Array2D.includes = function()

in slides/asset/common/Array2D.js [1155:1223]

• 44 lines of code
• 16 McCabe index (conditional complexity)

  Array2D.includes = function(grid1, grid2) {
    // Dimensions cache.
    var d1 = Array2D.dimensions(grid1);
    var d2 = Array2D.dimensions(grid2);
    var w1 = d1[0];
    var h1 = d1[1];
    var w2 = d2[0];
    var h2 = d2[1];

    // Size conditions under which we don't bother checking.
    if (w2 < 1) return false;
    if (h2 < 1) return false;
    if (w2 > w1) return false;
    if (h2 > h1) return false;

    var first = grid2[0][0];
    var starters = [];

    // Start by checking each cell of the outer grid.
    for (var i = 0; i < grid1.length; i++) {
      for (var j = 0; j < grid1[i].length; j++) {
        var cell1 = grid1[i][j];

        // If the first cell is a match, proceed.
        if (cell1 === first) {
          starters.push([i, j]);
        }
      }
    }

    // If no initial matches, no point checking the rest.
    var startersLen = starters.length;
    if (startersLen < 1) return false;

    // Check whether the comparee is present in the grid.
    for (var x = 0; x < startersLen; x++) {
      // Starting coordinates in the *outer* grid.
      var sr = starters[x][0];
      var sc = starters[x][1];

      // Assume a match for this starting point, then invalidate.
      var match = true;

      // Loop over the inner grid, comparing each cell.
      for (var i = 0; i < grid2.length; i++) {
        var row1 = grid1[i + sr];
        var row2 = grid2[i];

        // Fail early if we've already overstepped the bounds.
        if (!isArray(row1)) break;
        if (!isArray(row2)) break;

        for (var j = 0; j < grid2[i].length; j++) {
          var cell1 = row1[j + sc];
          var cell2 = row2[j];

          if (cell1 !== cell2) match = false;
        }
      }

      // Return as soon as we find our first match.
      if (match === true) {
        return true;
      }
    }

    // If we got this far, we never found a match.
    return false;
  };