mathjs/lib/esm/expression/transform/map.transform.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

import { applyCallback } from '../../utils/applyCallback.js';
import { map } from '../../utils/array.js';
import { factory } from '../../utils/factory.js';
import { isFunctionAssignmentNode, isSymbolNode } from '../../utils/is.js';
import { compileInlineExpression } from './utils/compileInlineExpression.js';
var name = 'map';
var dependencies = ['typed'];
export var createMapTransform = /* #__PURE__ */factory(name, dependencies, _ref => {
  var {
    typed
  } = _ref;
  /**
   * Attach a transform function to math.map
   * Adds a property transform containing the transform function.
   *
   * This transform creates a one-based index instead of a zero-based index
   */
  function mapTransform(args, math, scope) {
    var x, callback;
    if (args[0]) {
      x = args[0].compile().evaluate(scope);
    }
    if (args[1]) {
      if (isSymbolNode(args[1]) || isFunctionAssignmentNode(args[1])) {
        // a function pointer, like filter([3, -2, 5], myTestFunction)
        callback = args[1].compile().evaluate(scope);
      } else {
        // an expression like filter([3, -2, 5], x > 0)
        callback = compileInlineExpression(args[1], math, scope);
      }
    }
    return map(x, callback);
  }
  mapTransform.rawArgs = true;

  // one-based version of map function
  var map = typed('map', {
    'Array, function': function ArrayFunction(x, callback) {
      return _map(x, callback, x);
    },
    'Matrix, function': function MatrixFunction(x, callback) {
      return x.create(_map(x.valueOf(), callback, x));
    }
  });
  return mapTransform;
}, {
  isTransformFunction: true
});

/**
 * Map for a multidimensional array. One-based indexes
 * @param {Array} array
 * @param {function} callback
 * @param {Array} orig
 * @return {Array}
 * @private
 */
function _map(array, callback, orig) {
  function recurse(value, index) {
    if (Array.isArray(value)) {
      return map(value, function (child, i) {
        // we create a copy of the index array and append the new index value
        return recurse(child, index.concat(i + 1)); // one based index, hence i + 1
      });
    } else {
      // invoke the (typed) callback function with the right number of arguments
      return applyCallback(callback, value, index, orig, 'map');
    }
  }
  return recurse(array, []);
}