From af1378cc5598f7695e4301910dc2aabbcc919dcb Mon Sep 17 00:00:00 2001
From: Julian Kent <jkflying@gmail.com>
Date: Mon, 16 Sep 2019 15:53:15 +0200
Subject: [PATCH] Add Slice class

---
 matrix/Slice.hpp | 81 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 matrix/Slice.hpp

diff --git a/matrix/Slice.hpp b/matrix/Slice.hpp
new file mode 100644
index 0000000000..cff1521690
--- /dev/null
+++ b/matrix/Slice.hpp
@@ -0,0 +1,81 @@
+/**
+ * @file Slice.hpp
+ *
+ * A simple matrix template library.
+ *
+ * @author Julian Kent < julian@auterion.com >
+ */
+
+#pragma once
+
+#include "math.hpp"
+
+
+namespace matrix {
+
+template<typename Type, size_t M, size_t N>
+class Matrix;
+
+template<typename Type, size_t M>
+class Vector;
+
+template <typename Type, size_t P, size_t Q, size_t M, size_t N>
+class Slice {
+public:
+    Slice(size_t x0, size_t y0, const Matrix<Type, M, N>* data) :
+        _x0(x0),
+        _y0(y0),
+        _data(const_cast<Matrix<Type, M, N>*>(data)) {
+        static_assert(P <= M, "Slice rows bigger than backing matrix");
+        static_assert(Q <= N, "Slice cols bigger than backing matrix");
+    }
+
+    Type operator()(size_t i, size_t j) const
+    {
+        return (*_data)(_x0 + i, _y0 + j);
+    }
+
+    Type &operator()(size_t i, size_t j)
+    {
+        return (*_data)(_x0 + i, _y0 + j);
+    }
+
+    template<size_t MM, size_t NN>
+    Slice<Type, P, Q, M, N>& operator=(const Slice<Type, P, Q, MM, NN>& in_matrix)
+    {
+        Slice<Type, P, Q, M, N>& self = *this;
+        for (size_t i = 0; i < P; i++) {
+            for (size_t j = 0; j < Q; j++) {
+                self(i, j) = in_matrix(i, j);
+            }
+        }
+        return self;
+    }
+
+    Slice<Type, P, Q, M, N>& operator=(const Matrix<Type, P, Q>& in_matrix)
+    {
+        Slice<Type, P, Q, M, N>& self = *this;
+        for (size_t i = 0; i < P; i++) {
+            for (size_t j = 0; j < Q; j++) {
+                self(i, j) = in_matrix(i, j);
+            }
+        }
+        return self;
+    }
+
+    // allow assigning vectors to a slice that are in the axis
+    Slice<Type, 1, Q, M, N>& operator=(const Vector<Type, Q>& in_vector)
+    {
+        Slice<Type, 1, Q, M, N>& self = *this;
+        for (size_t j = 0; j < Q; j++) {
+            self(0, j) = in_vector(j);
+        }
+        return self;
+    }
+
+private:
+    size_t _x0, _y0;
+    Matrix<Type,M,N>* _data;
+};
+
+}