91 lines
2.1 KiB
JavaScript
91 lines
2.1 KiB
JavaScript
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/**
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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 isFunction = require( '@stdlib/assert/is-function' );
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// MAIN //
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/**
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* Returns a function of smaller arity by partially applying arguments from the right.
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*
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* @param {Function} fcn - function to partially apply
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* @param {...*} [args] - arguments to partially apply
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* @throws {TypeError} first argument must be a function
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* @returns {Function} partially applied function
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*
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* @example
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* function say( text, name ) {
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* return text + ', ' + name + '.';
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* }
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*
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* var toGrace = papplyRight( say, 'Grace Hopper' );
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*
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* var str = toGrace( 'Hello' );
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* // returns 'Hello, Grace Hopper.'
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*
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* str = toGrace( 'Thank you' );
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* // returns 'Thank you, Grace Hopper.'
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*/
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function papplyRight( fcn ) {
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var pargs;
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var len;
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var i;
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if ( !isFunction( fcn ) ) {
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throw new TypeError( 'invalid argument. First argument must be a function. Value: `' + fcn + '`.' );
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}
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len = arguments.length - 1;
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pargs = new Array( len );
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for ( i = 1; i < arguments.length; i++ ) {
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pargs[ i-1 ] = arguments[ i ];
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}
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return pappliedRight;
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/**
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* Partially applied function.
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*
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* @private
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* @param {...*} [args] - function arguments
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* @returns {*} partially applied function result
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*/
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function pappliedRight() {
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var nargs;
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var args;
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var j;
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nargs = arguments.length;
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args = new Array( len+nargs );
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for ( j = 0; j < args.length; j++ ) {
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if ( j >= nargs ) {
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args[ j ] = pargs[ j-nargs ];
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} else {
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args[ j ] = arguments[ j ];
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}
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}
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return fcn.apply( null, args );
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}
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}
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// EXPORTS //
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module.exports = papplyRight;
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