Recognizer.java

package org.softlang.company.features.recognizer;

import static org.softlang.company.features.recognizer.Token.*;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Scanner;

public class Recognizer implements Iterator<Token> {

    Scanner scanner;
    String lexeme;

    private static Map<String,Token> keywords;

    static {
        keywords = new HashMap <String,Token>();
        keywords.put("company",     COMPANY);
        keywords.put("department",     DEPARTMENT);
        keywords.put("manager",     MANAGER);        
        keywords.put("employee",     EMPLOYEE);
        keywords.put("name",         NAME);
        keywords.put("address",     ADDRESS);
        keywords.put("salary",         SALARY);
        keywords.put("{",             OPEN);
        keywords.put("}",             CLOSE);        
    }

    public Recognizer(String s) throws FileNotFoundException {
        scanner = new Scanner(new File(s));
    }

    public String getLexeme() {
        return lexeme;
    }

    public static Token classify(String s) {
        if (keywords.containsKey(s))
            return keywords.get(s);
        else if (s.matches("\"[^\"]*\""))
            return STRING;
        else if (s.matches("\\d+(\\.\\d*)?"))
            return FLOAT;
        else 
            throw new RecognitionException("Tokenizer failed at " + s);                    
    }

    public boolean hasNext() {
        return scanner.hasNext();
    }

    public Token next() {
        lexeme = scanner.next();
        return classify(lexeme);
    }

    public void remove() {
        throw new UnsupportedOperationException();
    }

    // Stress test: lex until end-of-file
    public void lexall() {
        while (hasNext()) {
            Token t = next();
            System.out.println(t + " : " + lexeme);
        }
    }

}