add @deque.to_array

Author: illusory0x0

deque/deque.mbt

@@ -1244,3 +1244,16 @@ pub fn from_iter[A](iter : Iter[A]) -> T[A] {
   iter.each(fn(e) { dq.push_back(e) })
   dq
 }
+
+///|
+pub fn to_array[A](self : T[A]) -> Array[A] {
+  if self.length() == 0 {
+    []
+  } else {
+    let xs = Array::make(self.length(), self[0])
+    for i in 0..<self.length() {
+      xs[i] = self[i]
+    }
+    xs
+  }
+}

deque/deque.mbti

@@ -50,6 +50,7 @@ impl T {
   rev_iter2[A](Self[A]) -> Iter2[Int, A]
   search[A : Eq](Self[A], A) -> Int?
   shrink_to_fit[A](Self[A]) -> Unit
+  to_array[A](Self[A]) -> Array[A]
   truncate[A](Self[A], Int) -> Unit
   unsafe_pop_back[A](Self[A]) -> Unit
   unsafe_pop_front[A](Self[A]) -> Unit

deque/deque_test.mbt

@@ -877,3 +877,27 @@ test "deque retain_map" {
     content="([4, 5, 6], [7, 8])",
   )
 }
+
+test "@deque.to_array/empty" {
+  let dq : T[Int] = @deque.new()
+  let arr = dq.to_array()
+  inspect!(arr, content="[]")
+}
+
+test "@deque.to_array/basic" {
+  let dq = @deque.of([1, 2, 3, 4, 5])
+  let arr = dq.to_array()
+  inspect!(arr, content="[1, 2, 3, 4, 5]")
+}
+
+test "@deque.to_array/wrapped_around" {
+  // Create a deque that will wrap around its internal buffer
+  let dq = @deque.new(capacity=3)
+  dq.push_back(1)
+  dq.push_back(2)
+  dq.push_back(3)
+  dq.pop_front() |> ignore
+  dq.push_back(4)
+  let arr = dq.to_array()
+  inspect!(arr, content="[2, 3, 4]")
+}