From fab96c14107f591a4cbd27af98aa8994dd81563e Mon Sep 17 00:00:00 2001
From: Xidorn Quan <xidorn+moz@upsuper.org>
Date: Tue, 23 Aug 2016 10:31:26 +1000
Subject: [PATCH] Bug 1291707 part 2 - Add GetAndRemove to nsDataHashtable.
 r=froydnj

MozReview-Commit-ID: 24zlYwsRGsF

--HG--
extra : rebase_source : 904c62cd779133666904d3167cb7e7c31f95a412
extra : source : 6c1df15aad607e70547b51011bd352d8a8bf826d
---
 xpcom/glue/nsDataHashtable.h | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/xpcom/glue/nsDataHashtable.h b/xpcom/glue/nsDataHashtable.h
index 18aa210b7e38..19c0728b4a81 100644
--- a/xpcom/glue/nsDataHashtable.h
+++ b/xpcom/glue/nsDataHashtable.h
@@ -9,6 +9,7 @@
 
 #include "nsHashKeys.h"
 #include "nsBaseHashtable.h"
+#include "mozilla/Maybe.h"
 
 /**
  * templated hashtable class maps keys to simple datatypes.
@@ -22,12 +23,36 @@ template<class KeyClass, class DataType>
 class nsDataHashtable
   : public nsBaseHashtable<KeyClass, DataType, DataType>
 {
+private:
+  typedef nsBaseHashtable<KeyClass, DataType, DataType> BaseClass;
+
 public:
+  using typename BaseClass::KeyType;
+  using typename BaseClass::EntryType;
+
   nsDataHashtable() {}
   explicit nsDataHashtable(uint32_t aInitLength)
-    : nsBaseHashtable<KeyClass, DataType, DataType>(aInitLength)
+    : BaseClass(aInitLength)
   {
   }
+
+  /**
+   * Retrieve the value for a key and remove the corresponding entry at
+   * the same time.
+   *
+   * @param aKey the key to retrieve and remove
+   * @return the found value, or Nothing if no entry was found with the
+   *   given key.
+   */
+  mozilla::Maybe<DataType> GetAndRemove(KeyType aKey)
+  {
+    mozilla::Maybe<DataType> value;
+    if (EntryType* ent = this->GetEntry(aKey)) {
+      value.emplace(mozilla::Move(ent->mData));
+      this->RemoveEntry(ent);
+    }
+    return value;
+  }
 };
 
 #endif // nsDataHashtable_h__