1 #// Usage: jjs -scripting -cp . jsobject_mapreduce.js
   2 
   3 /*
   4  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  *   - Redistributions of source code must retain the above copyright
  11  *     notice, this list of conditions and the following disclaimer.
  12  *
  13  *   - Redistributions in binary form must reproduce the above copyright
  14  *     notice, this list of conditions and the following disclaimer in the
  15  *     documentation and/or other materials provided with the distribution.
  16  *
  17  *   - Neither the name of Oracle nor the names of its
  18  *     contributors may be used to endorse or promote products derived
  19  *     from this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  22  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  23  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  25  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  27  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  28  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  29  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  30  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  31  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33 
  34 // Many Array.prototype functions such as map,
  35 // filter, reduce, reduceRight, every, some are generic.
  36 // These functions accept ECMAScript array as well as
  37 // many array-like objects including JSObjects.
  38 // See also http://en.wikipedia.org/wiki/MapReduce
  39 
  40 `javac BufferArray.java`;
  41 
  42 var BufferArray = Java.type("BufferArray");
  43 var buf = new BufferArray(10);
  44 
  45 var map = Array.prototype.map;
  46 var filter = Array.prototype.filter;
  47 var reduce = Array.prototype.reduce;
  48 
  49 // make random list of numbers
  50 for (var i = 0; i < 10; i++)
  51     buf[i] = Math.random();
  52 
  53 var forEach = Array.prototype.forEach;
  54 // print numbers in the list
  55 forEach.call(buf, function(x) print(x));
  56 
  57 // print sum of squares of the random numbers
  58 print("Square sum:",
  59     reduce.call(
  60         map.call(buf, function(x) x*x),
  61         function(x, y) x + y)
  62 );