Merge pull request #498 from rlevick/enumerable#drop_while

Add Enumerable#drop_while

AUTHORS.rst

@@ -19,3 +19,4 @@ Authors
 * Armin Rigo
 * Robin Schreiber
 * Jeremy Thurgood
+* Ryan Levick

lib-topaz/array.rb

@@ -256,10 +256,10 @@ def max(&block)
   def uniq!(&block)
     raise RuntimeError.new("can't modify frozen #{self.class}") if frozen?
     seen = {}
-    old_len = self.length
+    old_length = self.length
     i = 0
     shifted = 0
-    while i < self.length do
+    while i < old_length do
       item = self[i]
       item = yield(item) if block
       if seen.include? item

lib-topaz/enumerable.rb

@@ -41,13 +41,13 @@ def any?(&block)
   end
 
   def select(&block)
-    ary = []
+    result = []
     self.each do |o|
       if block.call(o)
-        ary << o
+        result << o
       end
     end
-    ary
+    result
   end
 
   def include?(obj)
@@ -59,9 +59,21 @@ def include?(obj)
 
   def drop(n)
     raise ArgumentError.new("attempt to drop negative size") if n < 0
-    ary = self.to_a
-    return [] if n > ary.size
-    ary[n...ary.size]
+    result = self.to_a
+    return [] if n > result.size
+    result[n...result.size]
+  end
+
+  def drop_while(&block)
+    result = []
+    dropping = true
+    self.each do |o|
+      unless dropping && yield(o)
+        result << o
+        dropping = false
+      end
+    end
+    result
   end
 
   def to_a

spec/tags/core/enumerable/drop_while_tags.txt

@@ -1,7 +1,2 @@
 fails:Enumerable#drop_while returns an Enumerator if no block given
-fails:Enumerable#drop_while returns no/all elements for {true/false} block
-fails:Enumerable#drop_while accepts returns other than true/false
-fails:Enumerable#drop_while passes elements to the block until the first false
-fails:Enumerable#drop_while will only go through what's needed
-fails:Enumerable#drop_while doesn't return self when it could
 fails:Enumerable#drop_while gathers whole arrays as elements when each yields multiple

tests/modules/test_enumerable.py

@@ -107,6 +107,16 @@ def test_drop(self, space):
         with self.raises(space, "ArgumentError", 'attempt to drop negative size'):
             space.execute("""return [0,1,2,3,4,5,6,7].drop -3""")
 
+    def test_drop_while(self, space):
+        w_res = space.execute("""return [1, 2, 3, 4, 5, 0].drop_while { |i| i < 3 }""")
+        assert self.unwrap(space, w_res) == [3, 4, 5, 0]
+
+        w_res = space.execute("""return [1, 2, 3].drop_while { |i| i == 0 } """)
+        assert self.unwrap(space, w_res) == [1, 2, 3]
+
+        w_res = space.execute("""return [].drop_while { |i| i > 3 }""")
+        assert self.unwrap(space, w_res) == []
+
     def test_to_a(self, space):
         w_res = space.execute("""return (5..10).to_a""")
         assert self.unwrap(space, w_res) == [x for x in range(5, 11)]