Move-to-front algorithm: Difference between revisions

=={{header|Julia}}==

{{works with|Julia|0.6}}

<lang julia>function encodeMTF(str::AbstractString, symtable::Vector{Char}=collect('a':'z'))

function encode(ch::Char)

r = findfirst(symtable, ch)

deleteat!(symtable, r)

prepend!(symtable, ch)

return r

end

collect(encode(ch) for ch in str)

end

function decodeMTF(arr::Vector{Int}, symtable::Vector{Char}=collect('a':'z'))

function decode(i::Int)

r = symtable[i]

deleteat!(symtable, i)

prepend!(symtable, r)

return r

end

join(decode(i) for i in arr)

end

testset = ["broood", "bananaaa", "hiphophiphop"]

encoded = encodeMTF.(testset)

decoded = decodeMTF.(encoded)

for (str, enc, dec) in zip(testset, encoded, decoded)

println("Test string: $str\n -> Encoded: $enc\n -> Decoded: $dec")

end

using Base.Test

@testset "Decoded string equal to original" begin

for (str, dec) in zip(testset, decoded)

@test str == dec

end

end</lang>

{{out}}

<pre>Test string: broood

-> Encoded: [2, 18, 16, 1, 1, 6]

-> Decoded: broood

Test string: bananaaa

-> Encoded: [2, 2, 14, 2, 2, 2, 1, 1]

-> Decoded: bananaaa

Test string: hiphophiphop

-> Encoded: [8, 9, 16, 3, 16, 3, 3, 4, 3, 3, 4, 3]

-> Decoded: hiphophiphop

Test Summary: | Pass Total

Decoded string equal to original | 3 3</pre>