113 lines
3.2 KiB
JavaScript
113 lines
3.2 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 isCollection = require( '@stdlib/assert/is-collection' );
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var validate = require( './validate.js' );
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var returnValues = require( './return_values.js' );
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var returnIndices = require( './return_indices.js' );
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var returnPairs = require( './return_pairs.js' );
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// MAIN //
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/**
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* Groups values as arrays associated with distinct keys.
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*
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* @param {Collection} collection - collection to group
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* @param {Options} [options] - function options
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* @param {string} [options.returns="values"] - if `values`, values are returned; if `indices`, indices are returned; if `*`, both indices and values are returned
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* @param {Collection} groups - collection defining which group an element in the input collection belongs to
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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} last argument must be a collection
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* @throws {TypeError} must provide valid options
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* @throws {RangeError} first and last arguments must be the same length
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* @returns {Object} group results
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*
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* @example
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* var arr = [ 'beep', 'boop', 'foo', 'bar' ];
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* var groups = [ 'b', 'b', 'f', 'b' ];
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*
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* var out = group( arr, groups );
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* // returns { 'b': [ 'beep', 'boop', 'bar' ], 'f': [ 'foo' ] }
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*
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* @example
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* var arr = [ 'beep', 'boop', 'foo', 'bar' ];
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* var groups = [ 'b', 'b', 'f', 'b' ];
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*
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* var opts = {
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* 'returns': 'indices'
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* };
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*
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* var out = group( arr, opts, groups );
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* // returns { 'b': [ 0, 1, 3 ], 'f': [ 2 ] }
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*
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* @example
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* var arr = [ 'beep', 'boop', 'foo', 'bar' ];
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* var groups = [ 'b', 'b', 'f', 'b' ];
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*
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* var opts = {
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* 'returns': '*'
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* };
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*
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* var out = group( arr, opts, groups );
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* // returns { 'b': [ [ 0, 'beep' ], [ 1, 'boop' ], [ 3, 'bar' ] ], 'f': [ [ 2, 'foo' ] ] }
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*/
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function group( collection, options, groups ) {
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var opts;
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var err;
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var g;
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if ( !isCollection( collection ) ) {
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throw new TypeError( 'invalid argument. First argument must be a collection. Value: `'+collection+'`.' );
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}
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opts = {
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'returns': 'values'
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};
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if ( arguments.length === 2 ) {
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g = options;
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} else {
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err = validate( opts, options );
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if ( err ) {
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throw err;
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}
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g = groups;
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}
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if ( !isCollection( g ) ) {
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throw new TypeError( 'invalid argument. Last argument must be a collection. Value: `'+g+'`.' );
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}
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if ( collection.length !== g.length ) {
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throw new RangeError( 'invalid arguments. First and last arguments must be the same length.' );
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}
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if ( opts.returns === 'values' ) {
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return returnValues( collection, g );
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}
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if ( opts.returns === 'indices' ) {
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return returnIndices( collection, g );
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}
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return returnPairs( collection, g );
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}
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// EXPORTS //
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module.exports = group;
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