Merge pull request #15 from azurefx/support_out_parameters

Support out parameters

Author: azurefx

Artifacts.toml

@@ -1,6 +1,6 @@
 [clrbridge]
-git-tree-sha1 = "a5d8e1de6e60b34ec42d252d2090965ccbca0022"
+git-tree-sha1 = "321e4d3676e1b4527c7d06dc6924869ef592662f"
 
     [[clrbridge.download]]
-    url = "https://github.com/azurefx/CLRBridge/releases/download/v0.1.2/CLRBridge.v0.1.2.tar.gz"
-    sha256 = "3fa12f3432b7f22af7f6ace98b1fd9539580776368a3192189baedc8d72c4972"
+    url = "https://github.com/azurefx/CLRBridge/releases/download/v0.1.3/CLRBridge.v0.1.3.tar.gz"
+    sha256 = "500f0fcc267e14c6ccbe2703ffa7283ff1ca43c0a7e6bb4bd72f5d049364c614"

README.md

@@ -89,16 +89,38 @@ julia> DotNET.unbox(s)
 "❤"
 ```
 
+To pass an argument by reference (`out`/`ref` in `C#`), wrap it into a `Ref` object:
+
+```julia
+julia> result = Ref{Int}()
+Base.RefValue{Int64}(212700848)
+
+julia> T"System.Int64".TryParse("1970", result)
+true
+
+julia> result[]
+1970
+
+julia> result = Ref(null)
+Base.RefValue{CLRObject}(null)
+
+julia> T"System.Int64".TryParse("2022", result)
+true
+
+julia> result[]
+System.Int64(2022)
+```
+
 ### Arrays and Collections
 
 To copy a multidimensional array from `.NET` to Julia, use `collect` method:
 
 ```julia
-julia> arr = convert(CLRObject, reshape(UnitRange{Int32}(1, 8), 2, 2, 2))
-System.Int32[,,]("System.Int32[,,]")
+julia> arr = convert(CLRObject, reshape(1:8, 2, 2, 2))
+System.Int64[,,]("System.Int64[,,]")
 
 julia> collect(arr)
-2×2×2 Array{Int32, 3}:
+2×2×2 Array{Int64, 3}:
 [:, :, 1] =
  1  3
  2  4
@@ -110,8 +132,8 @@ julia> collect(arr)
 
 CLI `Array` elements are stored in *row-major* order, thus the equivalent definition in `C#` is
 ```csharp
-public static int[,,] Get3DArray() {
-  return new int[2, 2, 2] {
+public static long[,,] Get3DArray() {
+  return new long[2, 2, 2] {
     {{1, 2}, {3, 4}},
     {{5, 6}, {7, 8}}
   };

src/CLRBridge.jl

@@ -51,6 +51,7 @@ empty_fp() = Ref{Ptr{Cvoid}}(0)
 const fp_Release = empty_fp()
 const fp_Duplicate = empty_fp()
 const fp_CreateArray = empty_fp()
+const fp_PutObject = empty_fp()
 const fp_PutString = empty_fp()
 const fp_GetString = empty_fp()
 const fp_FreeString = empty_fp()
@@ -101,6 +102,7 @@ function init(host::CLRHost)
     fp_Release[] = fp_primitive("Release")
     fp_Duplicate[] = fp_primitive("Duplicate")
     fp_CreateArray[] = fp_primitive("CreateArray")
+    fp_PutObject[] = fp_primitive("PutObject")
     fp_PutString[] = fp_primitive("PutString")
     fp_GetString[] = fp_primitive("GetString")
     fp_FreeString[] = fp_primitive("FreeString")
@@ -152,6 +154,10 @@ function CreateArray(argc)
     track(ccall(fp_CreateArray[], Handle, (UInt32,), argc))
 end
 
+function PutObject(handle, value)
+    ccall(fp_PutObject[], Handle, (Handle, Handle), handle, value)
+end
+
 function PutString(handle, value)
     ccall(fp_PutString[], Handle, (Handle, BStr), handle, value)
 end

src/marshalling.jl

@@ -57,18 +57,36 @@ box(x::Char, handle) = CLRBridge.PutChar(handle, x)
 boxedtype(::Type{Char}) = T"System.Char"
 box(x::String, handle) = CLRBridge.PutString(handle, x)
 boxedtype(::Type{String}) = T"System.String"
+box(x::Ref{CLRObject}, handle) = CLRBridge.PutObject(handle, gethandle(isassigned(x) ? x[] : CLRObject(0)))
+boxedtype(::Type{Ref{CLRObject}}) = boxedtype(CLRObject)
+box(x::Ref{T}, handle) where {T} = box(isassigned(x) ? x[] : Ref(CLRObject(0)), handle)
+boxedtype(::Type{Ref{T}}) where {T} = boxedtype(T)
 
 function Base.convert(::Type{CLRObject}, x)
     CLRBridge.Duplicate(box(x, 1))
 end
 
 Base.convert(::Type{CLRObject}, x::CLRObject) = x
 
+function updateref(x::Ref{CLRObject}, handle)
+    x[] = CLRBridge.Duplicate(handle)
+end
+
+function updateref(x::Ref{T}, handle) where {T}
+    x[] = unbox(CLRObject(handle))
+end
+
 function invokemember(flags, type::CLRObject, this::CLRObject, name, args...)
     boxed = map(args, 1:length(args)) do arg, i
         box(arg, i)
     end
-    unbox(CLRBridge.InvokeMember(gethandle(type), string(name), flags, 0, gethandle(this), boxed))
+    ret = CLRBridge.InvokeMember(gethandle(type), string(name), flags, 0, gethandle(this), boxed)
+    for (i, arg) in enumerate(args)
+        if arg isa Ref
+            updateref(arg, i)
+        end
+    end
+    unbox(ret)
 end
 
 function invokemember(type::CLRObject, this::CLRObject, name, args...)

test/runtests.jl

@@ -55,6 +55,25 @@ end
         t.Item1 = Int32(2)
         @test t.Item1 == Int32(2)
     end
+
+    # out parameters
+    let
+        tryparse(s, i) = T"System.Int64".TryParse(s, i)
+        @test tryparse("42", null)
+        @test !tryparse("abc", null)
+        r = Ref{Int64}()
+        @test !tryparse("abc", r)
+        tryparse("123", r)
+        @test r[] == 123
+        r = Ref{CLRObject}()
+        tryparse("def", r)
+        @test unbox(r[]) == 0
+        tryparse("456", r)
+        @test unbox(r[]) == 456
+        r = Ref{CLRObject}(1)
+        tryparse("789", r)
+        @test unbox(r[]) == 789
+    end
 end
 
 @testset "Generics" begin