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1 files changed, 110 insertions, 0 deletions

diff --git a/lib/boltex/pack_stream/encoder.ex b/lib/boltex/pack_stream/encoder.ex
new file mode 100644
index 0000000..bd7dc6e
--- /dev/null
+++ b/lib/boltex/pack_stream/encoder.ex
@@ -0,0 +1,110 @@
+defprotocol Boltex.PackStream.Encoder do
+  @doc "Encodes an item to its binary PackStream Representation"
+  def encode(entitiy)
+end
+
+defimpl Boltex.PackStream.Encoder, for: Atom do
+  def encode(nil),   do: << 0xC0 >>
+  def encode(true),  do: << 0xC3 >>
+  def encode(false), do: << 0xC2 >>
+  def encode(other) when is_atom(other) do
+    other
+    |> Atom.to_string
+    |> Boltex.PackStream.Encoder.encode
+  end
+end
+
+defimpl Boltex.PackStream.Encoder, for: Integer do
+  @int8 -127..-17
+  @int16_low  -32_768..-129
+  @int16_high 128..32_767
+  @int32_low  -2_147_483_648..-32_769
+  @int32_high 32_768..2_147_483_647
+  @int64_low  -9_223_372_036_854_775_808..-2_147_483_649
+  @int64_high 2_147_483_648..9_223_372_036_854_775_807
+
+  def encode(integer) when integer in -16..127 do
+    <<integer>>
+  end
+  def encode(integer) when integer in @int8 do
+    << 0xC8, integer >>
+  end
+  def encode(integer) when integer in @int16_low  or integer in @int16_high do
+    << 0xC9, integer >>
+  end
+  def encode(integer) when integer in @int32_low  or integer in @int32_high do
+    << 0xCA, integer >>
+  end
+  def encode(integer) when integer in @int64_low  or integer in @int64_high do
+    << 0xCB, integer >>
+  end
+end
+
+defimpl Boltex.PackStream.Encoder, for: BitString do
+  def encode(string), do: do_encode(string, byte_size(string))
+
+  defp do_encode(string, size) when size <= 15 do
+    << 0x8 :: 4, size :: 4 >> <> string
+  end
+  defp do_encode(string, size) when size <= 255 do
+    << 0xD0, size :: 8 >> <> string
+  end
+  defp do_encode(string, size) when size <= 65_535 do
+    << 0xD1, size :: 16 >> <> string
+  end
+  defp do_encode(string, size) when size <= 4_294_967_295 do
+    << 0xD2, size :: 32 >> <> string
+  end
+end
+
+defimpl Boltex.PackStream.Encoder, for: List do
+  def encode(list) do
+    binary = Enum.map_join list, &Boltex.PackStream.Encoder.encode/1
+
+    do_encode binary, byte_size(binary)
+  end
+
+  defp do_encode(binary, list_size) when list_size <= 15 do
+    << 0x9 :: 4, list_size :: 4 >> <> binary
+  end
+  defp do_encode(binary, list_size) when list_size <= 255 do
+    << 0xD4, list_size :: 8 >> <> binary
+  end
+  defp do_encode(binary, list_size) when list_size <= 65_535 do
+    << 0xD5, list_size :: 16 >> <> binary
+  end
+  defp do_encode(binary, list_size) when list_size <= 4_294_967_295 do
+    << 0xD6, list_size :: 32 >> <> binary
+  end
+  defp do_encode(binary, _size) do
+    << 0xD7 >> <> binary <> <<0xDF>>
+  end
+end
+
+defimpl Boltex.PackStream.Encoder, for: Map do
+  def encode(map) do
+    do_encode map, map_size(map)
+  end
+
+  defp do_encode(map, size) when size <= 15 do
+    << 0xA :: 4, size :: 4 >> <> encode_kv(map)
+  end
+  defp do_encode(map, size) when size <= 255 do
+    << 0xD8, size :: 8 >> <> encode_kv(map)
+  end
+  defp do_encode(map, size) when size <= 65_535 do
+    << 0xD9, size :: 16 >> <> encode_kv(map)
+  end
+  defp do_encode(map, size) when size <= 4_294_967_295 do
+    << 0xDA, size :: 32 >> <> encode_kv(map)
+  end
+
+  defp encode_kv(map) do
+    Boltex.Utils.reduce_to_binary map, &do_reduce_kv/1
+  end
+
+  defp do_reduce_kv({key, value}) do
+    Boltex.PackStream.Encoder.encode(key) <>
+    Boltex.PackStream.Encoder.encode(value)
+  end
+end