mathjs/src/expression/node/utils/access.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

'use strict'

const errorTransform = require('../../transform/error.transform').transform
const getSafeProperty = require('../../../utils/customs').getSafeProperty

function factory (type, config, load, typed) {
  const subset = load(require('../../../function/matrix/subset'))

  /**
   * Retrieve part of an object:
   *
   * - Retrieve a property from an object
   * - Retrieve a part of a string
   * - Retrieve a matrix subset
   *
   * @param {Object | Array | Matrix | string} object
   * @param {Index} index
   * @return {Object | Array | Matrix | string} Returns the subset
   */
  return function access (object, index) {
    try {
      if (Array.isArray(object)) {
        return subset(object, index)
      } else if (object && typeof object.subset === 'function') { // Matrix
        return object.subset(index)
      } else if (typeof object === 'string') {
        // TODO: move getStringSubset into a separate util file, use that
        return subset(object, index)
      } else if (typeof object === 'object') {
        if (!index.isObjectProperty()) {
          throw new TypeError('Cannot apply a numeric index as object property')
        }

        return getSafeProperty(object, index.getObjectProperty())
      } else {
        throw new TypeError('Cannot apply index: unsupported type of object')
      }
    } catch (err) {
      throw errorTransform(err)
    }
  }
}

exports.factory = factory