Changeset 4137

Timestamp:

Jan 21, 2022, 3:02:05 PM (20 months ago)

Author:

Peter

Message:

add proxy class to allow returnning a MatrixView? from a function (same solution as in VectorView?). closes #202

Location:

trunk

Files:

• test/matrix_view.cc (modified) (3 diffs)
• yat/utility/MatrixView.cc (modified) (1 diff)
• yat/utility/MatrixView.h (modified) (1 diff)

trunk/test/matrix_view.cc

@@ -198 +198 @@
 
 
+utility::MatrixView make_view(utility::Matrix& m)
+{
+  return utility::MatrixView(m);
+}
+
+
 void test_matrix_view(test::Suite& suite)
 {
@@ -212 +218 @@
   test_assignment<MatrixView>(suite, m);
   test_iterators<MatrixView>(suite, m);
+  MatrixView view = make_view(m);
+}
+
+
+utility::MatrixConstView make_const_view(const utility::Matrix& m)
+{
+  return utility::MatrixConstView(m);
 }
 
@@ -227 +240 @@
   test_constructors<MatrixConstView>(suite, m);
   test_iterators<MatrixConstView>(suite, m);
-}
+
+  MatrixConstView view = make_const_view(m);
+}

trunk/yat/utility/MatrixView.cc

@@ -134 +134 @@
 
 
+  MatrixView::MatrixView(MatrixView::proxy p)
+    : view_(nullptr)
+  {
+    std::swap(view_, p.view_);
+  }
+
+
+  MatrixView::operator proxy()
+  {
+    return proxy(std::move(view_));
+  }
+
+
+  MatrixView::proxy::proxy(gsl_matrix_view*&& v)
+    : view_(nullptr)
+  {
+    std::swap(view_, v);
+  }
+
 }}} // of namespace utility, yat and thep

trunk/yat/utility/MatrixView.h

@@ -132 +132 @@
     // x n2 and view(0,0) points to other(k1, k2)
     void copy(gsl_matrix* other, size_t k1, size_t k2, size_t n1, size_t n2);
+
+
+    // See VectorView::proxy for motivation.
+    struct proxy
+    {
+      proxy(void) = delete;
+      proxy(gsl_matrix_view*&& v);
+      gsl_matrix_view* view_;
+    };
+
+  public:
+    /**
+       \brief create a MatrixView from an internal proxy class.
+     */
+    MatrixView(proxy p);
+
+    /**
+       Conversion operator to a private proxy class.
+     */
+    operator proxy();
   };