Initial commit

.gitignore

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+/_build
+/deps
+erl_crash.dump
+*.ez

README.md

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+# Base62
+
+Base62 encoder/decoder in pure Elixir.
+
+## Usage
+
+### Encode
+
+```
+iex> Base62.encode(28)
+"S"
+
+iex> Base62.encode(44)
+"i"
+
+iex> Base62.encode(280)
+"4W"
+```
+
+### Decode
+
+```
+iex> Base62.decode("100")
+3844
+
+iex> Base62.decode("igas")
+10650166
+
+iex> Base62.decode("EvilMartians")
+776957886790921093120
+```

lib/base62.ex

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+defmodule Base62 do
+  def encode(0), do: "0"
+  def encode(1), do: "1"
+  def encode(2), do: "2"
+  def encode(3), do: "3"
+  def encode(4), do: "4"
+  def encode(5), do: "5"
+  def encode(6), do: "6"
+  def encode(7), do: "7"
+  def encode(8), do: "8"
+  def encode(9), do: "9"
+  def encode(10), do: "A"
+  def encode(11), do: "B"
+  def encode(12), do: "C"
+  def encode(13), do: "D"
+  def encode(14), do: "E"
+  def encode(15), do: "F"
+  def encode(16), do: "G"
+  def encode(17), do: "H"
+  def encode(18), do: "I"
+  def encode(19), do: "J"
+  def encode(20), do: "K"
+  def encode(21), do: "L"
+  def encode(22), do: "M"
+  def encode(23), do: "N"
+  def encode(24), do: "O"
+  def encode(25), do: "P"
+  def encode(26), do: "Q"
+  def encode(27), do: "R"
+  def encode(28), do: "S"
+  def encode(29), do: "T"
+  def encode(30), do: "U"
+  def encode(31), do: "V"
+  def encode(32), do: "W"
+  def encode(33), do: "X"
+  def encode(34), do: "Y"
+  def encode(35), do: "Z"
+  def encode(36), do: "a"
+  def encode(37), do: "b"
+  def encode(38), do: "c"
+  def encode(39), do: "d"
+  def encode(40), do: "e"
+  def encode(41), do: "f"
+  def encode(42), do: "g"
+  def encode(43), do: "h"
+  def encode(44), do: "i"
+  def encode(45), do: "j"
+  def encode(46), do: "k"
+  def encode(47), do: "l"
+  def encode(48), do: "m"
+  def encode(49), do: "n"
+  def encode(50), do: "o"
+  def encode(51), do: "p"
+  def encode(52), do: "q"
+  def encode(53), do: "r"
+  def encode(54), do: "s"
+  def encode(55), do: "t"
+  def encode(56), do: "u"
+  def encode(57), do: "v"
+  def encode(58), do: "w"
+  def encode(59), do: "x"
+  def encode(60), do: "y"
+  def encode(61), do: "z"
+  def encode(number) do
+    encode(div(number, 62)) <> encode(rem(number, 62))
+  end
+
+  def decode("0"), do: 0
+  def decode("1"), do: 1
+  def decode("2"), do: 2
+  def decode("3"), do: 3
+  def decode("4"), do: 4
+  def decode("5"), do: 5
+  def decode("6"), do: 6
+  def decode("7"), do: 7
+  def decode("8"), do: 8
+  def decode("9"), do: 9
+  def decode("A"), do: 10
+  def decode("B"), do: 11
+  def decode("C"), do: 12
+  def decode("D"), do: 13
+  def decode("E"), do: 14
+  def decode("F"), do: 15
+  def decode("G"), do: 16
+  def decode("H"), do: 17
+  def decode("I"), do: 18
+  def decode("J"), do: 19
+  def decode("K"), do: 20
+  def decode("L"), do: 21
+  def decode("M"), do: 22
+  def decode("N"), do: 23
+  def decode("O"), do: 24
+  def decode("P"), do: 25
+  def decode("Q"), do: 26
+  def decode("R"), do: 27
+  def decode("S"), do: 28
+  def decode("T"), do: 29
+  def decode("U"), do: 30
+  def decode("V"), do: 31
+  def decode("W"), do: 32
+  def decode("X"), do: 33
+  def decode("Y"), do: 34
+  def decode("Z"), do: 35
+  def decode("a"), do: 36
+  def decode("b"), do: 37
+  def decode("c"), do: 38
+  def decode("d"), do: 39
+  def decode("e"), do: 40
+  def decode("f"), do: 41
+  def decode("g"), do: 42
+  def decode("h"), do: 43
+  def decode("i"), do: 44
+  def decode("j"), do: 45
+  def decode("k"), do: 46
+  def decode("l"), do: 47
+  def decode("m"), do: 48
+  def decode("n"), do: 49
+  def decode("o"), do: 50
+  def decode("p"), do: 51
+  def decode("q"), do: 52
+  def decode("r"), do: 53
+  def decode("s"), do: 54
+  def decode("t"), do: 55
+  def decode("u"), do: 56
+  def decode("v"), do: 57
+  def decode("w"), do: 58
+  def decode("x"), do: 59
+  def decode("y"), do: 60
+  def decode("z"), do: 61
+  def decode(binary) do
+    binary
+    |> String.split("", trim: true)
+    |> Enum.reverse
+    |> decode(0)
+    |> round
+  end
+
+  defp decode([last], step) do
+    decode(last) * :math.pow(62, step)
+  end
+  defp decode([head|tail], step) do
+    decode(head) * :math.pow(62, step) + decode(tail, step + 1)
+  end
+end

