elliptical-observe-inline/lib-node/processor.js

Dynamic sideways Data Loading for Elliptical

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = createProcessor;

var _lodash = require('lodash');

var _lodash2 = _interopRequireDefault(_lodash);

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

function createProcessor(register, processor) {
  function observe(source) {
    if (processor) {
      source = processor(source);
    }
    return register(source);
  }

  function process(element) {
    const newElement = _lodash2.default.assign({}, element, { observe });

    // Don't worry about builtins, or Phrases with a visit
    if (_lodash2.default.isString(element.type) || !element.type.describe) {
      return newElement;
    }

    function describeAndTrackObserve() {
      const sources = [];
      const values = [];
      function trackedObserve(source) {
        if (processor) {
          source = processor(source);
        }
        const value = register(source);
        sources.push(source);
        values.push(value);
        return value;
      }
      const description = element.type.describe(_lodash2.default.assign({}, element, { observe: trackedObserve }));
      return { description, sources, values };
    }

    const { description: firstDescription, sources: firstSources, values: firstValues } = describeAndTrackObserve();
    let firstRun = true;

    // If it never called observe, it never WILL call observe during
    // a normal describe. It may with 'dynamic' or a child value,
    // but we can't track and optimize that - so we'll just
    // pass a naive observe
    if (firstSources.length === 0) {
      return newElement;
    } else {
      let oldValues = firstValues;
      let oldSources = firstSources;
      let oldDescription = firstDescription;

      function visit(option, e, traverse) {
        let sources, values, description;
        if (firstRun) {
          sources = firstSources;
          values = firstValues;
          description = firstDescription;
          firstRun = false;
        } else {
          ;({ sources, values, description } = describeAndTrackObserve());
        }
        if (oldDescription == null && description != null || values.length !== oldValues.length || // perf opt
        _lodash2.default.some(_lodash2.default.unzip([values, oldValues]), ([a, b]) => a !== b) || _lodash2.default.some(_lodash2.default.unzip([sources, oldSources]), ([a, b]) => !_lodash2.default.isEqual(a, b))) {
          oldValues = values;
          oldSources = sources;
          oldDescription = description;
        }

        return traverse(oldDescription, option);
      }
      const type = _lodash2.default.assign({}, element.type, {
        visit,
        _oldVisit: element.type.visit,
        describe: undefined
      });
      return _lodash2.default.assign({}, newElement, { type });
    }
  }

  process.observe = observe;

  return process;
}