1 | ;
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2 |
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3 | Object.defineProperty(exports, "__esModule", {
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4 | value: true
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5 | });
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6 | exports.default = transform;
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7 |
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8 | var _eachOf = require('./eachOf.js');
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9 |
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10 | var _eachOf2 = _interopRequireDefault(_eachOf);
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11 |
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12 | var _once = require('./internal/once.js');
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13 |
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14 | var _once2 = _interopRequireDefault(_once);
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15 |
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16 | var _wrapAsync = require('./internal/wrapAsync.js');
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17 |
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18 | var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
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19 |
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20 | var _promiseCallback = require('./internal/promiseCallback.js');
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21 |
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22 | function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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23 |
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24 | /**
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25 | * A relative of `reduce`. Takes an Object or Array, and iterates over each
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26 | * element in parallel, each step potentially mutating an `accumulator` value.
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27 | * The type of the accumulator defaults to the type of collection passed in.
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28 | *
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29 | * @name transform
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30 | * @static
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31 | * @memberOf module:Collections
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32 | * @method
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33 | * @category Collection
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34 | * @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
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35 | * @param {*} [accumulator] - The initial state of the transform. If omitted,
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36 | * it will default to an empty Object or Array, depending on the type of `coll`
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37 | * @param {AsyncFunction} iteratee - A function applied to each item in the
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38 | * collection that potentially modifies the accumulator.
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39 | * Invoked with (accumulator, item, key, callback).
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40 | * @param {Function} [callback] - A callback which is called after all the
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41 | * `iteratee` functions have finished. Result is the transformed accumulator.
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42 | * Invoked with (err, result).
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43 | * @returns {Promise} a promise, if no callback provided
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44 | * @example
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45 | *
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46 | * // file1.txt is a file that is 1000 bytes in size
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47 | * // file2.txt is a file that is 2000 bytes in size
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48 | * // file3.txt is a file that is 3000 bytes in size
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49 | *
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50 | * // helper function that returns human-readable size format from bytes
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51 | * function formatBytes(bytes, decimals = 2) {
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52 | * // implementation not included for brevity
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53 | * return humanReadbleFilesize;
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54 | * }
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55 | *
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56 | * const fileList = ['file1.txt','file2.txt','file3.txt'];
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57 | *
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58 | * // asynchronous function that returns the file size, transformed to human-readable format
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59 | * // e.g. 1024 bytes = 1KB, 1234 bytes = 1.21 KB, 1048576 bytes = 1MB, etc.
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60 | * function transformFileSize(acc, value, key, callback) {
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61 | * fs.stat(value, function(err, stat) {
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62 | * if (err) {
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63 | * return callback(err);
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64 | * }
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65 | * acc[key] = formatBytes(stat.size);
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66 | * callback(null);
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67 | * });
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68 | * }
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69 | *
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70 | * // Using callbacks
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71 | * async.transform(fileList, transformFileSize, function(err, result) {
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72 | * if(err) {
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73 | * console.log(err);
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74 | * } else {
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75 | * console.log(result);
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76 | * // [ '1000 Bytes', '1.95 KB', '2.93 KB' ]
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77 | * }
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78 | * });
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79 | *
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80 | * // Using Promises
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81 | * async.transform(fileList, transformFileSize)
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82 | * .then(result => {
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83 | * console.log(result);
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84 | * // [ '1000 Bytes', '1.95 KB', '2.93 KB' ]
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85 | * }).catch(err => {
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86 | * console.log(err);
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87 | * });
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88 | *
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89 | * // Using async/await
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90 | * (async () => {
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91 | * try {
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92 | * let result = await async.transform(fileList, transformFileSize);
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93 | * console.log(result);
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94 | * // [ '1000 Bytes', '1.95 KB', '2.93 KB' ]
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95 | * }
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96 | * catch (err) {
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97 | * console.log(err);
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98 | * }
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99 | * })();
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100 | *
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101 | * @example
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102 | *
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103 | * // file1.txt is a file that is 1000 bytes in size
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104 | * // file2.txt is a file that is 2000 bytes in size
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105 | * // file3.txt is a file that is 3000 bytes in size
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106 | *
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107 | * // helper function that returns human-readable size format from bytes
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108 | * function formatBytes(bytes, decimals = 2) {
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109 | * // implementation not included for brevity
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110 | * return humanReadbleFilesize;
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111 | * }
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112 | *
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113 | * const fileMap = { f1: 'file1.txt', f2: 'file2.txt', f3: 'file3.txt' };
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114 | *
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115 | * // asynchronous function that returns the file size, transformed to human-readable format
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116 | * // e.g. 1024 bytes = 1KB, 1234 bytes = 1.21 KB, 1048576 bytes = 1MB, etc.
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117 | * function transformFileSize(acc, value, key, callback) {
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118 | * fs.stat(value, function(err, stat) {
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119 | * if (err) {
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120 | * return callback(err);
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121 | * }
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122 | * acc[key] = formatBytes(stat.size);
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123 | * callback(null);
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124 | * });
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125 | * }
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126 | *
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127 | * // Using callbacks
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128 | * async.transform(fileMap, transformFileSize, function(err, result) {
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129 | * if(err) {
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130 | * console.log(err);
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131 | * } else {
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132 | * console.log(result);
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133 | * // { f1: '1000 Bytes', f2: '1.95 KB', f3: '2.93 KB' }
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134 | * }
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135 | * });
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136 | *
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137 | * // Using Promises
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138 | * async.transform(fileMap, transformFileSize)
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139 | * .then(result => {
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140 | * console.log(result);
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141 | * // { f1: '1000 Bytes', f2: '1.95 KB', f3: '2.93 KB' }
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142 | * }).catch(err => {
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143 | * console.log(err);
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144 | * });
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145 | *
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146 | * // Using async/await
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147 | * async () => {
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148 | * try {
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149 | * let result = await async.transform(fileMap, transformFileSize);
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150 | * console.log(result);
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151 | * // { f1: '1000 Bytes', f2: '1.95 KB', f3: '2.93 KB' }
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152 | * }
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153 | * catch (err) {
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154 | * console.log(err);
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155 | * }
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156 | * }
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157 | *
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158 | */
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159 | function transform(coll, accumulator, iteratee, callback) {
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160 | if (arguments.length <= 3 && typeof accumulator === 'function') {
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161 | callback = iteratee;
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162 | iteratee = accumulator;
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163 | accumulator = Array.isArray(coll) ? [] : {};
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164 | }
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165 | callback = (0, _once2.default)(callback || (0, _promiseCallback.promiseCallback)());
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166 | var _iteratee = (0, _wrapAsync2.default)(iteratee);
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167 |
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168 | (0, _eachOf2.default)(coll, (v, k, cb) => {
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169 | _iteratee(accumulator, v, k, cb);
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170 | }, err => callback(err, accumulator));
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171 | return callback[_promiseCallback.PROMISE_SYMBOL];
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172 | }
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173 | module.exports = exports.default; |
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