Mercurial > jdk8-mips64-public > nashorn / annotate
samples/array_mapreduce.js@b1a7da25b547 (annotated)
samples/array_mapreduce.js
Wed, 27 Apr 2016 01:36:41 +0800
- author
- aoqi
- date
- Wed, 27 Apr 2016 01:36:41 +0800
- changeset 0
- b1a7da25b547
- child 962
- ac62e33a99b0
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http://hg.openjdk.java.net/jdk8u/jdk8u/nashorn/
changeset: 1034:4b9cc65dd24d
tag: jdk8u25-b17
| aoqi@0 | 1 | /* |
| aoqi@0 | 2 | * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. |
| aoqi@0 | 3 | * |
| aoqi@0 | 4 | * Redistribution and use in source and binary forms, with or without |
| aoqi@0 | 5 | * modification, are permitted provided that the following conditions |
| aoqi@0 | 6 | * are met: |
| aoqi@0 | 7 | * |
| aoqi@0 | 8 | * - Redistributions of source code must retain the above copyright |
| aoqi@0 | 9 | * notice, this list of conditions and the following disclaimer. |
| aoqi@0 | 10 | * |
| aoqi@0 | 11 | * - Redistributions in binary form must reproduce the above copyright |
| aoqi@0 | 12 | * notice, this list of conditions and the following disclaimer in the |
| aoqi@0 | 13 | * documentation and/or other materials provided with the distribution. |
| aoqi@0 | 14 | * |
| aoqi@0 | 15 | * - Neither the name of Oracle nor the names of its |
| aoqi@0 | 16 | * contributors may be used to endorse or promote products derived |
| aoqi@0 | 17 | * from this software without specific prior written permission. |
| aoqi@0 | 18 | * |
| aoqi@0 | 19 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| aoqi@0 | 20 | * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| aoqi@0 | 21 | * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| aoqi@0 | 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| aoqi@0 | 23 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| aoqi@0 | 24 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| aoqi@0 | 25 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| aoqi@0 | 26 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| aoqi@0 | 27 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| aoqi@0 | 28 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| aoqi@0 | 29 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| aoqi@0 | 30 | */ |
| aoqi@0 | 31 | |
| aoqi@0 | 32 | // Usage: jjs array_mapreduce.js |
| aoqi@0 | 33 | |
| aoqi@0 | 34 | // Many Array.prototype functions such as map, |
| aoqi@0 | 35 | // filter, reduce, reduceRight, every, some are generic. |
| aoqi@0 | 36 | // These functions accept ECMAScript array as well as |
| aoqi@0 | 37 | // many array-like objects including java arrays. |
| aoqi@0 | 38 | // So, you can do map/filter/reduce with Java streams or |
| aoqi@0 | 39 | // you can also use Array.prototype functions as below. |
| aoqi@0 | 40 | // See also http://en.wikipedia.org/wiki/MapReduce |
| aoqi@0 | 41 | |
| aoqi@0 | 42 | var DoubleArray = Java.type("double[]"); |
| aoqi@0 | 43 | var StringArray = Java.type("java.lang.String[]"); |
| aoqi@0 | 44 | |
| aoqi@0 | 45 | var map = Array.prototype.map; |
| aoqi@0 | 46 | var filter = Array.prototype.filter; |
| aoqi@0 | 47 | var reduce = Array.prototype.reduce; |
| aoqi@0 | 48 | |
| aoqi@0 | 49 | var jarr = new StringArray(5); |
| aoqi@0 | 50 | jarr[0] = "nashorn"; |
| aoqi@0 | 51 | jarr[1] = "ecmascript"; |
| aoqi@0 | 52 | jarr[2] = "javascript"; |
| aoqi@0 | 53 | jarr[3] = "js"; |
| aoqi@0 | 54 | jarr[4] = "scheme"; |
| aoqi@0 | 55 | |
| aoqi@0 | 56 | // sum of word lengths |
| aoqi@0 | 57 | print("Sum word length:", |
| aoqi@0 | 58 | reduce.call( |
| aoqi@0 | 59 | map.call(jarr, function(x) x.length), |
| aoqi@0 | 60 | function(x, y) x + y) |
| aoqi@0 | 61 | ); |
| aoqi@0 | 62 | |
| aoqi@0 | 63 | // another array example involving numbers |
| aoqi@0 | 64 | jarr = new DoubleArray(10); |
| aoqi@0 | 65 | // make random array of numbers |
| aoqi@0 | 66 | for (var i = 0; i < jarr.length; i++) |
| aoqi@0 | 67 | jarr[i] = Math.random(); |
| aoqi@0 | 68 | |
| aoqi@0 | 69 | var forEach = Array.prototype.forEach; |
| aoqi@0 | 70 | // print numbers in the array |
| aoqi@0 | 71 | forEach.call(jarr, function(x) print(x)); |
| aoqi@0 | 72 | |
| aoqi@0 | 73 | // print sum of squares of the random numbers |
| aoqi@0 | 74 | print("Square sum:", |
| aoqi@0 | 75 | reduce.call( |
| aoqi@0 | 76 | map.call(jarr, function(x) x*x), |
| aoqi@0 | 77 | function(x, y) x + y) |
| aoqi@0 | 78 | ); |
