1 files changed, 146 insertions, 0 deletions
diff --git a/src/world.h b/src/world.h
new file mode 100644
index 0000000..297d0c5
--- /dev/null
+++ b/src/world.h
@@ -0,0 +1,146 @@
+#ifndef LIFE_SRC_WORLD_H_
+#define LIFE_SRC_WORLD_H_
+
+#include <array>
+#include <stack>
+#include <tuple>
+#include <cstdint>
+
+#include <termbox.h>
+
+namespace life {
+
+template<
+	std::size_t WIDTH,
+	std::size_t HEIGHT
+>
+class World {
+	public:
+		World() {
+			for ( std::size_t j = 0; j < HEIGHT; j++ ) {
+				for ( std::size_t i = 0; i < WIDTH; i++ ) {
+					this->matrix_[j][i] = false;
+				}
+			}
+		}
+
+		void summonLifeAt(std::size_t x, std::size_t y) {
+			this->matrix_[y][x] = true;
+		}
+
+		void extinguishLifeAt(std::size_t x, std::size_t y) {
+			this->matrix_[y][x] = false;
+		}
+
+		bool isLifeAt(std::ptrdiff_t x, std::ptrdiff_t y) {
+			if ( x >= 0      &&
+			     x <  WIDTH  &&
+			     y >= 0      &&
+			     y <  HEIGHT ) {
+				return this->matrix_[y][x];
+			} else {
+				return false; // end of world is dead
+			}
+		}
+
+		std::uint8_t lifeDensityAt(std::size_t x, std::size_t y) {
+			std::uint8_t counter = 0;
+
+			if ( this->isLifeAt(x - 1, y) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x + 1, y) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x, y - 1) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x, y + 1) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x - 1, y + 1) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x - 1, y - 1) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x + 1, y + 1) ) {
+				counter++;
+			}
+			if ( this->isLifeAt(x + 1, y - 1) ) {
+				counter++;
+			}
+
+			return counter;
+		}
+
+		void tick() {
+			this->age_++;
+
+			std::stack<std::tuple<std::size_t, std::size_t, bool>> updates;
+
+			for ( std::size_t j = 0; j < HEIGHT; j++ ) {
+				for ( std::size_t i = 0; i < WIDTH; i++ ) {
+					const std::uint8_t d = this->lifeDensityAt(i, j);
+
+					if ( this->matrix_[j][i] ) {
+						if ( d < 2 ) {
+							updates.push(std::make_tuple(i, j, false));	
+						} else if ( d == 2 || d == 3 ) {
+							updates.push(std::make_tuple(i, j, true));	
+						} else if ( d > 3 ) {
+							updates.push(std::make_tuple(i, j, false));	
+						}
+					} else {
+						if ( d == 3 ) {
+							updates.push(std::make_tuple(i, j, true));	
+						}
+					}
+				}
+			}
+
+			while ( !updates.empty() ) {
+				const auto& update = updates.top();
+
+				if ( std::get<2>(update) ) {
+					this->summonLifeAt(
+						std::get<0>(update),
+						std::get<1>(update)
+					);
+				} else {
+					this->extinguishLifeAt(
+						std::get<0>(update),
+						std::get<1>(update)
+					);
+				}
+				
+				updates.pop();
+			}
+		}
+
+		void draw() {
+			tb_clear();
+
+			for ( std::size_t j = 0; j < HEIGHT; j++ ) {
+				for ( std::size_t i = 0; i < WIDTH; i++ ) {
+					if ( this->matrix_[j][i] ) {
+						tb_change_cell(i, j, 0x2588, TB_BLACK, TB_GREEN);
+					} else {
+						tb_change_cell(i, j, 0x2591, TB_BLACK, TB_BLUE);
+					}
+				}
+			}
+
+			tb_present();
+		}
+
+	private:
+		std::size_t age_ = 0;
+
+		std::array<std::array<bool, WIDTH>, HEIGHT> matrix_;
+
+};
+
+}
+
+#endif  // LIFE_SRC_WORLD_H_