Merge branch 'devel' of github.com:nim-lang/Nim into devel

lib/pure/collections/tables.nim

@@ -269,6 +269,18 @@ proc del*[A, B](t: var Table[A, B], key: A) =
   ## deletes `key` from hash table `t`.
   delImpl()
 
+proc take*[A, B](t: var Table[A, B], key: A, val: var B): bool =
+  ## Deletes the ``key`` from the table.
+  ## Returns ``true``, if the ``key`` existed, and sets ``val`` to the
+  ## mapping of the key. Otherwise, returns ``false``, and the ``val`` is
+  ## unchanged.
+  var hc: Hash
+  var index = rawGet(t, key, hc)
+  result = index >= 0
+  if result:
+    shallowCopy(val, t.data[index].val)
+    delImplIdx(t, index)
+
 proc enlarge[A, B](t: var Table[A, B]) =
   var n: KeyValuePairSeq[A, B]
   newSeq(n, len(t.data) * growthFactor)
@@ -424,6 +436,13 @@ proc del*[A, B](t: TableRef[A, B], key: A) =
   ## deletes `key` from hash table `t`.
   t[].del(key)
 
+proc take*[A, B](t: TableRef[A, B], key: A, val: var B): bool =
+  ## Deletes the ``key`` from the table.
+  ## Returns ``true``, if the ``key`` existed, and sets ``val`` to the
+  ## mapping of the key. Otherwise, returns ``false``, and the ``val`` is
+  ## unchanged.
+  result = t[].take(key, val)
+
 proc newTable*[A, B](initialSize=64): TableRef[A, B] =
   new(result)
   result[] = initTable[A, B](initialSize)

tests/collections/ttables.nim

@@ -235,6 +235,21 @@ block withKeyTest:
   except KeyError:
     discard
 
+block takeTest:
+  var t = initTable[string, int]()
+  t["key"] = 123
+
+  var val = 0
+  assert(t.take("key", val))
+  assert(val == 123)
+
+  val = -1
+  assert(not t.take("key", val))
+  assert(val == -1)
+
+  assert(not t.take("otherkey", val))
+  assert(val == -1)
+
 proc orderedTableSortTest() =
   var t = initOrderedTable[string, int](2)
   for key, val in items(data): t[key] = val