Avoid copy by stealing allocation, and by presizing buffer.

1 files changed, 5 insertions, 0 deletions

diff --git a/vespalib/src/vespa/vespalib/util/array.h b/vespalib/src/vespa/vespalib/util/array.h
index 3cee5726793..b766ed56844 100644
--- a/vespalib/src/vespa/vespalib/util/array.h
+++ b/vespalib/src/vespa/vespalib/util/array.h
@@ -145,6 +145,11 @@ public:
     const T & operator [] (size_t i) const  { return *array(i); }
     bool operator == (const Array & rhs) const;
     bool operator != (const Array & rhs) const;
+
+    static Alloc stealAlloc(Array && rhs) {
+        rhs._sz = 0;
+        return std::move(rhs._array);
+    }
 private:
     T *       array(size_t i)       { return static_cast<T *>(_array.get()) + i; }
     const T * array(size_t i) const { return static_cast<const T *>(_array.get()) + i; }