mix.exs

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+defmodule Base62.Mixfile do
+  use Mix.Project
+
+  def project do
+    [app: :base62,
+     version: "1.0.0",
+     elixir: "~> 1.0",
+     description: description,
+     package: package,
+     deps: deps]
+  end
+
+  def application, do: []
+
+  defp deps, do: []
+
+  defp description do
+    "Base62 encoder/decoder in pure Elixir."
+  end
+
+  defp package do
+    [contributors: ["Igor Kapkov"],
+     files: ["lib", "mix.exs", "README.md"],
+     links: %{"Github" => "https://github.com/igas/base62"}]
+  end
+end

test/base62_test.exs

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+defmodule Base62Test do
+  use ExUnit.Case, async: true
+
+  import Base62
+
+  test :encode do
+    assert encode(0) == "0"
+    assert encode(1) == "1"
+    assert encode(2) == "2"
+    assert encode(3) == "3"
+    assert encode(4) == "4"
+    assert encode(5) == "5"
+    assert encode(6) == "6"
+    assert encode(7) == "7"
+    assert encode(8) == "8"
+    assert encode(9) == "9"
+    assert encode(10) == "A"
+    assert encode(11) == "B"
+    assert encode(12) == "C"
+    assert encode(13) == "D"
+    assert encode(14) == "E"
+    assert encode(15) == "F"
+    assert encode(16) == "G"
+    assert encode(17) == "H"
+    assert encode(18) == "I"
+    assert encode(19) == "J"
+    assert encode(20) == "K"
+    assert encode(21) == "L"
+    assert encode(22) == "M"
+    assert encode(23) == "N"
+    assert encode(24) == "O"
+    assert encode(25) == "P"
+    assert encode(26) == "Q"
+    assert encode(27) == "R"
+    assert encode(28) == "S"
+    assert encode(29) == "T"
+    assert encode(30) == "U"
+    assert encode(31) == "V"
+    assert encode(32) == "W"
+    assert encode(33) == "X"
+    assert encode(34) == "Y"
+    assert encode(35) == "Z"
+    assert encode(36) == "a"
+    assert encode(37) == "b"
+    assert encode(38) == "c"
+    assert encode(39) == "d"
+    assert encode(40) == "e"
+    assert encode(41) == "f"
+    assert encode(42) == "g"
+    assert encode(43) == "h"
+    assert encode(44) == "i"
+    assert encode(45) == "j"
+    assert encode(46) == "k"
+    assert encode(47) == "l"
+    assert encode(48) == "m"
+    assert encode(49) == "n"
+    assert encode(50) == "o"
+    assert encode(51) == "p"
+    assert encode(52) == "q"
+    assert encode(53) == "r"
+    assert encode(54) == "s"
+    assert encode(55) == "t"
+    assert encode(56) == "u"
+    assert encode(57) == "v"
+    assert encode(58) == "w"
+    assert encode(59) == "x"
+    assert encode(60) == "y"
+    assert encode(61) == "z"
+    assert encode(62) == "10"
+    assert encode(100) == "1c"
+    assert encode(124) == "20"
+  end
+
+  test :decode do
+    assert decode("0") == 0
+    assert decode("1") == 1
+    assert decode("2") == 2
+    assert decode("3") == 3
+    assert decode("4") == 4
+    assert decode("5") == 5
+    assert decode("6") == 6
+    assert decode("7") == 7
+    assert decode("8") == 8
+    assert decode("9") == 9
+    assert decode("A") == 10
+    assert decode("B") == 11
+    assert decode("C") == 12
+    assert decode("D") == 13
+    assert decode("E") == 14
+    assert decode("F") == 15
+    assert decode("G") == 16
+    assert decode("H") == 17
+    assert decode("I") == 18
+    assert decode("J") == 19
+    assert decode("K") == 20
+    assert decode("L") == 21
+    assert decode("M") == 22
+    assert decode("N") == 23
+    assert decode("O") == 24
+    assert decode("P") == 25
+    assert decode("Q") == 26
+    assert decode("R") == 27
+    assert decode("S") == 28
+    assert decode("T") == 29
+    assert decode("U") == 30
+    assert decode("V") == 31
+    assert decode("W") == 32
+    assert decode("X") == 33
+    assert decode("Y") == 34
+    assert decode("Z") == 35
+    assert decode("a") == 36
+    assert decode("b") == 37
+    assert decode("c") == 38
+    assert decode("d") == 39
+    assert decode("e") == 40
+    assert decode("f") == 41
+    assert decode("g") == 42
+    assert decode("h") == 43
+    assert decode("i") == 44
+    assert decode("j") == 45
+    assert decode("k") == 46
+    assert decode("l") == 47
+    assert decode("m") == 48
+    assert decode("n") == 49
+    assert decode("o") == 50
+    assert decode("p") == 51
+    assert decode("q") == 52
+    assert decode("r") == 53
+    assert decode("s") == 54
+    assert decode("t") == 55
+    assert decode("u") == 56
+    assert decode("v") == 57
+    assert decode("w") == 58
+    assert decode("x") == 59
+    assert decode("y") == 60
+    assert decode("z") == 61
+    assert decode("10") == 62
+    assert decode("1c") == 100
+    assert decode("20") == 124
+    assert decode("zzzzzz") == 56_800_235_583
+  end
+end

test/test_helper.exs

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+ExUnit.start