)
-    T = typeof(f(testvalue(data)))
+    T = Base._return_type(f, eltypes(data))
     ReadonlyMappedArray{T,ndims(data),typeof(data),typeof(f)}(f, data)
 end
 
@@ -67,7 +67,7 @@ function mappedarray(::Type{T}, data::AbstractArray) where T
 end
 
 function mappedarray(f, data::AbstractArray...)
-    T = typeof(f(map(testvalue, data)...))
+    T = Base._return_type(f, eltypes(data))
     ReadonlyMultiMappedArray{T,ndims(first(data)),typeof(data),typeof(f)}(f, data)
 end
 
@@ -86,20 +86,20 @@ the view and, correspondingly, the values in `A`.
 When multiple input arrays are supplied, `M[i] = f(A[i], B[i], C[i]...)`.
 """
 function mappedarray(f, finv, data::AbstractArray)
-    T = typeof(f(testvalue(data)))
+    T = Base._return_type(f, eltypes(data))
     MappedArray{T,ndims(data),typeof(data),typeof(f),typeof(finv)}(f, finv, data)
 end
 
 function mappedarray(f, finv, data::AbstractArray...)
-    T = typeof(f(map(testvalue, data)...))
+    T = Base._return_type(f, eltypes(data))
     MultiMappedArray{T,ndims(first(data)),typeof(data),typeof(f),typeof(finv)}(f, finv, data)
 end
 
 function mappedarray(::Type{T}, finv, data::AbstractArray...) where T
     MultiMappedArray{T,ndims(first(data)),typeof(data),Type{T},typeof(finv)}(T, finv, data)
 end
 function mappedarray(f, ::Type{Finv}, data::AbstractArray...) where Finv
-    T = typeof(f(map(testvalue, data)...))
+    T = Base._return_type(f, eltypes(data))
     MultiMappedArray{T,ndims(first(data)),typeof(data),typeof(f),Type{Finv}}(f, Finv, data)
 end
 

test/runtests.jl

@@ -177,3 +177,40 @@ end
     str = String(take!(io))
     @test occursin("x1 + x2", str)
 end
+
+@testset "eltype (issue #32)" begin
+    # Tests fix for
+    # https://github.com/JuliaArrays/MappedArrays.jl/issues/32#issuecomment-682985419
+    T = Union{Missing, Float32}
+    @test eltype(of_eltype(T, [missing, 3])) == T
+    @test eltype(of_eltype(T, [3, missing])) == T
+    @test eltype(of_eltype(Union{Missing, Float64}, [1, 2])) == Float64
+
+    @test eltype(mappedarray(identity, [1, missing])) == Union{Missing, Int}
+    @test eltype(mappedarray(identity, [missing, 1])) == Union{Missing, Int}
+
+    # ReadonlyMappedArray and MappedArray
+    _zero(x) = x > 0 ? x : 0
+    @test eltype(mappedarray(_zero, [1, 1.0])) == Union{Float64,Int}
+    @test eltype(mappedarray(_zero, [1.0, 1])) == Union{Float64,Int}
+    @test eltype(mappedarray(_zero, [1, 1])) == Int
+
+    @test eltype(mappedarray(_zero, identity, [1, 1.0])) == Union{Float64,Int}
+    @test eltype(mappedarray(_zero, identity, [1.0, 1])) == Union{Float64,Int}
+    @test eltype(mappedarray(_zero, identity, [1, 1])) == Int
+
+    # MultiMappedArray and ReadonlyMultiMappedArray
+    _sum(x, y) = _zero(x) + _zero(y)
+    inferred_type = VERSION >= v"1.6.0-RC1" ? Union{Missing, Float64, Int64} : Any
+    @test eltype(mappedarray(_sum, [1, 1.0], [1.0, missing])) == inferred_type
+    @test eltype(mappedarray(_sum, [1, 1], [2, 2])) == Int
+    @test eltype(mappedarray(_sum, identity, [1, 1.0], [1.0, missing])) == inferred_type
+    @test eltype(mappedarray(_sum, identity, [1, 1], [2, 2])) == Int
+
+    _maybe_int(x) = x > 0 ? x : Int(x)
+    @test eltype(mappedarray(_maybe_int, Float64, [1.0, 1, -1, -1.0])) == Union{Float64, Int64}
+    @test eltype(mappedarray(_maybe_int, Float64, [1.0, -1.0])) == Union{Float64, Int64}
+    @test eltype(mappedarray(_maybe_int, Float64, [1, -1])) == Int64
+    @test eltype(mappedarray(Float64, _maybe_int, [1.0, 1, -1, -1.0])) == Float64
+    @test eltype(mappedarray(Float64, _maybe_int, [1, -1])) == Float64
+end