angel-eval/dist/index.js

A conditional expression parser and interpreter.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.evaluate = evaluate;
exports.default = exports.parse = void 0;

var _memoize = _interopRequireDefault(require("lodash/memoize"));

var _isString = _interopRequireDefault(require("lodash/isString"));

var _isBoolean = _interopRequireDefault(require("lodash/isBoolean"));

var _nearley = require("nearley");

var _Evaluatable = _interopRequireDefault(require("./Evaluatable"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

const grammar = _nearley.Grammar.fromCompiled(require("./grammar.js"));

function createParser() {
  return new _nearley.Parser(grammar);
}
/**
 * Parses the given expression and returns an
 * `Evaluatable` that can be evaluated with a context.
 *
 * @param {string} expression
 * @returns {Evaluatable}
 */


const _parse = expression => {
  if (!(0, _isString.default)(expression) || expression.length === 0) {
    throw new Error("expression needs to be a non-empty string");
  }

  const parser = createParser();

  try {
    parser.feed(expression);
    const [node] = parser.results; // if (!(node instanceof Evaluatable)) {
    //   throw new Error("Result needs to be an instance of Evaluatable");
    // }

    return node;
  } catch (e) {
    const segments = e.message.split(/\r?\n/g).slice(0, 4);
    segments[2] = segments[2].substring(1);
    segments[3] = segments[3].substring(1);
    throw new Error(segments.join("\n"));
  }
};
/**
 * Parses the given expression and returns an
 * `Evaluatable` that can be evaluated with a context.
 *
 * This function is memoized for optimization.
 *
 * You can access the function's cache using `parse.cache`.
 */


const parse = (0, _memoize.default)(_parse);
/**
 * Evaluates the given expression using the context provided.
 *
 * @param {string} expression
 * @param {{ [key: string]: any }} [context]
 * @param {boolean} [strictBoolean] Whether to always return a boolean.
 * @returns {boolean}
 */

exports.parse = parse;

function evaluate(expression, context = {}, strictBoolean = true) {
  const node = parse(expression); // console.dir(node, { depth: 100 });

  let value = node.evaluate(context);

  if (!(0, _isBoolean.default)(value) && strictBoolean) {
    value = !!value;
  }

  return value;
}

var _default = {
  createParser,
  _parse,
  // public methods
  parse,
  evaluate
};
exports.default = _default;