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module Base64
import Base: read, write, close
export Base64Pipe, base64
# Base64Pipe is a pipe-like IO object, which converts writes (and
# someday reads?) into base64 encoded (decoded) data send to a stream.
# (You must close the pipe to complete the encode, separate from
# closing the target stream). We also have a function base64(f,
# args...) which works like sprint except that it produces
# base64-encoded data, along with base64(args...) which is equivalent
# to base64(write, args...), to return base64 strings.
#############################################################################
type Base64Pipe <: IO
io::IO
# writing works in groups of 3, so we need to cache last two bytes written
b0::Uint8
b1::Uint8
nb::Uint8 # number of bytes in cache: 0, 1, or 2
function Base64Pipe(io::IO)
b = new(io,0,0,0)
finalizer(b, close)
return b
end
end
#############################################################################
# Based on code by Stefan Karpinski from https://github.com/hackerschool/WebSockets.jl (distributed under the same MIT license as Julia)
const b64chars = ['A':'Z','a':'z','0':'9','+','/']
function b64(x::Uint8, y::Uint8, z::Uint8)
n = int(x)<<16 | int(y)<<8 | int(z)
b64chars[(n >> 18) + 1],
b64chars[(n >> 12) & 0b111111 + 1],
b64chars[(n >> 6) & 0b111111 + 1],
b64chars[(n ) & 0b111111 + 1]
end
function b64(x::Uint8, y::Uint8)
a, b, c = b64(x, y, 0x0)
a, b, c, '='
end
function b64(x::Uint8)
a, b = b64(x, 0x0, 0x0)
a, b, '=', '='
end
#############################################################################
function write(b::Base64Pipe, x::AbstractVector{Uint8})
n = length(x)
s = 1 # starting index
# finish any cached data to write:
if b.nb == 1
if n >= 2
write(b.io, b64(b.b0, x[1], x[2])...)
s = 3
elseif n == 1
b.b1 = x[1]
b.nb = 2
return
else
return
end
elseif b.nb == 2
if n >= 1
write(b.io, b64(b.b0, b.b1, x[1])...)
s = 2
else
return
end
end
# write all groups of three bytes:
while s + 2 <= n
write(b.io, b64(x[s], x[s+1], x[s+2])...)
s += 3
end
# cache any leftover bytes:
if s + 1 == n
b.b0 = x[s]
b.b1 = x[s+1]
b.nb = 2
elseif s == n
b.b0 = x[s]
b.nb = 1
else
b.nb = 0
end
end
function write(b::Base64Pipe, x::Uint8)
if b.nb == 0
b.b0 = x
b.nb = 1
elseif b.nb == 1
b.b1 = x
b.nb = 2
else
write(b.io, b64(b.b0,b.b1,x)...)
b.nb = 0
end
end
function close(b::Base64Pipe)
if b.nb > 0
# write leftover bytes + padding
if b.nb == 1
write(b.io, b64(b.b0)...)
else # b.nb == 2
write(b.io, b64(b.b0, b.b1)...)
end
b.nb = 0
end
end
# like sprint, but returns base64 string
function base64(f::Function, args...)
s = IOBuffer()
b = Base64Pipe(s)
f(b, args...)
close(b)
takebuf_string(s)
end
base64(x...) = base64(write, x...)
#############################################################################
# read(b::Base64Pipe, ::Type{Uint8}) = # TODO: decode base64
#############################################################################
end # module
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