97 lines
3.1 KiB
JavaScript
97 lines
3.1 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var factory = require( './factory.js' );
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// MAIN //
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/**
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* Applies a function against an accumulator and each element in a collection and return the accumulated result.
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*
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* ## Notes
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*
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* - If a provided function calls the provided callback with a truthy error argument, the function suspends execution and immediately calls the `done` callback for subsequent error handling.
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* - This function does **not** guarantee that execution is asynchronous. To do so, wrap the `done` callback in a function which either executes at the end of the current stack (e.g., `nextTick`) or during a subsequent turn of the event loop (e.g., `setImmediate`, `setTimeout`).
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*
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*
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* @param {Collection} collection - input collection
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* @param {*} initial - initial value
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* @param {Options} [options] - function options
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* @param {*} [options.thisArg] - execution context
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* @param {PositiveInteger} [options.limit] - maximum number of pending invocations at any one time
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* @param {boolean} [options.series=true] - boolean indicating whether to wait for a previous invocation to complete before invoking a provided function for the next element in a collection
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* @param {Function} fcn - function to invoke for each element in a collection
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* @param {Callback} done - function to invoke upon completion
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* @throws {TypeError} first argument must be a collection
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* @throws {TypeError} options argument must be an object
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* @throws {TypeError} must provide valid options
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* @throws {TypeError} second-to-last argument must be a function
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* @throws {TypeError} last argument must be a function
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* @returns {void}
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*
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* @example
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* var readFile = require( '@stdlib/fs/read-file' );
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*
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* function done( error, acc ) {
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* if ( error ) {
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* throw error;
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* }
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* console.log( acc.count );
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* }
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*
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* function read( acc, file, next ) {
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* var opts = {
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* 'encoding': 'utf8'
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* };
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* readFile( file, opts, onFile );
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*
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* function onFile( error ) {
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* if ( error ) {
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* return next( null, acc );
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* }
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* acc.count += 1;
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* next( null, acc );
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* }
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* }
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*
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* var files = [
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* './beep.js',
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* './boop.js'
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* ];
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* var acc = {
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* 'count': 0
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* };
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* reduceAsync( files, acc, read, done );
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*/
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function reduceAsync( collection, initial, options, fcn, done ) {
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if ( arguments.length < 5 ) {
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return factory( options )( collection, initial, fcn );
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}
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factory( options, fcn )( collection, initial, done );
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}
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// EXPORTS //
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module.exports = reduceAsync;
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