@oxog/string
Version:
Comprehensive string manipulation utilities with zero dependencies
285 lines (284 loc) • 8.75 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.levenshteinDistance = levenshteinDistance;
exports.jaroDistance = jaroDistance;
exports.cosineDistance = cosineDistance;
exports.soundex = soundex;
exports.metaphone = metaphone;
exports.boyerMooreSearch = boyerMooreSearch;
function levenshteinDistance(str1, str2) {
const matrix = [];
const len1 = str1.length;
const len2 = str2.length;
if (len1 === 0)
return len2;
if (len2 === 0)
return len1;
for (let i = 0; i <= len1; i++) {
matrix[i] = [i];
}
for (let j = 0; j <= len2; j++) {
matrix[0][j] = j;
}
for (let i = 1; i <= len1; i++) {
for (let j = 1; j <= len2; j++) {
const cost = str1[i - 1] === str2[j - 1] ? 0 : 1;
matrix[i][j] = Math.min(matrix[i - 1][j] + 1, matrix[i][j - 1] + 1, matrix[i - 1][j - 1] + cost);
}
}
return matrix[len1][len2];
}
function jaroDistance(str1, str2) {
const len1 = str1.length;
const len2 = str2.length;
if (len1 === 0 && len2 === 0)
return 1;
if (len1 === 0 || len2 === 0)
return 0;
const matchWindow = Math.floor(Math.max(len1, len2) / 2) - 1;
const str1Matches = new Array(len1).fill(false);
const str2Matches = new Array(len2).fill(false);
let matches = 0;
let transpositions = 0;
for (let i = 0; i < len1; i++) {
const start = Math.max(0, i - matchWindow);
const end = Math.min(i + matchWindow + 1, len2);
for (let j = start; j < end; j++) {
if (str2Matches[j] || str1[i] !== str2[j])
continue;
str1Matches[i] = true;
str2Matches[j] = true;
matches++;
break;
}
}
if (matches === 0)
return 0;
let k = 0;
for (let i = 0; i < len1; i++) {
if (!str1Matches[i])
continue;
while (!str2Matches[k])
k++;
if (str1[i] !== str2[k])
transpositions++;
k++;
}
return (matches / len1 + matches / len2 + (matches - transpositions / 2) / matches) / 3;
}
function cosineDistance(str1, str2) {
const vec1 = getCharacterBigrams(str1);
const vec2 = getCharacterBigrams(str2);
const intersection = new Set([...vec1].filter(x => vec2.has(x)));
const union = new Set([...vec1, ...vec2]);
if (union.size === 0)
return 1;
return intersection.size / Math.sqrt(vec1.size * vec2.size);
}
function getCharacterBigrams(str) {
const bigrams = new Set();
for (let i = 0; i < str.length - 1; i++) {
bigrams.add(str.slice(i, i + 2));
}
return bigrams;
}
function soundex(str) {
const word = str.toUpperCase();
const firstLetter = word[0] || '';
const mapping = {
'B': '1', 'F': '1', 'P': '1', 'V': '1',
'C': '2', 'G': '2', 'J': '2', 'K': '2', 'Q': '2', 'S': '2', 'X': '2', 'Z': '2',
'D': '3', 'T': '3',
'L': '4',
'M': '5', 'N': '5',
'R': '6'
};
let code = firstLetter;
for (let i = 1; i < word.length && code.length < 4; i++) {
const char = word[i];
const digit = mapping[char];
if (digit && digit !== (code[code.length - 1] || '')) {
code += digit;
}
}
return code.padEnd(4, '0').slice(0, 4);
}
function metaphone(str) {
const word = str.toUpperCase().replace(/[^A-Z]/g, '');
if (!word)
return '';
let metaphone = '';
let i = 0;
if (word.length >= 2) {
if (word.startsWith('KN') || word.startsWith('GN') || word.startsWith('PN') || word.startsWith('AE') || word.startsWith('WR')) {
i = 1;
}
}
if (word[0] === 'X') {
metaphone = 'S';
i = 1;
}
while (i < word.length && metaphone.length < 4) {
const char = word[i];
const next = word[i + 1];
const prev = word[i - 1];
switch (char) {
case 'B':
if (i === word.length - 1 && prev === 'M') {
}
else {
metaphone += 'B';
}
break;
case 'C':
if (next === 'H' || (next === 'I' && word[i + 2] === 'A')) {
metaphone += 'X';
i++;
}
else if (next === 'E' || next === 'I' || next === 'Y') {
metaphone += 'S';
}
else {
metaphone += 'K';
}
break;
case 'D':
if (next === 'G' && (word[i + 2] === 'E' || word[i + 2] === 'I' || word[i + 2] === 'Y')) {
metaphone += 'J';
i += 2;
}
else {
metaphone += 'T';
}
break;
case 'F':
metaphone += 'F';
break;
case 'G':
if (next === 'H' && i > 0) {
}
else if (next === 'N' && i === word.length - 2) {
}
else if (next === 'E' || next === 'I' || next === 'Y') {
metaphone += 'J';
}
else {
metaphone += 'K';
}
break;
case 'H':
if (i === 0 || ('AEIOU'.includes(prev || '') && 'AEIOU'.includes(next || ''))) {
metaphone += 'H';
}
break;
case 'J':
metaphone += 'J';
break;
case 'K':
if (prev !== 'C') {
metaphone += 'K';
}
break;
case 'L':
metaphone += 'L';
break;
case 'M':
metaphone += 'M';
break;
case 'N':
metaphone += 'N';
break;
case 'P':
if (next === 'H') {
metaphone += 'F';
i++;
}
else {
metaphone += 'P';
}
break;
case 'Q':
metaphone += 'K';
break;
case 'R':
metaphone += 'R';
break;
case 'S':
if (next === 'H' || (next === 'I' && (word[i + 2] === 'O' || word[i + 2] === 'A'))) {
metaphone += 'X';
if (next === 'H')
i++;
}
else {
metaphone += 'S';
}
break;
case 'T':
if (next === 'H') {
metaphone += '0';
i++;
}
else if (next === 'I' && (word[i + 2] === 'O' || word[i + 2] === 'A')) {
metaphone += 'X';
}
else {
metaphone += 'T';
}
break;
case 'V':
metaphone += 'F';
break;
case 'W':
if ('AEIOU'.includes(next || '')) {
metaphone += 'W';
}
break;
case 'X':
metaphone += 'KS';
break;
case 'Y':
if ('AEIOU'.includes(next || '')) {
metaphone += 'Y';
}
break;
case 'Z':
metaphone += 'S';
break;
}
i++;
}
return metaphone;
}
function boyerMooreSearch(text, pattern) {
var _a;
const indices = [];
const patternLength = pattern.length;
const textLength = text.length;
if (patternLength === 0 || textLength === 0 || patternLength > textLength) {
return indices;
}
const badCharTable = buildBadCharTable(pattern);
let skip = 0;
while (skip <= textLength - patternLength) {
let j = patternLength - 1;
while (j >= 0 && pattern[j] === text[skip + j]) {
j--;
}
if (j < 0) {
indices.push(skip);
skip += patternLength;
}
else {
const badCharShift = (_a = badCharTable.get(text[skip + j])) !== null && _a !== void 0 ? _a : patternLength;
skip += Math.max(1, j - badCharShift);
}
}
return indices;
}
function buildBadCharTable(pattern) {
const table = new Map();
for (let i = 0; i < pattern.length; i++) {
table.set(pattern[i], i);
}
return table;
}