working 2D CA functions + canvas draws in one go

src/js/automata.js

@@ -1,43 +1,45 @@
-// get the next evolution of a 1D CA
-function evolve(state, rules) {
-  function evolveAcc(s, acc) {
-    const [x, y, z, ...xs] = s;
-    if (!xs.length) {
-      return acc[acc.length - 1] + acc + acc[0];
-    }
-
-    const rule = x + y + z;
-    const newAcc = acc.concat(rules[rule]);
-    return evolveAcc(y + z + xs.join(''), newAcc);
-  }
-  return evolveAcc(state, '');
+// handles negative index and index bigger than its array length
+function guard(index, array) {
+  if (index > (array.length - 1)) return 0;
+  if (index < 0) return (array.length - 1);
+  return index;
 }
 
-// create a 2D board from a 1D initial state
+// get the next evolution of a 1D CA initial state
+function evolve(state, rules) {
+  function getCell(index) {
+    const safeIndex = guard(index, state);
+    return state[safeIndex];
+  }
+  const newState = state.map((_, x) => {
+    const cells = [
+      getCell(x - 1),
+      getCell(x),
+      getCell(x + 1)];
+    return rules[cells.join('')];
+  });
+
+  return newState.map(Number);
+}
+
+// create a 2D board from a 1D CA initial state
 function createBoard(state, rules, height) {
   function createBoardAcc(s, h, acc) {
     if (h === 0) return acc;
-    const newState = evolve(state, rules);
-    const newAcc = acc.concat(state);
+    const newState = evolve(s, rules);
+    const newAcc = acc.concat([s]);
     return createBoardAcc(newState, h - 1, newAcc);
   }
-  return createBoardAcc(state, height, []).map(
-    (row) => row.split(''))
+  return createBoardAcc(state, height, []);
 }
 
+// Find the neighbor of a given cell in a 2D CA board
 function getCellNeighbors(board, cellCoordinates) {
   const [x, y] = cellCoordinates;
   const rowLength = board[0].length; // caca?
 
   // handles board edges where the cell is missing neighbors
   function getCell(xx, yy) {
-    // handles negative index and index bigger than its array length
-    function guard(index, array) {
-      if (index > array.length - 1) return 0;
-      if (index < 0) return array.length - 1;
-      return index;
-    }
-
     const safeX = guard(xx, board);
     const safeY = guard(yy, rowLength);
     return board[safeX][safeY];
@@ -52,10 +54,13 @@ function getCellNeighbors(board, cellCoordinates) {
   ];
 }
 
+// Sums the value of a cell's neighbors
 function getNeighborsSum(cells) {
   return cells.reduce((cell, acc) => cell + acc, 0);
 }
 
+// Get the next evolution of a cell according to
+// Conway's game of life rules
 function conwayRules(cell, neighbors) {
   // loneliness rule
   if (cell === 1 && neighbors < 2) return 0;
@@ -67,6 +72,7 @@ function conwayRules(cell, neighbors) {
   return cell;
 }
 
+// get the next evolution of a 2D CA initial state
 function evolve2d(board, rulesFn) {
   return board.map((row, x) => row.map((cell, y) => {
     const neighbors = getCellNeighbors(board, [x, y]);
@@ -93,15 +99,21 @@ function getDrawingValues(state, acc, cell) {
   );
 }
 
+// Populates the first state of a 1D CA with cells returned
+// by initFn
 function initialState1d(width, initFn, args) {
   return [...Array(width)].map(
-    () => initFn(...args).toString(),
-  ).join('');
+    () => initFn(...args),
+  );
 }
 
+// Populates the first state of a 2D CA with cells returned
+// by initFn
 function initialState2d(width, height, initFn, args) {
   return [...Array(height)].map(
-    () => [...Array(width)].map(() => initFn(...args)),
+    () => [...Array(width)].map(
+      () => initFn(...args),
+    ),
   );
 }