hunspell-spellchecker
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Parse and use Hunspell dictionaries in Javascript
312 lines (239 loc) • 8.56 kB
JavaScript
var Dictionary = require("./dictionary");
var Spellchecker = function(dictionary) {
this.dict = null;
if (dictionary) this.use(dictionary);
};
// Use a parsed dictionary
Spellchecker.prototype.use = function(dictionary) {
this.dict = new Dictionary(dictionary);
};
// Parse a dicitonary
Spellchecker.prototype.parse = function(dictionary) {
var dict = new Dictionary();
dict.parse(dictionary);
this.use(dict);
return dict.toJSON();
};
/**
* Checks whether a word or a capitalization variant exists in the current dictionary.
* The word is trimmed and several variations of capitalizations are checked.
* If you want to check a word without any changes made to it, call checkExact()
*
* @see http://blog.stevenlevithan.com/archives/faster-trim-javascript re:trimming function
*
* @param {String} aWord The word to check.
* @returns {Boolean}
*/
Spellchecker.prototype.check = function (aWord) {
// Remove leading and trailing whitespace
var trimmedWord = aWord.replace(/^\s\s*/, '').replace(/\s\s*$/, '');
if (this.checkExact(trimmedWord)) {
return true;
}
// The exact word is not in the dictionary.
if (trimmedWord.toUpperCase() === trimmedWord) {
// The word was supplied in all uppercase.
// Check for a capitalized form of the word.
var capitalizedWord = trimmedWord[0] + trimmedWord.substring(1).toLowerCase();
if (this.hasFlag(capitalizedWord, "KEEPCASE")) {
// Capitalization variants are not allowed for this word.
return false;
}
if (this.checkExact(capitalizedWord)) {
return true;
}
}
var lowercaseWord = trimmedWord.toLowerCase();
if (lowercaseWord !== trimmedWord) {
if (this.hasFlag(lowercaseWord, "KEEPCASE")) {
// Capitalization variants are not allowed for this word.
return false;
}
// Check for a lowercase form
if (this.checkExact(lowercaseWord)) {
return true;
}
}
return false;
};
/**
* Checks whether a word exists in the current dictionary.
*
* @param {String} word The word to check.
* @returns {Boolean}
*/
Spellchecker.prototype.checkExact = function (word) {
var ruleCodes = this.dict.dictionaryTable[word];
if (typeof ruleCodes === 'undefined') {
// Check if this might be a compound word.
if ("COMPOUNDMIN" in this.dict.flags && word.length >= this.dict.flags.COMPOUNDMIN) {
for (var i = 0, _len = this.dict.compoundRules.length; i < _len; i++) {
if (word.match(this.dict.compoundRules[i])) {
return true;
}
}
}
return false;
}
else {
for (var i = 0, _len = ruleCodes.length; i < _len; i++) {
if (!this.hasFlag(word, "ONLYINCOMPOUND", ruleCodes[i])) {
return true;
}
}
return false;
}
};
/**
* Looks up whether a given word is flagged with a given flag.
*
* @param {String} word The word in question.
* @param {String} flag The flag in question.
* @return {Boolean}
*/
Spellchecker.prototype.hasFlag = function (word, flag, wordFlags) {
if (flag in this.dict.flags) {
if (typeof wordFlags === 'undefined') {
var wordFlags = Array.prototype.concat.apply([], this.dict.dictionaryTable[word]);
}
if (wordFlags && wordFlags.indexOf(this.dict.flags[flag]) !== -1) {
return true;
}
}
return false;
};
/**
* Returns a list of suggestions for a misspelled word.
*
* @see http://www.norvig.com/spell-correct.html for the basis of this suggestor.
* This suggestor is primitive, but it works.
*
* @param {String} word The misspelling.
* @param {Number} [limit=5] The maximum number of suggestions to return.
* @returns {String[]} The array of suggestions.
