- DecoderContext.ReadByte returns the byte value rather than an array…

… segment

Filbert.sln

@@ -83,8 +83,8 @@ Global
 		{0035839E-C9B3-4153-8689-00D3B1251A26}.Release|x86.ActiveCfg = Release|Any CPU
 		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|Mixed Platforms.ActiveCfg = Release|Any CPU
-		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|Mixed Platforms.Build.0 = Release|Any CPU
+		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
 		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Debug|x86.ActiveCfg = Debug|Any CPU
 		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{2EC7E114-9DB5-4AC0-9550-B4239B4BA946}.Release|Any CPU.Build.0 = Release|Any CPU

src/Filbert/Decoder.fs

@@ -10,9 +10,6 @@ open Checked
 
 [<AutoOpen>]
 module ArraySegmentReaders =
-    /// Reads a single byte
-    let inline byteReader (seg : ArraySegment<byte>) = seg.Array.[seg.Offset]
-
     /// Reads some bytes into an array
     let inline byteArrayReader n (seg : ArraySegment<byte>) = 
         let arr = Array.zeroCreate<byte> n
@@ -53,7 +50,7 @@ let inline readBigInt n (ctx : DecoderContext) =
     let bigInteger (buffer : byte[]) =
         buffer |> Seq.mapi (fun i digit -> (byteToBigInt digit) * (256I ** i)) |> Seq.sum
 
-    let sign = ctx.ReadByte() |> byteReader |> function | 0uy -> 1I | 1uy -> -1I
+    let sign = ctx.ReadByte() |> function | 0uy -> 1I | 1uy -> -1I
     ctx.ReadBytes n |> byteArrayReader n |> bigInteger |> (fun n -> n * sign)
 
 /// Converts a set of megasecond, second and microsecond values into a DateTime value
@@ -62,7 +59,7 @@ let inline toDateTime (mega : int) (sec :int) (micro : int) =
 
 [<AutoOpen>]
 module Decoders = 
-    let decodeSmallInt = byteReader >> int >> Integer
+    let decodeSmallInt = int >> Integer
     let decodeInt      = byteArrayReader 4 >> bigEndianInteger >> Integer
     let decodeFloat    = byteArrayReader 31 >> str >> float >> Float
     let decodeUint     = byteArrayReader 4 >> bigEndianUinteger
@@ -91,7 +88,7 @@ let inline readComplexBert (items : Bert[]) =
 /// Parses the Erlang External Term Format 
 /// see http://erlang.org/doc/apps/erts/erl_ext_dist.html
 let rec decodeType (ctx : DecoderContext) : Bert =
-    match byteReader <| ctx.ReadByte() with
+    match ctx.ReadByte() with
     // SMALL_INTEGER (unsigned 8 bit integer) 
     | Tags.smallInteger -> ctx.ReadByte() |> decodeSmallInt
     // INTEGER (32 bit integer in big-endian format)
@@ -105,7 +102,7 @@ let rec decodeType (ctx : DecoderContext) : Bert =
                            | 0 -> raise <| InvalidAtomLength len
                            | n -> ctx.ReadBytes len |> byteArrayReader len |> str |> Atom
     // SMALL_TUPLE
-    | Tags.smallTuple   -> let arity = ctx.ReadByte() |> byteReader |> int
+    | Tags.smallTuple   -> let arity = ctx.ReadByte() |> int
                            match arity with
                            | 0 -> [||] |> Tuple
                            | n -> ctx |> readTuple n
@@ -126,7 +123,7 @@ let rec decodeType (ctx : DecoderContext) : Bert =
                            // as per specified by LIST_EXT, it should end with NIL_EXT for a
                            // proper list, for simplicity sake, for now impropert list is not
                            // going to be supported here
-                           match ctx.ReadByte() |> byteReader with
+                           match ctx.ReadByte() with
                            | Tags.nil -> List berts
                            | _ -> raise ImpropertyListNotSupported
     // BINARY
@@ -135,7 +132,7 @@ let rec decodeType (ctx : DecoderContext) : Bert =
                            | 0 -> Binary [||]
                            | n -> ctx.ReadBytes n |> byteArrayReader n |> Binary
     // SMALL_BIG
-    | Tags.smallBig     -> let n = ctx.ReadByte() |> byteReader |> int
+    | Tags.smallBig     -> let n = ctx.ReadByte() |> int
                            ctx |> readBigInt n |> BigInteger
     // LARGE_BIG
     | Tags.largeBig     -> let n = ctx.ReadBytes 4 |> decodeUint |> int
@@ -160,6 +157,6 @@ and readTuple arity (ctx : DecoderContext) =
 
 let decode (stream : Stream) =
     use ctx = new DecoderContext(stream)
-    match byteReader <| ctx.ReadByte() with
+    match ctx.ReadByte() with
     | Constants.version -> decodeType ctx
     | n   -> raise <| InvalidVersion n

src/Filbert/Utils.fs

@@ -85,8 +85,16 @@ type internal DecoderContext (stream : Stream) =
                 swapBuffer()
                 if n > bufferSize then raise <| InsufficientNumberOfBytes(n, bufferSize)
                 readBytes n
+
+    let readByte () =
+        if bufferSize = 0 then raise <| InsufficientNumberOfBytes(1, bufferSize)
+        if index = bufferSize then initBuffer()
+        try
+            buffer.[index]
+        finally
+            index <- index + 1
 
-    member this.ReadByte()   = readBytes 1
+    member this.ReadByte()   = readByte()
 
     member this.ReadBytes(n) = readBytes n
 

tests/Filbert.Tests/DecoderContext.fs

@@ -25,9 +25,9 @@ type ``Given a decoder context`` () =
         use memStream = new MemoryStream(input)
         use ctx       = new DecoderContext(memStream)
 
-        ctx.ReadByte() |> should equal <| new ArraySegment<byte>(input, 0, 1)
-        ctx.ReadByte() |> should equal <| new ArraySegment<byte>(input, 1, 1)
-        ctx.ReadByte() |> should equal <| new ArraySegment<byte>(input, 2, 1)
+        ctx.ReadByte() |> should equal <| 1uy
+        ctx.ReadByte() |> should equal <| 2uy
+        ctx.ReadByte() |> should equal <| 3uy
 
     [<Test>]
     member test.``when there is sufficient data in the stream, read bytes should return them all`` () =
@@ -52,7 +52,7 @@ type ``Given a decoder context`` () =
         use memStream = new MemoryStream(input)
         use ctx       = new DecoderContext(memStream)
 
-        ctx.ReadByte()     |> should equal <| new ArraySegment<byte>(input, 0, 1)
+        ctx.ReadByte()     |> should equal 1uy
         ctx.ReadBytes 1024 |> should equal <| new ArraySegment<byte>(input, 1, 1024)
 
     [<Test>]

tests/Filbert.Tests/Filbert.Tests.fsproj

@@ -40,6 +40,7 @@
   <Import Project="$(SolutionDir)\.nuget\nuget.targets" />
   <ItemGroup>
     <Compile Include="BufferPool.fs" />
+    <Compile Include="DecoderContext.fs" />
     <Compile Include="Encoder.fs" />
     <Compile Include="Decoder.fs" />
     <None Include="packages.config" />