Merge pull request #296 from GenieFramework/hh-parsing

Better support for Union types with Nothing

Project.toml

@@ -1,7 +1,7 @@
 name = "Stipple"
 uuid = "4acbeb90-81a0-11ea-1966-bdaff8155998"
 authors = ["Adrian <[email protected]>"]
-version = "0.30.10"
+version = "0.30.11"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"

src/stipple/parsers.jl

@@ -15,6 +15,10 @@ function stipple_parse(::Type{T}, value) where T
   end
 end
 
+function stipple_parse(::Type{T}, value::AbstractString) where T<:AbstractString
+  convert(T, value)
+end
+
 # function stipple_parse(::Type{T}, value::Dict) where T <: AbstractDict
 #   convert(T, value)
 # end
@@ -79,11 +83,16 @@ function stipple_parse(::Type{Union{Nothing, T}}, ::Nothing) where T
   nothing
 end
 
-# Union with Nothing
+# Union with Nothing, part I
 function stipple_parse(::Type{Union{Nothing, T}}, value) where T
   stipple_parse(T, value)
 end
 
+# Union with Nothing, part II
+function stipple_parse(::Type{Union{Nothing, T}}, value::Union{Nothing, T}) where T
+  stipple_parse(T, value)
+end
+
 # define an explicit function for Type{Any} to avoid ambiguities between Type{Union{Nothing, T}} and Type{T} (line 35 and line 64) in case of T == Any
 function stipple_parse(::Type{Any}, v::T) where {T}
   v::T

test/runtests.jl

@@ -594,4 +594,15 @@ end
     @test Stipple.stipple_parse(T2, t2_dict) == T2(1, T1(2, 3))
     @test Stipple.stipple_parse(T3, Dict()) == T3(1, 3)
     @test Stipple.stipple_parse(T4, Dict()) == T4(1, T3(1, 3))
+
+    @test Stipple.stipple_parse(Union{Nothing, String}, "hi") == "hi"
+    @test Stipple.stipple_parse(Union{Nothing, String}, SubString("hi")) == "hi"
+    # the following test is only valid for Julia 1.7 and above because specifity of methods
+    # changed in Julia 1.7. As the latest LTS version of Julia is now 1.10, we accept that
+    # this specific stipple_parse for Union{Nothing, T} fails for Julia 1.6
+    # people can define explicit methods for their types if they need this functionality
+    @static if VERSION ≥ v"1.7"
+        @test Stipple.stipple_parse(Union{Nothing, SubString}, "hi") == SubString("hi")
+    end
+    @test Stipple.stipple_parse(Union{Nothing, String}, nothing) === nothing
 end