reselect/es/index.js

import { defaultMemoize, defaultEqualityCheck } from './defaultMemoize';
export { defaultMemoize, defaultEqualityCheck };

function getDependencies(funcs) {
  var dependencies = Array.isArray(funcs[0]) ? funcs[0] : funcs;

  if (!dependencies.every(function (dep) {
    return typeof dep === 'function';
  })) {
    var dependencyTypes = dependencies.map(function (dep) {
      return typeof dep === 'function' ? "function " + (dep.name || 'unnamed') + "()" : typeof dep;
    }).join(', ');
    throw new Error("createSelector expects all input-selectors to be functions, but received the following types: [" + dependencyTypes + "]");
  }

  return dependencies;
}

export function createSelectorCreator(memoize) {
  for (var _len = arguments.length, memoizeOptionsFromArgs = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
    memoizeOptionsFromArgs[_key - 1] = arguments[_key];
  }

  var createSelector = function createSelector() {
    for (var _len2 = arguments.length, funcs = new Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
      funcs[_key2] = arguments[_key2];
    }

    var _recomputations = 0;

    var _lastResult; // Due to the intricacies of rest params, we can't do an optional arg after `...funcs`.
    // So, start by declaring the default value here.
    // (And yes, the words 'memoize' and 'options' appear too many times in this next sequence.)


    var directlyPassedOptions = {
      memoizeOptions: undefined
    }; // Normally, the result func or "output selector" is the last arg

    var resultFunc = funcs.pop(); // If the result func is actually an _object_, assume it's our options object

    if (typeof resultFunc === 'object') {
      directlyPassedOptions = resultFunc; // and pop the real result func off

      resultFunc = funcs.pop();
    }

    if (typeof resultFunc !== 'function') {
      throw new Error("createSelector expects an output function after the inputs, but received: [" + typeof resultFunc + "]");
    } // Determine which set of options we're using. Prefer options passed directly,
    // but fall back to options given to createSelectorCreator.


    var _directlyPassedOption = directlyPassedOptions,
        _directlyPassedOption2 = _directlyPassedOption.memoizeOptions,
        memoizeOptions = _directlyPassedOption2 === void 0 ? memoizeOptionsFromArgs : _directlyPassedOption2; // Simplifying assumption: it's unlikely that the first options arg of the provided memoizer
    // is an array. In most libs I've looked at, it's an equality function or options object.
    // Based on that, if `memoizeOptions` _is_ an array, we assume it's a full
    // user-provided array of options. Otherwise, it must be just the _first_ arg, and so
    // we wrap it in an array so we can apply it.

    var finalMemoizeOptions = Array.isArray(memoizeOptions) ? memoizeOptions : [memoizeOptions];
    var dependencies = getDependencies(funcs);
    var memoizedResultFunc = memoize.apply(void 0, [function recomputationWrapper() {
      _recomputations++; // apply arguments instead of spreading for performance.

      return resultFunc.apply(null, arguments);
    }].concat(finalMemoizeOptions)); // If a selector is called with the exact same arguments we don't need to traverse our dependencies again.

    var selector = memoize(function dependenciesChecker() {
      var params = [];
      var length = dependencies.length;

      for (var i = 0; i < length; i++) {
        // apply arguments instead of spreading and mutate a local list of params for performance.
        // @ts-ignore
        params.push(dependencies[i].apply(null, arguments));
      } // apply arguments instead of spreading for performance.


      _lastResult = memoizedResultFunc.apply(null, params);
      return _lastResult;
    });
    Object.assign(selector, {
      resultFunc: resultFunc,
      memoizedResultFunc: memoizedResultFunc,
      dependencies: dependencies,
      lastResult: function lastResult() {
        return _lastResult;
      },
      recomputations: function recomputations() {
        return _recomputations;
      },
      resetRecomputations: function resetRecomputations() {
        return _recomputations = 0;
      }
    });
    return selector;
  }; // @ts-ignore


  return createSelector;
}
export var createSelector = /* #__PURE__ */createSelectorCreator(defaultMemoize);
// Manual definition of state and output arguments
export var createStructuredSelector = function createStructuredSelector(selectors, selectorCreator) {
  if (selectorCreator === void 0) {
    selectorCreator = createSelector;
  }

  if (typeof selectors !== 'object') {
    throw new Error('createStructuredSelector expects first argument to be an object ' + ("where each property is a selector, instead received a " + typeof selectors));
  }

  var objectKeys = Object.keys(selectors);
  var resultSelector = selectorCreator( // @ts-ignore
  objectKeys.map(function (key) {
    return selectors[key];
  }), function () {
    for (var _len3 = arguments.length, values = new Array(_len3), _key3 = 0; _key3 < _len3; _key3++) {
      values[_key3] = arguments[_key3];
    }

    return values.reduce(function (composition, value, index) {
      composition[objectKeys[index]] = value;
      return composition;
    }, {});
  });
  return resultSelector;
};