feat: add cocktail shaker sort

Abbreviated as cocktail sort for now to save screen space.

Author: danielzting

levels/cocktail_sort.gd

@@ -0,0 +1,58 @@
+class_name CocktailSort
+extends ComparisonSort
+
+const NAME = "COCKTAIL SORT"
+const ABOUT = """
+Cocktail shaker sort is a variation of bubble sort that
+alternates going backwards and forwards.
+"""
+const CONTROLS = """
+If the two highlighted elements are out of order, hit LEFT ARROW to swap
+them. Otherwise, hit RIGHT ARROW to continue.
+"""
+
+const ACTIONS = {
+    "SWAP": "Left",
+    "CONTINUE": "Right",
+}
+var _index = 0 # First of two elements being compared
+var _sorted = 0 # Size of the sorted subarray at the end of the array
+var _forwards = true
+var _swapped = false
+
+func _init(array).(array):
+    pass
+
+func next(action):
+    if array.at(_index) > array.at(_index + 1):
+        if action != null and action != ACTIONS.SWAP:
+            return emit_signal("mistake")
+        array.swap(_index, _index + 1)
+        _swapped = true
+    else:
+        if action != null and action != ACTIONS.CONTINUE:
+            return emit_signal("mistake")
+    if _forwards:
+        _index += 1
+        if _index == array.size - _sorted - 1:
+            if not _swapped:
+                emit_signal("done")
+            _swapped = false
+            _forwards = false
+            _index -= 2
+            _sorted += 1
+    else:
+        _index -= 1
+        if _index == _sorted - 2:
+            if not _swapped:
+                emit_signal("done")
+            _swapped = false
+            _forwards = true
+            _index += 2
+
+func get_effect(i):
+    if i == _index or i == _index + 1:
+        return EFFECTS.HIGHLIGHTED
+    if i < _sorted and _forwards == true or i < _sorted - 1 or i >= array.size - _sorted:
+        return EFFECTS.DIMMED
+    return EFFECTS.NONE

levels/quick_sort.gd

@@ -21,8 +21,8 @@ const ACTIONS = {
     "SWAP": "Left",
     "CONTINUE": "Right",
 }
-var _index = 0
-var _pointer = 0
+var _index = 0 # Index of element being compared with pivot
+var _pointer = 0 # Boundary between partitions
 # Bookkeep simulated recursion with a binary tree of subarray bounds
 var _stack = BinaryTreeModel.new(Vector2(0, array.size - 1))
 

project.godot

@@ -34,6 +34,11 @@ _global_script_classes=[ {
 "language": "GDScript",
 "path": "res://levels/bubble_sort.gd"
 }, {
+"base": "ComparisonSort",
+"class": "CocktailSort",
+"language": "GDScript",
+"path": "res://levels/cocktail_sort.gd"
+}, {
 "base": "Node",
 "class": "ComparisonSort",
 "language": "GDScript",
@@ -70,6 +75,7 @@ _global_script_class_icons={
 "BinaryTreeModel": "",
 "BogoSort": "",
 "BubbleSort": "",
+"CocktailSort": "",
 "ComparisonSort": "",
 "InsertionSort": "",
 "MergeSort": "",

scripts/levels.gd

@@ -6,6 +6,7 @@ const LEVELS = [
     SelectionSort,
     MergeSort,
     QuickSort,
+    CocktailSort,
 ]
 const MIN_WAIT = 1.0 / 32 # Should be greater than maximum frame time
 const MAX_WAIT = 4