makemeahanzi/lib/util.js

"use strict";

// Prints the message and throws an error if the conditionis false.
this.assert = (condition, message) => {
  if (!condition) {
    console.error(message);
    throw new Error;
  }
}

this.maybeRequire = (module) => Meteor.isServer ? Npm.require(module) : null;

if (Meteor.isServer) {
  Meteor.npmRequire('es6-shim');
}

// Returns a list of the unique values in the given array, ordered by their
// first appearance in the array.
Array.prototype.unique = function() {
  const result = [];
  const seen = {};
  this.map((x) => {
    if (!seen[x]) {
      result.push(x);
      seen[x] = true;
    }
  });
  return result;
}

// Helper methods for use with angles, which are floats in [-pi, pi).
assert(this.Angle === undefined, 'Redefining Angle global!');
this.Angle = {
  subtract: (angle1, angle2) => {
    var result = angle1 - angle2;
    if (result < -Math.PI) {
      result += 2*Math.PI;
    }
    if (result >= Math.PI) {
      result -= 2*Math.PI;
    }
    return result;
  },
  penalty: (diff) => diff*diff,
};

const isNumber = (x) => Number.isFinite(x) && !Number.isNaN(x);

// Helper methods for use with "points", which are pairs of integers.
assert(this.Point === undefined, 'Redefining Point global!');
this.Point = {
  angle: (point) => Math.atan2(point[1], point[0]),
  clone: (point) => [point[0], point[1]],
  distance2(point1, point2) {
    var diff = Point.subtract(point1, point2);
    return Math.pow(diff[0], 2) + Math.pow(diff[1], 2);
  },
  equal: (point1, point2) => point1[0] === point2[0] && point1[1] === point2[1],
  key: (point) => point.join(','),
  subtract: (point1, point2) => [point1[0] - point2[0], point1[1] - point2[1]],
  valid: (point) => isNumber(point[0]) && isNumber(point[1]),
};