Switch to toroidial world matrix

i.e. glue together top and bottom respectively right hand side and left hand side borders.

This makes for nicer life behaviour in constrained worlds.

1 files changed, 52 insertions, 0 deletions

diff --git a/src/util/torus_array.h b/src/util/torus_array.h
new file mode 100644
index 0000000..bef0c9f
--- /dev/null
+++ b/src/util/torus_array.h
@@ -0,0 +1,52 @@
+#ifndef LIFE_SRC_UTIL_TORUS_ARRAY_
+#define LIFE_SRC_UTIL_TORUS_ARRAY_
+
+#include <array>
+#include <cstdint>
+
+namespace life {
+namespace util {
+
+template<
+	typename    TYPE,
+	std::size_t WIDTH,
+	std::size_t HEIGHT
+>
+class TorusArray {
+	static std::size_t toMatrixColumn(const std::ptrdiff_t x) {
+		if ( x >= 0 ) {
+			return x % WIDTH;
+		} else {
+			return WIDTH - ( std::abs(x) % WIDTH );
+		}
+	}
+
+	static std::size_t toMatrixRow(const std::ptrdiff_t y) {
+		if ( y >= 0 ) {
+			return y % HEIGHT;
+		} else {
+			return HEIGHT - ( std::abs(y) % HEIGHT );
+		}
+	}
+
+	public:
+		static const std::size_t width  = WIDTH;
+		static const std::size_t height = HEIGHT;
+
+		TYPE get(const std::ptrdiff_t x, const std::ptrdiff_t y) const {
+			return this->matrix_[toMatrixRow(y)][toMatrixColumn(x)];
+		}
+
+		void set(const std::ptrdiff_t x, const std::ptrdiff_t y, TYPE&& value) {
+			this->matrix_[toMatrixRow(y)][toMatrixColumn(x)] = value;
+		}
+	
+	private:
+		std::array<std::array<TYPE, WIDTH>, HEIGHT> matrix_;
+
+};
+
+}
+}
+
+#endif  // LIFE_SRC_UTIL_TORUS_ARRAY_