scontainers/dist/types/object_enumerable_properties.js

A container/collection/iterator library for JavaScript, comfortable to use, performant and versatile.

"use strict";

function _implSymbol(target, sym, value) {
  Object.defineProperty(target, sym, {
    value,
    configurable: true
  });
  return target[sym];
}

function _getSymbol(targetSymName, ...traitSets) {
  let symbol;
  traitSets.forEach(traitSet => {
    const sym = traitSet[targetSymName];

    if (typeof sym === 'symbol') {
      if (!!symbol && symbol !== sym) {
        throw new Error(`Symbol ${targetSymName} offered by multiple trait sets.`);
      }

      symbol = sym;
    }
  });

  if (!symbol) {
    throw new Error(`No trait set is providing symbol ${targetSymName}.`);
  }

  return symbol;
}

function _testTraitSet(traitSet) {
  if (!traitSet || typeof traitSet === 'boolean' || typeof traitSet === 'number' || typeof traitSet === 'string') {
    throw new Error(`${traitSet} cannot be used as a trait set.`);
  }
}

const {
  assert,
  traits,
  toStr,
  KVN
} = require('../utils.js');

_testTraitSet(traits.utils);

_testTraitSet(traits.scontainers);

_testTraitSet(traits.semantics);

const _describeScontainer = _getSymbol("describeScontainer", traits.utils, traits.scontainers, traits.semantics);

const _implCoreTraits = _getSymbol("implCoreTraits", traits.utils, traits.scontainers, traits.semantics);

const _hasKey = _getSymbol("hasKey", traits.utils, traits.scontainers, traits.semantics);

const _iterator = _getSymbol("iterator", traits.utils, traits.scontainers, traits.semantics);

module.exports = function (ParentCollection) {
  assert(ParentCollection === Object, `EnumerableProperties is only needed by Object...`);
  return function () {
    class EnumerableProperties {
      static get name() {
        return `ObjectProperties`;
      }

      constructor(coll) {
        this.wrapped = coll;
      }

      toString() {
        var _context;

        return `${(_context = this.wrapped, toStr).call(_context)}::properties()`;
      }

    }

    EnumerableProperties[_describeScontainer]({
      argKeys: []
    });

    EnumerableProperties[_implCoreTraits]({
      get(key) {
        return this[_hasKey](key) && this.wrapped[key];
      },

      set(key, value) {
        this.wrapped[key] = value;
      },

      hasKey(key) {
        return this.wrapped.propertyIsEnumerable(key);
      },

      *iterator() {
        for (let key in this.wrapped) {
          yield [key, this.wrapped[key]];
        }
      },

      kvIterator() {
        return {
          it: this[_iterator](),

          next() {
            const next = this.it.next();

            if (!next.done) {
              return new KVN(next.value[0], next.value[1]);
            }
          }

        };
      },

      forEach(fn) {
        for (let key in this.wrapped) {
          fn(this.wrapped[key], key);
        }
      },

      whileEach(fn) {
        for (let key in this.wrapped) {
          const value = this.wrapped[key];

          if (!fn(value, key, this)) {
            return [key, value];
          }
        }
      }

    });

    return EnumerableProperties;
  };
};