82 lines
2.0 KiB
JavaScript
82 lines
2.0 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 isString = require( '@stdlib/assert/is-string' ).isPrimitive;
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// VARIABLES //
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var RE_CHARS = /[-\/\\^$*+?.()|[\]{}]/g; // eslint-disable-line no-useless-escape
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// MAIN //
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/**
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* Escapes a regular expression string.
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*
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* @param {string} str - regular expression string
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* @throws {TypeError} first argument must be a string primitive
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* @returns {string} escaped string
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*
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* @example
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* var str = rescape( '[A-Z]*' );
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* // returns '\\[A\\-Z\\]\\*'
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*/
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function rescape( str ) {
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var len;
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var s;
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var i;
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if ( !isString( str ) ) {
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throw new TypeError( 'invalid argument. Must provide a regular expression string. Value: `' + str + '`.' );
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}
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// Check if the string starts with a forward slash...
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if ( str[ 0 ] === '/' ) {
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// Find the last forward slash...
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len = str.length;
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for ( i = len-1; i >= 0; i-- ) {
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if ( str[ i ] === '/' ) {
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break;
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}
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}
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}
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// If we searched the string to no avail or if the first letter is not `/`, assume that the string is not of the form `/[...]/[guimy]`:
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if ( i === void 0 || i <= 0 ) {
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return str.replace( RE_CHARS, '\\$&' );
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}
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// We need to de-construct the string...
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s = str.substring( 1, i );
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// Only escape the characters between the `/`:
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s = s.replace( RE_CHARS, '\\$&' );
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// Reassemble:
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str = str[ 0 ] + s + str.substring( i );
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return str;
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}
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// EXPORTS //
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module.exports = rescape;
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