Merge branch 'swapRange.RootUtils-20231020' into 'main'

RootUtils: Add Type::swapRange.

See merge request !66604

Control/RootUtils/RootUtils/Type.h

 // This file's extension implies that it's C, but it's really -*- C++ -*-.
-
 /*
   Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
 */
-
-// $Id$
 /**
  * @file RootUtils/Type.h
  * @author scott snyder <snyder@bnl.gov>
@@ -263,6 +260,22 @@ public:
   void swap (void* a, void* b) const;
 
 
+  /**
+   * @brief Swap a range of objects between vectors.
+   * @param a Pointer to the start of the first vector's data.
+   * @param aindex Index of the first object in the first vector.
+   * @param b Pointer to the start of the second vector's data.
+   * @param bindex Index of the second object in the second vector.
+   * @param n Number of objects to swap.
+   *
+   * @c a and @ b can be either the same or different.
+   * However, the ranges should not overlap.
+   */
+  void swapRange (void* a, size_t a_index,
+                  void* b, size_t b_index,
+                  size_t n) const;
+
+
   /**
    * @brief Initialize an object from a string.
    * @param p Pointer to the object to initialize.

Control/RootUtils/src/Type.cxx

@@ -537,6 +537,44 @@ void Type::swap (void* a, void* b) const
 }
 
 
+/**
+ * @brief Swap a range of objects between vectors.
+ * @param a Pointer to the start of the first vector's data.
+ * @param aindex Index of the first object in the first vector.
+ * @param b Pointer to the start of the second vector's data.
+ * @param bindex Index of the second object in the second vector.
+ * @param n Number of objects to swap.
+ *
+ * @c a and @ b can be either the same or different.
+ * However, the ranges should not overlap.
+ */
+void Type::swapRange (void* a, size_t a_index,
+                      void* b, size_t b_index,
+                      size_t n) const
+{
+  char* aptr = reinterpret_cast<char*>(a) + m_size * a_index;
+  char* bptr = reinterpret_cast<char*>(b) + m_size * b_index;
+
+  if (m_assign.call() != nullptr) {
+    void* tmp = create();
+    for (size_t i = 0; i < n; i++) {
+      assign (tmp, aptr);
+      assign (aptr, bptr);
+      assign (bptr, tmp);
+      aptr += m_size;
+      bptr += m_size;
+    }
+    destroy (tmp);
+  }
+  else {
+    std::vector<char> tmp (m_size * n);
+    memcpy (tmp.data(), aptr, m_size * n);
+    memcpy (aptr, bptr, m_size * n);
+    memcpy (bptr, tmp.data(), m_size * n);
+  }
+}
+
+
 /**
  * @brief Initialize an object from a string.
  * @param p Pointer to the object to initialize.

Control/RootUtils/test/Type_test.cxx

@@ -77,10 +77,17 @@ void testit (const RootUtils::Type& type)
   assert (v[8] == fromInt<T>(6));
 
   // 0 1 2 3 4 2 8 1 6 9
+  type.swapRange (v.data(), 1, v.data(), 5, 2);
+  assert (v[1] == fromInt<T>(2));
+  assert (v[2] == fromInt<T>(8));
+  assert (v[5] == fromInt<T>(1));
+  assert (v[6] == fromInt<T>(2));
+
+  // 0 2 8 3 4 1 2 1 6 9
   type.copyRange (&v[1], &v[3], 5);
-  checkit (v, {0, 3, 4, 2, 8, 1, 8, 1, 6, 9});
+  checkit (v, {0, 3, 4, 1, 2, 1, 2, 1, 6, 9});
   type.copyRange (&v[3], &v[1], 5);
-  checkit (v, {0, 3, 4, 3, 4, 2, 8, 1, 6, 9});
+  checkit (v, {0, 3, 4, 3, 4, 1, 2, 1, 6, 9});
 }