Add empty? guard clause to Deque#rotate!

crystal-lang · Dec 18, 2017 · 9985d87 · 9985d87
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commit 9985d87
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diff --git a/spec/std/deque_spec.cr b/spec/std/deque_spec.cr
@@ -472,6 +472,12 @@ describe "Deque" do
       a.rotate!(8)
       a.should eq(Deque{4, 1, 2, 3})
     end
+
+    it "rotates with size=0" do
+      a = Deque(Int32).new
+      a.rotate!
+      a.should eq(Deque(Int32).new)
+    end
   end
 
   describe "shift" do

diff --git a/src/deque.cr b/src/deque.cr
@@ -416,6 +416,7 @@ class Deque(T)
   # * For positive *n*, equivalent to `n.times { push(shift) }`.
   # * For negative *n*, equivalent to `(-n).times { unshift(pop) }`.
   def rotate!(n : Int = 1)
+    return if empty?
     if @size == @capacity
       @start = (@start + n) % @capacity
     else