'Polyfill' std::make_unique to qgis::make_unique

qgis · Oct 13, 2017 · 85321b4 · 85321b4
1 parent 24a9c52
commit 85321b4
Showing 1 changed file with 39 additions and 0 deletions.
diff --git a/src/core/qgis.h b/src/core/qgis.h
@@ -30,6 +30,8 @@
 #include <QHash>
 #include <cstdlib>
 #include <cfloat>
+#include <memory>
+#include <type_traits>
 #include <cmath>
 #include <qnumeric.h>
 
@@ -282,6 +284,7 @@ inline double qgsRound( double number, double places )
  */
 namespace qgis
 {
+  // as_const
 
   /**
    * Adds const to non-const objects.
@@ -298,6 +301,42 @@ namespace qgis
 
   template <typename T>
   void as_const( const T && ) = delete;
+
+  // make_unique - from https://stackoverflow.com/a/17902439/1861260
+
+  template<class T> struct _Unique_if
+  {
+    typedef std::unique_ptr<T> _Single_object;
+  };
+
+  template<class T> struct _Unique_if<T[]>
+  {
+    typedef std::unique_ptr<T[]> _Unknown_bound;
+  };
+
+  template<class T, size_t N> struct _Unique_if<T[N]>
+  {
+    typedef void _Known_bound;
+  };
+
+  template<class T, class... Args>
+  typename _Unique_if<T>::_Single_object
+  make_unique( Args &&... args )
+  {
+    return std::unique_ptr<T>( new T( std::forward<Args>( args )... ) );
+  }
+
+  template<class T>
+  typename _Unique_if<T>::_Unknown_bound
+  make_unique( size_t n )
+  {
+    typedef typename std::remove_extent<T>::type U;
+    return std::unique_ptr<T>( new U[n]() );
+  }
+
+  template<class T, class... Args>
+  typename _Unique_if<T>::_Known_bound
+  make_unique( Args &&... ) = delete;
 }
 ///@endcond
 #endif