visit(callback, predicate)

Iterates cells in row-major order and calls callback({ row, col, value }) for each cell where predicate({ row, col, value }) returns true. Return false from the callback to stop early. Reading and mutating the grid inside the callback is allowed.

Example

(move mouse to highlight 🐸 filled cells in the hovered col, and click to randomize q)

code

Quadrille.cellLength = 50;
let q, hint;

function setup() {
  createCanvas(8 * Quadrille.cellLength, 8 * Quadrille.cellLength);
  q = createQuadrille(8, 8).rand(15, '🐸').rand(15, '🐯').rand(15, '🐮');
  highlight();
}

function draw() {
  background('#D7BDE2');
  drawQuadrille(q);
  drawQuadrille(hint);
}

function mousePressed() {
  q.randomize();
  highlight();
}

function mouseMoved() {
  highlight();
}

function highlight() {
  hint = createQuadrille(8, 8);
  q.visit(
    ({ row, col }) => hint.fill(row, col, color(0, 140)),
    ({ value, col }) => value === '🐸' && col === q.mouseCol
  );
}

The predicate decides which cells are visited (e.g., only 🐸 in the current column).
The callback defines what to do with those visited cells (e.g., fill them with semi-transparent color).

Syntax

visit(callback, predicate)

Parameters

Param	Description
`callback`	Receives `{ row, col, value }`. Return `false` to stop early; any other return is ignored
`predicate`	A function `({ row, col, value }) => boolean`. Only cells for which the predicate returns `true` are visited

visit(callback, collection)