Parser Tugas 6

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
/**
 * This parser reads user input and tries to interpret
 * it as an "Adventure" command. Every time it is called it reads a line
 * from the terminal and tries to interpret the line as a two word command.
 * It returns the command as an object of class Command.
 *
 * The parser has a set of known command words. It
 * checks user input against the known commands, and if the input is not one of
 * the known commands, it returns a command object that is marked as an
 * unknown command.
 *
 * @author Muhammad Naufaldillah
 * @version 24 Novemebr 2020
 */
public class Parser
{
    private CommandWords commands; // holds all valid command words

    public Parser()
    {
        commands = new CommandWords();
    }

    public Command getCommand()
    {
        String inputLine = ""; // will hold the full line
        String word1;
        String word2;

        System.out.print("> "); // print prompt

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        try
        {
            inputLine = reader.readLine();
        }
        catch(java.io.IOException exc)
        {
            System.out.println("There was an error during reading: " + exc.getMessage());
        }

        StringTokenizer tokenizer = new StringTokenizer(inputLine);

        if(tokenizer.hasMoreTokens())
        {
            word1 = tokenizer.nextToken(); // get first word
        }
        else
        {
            word1 = null;
        }

        if(tokenizer.hasMoreTokens())
        {
            word2 = tokenizer.nextToken(); // get second word word
        }
        else
        {
            word2 = null;
        }

        // note: we just ignore the rest of the input line.

        // Now check whether this word is known. If so, create a command
        // with it. If not, create a "null" command (for unknown command).

        if(commands.isCommand(word1))
        {
            return new Command(word1, word2);
        }
        else
        {
            return new Command(null, word2);
        }
    }
}