Cancellable: add safer APIs to check the token (#18175)

Author: auduchinok

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -32,6 +32,7 @@
 * Sink: report SynPat.ArrayOrList type ([PR #18127](https://github.com/dotnet/fsharp/pull/18127))
 * Show the default value of compiler options ([PR #18054](https://github.com/dotnet/fsharp/pull/18054))
 * Support ValueOption + Struct attribute as optional parameter for methods ([Language suggestion #1136](https://github.com/fsharp/fslang-suggestions/issues/1136), [PR #18098](https://github.com/dotnet/fsharp/pull/18098))
+* Cancellable: add safer APIs to check the token ([PR #18175](https://github.com/dotnet/fsharp/pull/18175))
 
 ### Changed
 

src/Compiler/Utilities/Cancellable.fs

@@ -14,6 +14,8 @@ type Cancellable =
         tokenHolder.Value
         |> ValueOption.defaultWith (fun () -> if guard then failwith msg else CancellationToken.None)
 
+    static member HasCancellationToken = tokenHolder.Value.IsSome
+
     static member Token = ensureToken "Token not available outside of Cancellable computation."
 
     static member UsingToken(ct) =
@@ -28,6 +30,11 @@ type Cancellable =
         let token = ensureToken "CheckAndThrow invoked outside of Cancellable computation."
         token.ThrowIfCancellationRequested()
 
+    static member TryCheckAndThrow() =
+        match tokenHolder.Value with
+        | ValueNone -> ()
+        | ValueSome token -> token.ThrowIfCancellationRequested()
+
 namespace Internal.Utilities.Library
 
 open System

src/Compiler/Utilities/Cancellable.fsi

@@ -7,8 +7,12 @@ open System.Threading
 type Cancellable =
     /// For use in testing only. Cancellable.token should be set only by the cancellable computation.
     static member internal UsingToken: CancellationToken -> IDisposable
+
+    static member HasCancellationToken: bool
     static member Token: CancellationToken
+
     static member CheckAndThrow: unit -> unit
+    static member TryCheckAndThrow: unit -> unit
 
 namespace Internal.Utilities.Library
 

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl

@@ -2011,9 +2011,12 @@ FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryRe
 FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryReader+MetadataOnlyFlag
 FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag
 FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryReader+Shim
+FSharp.Compiler.Cancellable: Boolean HasCancellationToken
+FSharp.Compiler.Cancellable: Boolean get_HasCancellationToken()
 FSharp.Compiler.Cancellable: System.Threading.CancellationToken Token
 FSharp.Compiler.Cancellable: System.Threading.CancellationToken get_Token()
 FSharp.Compiler.Cancellable: Void CheckAndThrow()
+FSharp.Compiler.Cancellable: Void TryCheckAndThrow()
 FSharp.Compiler.CodeAnalysis.DelayedILModuleReader: System.String OutputFile
 FSharp.Compiler.CodeAnalysis.DelayedILModuleReader: System.String get_OutputFile()
 FSharp.Compiler.CodeAnalysis.DelayedILModuleReader: Void .ctor(System.String, Microsoft.FSharp.Core.FSharpFunc`2[System.Threading.CancellationToken,Microsoft.FSharp.Core.FSharpOption`1[System.IO.Stream]])

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl

@@ -2011,9 +2011,12 @@ FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryRe
 FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryReader+MetadataOnlyFlag
 FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryReader+ReduceMemoryFlag
 FSharp.Compiler.AbstractIL.ILBinaryReader: FSharp.Compiler.AbstractIL.ILBinaryReader+Shim
+FSharp.Compiler.Cancellable: Boolean HasCancellationToken
+FSharp.Compiler.Cancellable: Boolean get_HasCancellationToken()
 FSharp.Compiler.Cancellable: System.Threading.CancellationToken Token
 FSharp.Compiler.Cancellable: System.Threading.CancellationToken get_Token()
 FSharp.Compiler.Cancellable: Void CheckAndThrow()
+FSharp.Compiler.Cancellable: Void TryCheckAndThrow()
 FSharp.Compiler.CodeAnalysis.DelayedILModuleReader: System.String OutputFile
 FSharp.Compiler.CodeAnalysis.DelayedILModuleReader: System.String get_OutputFile()
 FSharp.Compiler.CodeAnalysis.DelayedILModuleReader: Void .ctor(System.String, Microsoft.FSharp.Core.FSharpFunc`2[System.Threading.CancellationToken,Microsoft.FSharp.Core.FSharpOption`1[System.IO.Stream]])