add object map/reduce/filter

Author: phpnode

index.js

@@ -38,6 +38,9 @@ Fast['try'] = Fast.attempt = require( './function/try' );
 
 Fast.assign = require('./object/assign');
 Fast.cloneObject = require('./object/clone');
+Fast.mapObject = require('./object/map');
+Fast.filterObject = require('./object/filter');
+Fast.reduceObject = require('./object/reduce');
 
 Fast.cloneArray = require('./array/clone');
 Fast.concat = require('./array/concat');

object/filter.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var bindInternal3 = require('../function/bindInternal3');
+
+/**
+ * # Filter
+ *
+ * A fast object `.filter()` implementation.
+ *
+ * @param  {Object}    subject    The object to filter.
+ * @param  {Function} fn          The filter function.
+ * @param  {Object}   thisContext The context for the filter.
+ * @return {Object}               The new object containing the filtered results.
+ */
+module.exports = function fastFilterObject (subject, fn, thisContext) {
+  var keys = Object.keys(subject),
+      length = keys.length,
+      result = {},
+      iterator = thisContext !== undefined ? bindInternal3(fn, thisContext) : fn,
+      i, key;
+  for (i = 0; i < length; i++) {
+    key = keys[i];
+    if (iterator(subject[key], key, subject)) {
+      result[key] = subject[key];
+    }
+  }
+  return result;
+};

object/map.js

@@ -0,0 +1,26 @@
+'use strict';
+
+var bindInternal3 = require('../function/bindInternal3');
+
+/**
+ * # Map
+ *
+ * A fast object `.map()` implementation.
+ *
+ * @param  {Object}    subject    The object to map over.
+ * @param  {Function} fn          The mapper function.
+ * @param  {Object}   thisContext The context for the mapper.
+ * @return {Object}               The new object containing the results.
+ */
+module.exports = function fastMapObject (subject, fn, thisContext) {
+  var keys = Object.keys(subject),
+      length = keys.length,
+      result = {},
+      iterator = thisContext !== undefined ? bindInternal3(fn, thisContext) : fn,
+      i, key;
+  for (i = 0; i < length; i++) {
+    key = keys[i];
+    result[key] = iterator(subject[key], key, subject);
+  }
+  return result;
+};

object/reduce.js

@@ -0,0 +1,37 @@
+'use strict';
+
+var bindInternal4 = require('../function/bindInternal4');
+
+/**
+ * # Reduce
+ *
+ * A fast object `.reduce()` implementation.
+ *
+ * @param  {Object}    subject     The object to reduce over.
+ * @param  {Function} fn           The reducer function.
+ * @param  {mixed}    initialValue The initial value for the reducer, defaults to subject[0].
+ * @param  {Object}   thisContext  The context for the reducer.
+ * @return {mixed}                 The final result.
+ */
+module.exports = function fastReduceObject (subject, fn, initialValue, thisContext) {
+  var keys = Object.keys(subject),
+      length = keys.length,
+      iterator = thisContext !== undefined ? bindInternal4(fn, thisContext) : fn,
+      i, key, result;
+
+  if (initialValue === undefined) {
+    i = 1;
+    result = subject[keys[0]];
+  }
+  else {
+    i = 0;
+    result = initialValue;
+  }
+
+  for (; i < length; i++) {
+    key = keys[i];
+    result = iterator(result, subject[key], key, subject);
+  }
+
+  return result;
+};

test/test.js

@@ -726,6 +726,85 @@ describe('fast.intern()', function () {
   });
 });
 
+describe('fast.mapObject', function () {
+  it('should map over the keys / values in an object', function () {
+    var result = fast.mapObject({a: 1, b: 2, c: 3}, function (value, key) {
+      return [key, value];
+    });
+    result.should.eql({
+      a: ["a", 1],
+      b: ["b", 2],
+      c: ["c", 3]
+    });
+  });
+  it('should map over the keys / values in an object, with a context', function () {
+    var context = {val: 1};
+    var result = fast.mapObject({a: 1, b: 2, c: 3}, function (value, key) {
+      return [key, value + this.val];
+    }, context);
+    result.should.eql({
+      a: ["a", 2],
+      b: ["b", 3],
+      c: ["c", 4]
+    });
+  });
+});
+
+describe('fast.filterObject', function () {
+  it('should filter keys / values from an object', function () {
+    var result = fast.filterObject({a: 1, b: 2, c: 3, d: 4}, function (value) {
+      return (value % 2) === 0;
+    });
+    result.should.eql({
+      b: 2,
+      d: 4
+    });
+  });
+  it('should filter keys / values from an object, with a context', function () {
+    var context = {val: 1};
+    var result = fast.filterObject({a: 1, b: 2, c: 3, d: 4}, function (value) {
+      return ((value + this.val) % 2) === 0;
+    }, context);
+    result.should.eql({
+      a: 1,
+      c: 3
+    });
+  });
+});
+
+describe('fast.reduceObject', function () {
+  it('should apply a reducer to an object', function () {
+    var result = fast.reduceObject({a: 1, b: 2, c: 3, d: 4}, function (total, value, key) {
+      return total + value;
+    },0);
+
+    result.should.equal(10);
+  });
+
+  it('should apply a reducer to an object, with a context', function () {
+    var context = {val:1};
+    var result = fast.reduceObject({a: 1, b: 2, c: 3, d: 4}, function (total, value, key) {
+      return total + value + this.val;
+    },0, context);
+
+    result.should.equal(14);
+  });
+
+  it('should apply a reducer to an object, with no initial value', function () {
+    var result = fast.reduceObject({a: 1, b: 2, c: 3, d: 4}, function (acc, value, key) {
+      return acc + value + 1;
+    });
+    result.should.equal(13);
+  });
+  it('should apply a reducer to an object, with no initial value, with a context', function () {
+    var context = {val: 1};
+    var result = fast.reduceObject({a: 1, b: 2, c: 3, d: 4}, function (acc, value, key) {
+      return acc + value + this.val;
+    }, undefined, context);
+    result.should.equal(13);
+  });
+});
+
 describe('Fast', function () {
   var input = fast([1,2,3,4,5,6]);