feat(stdlib): Add toArray to Queue (#1930)

compiler/test/stdlib/queue.test.gr

@@ -87,6 +87,45 @@ assert Queue.pop(queue) == Some(9)
 assert Queue.pop(queue) == Some(10)
 assert Queue.pop(queue) == None
 
+// Queue.toArray
+let queue1 = Queue.make()
+assert Queue.toArray(queue1) == [>]
+let queue2 = Queue.make()
+Queue.push(1, queue2)
+Queue.push(2, queue2)
+Queue.push(3, queue2)
+Queue.push(4, queue2)
+Queue.pop(queue2)
+Queue.pop(queue2)
+Queue.push(5, queue2)
+Queue.pop(queue2)
+Queue.pop(queue2)
+Queue.pop(queue2)
+Queue.push(6, queue2)
+Queue.push(7, queue2)
+Queue.push(8, queue2)
+Queue.push(9, queue2)
+Queue.push(10, queue2)
+Queue.push(11, queue2)
+Queue.push(12, queue2)
+Queue.push(13, queue2)
+Queue.push(14, queue2)
+Queue.push(15, queue2)
+Queue.push(16, queue2)
+Queue.push(17, queue2)
+Queue.push(18, queue2)
+Queue.push(19, queue2)
+assert Queue.toArray(queue2) ==
+  [> 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
+let queue3 = Queue.make()
+Queue.push(1, queue3)
+Queue.push(2, queue3)
+Queue.push(3, queue3)
+assert Queue.toArray(queue3) == [> 1, 2, 3]
+let queue4 = Queue.copy(queue3)
+Queue.pop(queue4)
+assert Queue.toArray(queue4) == [> 2, 3]
+
 module Immutable {
   from Queue use { module Immutable as Queue }
 

stdlib/queue.gr

@@ -164,6 +164,43 @@ provide let copy = queue => {
   { size, array: Array.copy(array), headIndex, tailIndex }
 }
 
+/**
+ * Converts a queue into an array of its values.
+ *
+ * @param queue: The queue to convert
+ * @returns An array containing all values from the given queue
+ *
+ * @since v0.6.0
+ */
+provide let toArray = queue => {
+  let arr = Array.make(queue.size, None)
+  let mut outIndex = 0
+  if (queue.tailIndex < queue.headIndex) {
+    // Get the first half
+    for (let mut i = queue.headIndex; i < Array.length(queue.array); i += 1) {
+      arr[outIndex] = queue.array[i]
+      outIndex += 1
+    }
+    // Get the second half
+    let endOffset = Array.length(queue.array) - queue.headIndex
+    for (let mut i = 0; i < queue.tailIndex; i += 1) {
+      arr[outIndex] = queue.array[i]
+      outIndex += 1
+    }
+  } else {
+    for (let mut i = queue.headIndex; i < queue.tailIndex; i += 1) {
+      arr[outIndex] = queue.array[i]
+      outIndex += 1
+    }
+  }
+  Array.map(e => {
+    match (e) {
+      Some(v) => v,
+      None => fail "Impossible: empty bucket in Queue.toArray",
+    }
+  }, arr)
+}
+
 /**
  * An immutable queue implementation.
  */

stdlib/queue.md

@@ -244,6 +244,31 @@ Returns:
 |----|-----------|
 |`Queue<a>`|A new queue containing the elements from the input|
 
+### Queue.**toArray**
+
+<details disabled>
+<summary tabindex="-1">Added in <code>next</code></summary>
+No other changes yet.
+</details>
+
+```grain
+toArray : (queue: Queue<a>) => Array<a>
+```
+
+Converts a queue into an array of its values.
+
+Parameters:
+
+|param|type|description|
+|-----|----|-----------|
+|`queue`|`Queue<a>`|The queue to convert|
+
+Returns:
+
+|type|description|
+|----|-----------|
+|`Array<a>`|An array containing all values from the given queue|
+
 ## Queue.Immutable
 
 An immutable queue implementation.