mute-structs
Version:
NodeJS module providing an implementation of the LogootSplit CRDT algorithm
63 lines (59 loc) • 2.65 kB
JavaScript
/*
This file is part of MUTE-structs.
Copyright (C) 2017 Matthieu Nicolas, Victorien Elvinger
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/**
* Insert a string at a specific position in an existing string.
* @param {string} aOriginal - the string in which to insert the new content.
* @param {number} index - the position where to perform the insertion.
* @param {string} string - the string to be inserted.
* @return {string} the resulting string aOriginal[0:index]+string+aOriginal[index+1:aOriginal.length-1].
*/
function insert(aOriginal, index, str) {
console.assert(Number.isSafeInteger(index), "index ∈ safe integer");
var positiveIndex = Math.max(0, index);
return aOriginal.slice(0, positiveIndex) +
str +
aOriginal.slice(positiveIndex);
}
/**
* Remove a range of characters from a string.
* @param {string} aOriginal - the string in which to insert the new content.
* @param {number} begin - the beginning index of the range to be removed.
* @param {number} end - the end index of the range to be removed.
* @return {string} the resulting string aOriginal[0:begin]+aOriginal[end:aOriginal.length-1].
*/
function del(aOriginal, begin, end) {
console.assert(Number.isSafeInteger(begin), "begin ∈ safe integer");
console.assert(Number.isSafeInteger(end), "end ∈ safe integer");
return aOriginal.slice(0, begin) +
aOriginal.slice(end + 1);
}
/**
* Compute the number of disjoint-occurence of a string within a string.
* @param {string} string - the string in which to count occurences.
* @param {string} substring - the substring to look for.
* @return {number} the occurence count.
*/
function occurrences(str, substring) {
var result = 0;
var substringLength = substring.length;
var pos = str.indexOf(substring);
while (pos !== -1) {
result++;
pos = str.indexOf(substring, pos + substringLength);
}
return result;
}
export { insert, del, occurrences };
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