feat(TypeSafeEnum): Add caseValues (#115)

Author: bartelink

CHANGELOG.md

@@ -9,6 +9,11 @@ The `Unreleased` section name is replaced by the expected version of next releas
 ## [Unreleased]
 
 ### Added
+
+### Added
+
+- `TypeSafeEnum.caseValues<'t>`: Yields all values of a union (that is a `TypeSafeEnum`) [#115](https://github.com/jet/FsCodec/pull/115)
+
 ### Changed
 ### Removed
 ### Fixed

src/FsCodec/TypeSafeEnum.fs

@@ -30,3 +30,6 @@ let parseF<'T> f =
 let parse<'T> = parseF<'T> (=)
 
 let toString<'t> : 't -> string = Union.caseName<'t>
+
+/// <summary>Yields all the cases available for <c>'t</c>, which must be a <c>TypeSafeEnum</c>, i.e. have only nullary cases.</summary>
+let caseValues<'t> : 't[] = Union.Info.caseValues<'t>

src/FsCodec/Union.fs

@@ -26,10 +26,11 @@ module Info =
         let getCase value = cases[getTag value]
         { cases = cases; getCase = getCase })
     let tryFindCaseWithName u (predicate: string -> bool): CaseInfo option = u.cases |> Array.tryFind (fun c -> predicate c.name)
-    let private caseValues: Type -> obj[] = memoize (fun t -> (get t).cases |> Array.map (fun c -> c.construct Array.empty))
+    let caseValues<'t> : 't[] = (get typeof<'t>).cases |> Array.map (fun c -> c.construct Array.empty :?> 't)
+    let caseValuesT: Type -> obj[] = memoize (fun t -> (get t).cases |> Array.map (fun c -> c.construct Array.empty))
     let tryFindCaseValueWithName (t: Type): (string -> bool) -> obj option =
         let u = get t
-        let caseValue = let values = caseValues t in fun i -> values[i]
+        let caseValue = let values = caseValuesT t in fun i -> values[i]
         fun predicate -> u.cases |> Array.tryFindIndex (fun c -> predicate c.name) |> Option.map caseValue
 
 /// Determines whether the type is a Union

tests/FsCodec.Tests/FsCodec.Tests.fsproj

@@ -8,6 +8,7 @@
   <ItemGroup>
     <Compile Include="StreamNameTests.fs" />
     <Compile Include="CompressionTests.fs" />
+    <Compile Include="TypeSafeEnumTests.fs" />
   </ItemGroup>
 
   <ItemGroup>

tests/FsCodec.Tests/TypeSafeEnumTests.fs

@@ -0,0 +1,10 @@
+module FsCodec.Tests.TypeSafeEnumTests
+
+open FsCodec
+open Swensen.Unquote
+open Xunit
+
+type Outcome = Joy | Pain | Misery
+
+let [<Fact>] caseNames () =
+    [| Joy; Pain; Misery |] =! TypeSafeEnum.caseValues<_>