*/
Spellchecker.prototype.suggest = function (word, limit) {
if (!limit) limit = 5;
if (this.check(word)) return [];
// Check the replacement table.
for (var i = 0, _len = this.dict.replacementTable.length; i < _len; i++) {
var replacementEntry = this.dict.replacementTable[i];
if (word.indexOf(replacementEntry[0]) !== -1) {
var correctedWord = word.replace(replacementEntry[0], replacementEntry[1]);
if (this.check(correctedWord)) {
return [ correctedWord ];
}
}
}
var self = this;
self.dict.alphabet = "abcdefghijklmnopqrstuvwxyz";
/*
if (!self.alphabet) {
// Use the alphabet as implicitly defined by the words in the dictionary.
var alphaHash = {};
for (var i in self.dictionaryTable) {
for (var j = 0, _len = i.length; j < _len; j++) {
alphaHash[i[j]] = true;
}
}
for (var i in alphaHash) {
self.alphabet += i;
}
var alphaArray = self.alphabet.split("");
alphaArray.sort();
self.alphabet = alphaArray.join("");
}
*/
function edits1(words) {
var rv = [];
for (var ii = 0, _iilen = words.length; ii < _iilen; ii++) {
var word = words[ii];
var splits = [];
for (var i = 0, _len = word.length + 1; i < _len; i++) {
splits.push([ word.substring(0, i), word.substring(i, word.length) ]);
}
var deletes = [];
for (var i = 0, _len = splits.length; i < _len; i++) {
var s = splits[i];
if (s[1]) {
deletes.push(s[0] + s[1].substring(1));
}
}
var transposes = [];
for (var i = 0, _len = splits.length; i < _len; i++) {
var s = splits[i];
if (s[1].length > 1) {
transposes.push(s[0] + s[1][1] + s[1][0] + s[1].substring(2));
}
}
var replaces = [];
for (var i = 0, _len = splits.length; i < _len; i++) {
var s = splits[i];
if (s[1]) {
for (var j = 0, _jlen = self.dict.alphabet.length; j < _jlen; j++) {
replaces.push(s[0] + self.dict.alphabet[j] + s[1].substring(1));
}
}
}
var inserts = [];
for (var i = 0, _len = splits.length; i < _len; i++) {
var s = splits[i];
if (s[1]) {
for (var j = 0, _jlen = self.dict.alphabet.length; j < _jlen; j++) {
replaces.push(s[0] + self.dict.alphabet[j] + s[1]);
}
}
}
rv = rv.concat(deletes);
rv = rv.concat(transposes);
rv = rv.concat(replaces);
rv = rv.concat(inserts);
}
return rv;
}
function known(words) {
var rv = [];
for (var i = 0; i < words.length; i++) {
if (self.check(words[i])) {
rv.push(words[i]);
}
}
return rv;
}
function correct(word) {
// Get the edit-distance-1 and edit-distance-2 forms of this word.
var ed1 = edits1([word]);
var ed2 = edits1(ed1);
var corrections = known(ed1).concat(known(ed2));
// Sort the edits based on how many different ways they were created.
var weighted_corrections = {};
for (var i = 0, _len = corrections.length; i < _len; i++) {
if (!(corrections[i] in weighted_corrections)) {
weighted_corrections[corrections[i]] = 1;
}
else {
weighted_corrections[corrections[i]] += 1;
}
}
var sorted_corrections = [];
for (var i in weighted_corrections) {
sorted_corrections.push([ i, weighted_corrections[i] ]);
}
function sorter(a, b) {
if (a[1] < b[1]) {
return -1;
}
return 1;
}
sorted_corrections.sort(sorter).reverse();
var rv = [];
for (var i = 0, _len = Math.min(limit, sorted_corrections.length); i < _len; i++) {
if (!self.hasFlag(sorted_corrections[i][0], "NOSUGGEST")) {
rv.push(sorted_corrections[i][0]);
}
}
return rv;
}
return correct(word);
};
module.exports = Spellchecker;