assertRecord.js

'use strict';

var GetIntrinsic = require('../GetIntrinsic');

var $TypeError = GetIntrinsic('%TypeError%');
var $SyntaxError = GetIntrinsic('%SyntaxError%');

var has = require('has');

var predicates = {
  // https://ecma-international.org/ecma-262/6.0/#sec-property-descriptor-specification-type
  'Property Descriptor': function isPropertyDescriptor(ES, Desc) {
    if (ES.Type(Desc) !== 'Object') {
      return false;
    }
    var allowed = {
      '[[Configurable]]': true,
      '[[Enumerable]]': true,
      '[[Get]]': true,
      '[[Set]]': true,
      '[[Value]]': true,
      '[[Writable]]': true
    };

    for (var key in Desc) { // eslint-disable-line
      if (has(Desc, key) && !allowed[key]) {
        return false;
      }
    }

    var isData = has(Desc, '[[Value]]');
    var IsAccessor = has(Desc, '[[Get]]') || has(Desc, '[[Set]]');
    if (isData && IsAccessor) {
      throw new $TypeError('Property Descriptors may not be both accessor and data descriptors');
    }
    return true;
  }
};

module.exports = function assertRecord(ES, recordType, argumentName, value) {
  var predicate = predicates[recordType];
  if (typeof predicate !== 'function') {
    throw new $SyntaxError('unknown record type: ' + recordType);
  }
  if (!predicate(ES, value)) {
    throw new $TypeError(argumentName + ' must be a ' + recordType);
  }
  console.log(predicate(ES, value), value);
};