add transcode

Author: bicycle1885

src/buffer.jl

@@ -23,9 +23,12 @@ mutable struct Buffer
     marginpos::Int
 
     function Buffer(size::Integer)
-        @assert size > 0
         return new(Vector{UInt8}(size), 0, 1, 1)
     end
+
+    function Buffer(data::Vector{UInt8})
+        return new(data, 0, 1, length(data)+1)
+    end
 end
 
 function Base.length(buf::Buffer)
@@ -167,6 +170,12 @@ function initbuffer!(buf::Buffer)
     return buf
 end
 
+# Copy marked data.
+function copymarked(buf::Buffer)
+    @assert buf.markpos > 0
+    return buf.data[buf.markpos:buf.marginpos-1]
+end
+
 # Read as much data as possbile from `input` to the margin of `output`.
 # This function will not block if `input` has buffered data.
 function readdata!(input::IO, output::Buffer)

src/state.jl

@@ -23,4 +23,8 @@ mutable struct State
     function State(size::Integer)
         return new(:idle, :ok, Buffer(size), Buffer(size))
     end
+
+    function State(buffer1::Buffer, buffer2::Buffer)
+        return new(:idle, :ok, buffer1, buffer2)
+    end
 end

src/stream.jl

@@ -45,6 +45,10 @@ function TranscodingStream(codec::Codec, stream::IO; bufsize::Integer=DEFAULT_BU
     return TranscodingStream{typeof(codec),typeof(stream)}(codec, stream, State(bufsize))
 end
 
+function TranscodingStream(codec::Codec, stream::IO, state::State)
+    return TranscodingStream{typeof(codec),typeof(stream)}(codec, stream, state)
+end
+
 function Base.show(io::IO, stream::TranscodingStream)
     print(io, summary(stream), "(<state=$(stream.state.state)>)")
 end
@@ -267,6 +271,22 @@ function Base.write(stream::TranscodingStream, ::EndToken)
 end
 
 
+# Transcode
+# ---------
+
+"""
+    transcode(codec::Codec, data::Vector{UInt8})::Vector{UInt8}
+
+Transcode `data` by applying `codec`.
+"""
+function Base.transcode(codec::Codec, data::Vector{UInt8})
+    buffer2 = Buffer(length(data))
+    mark!(buffer2)
+    write(TranscodingStream(codec, DevNull, State(Buffer(data), buffer2)), TOKEN_END)
+    return copymarked(buffer2)
+end
+
+
 # Buffering
 # ---------
 

src/testtools.jl

@@ -23,3 +23,11 @@ function test_roundtrip_write(encoder, decoder)
         close(stream)
     end
 end
+
+function test_roundtrip_transcode(encode, decode)
+    srand(12345)
+    for n in vcat(0:30, sort!(rand(500:100_000, 30))), alpha in (0x00:0xff, 0x00:0x0f)
+        data = rand(alpha, n)
+        Base.Test.@test hash(transcode(decode(), transcode(encode(), data))) == hash(data)
+    end
+end

test/runtests.jl

@@ -79,6 +79,11 @@ using Base.Test
     mark(stream)
     @test hash(read(stream)) == hash(data)
     @test hash(stream.state.buffer1.data[1:length(data)]) == hash(data)
+
+    # transcode
+    @test transcode(Identity(), b"") == b""
+    @test transcode(Identity(), b"foo") == b"foo"
+    TranscodingStreams.test_roundtrip_transcode(Identity, Identity)
 end
 
 Pkg.test("CodecZlib")