232 lines
5.8 KiB
JavaScript
232 lines
5.8 KiB
JavaScript
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/*
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Copyright (c) 2014 Ken Koch
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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/**
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* The basis of the TRIE structure.
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**/
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function Trie(caseSensitive) {
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this.dictionary = {};
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this.$ = false;
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if(typeof caseSensitive === "undefined") {
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caseSensitive = true;
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}
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this.cs = caseSensitive;
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}
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/**
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* Add a single string to the TRIE, returns true if the word was already in the
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* trie.
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**/
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Trie.prototype.addString = function(string) {
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if(this.cs === false) {
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string = string.toLowerCase();
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}
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// If the string has only one letter, mark this as a word.
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if(string.length === 0) {
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var wasWord = this.$;
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this.$ = true;
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return wasWord;
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}
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// Make sure theres a Trie node in our dictionary
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var next = this.dictionary[string[0]];
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if(!next) {
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this.dictionary[string[0]] = new Trie(this.cs);
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next = this.dictionary[string[0]];
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}
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// Continue adding the string
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return next.addString(string.substring(1));
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};
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/**
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* Add multiple strings to the TRIE
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**/
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Trie.prototype.addStrings = function(list) {
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for(var i in list) {
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this.addString(list[i]);
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}
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};
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/**
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* A function to search the TRIE and return an array of
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* words which have same prefix <prefix>
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* for example if we had the following words in our database:
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* a, ab, bc, cd, abc, abd
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* and we search the string: a
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* we will get :
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* [a, ab, abc, abd]
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**/
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Trie.prototype.keysWithPrefix = function(prefix) {
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if(this.caseSensitive === false) {
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prefix = prefix.toLowerCase();
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}
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function isEmpty (object) {
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for (var key in object) if (object.hasOwnProperty(key)) return false;
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return true;
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}
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function get (node, word) {
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if(!node) return null;
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if(word.length == 0) return node;
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return get(node.dictionary[word[0]], word.substring(1));
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}
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function recurse ( node, stringAgg, resultsAgg) {
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if (!node) return;
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// Check if this is a word
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if (node.$) {
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resultsAgg.push(stringAgg);
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}
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if (isEmpty(node.dictionary)) {
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return ;
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}
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for (var c in node.dictionary) {
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recurse (node.dictionary[c],stringAgg + c, resultsAgg);
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}
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}
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var results = [];
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recurse (get(this, prefix), prefix, results);
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return results;
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};
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/**
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* A function to search the given string and return true if it lands
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* on on a word. Essentially testing if the word exists in the database.
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**/
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Trie.prototype.contains = function(string) {
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if(this.cs === false) {
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string = string.toLowerCase();
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}
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if(string.length === 0) {
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return this.$;
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}
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// Otherwise, we need to continue searching
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var firstLetter = string[0];
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var next = this.dictionary[firstLetter];
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// If we don't have a node, this isn't a word
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if(!next) {
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return false;
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}
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// Otherwise continue the search at the next node
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return next.contains(string.substring(1));
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}
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/**
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* A function to search the TRIE and return an array of words which were encountered along the way.
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* This will only return words with full prefix matches.
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* for example if we had the following words in our database:
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* a, ab, bc, cd, abc
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* and we searched the string: abcd
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* we would get only:
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* [a, ab, abc]
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**/
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Trie.prototype.findMatchesOnPath = function(search) {
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if(this.cs === false) {
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search = search.toLowerCase();
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}
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function recurse(node, search, stringAgg, resultsAgg) {
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// Check if this is a word.
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if(node.$) {
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resultsAgg.push(stringAgg);
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}
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// Check if the have completed the seearch
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if(search.length === 0) {
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return resultsAgg;
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}
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// Otherwise, continue searching
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var next = node.dictionary[search[0]];
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if(!next) {
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return resultsAgg;
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}
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return recurse(next, search.substring(1), stringAgg + search[0], resultsAgg);
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};
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return recurse(this, search, "", []);
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};
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/**
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* Returns the longest match and the remaining part that could not be matched.
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* inspired by [NLTK containers.trie.find_prefix](http://nltk.googlecode.com/svn-/trunk/doc/api/nltk.containers.Trie-class.html).
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**/
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Trie.prototype.findPrefix = function(search) {
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if(this.cs === false) {
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search = search.toLowerCase();
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}
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function recurse(node, search, stringAgg, lastWord) {
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// Check if this is a word
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if(node.$) {
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lastWord = stringAgg;
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}
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// Check if we have no more to search
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if(search.length === 0) {
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return [lastWord, search];
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}
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// Continue searching
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var next = node.dictionary[search[0]];
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if(!next) {
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return [lastWord, search];
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}
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return recurse(next, search.substring(1), stringAgg + search[0], lastWord);
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};
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return recurse(this, search, "", null);
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};
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/**
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* Computes the number of actual nodes from this node to the end.
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* Note: This involves traversing the entire structure and may not be
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* good for frequent use.
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**/
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Trie.prototype.getSize = function() {
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var total = 1;
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for(var c in this.dictionary) {
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total += this.dictionary[c].getSize();
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}
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return total;
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};
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/**
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* EXPORT THE TRIE
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**/
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module.exports = Trie;
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