Rewrite lib/array.js methods

Rewrited asyncIter in some methods.

Author: Yehor Khilchenko

lib/array.js

@@ -3,34 +3,6 @@
 const common = require('@metarhia/common');
 const { asyncIter } = require('./async-iterator.js');
 
-const copyClass = name => {
-  switch (name) {
-    case 'Set':
-      return Set;
-    case 'Map':
-      return Map;
-    case 'Array':
-      return Array;
-    case 'String':
-      return String;
-  }
-  return null;
-};
-
-const copyInstance = name => {
-  switch (name) {
-    case 'Set':
-      return new Set();
-    case 'Map':
-      return new Map();
-    case 'Array':
-      return [];
-    case 'String':
-      return '';
-  }
-  return null;
-};
-
 const map = (
   // Asynchronous map (iterate parallel)
   items, // array, incoming
@@ -40,13 +12,12 @@ const map = (
   //   callback - function(err, value)
   done // function (optional), on done callback function(err, result)
 ) => {
-  done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
+  if (!items[Symbol.iterator]) {
     done(null, null);
     return;
   }
+  done = done || common.emptyness;
+  const isArray = Array.isArray(items);
   const data = asyncIter(items).map(
     item =>
       new Promise((resolve, reject) => {
@@ -56,22 +27,17 @@ const map = (
         });
       })
   );
-  if (name === 'Array') {
-    data
-      .toArray()
-      .then(r => done(null, r))
-      .catch(e => done(e));
-  } else if (name === 'String') {
-    data
-      .toArray()
-      .then(r => done(null, r.join('')))
-      .catch(e => done(e));
-  } else {
-    data
-      .collectTo(result)
-      .then(r => done(null, r))
-      .catch(e => done(e));
-  }
+  const promise =
+    isArray || items.constructor.name === 'String'
+      ? data.toArray()
+      : data.collectTo(items.constructor);
+  promise.then(
+    res =>
+      items.constructor.name === 'String'
+        ? done(null, res.join(''))
+        : done(null, res),
+    err => done(err)
+  );
 };
 
 const DEFAULT_OPTIONS = { min: 5, percent: 0.7 };
@@ -95,7 +61,7 @@ const asyncMap = (items, fn, options = {}, done) => {
 
   const len = items.length || items.size;
   const name = items.constructor.name;
-  let result = done ? copyInstance(name) : null;
+  let result = done ? new items.constructor() : null;
   const data = common.iter(items);
 
   if (!len || result === null) {
@@ -158,12 +124,11 @@ const asyncMap = (items, fn, options = {}, done) => {
 //     result - <Array>
 const filter = (items, fn, done) => {
   done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
+  if (!items[Symbol.iterator]) {
     done(null, null);
     return;
   }
+  const isArray = Array.isArray(items);
   const data = asyncIter(items).filter(
     item =>
       new Promise((resolve, reject) => {
@@ -173,22 +138,17 @@ const filter = (items, fn, done) => {
         });
       })
   );
-  if (name === 'Array') {
-    data
-      .toArray()
-      .then(r => done(null, r))
-      .catch(e => done(e));
-  } else if (name === 'String') {
-    data
-      .toArray()
-      .then(r => done(null, r.join('')))
-      .catch(e => done(e));
-  } else {
-    data
-      .collectTo(result)
-      .then(r => done(null, r))
-      .catch(e => done(e));
-  }
+  const promise =
+    isArray || items.constructor.name === 'String'
+      ? data.toArray()
+      : data.collectTo(items.constructor);
+  promise.then(
+    res =>
+      items.constructor.name === 'String'
+        ? done(null, res.join(''))
+        : done(null, res),
+    err => done(err)
+  );
 };
 
 // Asynchronous reduce
@@ -210,12 +170,6 @@ const filter = (items, fn, done) => {
 //       argument in first iteration
 const reduce = (items, fn, done, initial) => {
   done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
-    done(null, null);
-    return;
-  }
   asyncIter(items)
     .reduce(
       (prev, cur) =>
@@ -299,12 +253,6 @@ const each = (
   done // function (optional), on done callback function(err, items)
 ) => {
   done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
-    done(null, null);
-    return;
-  }
   asyncIter(items)
     .each(
       item =>
@@ -361,12 +309,6 @@ const series = (
 //     result - <any>
 const find = (items, fn, done) => {
   done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
-    done(null, null);
-    return;
-  }
   asyncIter(items)
     .find(
       item =>
@@ -390,12 +332,6 @@ const every = (
   done // function, optional on done callback function(err, result)
 ) => {
   done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
-    done(null, null);
-    return;
-  }
   asyncIter(items)
     .every(
       item =>
@@ -422,12 +358,6 @@ const every = (
 //     result - <boolean>
 const some = (items, fn, done) => {
   done = done || common.emptyness;
-  const name = items.constructor.name;
-  const result = copyClass(name);
-  if (result === null) {
-    done(null, null);
-    return;
-  }
   asyncIter(items)
     .some(
       item =>

lib/chain.js

@@ -66,37 +66,6 @@ ArrayChain.prototype.fetch = function(fn) {
   return this;
 };
 
-// ArrayChain.prototype.execute = function(chain) {
-//   this.chain = [];
-//   return new Promise((resolve, reject) => {
-//     reduce(
-//       chain,
-//       (prev, cur, cb) => {
-//         async(cur.op)(prev, cur.fn, (err, res) => {
-//           if (err) cb(err);
-//           else cb(null, res);
-//         });
-//       },
-//       (err, res) => {
-//         if (err) reject(err);
-//         else resolve(res);
-//       },
-//       this.array.slice()
-//     );
-//   });
-// };
-
-// ArrayChain.prototype.fetch = function(fn) {
-//   const next = (err, data) => {
-//     this.array = data;
-//     if (err) throw err;
-//   };
-//   this.execute(this.chain)
-//     .then(r => fn(null, r, next))
-//     .catch(e => fn(e));
-//   return this;
-// };
-
 ArrayChain.prototype.map = function(fn) {
   this.chain.push({ op: 'map', fn });
   return this;

test/array.filter.js

@@ -196,7 +196,7 @@ metatests.test('filter with empty / string', test => {
 metatests.test('filter with another object', test => {
   const obj = { a: '1', b: '2', c: '3' };
 
-  metasync.map(
+  metasync.filter(
     obj,
     (x, callback) =>
       process.nextTick(() => {