Add optional multibyte characters support, closes #21 (#22)

README.md

@@ -36,7 +36,9 @@ The package can be installed by adding `owl` to your list of dependencies in `mi
 ```elixir
 def deps do
   [
-    {:owl, "~> 0.8"}
+    {:owl, "~> 0.8"},
+    # ucwidth is an optional dependency, uncomment it for multibyte characters support (emoji, etc)
+    # {:ucwidth, "~> 0.2"}
   ]
 end
 ```

lib/owl/data.ex

@@ -171,10 +171,20 @@ defmodule Owl.Data do
 
       iex> Owl.Data.length(["222", Owl.Data.tag(["333", "444"], :green)])
       9
+
+      # if ucwidth dependency is present, then it is used to calculate the length of the string
+      iex> Owl.Data.length("😂")
+      2
   """
   @spec length(t()) :: non_neg_integer()
-  def length(data) when is_binary(data) do
-    String.length(data)
+  if Code.ensure_loaded?(Ucwidth) do
+    def length(data) when is_binary(data) do
+      Ucwidth.width(data)
+    end
+  else
+    def length(data) when is_binary(data) do
+      String.length(data)
+    end
   end
 
   def length(data) when is_list(data) do

mix.exs

@@ -47,6 +47,7 @@ defmodule Owl.MixProject do
 
   defp deps do
     [
+      {:ucwidth, "~> 0.2", optional: true},
       {:ex_doc, "~> 0.24", only: :dev, runtime: false},
       {:excoveralls, "~> 0.10", only: :test},
       {:dialyxir, "~> 1.0", only: :dev, runtime: false}

mix.lock

@@ -16,5 +16,6 @@
   "nimble_parsec": {:hex, :nimble_parsec, "1.2.3", "244836e6e3f1200c7f30cb56733fd808744eca61fd182f731eac4af635cc6d0b", [:mix], [], "hexpm", "c8d789e39b9131acf7b99291e93dae60ab48ef14a7ee9d58c6964f59efb570b0"},
   "parse_trans": {:hex, :parse_trans, "3.3.1", "16328ab840cc09919bd10dab29e431da3af9e9e7e7e6f0089dd5a2d2820011d8", [:rebar3], [], "hexpm", "07cd9577885f56362d414e8c4c4e6bdf10d43a8767abb92d24cbe8b24c54888b"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.6", "cf344f5692c82d2cd7554f5ec8fd961548d4fd09e7d22f5b62482e5aeaebd4b0", [:make, :mix, :rebar3], [], "hexpm", "bdb0d2471f453c88ff3908e7686f86f9be327d065cc1ec16fa4540197ea04680"},
+  "ucwidth": {:hex, :ucwidth, "0.2.0", "1f0a440f541d895dff142275b96355f7e91e15bca525d4a0cc788ea51f0e3441", [:mix], [], "hexpm", "c1efd1798b8eeb11fb2bec3cafa3dd9c0c3647bee020543f0340b996177355bf"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.7.0", "bc84380c9ab48177092f43ac89e4dfa2c6d62b40b8bd132b1059ecc7232f9a78", [:rebar3], [], "hexpm", "25eee6d67df61960cf6a794239566599b09e17e668d3700247bc498638152521"},
 }