Introduce `BoxIndicator` and `BoxTraverser` helper classes

`BoxIndicator` implements an indicator function for the world area. Together with `BoxTraverser` it is used to simplifiy action validation and area traversion.

1 files changed, 40 insertions, 0 deletions

diff --git a/src/box_indicator.h b/src/box_indicator.h
new file mode 100644
index 0000000..db750e4
--- /dev/null
+++ b/src/box_indicator.h
@@ -0,0 +1,40 @@
+#ifndef LIFE_SRC_BOX_INDICATOR_
+#define LIFE_SRC_BOX_INDICATOR_
+
+namespace life {
+namespace util {
+
+class BoxIndicator {
+	public:
+	   	BoxIndicator(
+			const std::size_t offset_x,
+			const std::size_t offset_y,
+			const std::size_t size_x,
+			const std::size_t size_y):
+			a_x_{offset_x},
+			a_y_{offset_y},
+			b_x_{a_x_ + size_x},
+			b_y_{a_y_ + size_y} { }
+
+	   	BoxIndicator(const std::size_t size_x, const std::size_t size_y):
+			BoxIndicator(0, 0, size_x, size_y) { }
+
+		bool operator()(const std::size_t x, const std::size_t y) const {
+			return x >= this->a_x_
+			    && x <  this->b_x_
+			    && y >= this->a_y_
+			    && y <  this->b_y_;
+		}
+	
+	protected:
+		const std::size_t a_x_;
+		const std::size_t a_y_;
+		const std::size_t b_x_;
+		const std::size_t b_y_;
+
+};
+		
+}
+}
+
+#endif  // LIFE_SRC_BOX_INDICATOR_