Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 | 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x | /**
* @license Apache-2.0
*
* Copyright (c) 2024 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// VARIABLES //
var RE_UTF16_LOW_SURROGATE = /[\uDC00-\uDFFF]/; // TODO: replace with stdlib pkg
var RE_UTF16_HIGH_SURROGATE = /[\uD800-\uDBFF]/; // TODO: replace with stdlib pkg
// MAIN //
/**
* Invokes a function for each Unicode code point in a string, iterating from right to left.
*
* @param {string} str - input string
* @param {Function} clbk - function to invoke
* @param {*} [thisArg] - execution context
* @returns {string} input string
*
* @example
* function log( value, index ) {
* console.log( '%d: %s', index, value );
* }
*
* forEachRight( 'Hello', log );
*/
function forEachRight( str, clbk, thisArg ) {
var len;
var ch1;
var ch2;
var idx;
var ch;
var i;
len = str.length;
// Process the string one Unicode code unit at a time and handle UTF-16 surrogate pairs as a single Unicode code point...
for ( i = len-1; i >= 0; i-- ) {
ch1 = str[ i ];
idx = i;
ch = ch1;
// Check for a UTF-16 surrogate pair...
if ( i > 0 && RE_UTF16_LOW_SURROGATE.test( ch1 ) ) {
// Check whether the low surrogate is preceded by a high surrogate...
ch2 = str[ i-1 ];
if ( RE_UTF16_HIGH_SURROGATE.test( ch2 ) ) {
// We found a surrogate pair:
ch = ch2 + ch1;
i -= 1; // decrement the index to process the next code unit
}
}
// Note: `ch` may be a lone surrogate (e.g., a high surrogate without a following low surrogate or a low surrogate at the start of the input string).
// Invoke the callback with the code point:
clbk.call( thisArg, ch, idx, str );
}
return str;
}
// EXPORTS //
module.exports = forEachRight;
|