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src/com/bayviewglen/zork/Parser.java

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+
+package com.bayviewglen.zork;
+
+/*
+ * Author:  Michael Kolling
+ * Version: 1.0
+ * Date:    July 1999
+ * 
+ * This class is part of Zork. Zork is a simple, text based adventure game.
+ *
+ * This parser reads user input and tries to interpret it as a "Zork"
+ * 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.
+ */
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+class Parser {
+	private CommandWords commands; // holds all valid command words
+
+	public Parser() {
+		commands = new CommandWords();
+	}
+
+	public Command getCommand() {
+		String inputLine = ""; // will hold the full input 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
+		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 "nil" command (for unknown command).
+		if (commands.isCommand(word1))
+			return new Command(word1, word2);
+		else
+			return new Command(null, word2);
+	}
+
+	/**
+	 * Print out a list of valid command words.
+	 */
+	public void showCommands() {
+		commands.showAll();
+	}
+}