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Semester 1/Programming 1/Java/examples/projects/chapter08/zuul-with-enums-v1/Parser.java

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+import java.util.Scanner;
+
+/**
+ * This class is part of the "World of Zuul" application. 
+ * "World of Zuul" is a very simple, text based adventure game.  
+ * 
+ * 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  Michael Kölling and David J. Barnes
+ * @version 2016.02.29
+ */
+public class Parser 
+{
+    private CommandWords commands;  // holds all valid command words
+    private Scanner reader;         // source of command input
+
+    /**
+     * Create a parser to read from the terminal window.
+     */
+    public Parser() 
+    {
+        commands = new CommandWords();
+        reader = new Scanner(System.in);
+    }
+
+    /**
+     * @return The next command from the user.
+     */
+    public Command getCommand() 
+    {
+        String inputLine;   // will hold the full input line
+        String word1 = null;
+        String word2 = null;
+
+        System.out.print("> ");     // print prompt
+
+        inputLine = reader.nextLine();
+
+        // Find up to two words on the line.
+        Scanner tokenizer = new Scanner(inputLine);
+        if(tokenizer.hasNext()) {
+            word1 = tokenizer.next();      // get first word
+            if(tokenizer.hasNext()) {
+                word2 = tokenizer.next();      // get second word
+                // note: we just ignore the rest of the input line.
+            }
+        }
+
+        return new Command(commands.getCommandWord(word1), word2);
+    }
+
+    /**
+     * Print out a list of valid command words.
+     */
+    public void showCommands()
+    {
+        commands.showAll();
+    }
+}