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LZW compression: Difference between revisions
Added Elixir
(Added Elixir) |
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Line 1,409:
84 79 66 69 79 82 78 79 84 257 259 261 266 260 262 264
TOBEORNOTTOBEORTOBEORNOT
</pre>
=={{header|Elixir}}==
{{trans|Erlang}}
<lang elixir>defmodule LZW do
def encode(str), do: encode(to_char_list(str), init, 256, [])
defp encode([h], d, _, out), do: Enum.reverse([Dict.get(d, [h]) | out])
defp encode([h|t], d, free, out) do
val = Dict.get(d, [h])
find_match(t, [h], val, d, free, out)
end
defp find_match([h|t], l, lastval, d, free, out) do
case Dict.fetch(d, [h|l]) do
{:ok, val} -> find_match(t, [h|l], val, d, free, out)
:error ->
d1 = Dict.put(d, [h|l], free)
encode([h|t], d1, free+1, [lastval | out])
end
end
defp find_match([], _, lastval, _, _, out), do: Enum.reverse([lastval | out])
defp init, do: init(255, Map.new)
defp init(0, d), do: d
defp init(n, d), do: init(n-1, Dict.put(d,[n],n))
def decode([h|t]) do
d = init1(Map.new)
val = Dict.get(d, h)
decode(t, val, 256, d, val)
end
defp decode([], _, _, _, l), do: Enum.reverse(l) |> to_string
defp decode([h|t], old, free, d, l) do
val = Dict.get(d, h)
add = [List.last(val) | old]
d1 = Dict.put(d, free, add)
decode(t, val, free+1, d1, val++l)
end
defp init1(d), do: init1(255, d)
defp init1(0, d), do: d
defp init1(n, d), do: init1(n-1, Dict.put(d, n, [n]))
end
str = "TOBEORNOTTOBEORTOBEORNOT"
IO.inspect enc = LZW.encode(str)
IO.inspect dec = LZW.decode(enc)
IO.inspect str == dec</lang>
{{out}}
<pre>
[84, 79, 66, 69, 79, 82, 78, 79, 84, 256, 258, 260, 265, 259, 261, 263]
"TOBEORNOTTOBEORTOBEORNOT"
true
</pre>
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