#132 allow users to optionally provide an output buffer when calling transcode

src/noop.jl

@@ -120,10 +120,11 @@ function Base.transcode(::Type{Noop}, data::ByteData)
     return transcode(Noop(), data)
 end
 
-function Base.transcode(::Noop, data::ByteData)
-    # Copy data because the caller may expect the return object is not the same
+function Base.transcode(codec::Noop, input::Buffer, output::Buffer = Buffer(Vector{UInt8}()))
+    # copy data because the caller may expect the return object is not the same
     # as from the input.
-    return Vector{UInt8}(data)
+    copydata!(output, bufferptr(input), length(input))
+    return output.data
 end
 
 

src/transcode.jl

@@ -2,7 +2,7 @@
 # =========
 
 """
-    transcode(::Type{C}, data::Vector{UInt8})::Vector{UInt8} where C<:Codec
+    transcode(::Type{C}, data::ByteData)::ByteData where {C<:Codec}
 
 Transcode `data` by applying a codec `C()`.
 
@@ -27,7 +27,7 @@ julia> String(decompressed)
 
 ```
 """
-function Base.transcode(::Type{C}, data::ByteData) where C<:Codec
+function Base.transcode(::Type{C}, data::ByteData) where {C<:Codec}
     codec = C()
     initialize(codec)
     try
@@ -38,10 +38,12 @@ function Base.transcode(::Type{C}, data::ByteData) where C<:Codec
 end
 
 """
-    transcode(codec::Codec, data::Vector{UInt8})::Vector{UInt8}
+    transcode(codec::Codec, data::Union{ByteData, Buffer}[, output::Union{ByteData, Buffer}])::ByteData
 
 Transcode `data` by applying `codec`.
 
+If `output` is unspecified, then this method will allocate it.
+
 Note that this method does not initialize or finalize `codec`. This is
 efficient when you transcode a number of pieces of data, but you need to call
 [`TranscodingStreams.initialize`](@ref) and
@@ -59,7 +61,9 @@ julia> codec = ZlibCompressor();
 
 julia> TranscodingStreams.initialize(codec)
 
-julia> compressed = transcode(codec, data);
+julia> compressed = Vector{UInt8}()
+
+julia> transcode(codec, data, compressed);
 
 julia> TranscodingStreams.finalize(codec)
 
@@ -76,9 +80,11 @@ julia> String(decompressed)
 
 ```
 """
-function Base.transcode(codec::Codec, data::ByteData)
-    input = Buffer(data)
-    output = Buffer(initial_output_size(codec, buffermem(input)))
+function Base.transcode(
+    codec::Codec,
+    input::Buffer,
+    output::Buffer = Buffer(initial_output_size(codec, buffermem(input))),
+)
     error = Error()
     code = startproc(codec, :write, error)
     if code === :error
@@ -121,6 +127,14 @@ function Base.transcode(codec::Codec, data::ByteData)
     throw(error[])
 end
 
+Base.transcode(codec::Codec, data::ByteData, output::ByteData) =
+    transcode(codec, data, Buffer(output))
+
+Base.transcode(codec::Codec, data::ByteData) = transcode(codec, Buffer(data))
+
+Base.transcode(codec::Codec, data::ByteData, output::Buffer) =
+    transcode(codec, Buffer(data), output)
+
 # Return the initial output buffer size.
 function initial_output_size(codec::Codec, input::Memory)
     return max(

test/codecnoop.jl

@@ -192,9 +192,26 @@
     data = b""
     @test transcode(Noop(), data)  == data
     @test transcode(Noop(), data) !== data
+    @test transcode(Noop(), data, Vector{UInt8}()) == data
+    @test transcode(Noop(), data, TranscodingStreams.Buffer(Vector{UInt8}())) == data
+    @test transcode(Noop(), data, Vector{UInt8}()) !== data
+    @test transcode(Noop(), data, TranscodingStreams.Buffer(Vector{UInt8}())) !== data
+    output = Vector{UInt8}()
+    @test transcode(Noop(), data, output) === output
+    output = TranscodingStreams.Buffer(Vector{UInt8}())
+    @test transcode(Noop(), data, output) === output.data
+
     data = b"foo"
     @test transcode(Noop(), data)  == data
     @test transcode(Noop(), data) !== data
+    @test transcode(Noop(), data, Vector{UInt8}()) == data
+    @test transcode(Noop(), data, TranscodingStreams.Buffer(Vector{UInt8}())) == data
+    @test transcode(Noop(), data, Vector{UInt8}()) !== data
+    @test transcode(Noop(), data, TranscodingStreams.Buffer(Vector{UInt8}())) !== data
+    output = Vector{UInt8}()
+    @test transcode(Noop(), data, output) === output
+    output = TranscodingStreams.Buffer(Vector{UInt8}())
+    @test transcode(Noop(), data, output) === output.data
 
     TranscodingStreams.test_roundtrip_transcode(Noop, Noop)
     TranscodingStreams.test_roundtrip_read(NoopStream, NoopStream)