commit 3082c2845896c5d69b56a0f3a9c0d93fab6ee32b
Author: Joop Schilder <jnmschilder@protonmail.com>
Date:   Sun Dec 22 00:00:47 2019 +0100

    Initial (and probably only) commit

diff --git a/game_of_life.php b/game_of_life.php
new file mode 100644
index 0000000..27bba6d
--- /dev/null
+++ b/game_of_life.php
@@ -0,0 +1,84 @@
+<?php
+/*
+ * Game of Life in PHP using pure functions
+ *
+ * Joop Schilder
+ */
+if (version_compare(PHP_VERSION, '7.0') < 1) {
+	throw new RuntimeException('PHP>=7.0 required');
+}
+
+const BOARDSIZE = 32;
+CONST DELAY_MS = 200;
+const DEAD = 0;
+const ALIVE = 1;
+
+function get_neighbours(array $board, int $i, int $j): array
+{
+	$neighbours = [];
+	for ($ni = $i - 1; $ni <= $i + 1; $ni++) {
+		for ($nj = $j - 1; $nj <= $j + 1; $nj++) {
+			if (isset($board[$ni][$nj]) && ($ni !== $i || $nj !== $j)) {
+				$neighbours[] = $board[$ni][$nj];
+			}
+		}
+	}
+
+	return $neighbours;
+}
+
+function get_next_cell_state(array $board, int $i, int $j): int
+{
+	$living_neighbours = count(array_filter(get_neighbours($board, $i, $j), function (int $state): bool {
+		return $state === ALIVE;
+	}));
+	$is_alive = $board[$i][$j] === ALIVE ? ($living_neighbours > 1 && $living_neighbours < 4) : $living_neighbours === 3;
+
+	return $is_alive ? ALIVE : DEAD;
+}
+
+function get_next_board_state(array $board): array
+{
+	$next_board = [];
+	for ($i = 0; $i < BOARDSIZE; $i++) {
+		for ($j = 0; $j < BOARDSIZE; $j++) {
+			$next_board[$i][$j] = get_next_cell_state($board, $i, $j);
+		}
+	}
+
+	return $next_board;
+}
+
+function print_board(array $board): void
+{
+	system('WIN' === strtoupper(substr(PHP_OS, 0, 3)) ? 'cls' : 'clear');
+	print('┌' . str_repeat('─', 2 * BOARDSIZE) . '┐' . PHP_EOL);
+	for ($i = 0; $i < BOARDSIZE; $i++) {
+		print('│');
+		for ($j = 0; $j < BOARDSIZE; $j++) {
+			print($board[$i][$j] === ALIVE ? '██' : '░░');
+		}
+		print('│' . PHP_EOL);
+	}
+	print('└' . str_repeat('─', 2 * BOARDSIZE) . '┘' . PHP_EOL);
+}
+
+$board = [];
+for ($i = 0; $i < BOARDSIZE; $i++) {
+	for ($j = 0; $j < BOARDSIZE; $j++) {
+		$board[$i][$j] = DEAD;
+	}
+}
+
+// Glider
+$board[1][3] = ALIVE;
+$board[2][4] = ALIVE;
+$board[3][2] = ALIVE;
+$board[3][3] = ALIVE;
+$board[3][4] = ALIVE;
+
+while (true) {
+	print_board($board);
+	usleep(DELAY_MS * 1000);
+	$board = get_next_board_state($board);
+}