[ANN] TruncatedStreams.jl - Streams that lie about EOF

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Synopsis

TruncatedStreams.jl provides types that meet the following four criteria:

  1. Inherit from Base.IO;
  2. Transparently pass all basic IO methods through to a wrapped IO object, except…
  3. Lie about eof and…
  4. Do not read a single byte more from the wrapped IO object than what is necessary to determine EOF.
using TruncatedStreams

io = IOBuffer(collect(0x00:0xff))

fixed_io = FixedLengthIO(io, 10)  # pretend EOF occurs after the first 10 bytes are read
@assert read(fixed_io) == collect(0x00:0x09)
@assert eof(fixed_io) == true
@assert eof(io) == false  # a lie, but a useful one!
@assert peek(io) == 0x0a  # read exactly 10 bytes from io and not a byte more

sentinel_io = SentinelIO(io, [0x10, 0x11])  # pretend EOF occurs as soon as the sentinel is read
@assert read(sentinel_io) == collect(0x0a:0x0f)
@assert eof(sentinel_io) == true
@assert eof(io) == false
@assert peek(io) == 0x12  # the sentinel is consumed, but not a byte more

close(io)
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