Port over jruby's Enumerable#slice_when

rubinius · May 27, 2015 · f21d58d · f21d58d
1 parent 7111811
commit f21d58d
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Showing 2 changed files with 29 additions and 6 deletions.
diff --git a/kernel/common/enumerable.rb b/kernel/common/enumerable.rb
@@ -185,6 +185,33 @@ def slice_after(pattern = undefined, &block)
     end
   end
 
+  def slice_when(&block)
+    raise ArgumentError, "wrong number of arguments (0 for 1)" unless block_given?
+
+    Enumerator.new do |enum|
+      ary = nil
+      last_after = nil
+      each_cons(2) do |before, after|
+        last_after = after
+        match = block.call before, after
+
+        ary ||= []
+        if match
+          ary << before
+          enum.yield ary
+          ary = []
+        else
+          ary << before
+        end
+      end
+
+      unless ary.nil?
+        ary << last_after
+        enum.yield ary
+      end
+    end
+  end
+
   def to_a(*arg)
     ary = []
     each(*arg) do
@@ -443,8 +470,8 @@ def each_cons(num)
     unless block_given?
       return to_enum(:each_cons, num) do
         enum_size = enumerator_size
-        if enum_size.nil? 
-          nil 
+        if enum_size.nil?
+          nil
         elsif enum_size == 0
           0
         else

diff --git a/spec/tags/ruby/core/enumerable/slice_when_tags.txt b/spec/tags/ruby/core/enumerable/slice_when_tags.txt