jdk8-mips64-public/nashorn: samples/list_mapreduce.js@2f1b9f4daec1 (annotated)

samples/list_mapreduce.js@2f1b9f4daec1 (annotated)

samples/list_mapreduce.js

Fri, 05 Jun 2015 12:38:53 +0200

author: mhaupt
date: Fri, 05 Jun 2015 12:38:53 +0200
changeset 1398: 2f1b9f4daec1
parent 962: ac62e33a99b0
permissions: -rw-r--r--

8080087: Nashorn $ENV.PWD is originally undefined
Summary: On Windows, the PWD environment variable does not exist and cannot be imported in scripting mode, so it is set explicitly.
Reviewed-by: lagergren, sundar

 /*
  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  *   - Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  *
  *   - Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  *
  *   - Neither the name of Oracle nor the names of its
  *     contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 // Usage: jjs list_mapreduce.js
 // Many Array.prototype functions such as map,
 // filter, reduce, reduceRight, every, some are generic.
 // These functions accept ECMAScript array as well as
 // many array-like objects including java.util.ArrayLists.
 // So, you can do map/filter/reduce with Java streams or
 // you can also use Array.prototype functions as below.
 // See also http://en.wikipedia.org/wiki/MapReduce
 var ArrayList = Java.type("java.util.ArrayList");
 var list = new ArrayList();
 list.add("nashorn");
 list.add("ecmascript");
 list.add("javascript");
 list.add("js");
 list.add("scheme");
 var map = Array.prototype.map;
 var filter = Array.prototype.filter;
 var reduce = Array.prototype.reduce;
 // sum of word lengths
 print("Sum word length:",
     reduce.call(
         map.call(list, function(x) x.length),
         function(x, y) x + y)
 );
 // filter use to filter out "j*" and concatenate rest with ":"
 // after uppercasing all strings
 print(
     reduce.call(
         map.call(
             filter.call(list, function(x) !x.startsWith("j")),
             function(x) x.toUpperCase()),
         function(x, y) x + ":" + y)
 );
 // another list example involving numbers
 list.clear();
 // make random list of numbers
 for (var i = 0; i < 10; i++)
     list.add(Math.random());
 var forEach = Array.prototype.forEach;
 // print numbers in the list
 forEach.call(list, function(x) print(x));
 // print sum of squares of the random numbers
 print("Square sum:",
     reduce.call(
         map.call(list, function(x) x*x),
         function(x, y) x + y)
 );