fixes #592

tests/overload/toverl4.nim

@@ -0,0 +1,77 @@
+discard """
+  output: '''true'''
+"""
+
+#bug #592
+
+type
+  ElementKind = enum inner, leaf
+  TElement[TKey, TData] = object
+    case kind: ElementKind
+    of inner:
+      key: TKey
+      left, right: ref TElement[Tkey, TData]
+    of leaf:
+      data: TData
+  PElement[TKey, TData] = ref TElement[TKey, TData]
+
+proc newElement[Tkey, TData](other: PElement[TKey, TData]): PElement[Tkey, TData] =
+  case other.kind:
+  of inner:
+    PElement[TKey, TData](kind: ElementKind.inner, key: other.key, left: other.left, right: other.right)
+  of leaf:
+    PElement[TKey, TData](kind: ElementKind.leaf, data: other.data)
+
+proc newElement[TKey, TData](key: TKey, left: PElement[TKey, TData] = nil, right: PElement[TKey, TData] = nil) : PElement[TKey, TData] =
+  PElement[TKey, TData](kind: ElementKind.inner, key: key, left: left, right: right)
+
+proc newElement[Tkey, TData](key: Tkey, data: TData) : PElement[Tkey, TData] =
+  PElement[TKey, TData](kind: ElementKind.leaf, data: data)
+
+proc find*[TKey, TData](root: PElement[TKey, TData], key: TKey): TData {.raises: [EInvalidKey].} =
+  if root.left == nil:
+    raise newException(EInvalidKey, "key does not exist: " & key)
+
+  var tmp_element = addr(root)
+
+  while tmp_element.kind == inner and tmp_element.right != nil:
+    tmp_element = if tmp_element.key > key:
+                    addr(tmp_element.left)
+                  else:
+                    addr(tmp_element.right)
+
+  if tmp_element.key == key:
+    return tmp_element.left.data
+  else:
+    raise newException(EInvalidKey, "key does not exist: " & key)
+
+proc add*[TKey, TData](root: var PElement[TKey, TData], key: TKey, data: TData) : bool =
+  if root.left == nil:
+    root.key = key
+    root.left = newElement[TKey, TData](key, data)
+    return true
+
+  var tmp_element = addr(root)
+
+  while tmp_element.kind == ElementKind.inner and tmp_element.right != nil:
+    tmp_element = if tmp_element.key > key:
+                    addr(tmp_element.left)
+                  else:
+                    addr(tmp_element.right)
+
+  if tmp_element.key == key:
+    return false
+
+  var old_element = newElement[TKey, TData](tmp_element[])
+  var new_element = newElement[TKey, TData](key, data)
+
+  tmp_element[] = if tmp_element.key < key:
+                    newElement(key, old_element, new_element)
+                  else:
+                    newElement(tmp_element.key, new_element, old_element)
+
+  return true
+
+var tree = PElement[int, int](kind: ElementKind.inner, key: 0, left: nil, right: nil)
+let result = add(tree, 1, 1)
+echo(result)