/*--------------------------------------------------------------------------------------------- * Copyright (c) Microsoft Corporation. All rights reserved. * Licensed under the MIT License. See License.txt in the project root for license information. *--------------------------------------------------------------------------------------------*/ 'use strict'; export function startsWith(haystack, needle) { if (haystack.length < needle.length) { return false; } for (let i = 0; i < needle.length; i++) { if (haystack[i] !== needle[i]) { return false; } } return true; } /** * Determines if haystack ends with needle. */ export function endsWith(haystack, needle) { let diff = haystack.length - needle.length; if (diff > 0) { return haystack.lastIndexOf(needle) === diff; } else if (diff === 0) { return haystack === needle; } else { return false; } } /** * Computes the difference score for two strings. More similar strings have a higher score. * We use largest common subsequence dynamic programming approach but penalize in the end for length differences. * Strings that have a large length difference will get a bad default score 0. * Complexity - both time and space O(first.length * second.length) * Dynamic programming LCS computation http://en.wikipedia.org/wiki/Longest_common_subsequence_problem * * @param first a string * @param second a string */ export function difference(first, second, maxLenDelta = 4) { let lengthDifference = Math.abs(first.length - second.length); // We only compute score if length of the currentWord and length of entry.name are similar. if (lengthDifference > maxLenDelta) { return 0; } // Initialize LCS (largest common subsequence) matrix. let LCS = []; let zeroArray = []; let i, j; for (i = 0; i < second.length + 1; ++i) { zeroArray.push(0); } for (i = 0; i < first.length + 1; ++i) { LCS.push(zeroArray); } for (i = 1; i < first.length + 1; ++i) { for (j = 1; j < second.length + 1; ++j) { if (first[i - 1] === second[j - 1]) { LCS[i][j] = LCS[i - 1][j - 1] + 1; } else { LCS[i][j] = Math.max(LCS[i - 1][j], LCS[i][j - 1]); } } } return LCS[first.length][second.length] - Math.sqrt(lengthDifference); } /** * Limit of string length. */ export function getLimitedString(str, ellipsis = true) { if (!str) { return ''; } if (str.length < 140) { return str; } return str.slice(0, 140) + (ellipsis ? '\u2026' : ''); } /** * Limit of string length. */ export function trim(str, regexp) { const m = regexp.exec(str); if (m && m[0].length) { return str.substr(0, str.length - m[0].length); } return str; } export function repeat(value, count) { let s = ''; while (count > 0) { if ((count & 1) === 1) { s += value; } value += value; count = count >>> 1; } return s; }