Lemmatizer.swift

// Lemmatizer.swift
//
// Copyright (c) 2015 Ayaka Nonaka
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

import Foundation

public struct Lemmatizer: Analyzer {
    let seed: Seed

    var scheme: String {
        return NSLinguisticTagSchemeLemma
    }

    public init(seed: Seed = Seed()) {
        self.seed = seed
    }

    /**
        Returns the lemmatized tokens for the input text using the specified linguistic tagger options.

        @param text Text to lemmatized
        @param options Linguistic tagger options
        @return The lemmatized tokens
    */
    public func lemmatizeWordsInText(text: String, options: NSLinguisticTaggerOptions? = nil) -> [String] {
        return analyze(self, text: text, options: options).map { (token, lemma) in lemma.lowercaseString }.filter {
            !$0.isEmpty
        }
    }
}