Life 4: board as string, in AWK.

diff --git a/004/life.awk b/004/life.awk
new file mode 100755 (executable)
index 0000000..5116adc
--- /dev/null
+++ b/004/life.awk
@@ -0,0 +1,132 @@
+#! /usr/bin/env awk -f
+
+
+function CHAR_BORDER() {return "-"}
+function CHAR_ALIVE()  {return "o"}
+function CHAR_DEAD()   {return " "}
+
+
+function init_cell() {
+    return int(2 * rand())
+}
+
+
+function init_board(n) {
+    board = "";
+
+    for (i=1; i <= n; i++) {
+        board = sprintf("%s%d", board, init_cell())
+    };
+
+    return board
+}
+
+
+function print_border(x) {
+    for (i=1; i <= x; i++) {
+        printf CHAR_BORDER()
+    };
+    print;
+}
+
+
+function char_of_state(state) {
+    if (state == 1) {
+        return CHAR_ALIVE()
+    } else if (state == 0) {
+        return CHAR_DEAD()
+    }
+}
+
+
+function print_board(x, n, board) {
+    print_border(x);
+
+    for (i=1; i <= n; i++) {
+        printf "%s", char_of_state(substr(board, i, 1));
+
+        if (i % x == 0) {
+            printf "\n"
+        }
+    };
+
+    print_border(x);
+}
+
+
+function new_state(state, live_neighbors) {
+    if (state == 1 && live_neighbors < 2) {
+        return 0
+    } else if (state == 1 && live_neighbors < 4) {
+        return 1
+    } else if (state == 1 && live_neighbors > 3) {
+        return 0
+    } else if (state == 0 && live_neighbors == 3) {
+        return 1
+    } else {
+        return state
+    }
+}
+
+
+function ensure_negative(n) {
+    if (n < 0) {
+        return n
+    } else {
+        return -n
+    }
+}
+
+
+function new_generation(x, n, board) {
+    offsets["N" ] = ensure_negative(x    );
+    offsets["NE"] = ensure_negative(x - 1);
+    offsets["E" ] =                     1 ;
+    offsets["SE"] =                 x + 1 ;
+    offsets["S" ] =                 x     ;
+    offsets["SW"] =                 x - 1 ;
+    offsets["W" ] =                   - 1 ;
+    offsets["NW"] = ensure_negative(x + 1);
+
+    new_board = "";
+
+    for (cell_id=1; cell_id <= n; cell_id++) {
+        cell_state = substr(board, cell_id, 1);
+        live_neighbors = 0;
+
+        for (direction in offsets) {
+            neighbor = offsets[direction] + cell_id;
+
+            # Make sure we're within limmits of the board
+            if ( !(neighbor < 1) && !(neighbor > n)) {
+                neighbor_state = substr(board, neighbor, 1);
+                live_neighbors += neighbor_state;
+            }
+        }
+
+        new_cell_state = new_state(cell_state, live_neighbors);
+        new_board = sprintf("%s%d", new_board, new_cell_state);
+    };
+
+    return new_board
+}
+
+
+function life() {
+    "stty size" | getline stty_size_out;
+    split(stty_size_out, stty_size);
+
+    x = stty_size[2];
+    y = stty_size[1] - 3;  # Minus 1 char for each: border, border, cursor
+    n = x * y;
+
+    board = init_board(n);
+
+    while (1) {
+        print_board(x, n, board);
+        board = new_generation(x, n, board);
+    }
+}
+
+
+BEGIN {life()}