aoqi@0: /*
aoqi@0:  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
attila@962:  *
aoqi@0:  * Redistribution and use in source and binary forms, with or without
aoqi@0:  * modification, are permitted provided that the following conditions
aoqi@0:  * are met:
attila@962:  *
aoqi@0:  *   - Redistributions of source code must retain the above copyright
aoqi@0:  *     notice, this list of conditions and the following disclaimer.
attila@962:  *
aoqi@0:  *   - Redistributions in binary form must reproduce the above copyright
aoqi@0:  *     notice, this list of conditions and the following disclaimer in the
aoqi@0:  *     documentation and/or other materials provided with the distribution.
attila@962:  *
aoqi@0:  *   - Neither the name of Oracle nor the names of its
aoqi@0:  *     contributors may be used to endorse or promote products derived
aoqi@0:  *     from this software without specific prior written permission.
attila@962:  *
aoqi@0:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
aoqi@0:  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
aoqi@0:  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
aoqi@0:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
aoqi@0:  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
aoqi@0:  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
aoqi@0:  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
aoqi@0:  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
aoqi@0:  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
aoqi@0:  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
aoqi@0:  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
aoqi@0:  */
aoqi@0: 
aoqi@0: // Usage: jjs array_mapreduce.js
aoqi@0: 
attila@962: // Many Array.prototype functions such as map,
aoqi@0: // filter, reduce, reduceRight, every, some are generic.
attila@962: // These functions accept ECMAScript array as well as
aoqi@0: // many array-like objects including java arrays.
aoqi@0: // So, you can do map/filter/reduce with Java streams or
aoqi@0: // you can also use Array.prototype functions as below.
aoqi@0: // See also http://en.wikipedia.org/wiki/MapReduce
aoqi@0: 
aoqi@0: var DoubleArray = Java.type("double[]");
aoqi@0: var StringArray = Java.type("java.lang.String[]");
aoqi@0: 
aoqi@0: var map = Array.prototype.map;
aoqi@0: var filter = Array.prototype.filter;
aoqi@0: var reduce = Array.prototype.reduce;
aoqi@0: 
aoqi@0: var jarr = new StringArray(5);
aoqi@0: jarr[0] = "nashorn";
aoqi@0: jarr[1] = "ecmascript";
aoqi@0: jarr[2] = "javascript";
aoqi@0: jarr[3] = "js";
aoqi@0: jarr[4] = "scheme";
aoqi@0: 
aoqi@0: // sum of word lengths
aoqi@0: print("Sum word length:",
aoqi@0:     reduce.call(
aoqi@0:         map.call(jarr, function(x) x.length),
aoqi@0:         function(x, y) x + y)
aoqi@0: );
aoqi@0: 
aoqi@0: // another array example involving numbers
aoqi@0: jarr = new DoubleArray(10);
aoqi@0: // make random array of numbers
aoqi@0: for (var i = 0; i < jarr.length; i++)
aoqi@0:     jarr[i] = Math.random();
aoqi@0: 
aoqi@0: var forEach = Array.prototype.forEach;
aoqi@0: // print numbers in the array
aoqi@0: forEach.call(jarr, function(x) print(x));
aoqi@0: 
aoqi@0: // print sum of squares of the random numbers
aoqi@0: print("Square sum:",
aoqi@0:     reduce.call(
attila@962:         map.call(jarr, function(x) x*x),
aoqi@0:         function(x, y) x + y)
aoqi@0: );