Merge bc6e315 into a298505

lib/hypex.ex

@@ -122,27 +122,11 @@ defmodule Hypex do
 
   """
   @spec merge([ hypex :: Hypex.t ]) :: hypex :: Hypex.t
-  def merge([ { _mod, _width, _registers } = hypex ]),
-  do: hypex
-  def merge([ { mod, width, _registers } | _ ] = hypices) do
-    unless Enum.all?(hypices, &(match?({ ^mod, ^width, _ }, &1))) do
-      raise ArgumentError, message: @merge_err
-    end
-
-    registers = Enum.map(hypices, fn({ mod, _width, registers }) ->
-      mod.to_list(registers)
-    end)
-
-    m_reg =
-      registers
-      |> Util.ziplist
-      |> Enum.reduce([], &([ :lists.max(&1) | &2 ]))
-      |> Enum.reverse
-      |> mod.from_list
-
-    { mod, width, m_reg }
+  def merge(hypices) when is_list(hypices) do
+    Enum.reduce(hypices, &merge/2)
   end
-  def merge(_hypices) do
+
+  def merge(_hypex) do
     raise ArgumentError, message: @merge_err
   end
 
@@ -153,8 +137,13 @@ defmodule Hypex do
   throguh to `merge/1`.
   """
   @spec merge(hypex :: Hypex.t, hypex :: Hypex.t) :: hypex :: Hypex.t
-  def merge(h1, h2),
-  do: merge([ h1, h2 ])
+  def merge({mod, width, registers1}, {mod, width, registers2}) do
+    {mod, width, mod.merge(registers1, registers2)}
+  end
+
+  def merge(_hypex1, _hypex2) do
+    raise ArgumentError, message: @merge_err
+  end
 
   @doc """
   Updates a Hypex instance with a value.

lib/hypex/array.ex

@@ -78,4 +78,19 @@ defmodule Hypex.Array do
     end, acc, registers)
   end
 
+  @doc false
+  @spec merge(array, array) :: array
+  def merge(registers1, registers2) do
+    list1 = to_list(registers1)
+    list2 = to_list(registers2)
+    merge2(list1, list2) |> from_list()
+  end
+
+  defp merge2([value1 | list1], [value2 | list2]) do
+    [max(value1, value2) | merge2(list1, list2)]
+  end
+
+  defp merge2([], []) do
+    []
+  end
 end

lib/hypex/bitstring.ex

@@ -70,4 +70,17 @@ defmodule Hypex.Bitstring do
   @spec reduce(bitstring, width :: number, accumulator :: any, (number, any -> any)) :: accumulator :: any
   defdelegate reduce(registers, width, acc, fun), to: Hypex.Util, as: :binary_reduce
 
+  @doc false
+  @spec merge(bitstring, bitstring) :: bitstring
+  def merge(registers1, registers2) do
+    merge2(registers1, registers2) |> from_list()
+  end
+
+  defp merge2(<<value1, registers1::bitstring>>, <<value2, registers2::bitstring>>) do
+    [max(value1, value2) | merge2(registers1, registers2)]
+  end
+
+  defp merge2(<<>>, <<>>) do
+    []
+  end
 end

lib/hypex/util.ex

@@ -94,36 +94,4 @@ defmodule Hypex.Util do
   def normalize_module(mod) when mod in [ Bitstring, Hypex.Bitstring ],
   do: Hypex.Bitstring
   def normalize_module(mod) when is_atom(mod), do: mod
-
-  @doc """
-  Zips corresponding elements from each list in list_of_lists.
-
-  This function acts in an identical way to `List.zip/1` except that the zipped
-  values are lists rather than tuples. This is because Hypex merge performance
-  can be improved without the jumps to/from Tuple structures.
-  """
-  @spec ziplist(lists :: [ ]) :: zipped_list :: []
-  def ziplist(list_of_lists) when is_list(list_of_lists),
-  do: zip(list_of_lists, [])
-
-  # The internal zip of `ziplist/1`, accepting a list and an accumulator. This
-  # function will move through each list and blend each index into a single list
-  # in which each index is grouped as a list.
-  #
-  # This implementation contains slight optimizations for the Hypex use case vs
-  # the implementation inside the `List` module.
-  defp zip(list, acc) do
-    case :lists.mapfoldl(&zip_each/2, [], list) do
-      { _, nil } ->
-        :lists.reverse(acc)
-      { mlist, heads } ->
-        zip(mlist, [heads | acc])
-    end
-  end
-
-  # The handlers for the `:lists.mapfoldl/3` call inside `zip/2`. If we reach
-  # the end of a list, we pass back a set of `nil` tuples to avoid continuing.
-  defp zip_each([h | t], acc), do: { t, [h | acc] }
-  defp zip_each(_lists, _acc), do: { nil, nil }
-
 end

test/hypex/array_test.exs

@@ -13,12 +13,18 @@ defmodule Hypex.ArrayTest do
   test "updating a Hypex with a duplicate value will short-circuit" do
     hypex = Hypex.new(16, Hypex.Array)
 
-    { time1, hypex } = :timer.tc(fn ->
-      Hypex.update(hypex, "Hypex")
+    { time1, _hypex } = :timer.tc(fn ->
+      for _ <- 1..1000 do
+        Hypex.update(hypex, "Hypex")
+      end
     end)
 
+    hypex = Hypex.update(hypex, "Hypex")
+
     { time2, _hypex } = :timer.tc(fn ->
-      Hypex.update(hypex, "Hypex")
+      for _ <- 1..1000 do
+        Hypex.update(hypex, "Hypex")
+      end
     end)
 
     assert(time2 < time1 * 0.75)

test/hypex/bitstring_text.exs

@@ -13,12 +13,18 @@ defmodule Hypex.BitstringTest do
   test "updating a Hypex with a duplicate value will short-circuit" do
     hypex = Hypex.new(16)
 
-    { time1, hypex } = :timer.tc(fn ->
-      Hypex.update(hypex, "Hypex")
+    { time1, _hypex } = :timer.tc(fn ->
+      for _ <- 1..1000 do
+        Hypex.update(hypex, "Hypex")
+      end
     end)
 
+    hypex = Hypex.update(hypex, "Hypex")
+
     { time2, _hypex } = :timer.tc(fn ->
-      Hypex.update(hypex, "Hypex")
+      for _ <- 1..1000 do
+        Hypex.update(hypex, "Hypex")
+      end
     end)
 
     assert(time2 < time1 * 0.75)