time-to-botec

Benchmark sampling in different programming languages
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left_pad.js (2790B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2018 The Stdlib Authors.
      5 *
      6 * Licensed under the Apache License, Version 2.0 (the "License");
      7 * you may not use this file except in compliance with the License.
      8 * You may obtain a copy of the License at
      9 *
     10 *    http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing, software
     13 * distributed under the License is distributed on an "AS IS" BASIS,
     14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15 * See the License for the specific language governing permissions and
     16 * limitations under the License.
     17 */
     18 
     19 'use strict';
     20 
     21 // MODULES //
     22 
     23 var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
     24 var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
     25 var repeat = require( './../../repeat' );
     26 var ceil = require( '@stdlib/math/base/special/ceil' );
     27 var format = require( './../../format' );
     28 var FLOAT64_MAX_SAFE_INTEGER = require( '@stdlib/constants/float64/max-safe-integer' );
     29 
     30 
     31 // MAIN //
     32 
     33 /**
     34 * Left pads a string such that the padded string has a length of at least `len`.
     35 *
     36 * @param {string} str - string to pad
     37 * @param {NonNegativeInteger} len - minimum string length
     38 * @param {string} [pad=' '] - string used to pad
     39 * @throws {TypeError} first argument must be a string
     40 * @throws {TypeError} second argument must be a nonnegative integer
     41 * @throws {TypeError} third argument must be a string
     42 * @throws {RangeError} padding must have a length greater than `0`
     43 * @returns {string} padded string
     44 *
     45 * @example
     46 * var str = lpad( 'a', 5 );
     47 * // returns '    a'
     48 *
     49 * @example
     50 * var str = lpad( 'beep', 10, 'b' );
     51 * // returns 'bbbbbbbeep'
     52 *
     53 * @example
     54 * var str = lpad( 'boop', 12, 'beep' );
     55 * // returns 'beepbeepboop'
     56 */
     57 function lpad( str, len, pad ) {
     58 	var n;
     59 	var p;
     60 	if ( !isString( str ) ) {
     61 		throw new TypeError( format( 'invalid argument. First argument must be a string. Value: `%s`.', str ) );
     62 	}
     63 	if ( !isNonNegativeInteger( len ) ) {
     64 		throw new TypeError( format( 'invalid argument. Second argument must be a nonnegative integer. Value: `%s`.', len ) );
     65 	}
     66 	if ( arguments.length > 2 ) {
     67 		p = pad;
     68 		if ( !isString( p ) ) {
     69 			throw new TypeError( format( 'invalid argument. Third argument must be a string. Value: `%s`.', p ) );
     70 		}
     71 		if ( p.length === 0 ) {
     72 			throw new RangeError( 'invalid argument. Third argument must not be an empty string.' );
     73 		}
     74 	} else {
     75 		p = ' ';
     76 	}
     77 	if ( len > FLOAT64_MAX_SAFE_INTEGER ) {
     78 		throw new RangeError( format( 'invalid argument. Output string length exceeds maximum allowed string length. Value: `%u`.', len ) );
     79 	}
     80 	n = ( len - str.length ) / p.length;
     81 	if ( n <= 0 ) {
     82 		return str;
     83 	}
     84 	n = ceil( n );
     85 	return repeat( p, n ) + str;
     86 }
     87 
     88 
     89 // EXPORTS //
     90 
     91 module.exports = lpad;