Accept the trim option for Regex.split/3

By default `trim` will be set to true. However, since the `global` option
was implemented with the `parts` option (`{ :parts, :infinity }`), we
have to apply a filter to the final result to support `trim`.

Author: vanstee

lib/elixir/lib/regex.ex

@@ -264,16 +264,17 @@ defmodule Regex do
   def split(regex, string, options // [])
 
   def split(regex(re_pattern: compiled), string, options) do
-    parts =
-      cond do
-        Keyword.get(options, :global) == false -> 2
-        p = Keyword.get(options, :parts)       -> p
-        true                                   -> :infinity
-      end
+    defaults = [global: true, trim: true, parts: :infinity, return: return_for(string)]
+    options = Keyword.merge(defaults, options)
 
-    return = Keyword.get(options, :return, return_for(string))
-    opts   = [return: return, parts: parts]
-    :re.split(string, compiled, opts)
+    unless options[:global], do: options = Keyword.put(options, :parts, 2)
+
+    valid_options = Dict.take(options, [:parts, :return])
+    splits = :re.split(string, compiled, valid_options)
+
+    if options[:trim], do: splits = Enum.filter(splits, &(&1 != ""))
+
+    splits
   end
 
   @doc %B"""

lib/elixir/test/elixir/regex_test.exs

@@ -113,13 +113,14 @@ defmodule Regex.BinaryTest do
   end
 
   test :split do
-    assert Regex.split(%r",", "") == [""]
+    assert Regex.split(%r",", "") == []
     assert Regex.split(%r" ", "foo bar baz") == ["foo", "bar", "baz"]
     assert Regex.split(%r" ", "foo bar baz", parts: 2) == ["foo", "bar baz"]
     assert Regex.split(%r"\s", "foobar") == ["foobar"]
     assert Regex.split(%r" ", "foo bar baz") == ["foo", "bar", "baz"]
-    assert Regex.split(%r"=", "key=") == ["key", ""]
-    assert Regex.split(%r"=", "=value") == ["", "value"]
+    assert Regex.split(%r" ", " foo bar baz ", trim: false) == ["", "foo", "bar", "baz", ""]
+    assert Regex.split(%r"=", "key=") == ["key"]
+    assert Regex.split(%r"=", "=value") == ["value"]
   end
 
   test :replace do

lib/elixir/test/elixir/string_test.exs

@@ -43,6 +43,8 @@ defmodule StringTest do
     assert String.split("a,b", %r{,}) == ["a", "b"]
     assert String.split("a,b,c", %r{,}) == ["a", "b", "c"]
     assert String.split("a,b,c", %r{,}, global: false) == ["a", "b,c"]
+    assert String.split("a,b.c ", %r{\W}) == ["a", "b", "c"]
+    assert String.split("a,b.c ", %r{\W}, trim: false) == ["a", "b", "c", ""]
     assert String.split("a,b", %r{\.}) == ["a,b"]
   end
 

lib/ex_unit/lib/ex_unit/doc_test.ex

@@ -331,7 +331,7 @@ defmodule ExUnit.DocTest do
   end
 
   defp extract_tests(line, doc) do
-    lines = String.split(doc, %r/\n/) |> adjust_indent
+    lines = String.split(doc, %r/\n/, trim: false) |> adjust_indent
     extract_tests(lines, line, "", "", [], true)
   end