76 lines
2.9 KiB
JavaScript
76 lines
2.9 KiB
JavaScript
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"use strict";
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// Licensed to Cloudera, Inc. under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. Cloudera, Inc. licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. 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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Object.defineProperty(exports, "__esModule", { value: true });
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/**
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* Calculates the Optimal String Alignment distance between two strings. Returns 0 when the strings are equal and the
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* distance when not, distances is less than or equal to the length of the longest string.
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*
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* @param strA
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* @param strB
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* @param [ignoreCase]
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* @returns {number} The similarity
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*/
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const stringDistance = function (strA, strB, ignoreCase) {
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if (ignoreCase) {
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strA = strA.toLowerCase();
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strB = strB.toLowerCase();
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}
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// TODO: Consider other algorithms for performance
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const strALength = strA.length;
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const strBLength = strB.length;
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if (strALength === 0) {
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return strBLength;
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}
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if (strBLength === 0) {
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return strALength;
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}
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const distances = new Array(strALength);
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let cost, deletion, insertion, substitution, transposition;
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for (let i = 0; i <= strALength; i++) {
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distances[i] = new Array(strBLength);
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distances[i][0] = i;
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for (let j = 1; j <= strBLength; j++) {
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if (!i) {
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distances[0][j] = j;
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}
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else {
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cost = strA[i - 1] === strB[j - 1] ? 0 : 1;
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deletion = distances[i - 1][j] + 1;
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insertion = distances[i][j - 1] + 1;
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substitution = distances[i - 1][j - 1] + cost;
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if (deletion <= insertion && deletion <= substitution) {
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distances[i][j] = deletion;
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}
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else if (insertion <= deletion && insertion <= substitution) {
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distances[i][j] = insertion;
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}
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else {
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distances[i][j] = substitution;
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}
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if (i > 1 && j > 1 && strA[i] === strB[j - 1] && strA[i - 1] === strB[j]) {
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transposition = distances[i - 2][j - 2] + cost;
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if (transposition < distances[i][j]) {
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distances[i][j] = transposition;
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}
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}
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}
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}
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}
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return distances[strALength][strBLength];
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};
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exports.default = stringDistance;
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