| 1 | define(["dojo/_base/lang", "dojo/_base/array", "dojo/_base/kernel", "./lambda"], |
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| 2 | function(lang, arr, kernel, df){ |
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| 3 | |
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| 4 | // This module adds high-level functions and related constructs: |
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| 5 | // - "fold" family of functions |
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| 6 | |
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| 7 | // Notes: |
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| 8 | // - missing high-level functions are provided with the compatible API: |
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| 9 | // foldl, foldl1, foldr, foldr1 |
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| 10 | // - missing JS standard functions are provided with the compatible API: |
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| 11 | // reduce, reduceRight |
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| 12 | // - the fold's counterpart: unfold |
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| 13 | |
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| 14 | // Defined methods: |
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| 15 | // - take any valid lambda argument as the functional argument |
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| 16 | // - operate on dense arrays |
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| 17 | // - take a string as the array argument |
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| 18 | // - take an iterator objects as the array argument (only foldl, foldl1, and reduce) |
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| 19 | |
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| 20 | var empty = {}; |
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| 21 | |
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| 22 | lang.mixin(df, { |
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| 23 | // classic reduce-class functions |
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| 24 | foldl: function(/*Array|String|Object*/ a, /*Function*/ f, /*Object*/ z, /*Object?*/ o){ |
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| 25 | // summary: |
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| 26 | // repeatedly applies a binary function to an array from left |
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| 27 | // to right using a seed value as a starting point; returns the final |
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| 28 | // value. |
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| 29 | if(typeof a == "string"){ a = a.split(""); } |
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| 30 | o = o || kernel.global; f = df.lambda(f); |
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| 31 | var i, n; |
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| 32 | if(lang.isArray(a)){ |
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| 33 | // array |
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| 34 | for(i = 0, n = a.length; i < n; z = f.call(o, z, a[i], i, a), ++i); |
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| 35 | }else if(typeof a.hasNext == "function" && typeof a.next == "function"){ |
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| 36 | // iterator |
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| 37 | for(i = 0; a.hasNext(); z = f.call(o, z, a.next(), i++, a)); |
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| 38 | }else{ |
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| 39 | // object/dictionary |
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| 40 | for(i in a){ |
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| 41 | if(!(i in empty)){ |
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| 42 | z = f.call(o, z, a[i], i, a); |
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| 43 | } |
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| 44 | } |
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| 45 | } |
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| 46 | return z; // Object |
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| 47 | }, |
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| 48 | foldl1: function(/*Array|String|Object*/ a, /*Function|String|Array*/ f, /*Object?*/ o){ |
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| 49 | // summary: |
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| 50 | // repeatedly applies a binary function to an array from left |
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| 51 | // to right; returns the final value. |
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| 52 | if(typeof a == "string"){ a = a.split(""); } |
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| 53 | o = o || kernel.global; f = df.lambda(f); |
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| 54 | var z, i, n; |
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| 55 | if(lang.isArray(a)){ |
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| 56 | // array |
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| 57 | z = a[0]; |
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| 58 | for(i = 1, n = a.length; i < n; z = f.call(o, z, a[i], i, a), ++i); |
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| 59 | }else if(typeof a.hasNext == "function" && typeof a.next == "function"){ |
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| 60 | // iterator |
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| 61 | if(a.hasNext()){ |
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| 62 | z = a.next(); |
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| 63 | for(i = 1; a.hasNext(); z = f.call(o, z, a.next(), i++, a)); |
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| 64 | } |
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| 65 | }else{ |
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| 66 | // object/dictionary |
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| 67 | var first = true; |
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| 68 | for(i in a){ |
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| 69 | if(!(i in empty)){ |
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| 70 | if(first){ |
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| 71 | z = a[i]; |
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| 72 | first = false; |
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| 73 | }else{ |
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| 74 | z = f.call(o, z, a[i], i, a); |
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| 75 | } |
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| 76 | } |
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| 77 | } |
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| 78 | } |
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| 79 | return z; // Object |
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| 80 | }, |
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| 81 | foldr: function(/*Array|String*/ a, /*Function|String|Array*/ f, /*Object*/ z, /*Object?*/ o){ |
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| 82 | // summary: |
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| 83 | // repeatedly applies a binary function to an array from right |
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| 84 | // to left using a seed value as a starting point; returns the final |
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| 85 | // value. |
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| 86 | if(typeof a == "string"){ a = a.split(""); } |
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| 87 | o = o || kernel.global; f = df.lambda(f); |
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| 88 | for(var i = a.length; i > 0; --i, z = f.call(o, z, a[i], i, a)); |
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| 89 | return z; // Object |
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| 90 | }, |
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| 91 | foldr1: function(/*Array|String*/ a, /*Function|String|Array*/ f, /*Object?*/ o){ |
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| 92 | // summary: |
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| 93 | // repeatedly applies a binary function to an array from right |
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| 94 | // to left; returns the final value. |
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| 95 | if(typeof a == "string"){ a = a.split(""); } |
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| 96 | o = o || kernel.global; f = df.lambda(f); |
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| 97 | var n = a.length, z = a[n - 1], i = n - 1; |
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| 98 | for(; i > 0; --i, z = f.call(o, z, a[i], i, a)); |
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| 99 | return z; // Object |
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| 100 | }, |
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| 101 | // JS 1.8 standard array functions, which can take a lambda as a parameter. |
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| 102 | reduce: function(/*Array|String|Object*/ a, /*Function|String|Array*/ f, /*Object?*/ z){ |
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| 103 | // summary: |
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| 104 | // apply a function simultaneously against two values of the array |
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| 105 | // (from left-to-right) as to reduce it to a single value. |
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| 106 | return arguments.length < 3 ? df.foldl1(a, f) : df.foldl(a, f, z); // Object |
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| 107 | }, |
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| 108 | reduceRight: function(/*Array|String*/ a, /*Function|String|Array*/ f, /*Object?*/ z){ |
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| 109 | // summary: |
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| 110 | // apply a function simultaneously against two values of the array |
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| 111 | // (from right-to-left) as to reduce it to a single value. |
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| 112 | return arguments.length < 3 ? df.foldr1(a, f) : df.foldr(a, f, z); // Object |
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| 113 | }, |
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| 114 | // the fold's counterpart: unfold |
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| 115 | unfold: function(/*Function|String|Array*/ pr, /*Function|String|Array*/ f, |
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| 116 | /*Function|String|Array*/ g, /*Object*/ z, /*Object?*/ o){ |
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| 117 | // summary: |
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| 118 | // builds an array by unfolding a value |
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| 119 | o = o || kernel.global; f = df.lambda(f); g = df.lambda(g); pr = df.lambda(pr); |
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| 120 | var t = []; |
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| 121 | for(; !pr.call(o, z); t.push(f.call(o, z)), z = g.call(o, z)); |
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| 122 | return t; // Array |
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| 123 | } |
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| 124 | }); |
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| 125 | }); |
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