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Author: ZeroTrepidation

IT327/Asg1/LL1.class

@@ -0,0 +1,152 @@
+/*
+ * LL1 is a recirsive descent parser created by Seth Tummillo, a student at Illinois State University
+ * I own the code written below and forbid anyone to use the code below without my written consent.
+ * 
+ */
+
+
+import java.util.StringTokenizer;
+import java.util.NoSuchElementException;
+
+public class LL1 {
+	
+	public static String token;
+	public static StringTokenizer st;
+
+	public static void main(String[] args) {
+
+		String expression = convertExp(args[0]);
+		st = new StringTokenizer(expression, "()*/+-$", true );
+		token = st.nextToken();
+		try {
+			e();
+			System.out.println("Yes");
+		} catch (IllegalArgumentException e) {
+			System.out.println("No");
+		} catch (NoSuchElementException e) {
+			System.out.println("No");
+		}		
+	}
+	
+	public static void e() {
+		switch (token) {
+		case "n":
+			t();ePrime();
+			break;
+		case "(":
+			t();ePrime();
+			break;
+		default:
+			throw new IllegalArgumentException();
+		}
+		return;
+	}
+	
+	public static void ePrime(){
+		switch (token) {
+		case "+":
+			token=st.nextToken();t();ePrime();
+			break;
+		case "-":
+			token=st.nextToken();t();ePrime();
+			break;
+		case ")":
+			return;
+			//break;
+		case "$":
+			return;
+			//break;
+		default:
+			throw new IllegalArgumentException();
+		}
+		return;
+	}
+	
+	public static void t() {
+		switch (token) {
+		case "n":
+			f();tPrime();
+			break;
+		case "(":
+			f();tPrime();
+			break;
+		default:
+			throw new IllegalArgumentException();
+		}
+		return;
+	}
+	
+	public static void tPrime() {
+		switch (token) {
+		case "+":
+			return;
+			//break;
+		case "-":
+			return;
+			//break;
+		case "*":
+			token=st.nextToken();f();tPrime();
+			break;
+		case "/":
+			token=st.nextToken();f();tPrime();
+			break;
+		case ")":
+			return;
+			//break;
+		case "$":
+			return;
+			//break;
+		default:
+			throw new IllegalArgumentException();
+		}
+		return;
+	}
+	
+	public static void f() {
+		switch (token) {
+		case "n":
+			token=st.nextToken();
+			break;
+		case "(":
+			token=st.nextToken();e();token=st.nextToken();
+			break;
+		default:
+			throw new IllegalArgumentException();
+		}
+		return;
+		
+	}
+	
+	
+	
+	//Converts the numbers in a string to n if they are valid numbers
+	public static String convertExp(String initial) {
+		String converted = ""; 
+		
+		StringTokenizer temp = new StringTokenizer(initial.concat("$"),"()*/+-$", true );
+		while (temp.hasMoreTokens()) {
+			String token = temp.nextToken();
+			if (isNumeric(token)) {
+				token = "n";
+			}
+			converted=converted.concat(token);
+			
+		}
+		return converted;
+	}
+	
+	//checks if a given string is a numeric number. Used in the convertExp method.
+	public static boolean isNumeric(String strNum) {
+	    try {
+	        double d = Integer.parseInt(strNum);
+	    } catch (NumberFormatException | NullPointerException nfe) {
+	        return false;
+	    }
+	    return true;
+	}
+
+}
+
+
+
+

IT327/Asg1/LL1.java

@@ -0,0 +1,4 @@
+No
+Yes
+Yes
+Yes

IT327/Asg1/output.txt

@@ -0,0 +1,64 @@
+
+public class Key {
+	private int state;
+	private String symbol;
+	private int value;
+	
+	public Key(String symbol, int state, int value) {
+		this.state = state;
+		this.symbol = symbol;
+		this.value = value;
+	}
+	
+	
+
+	public Key() {
+		this.state = 0;
+		this.symbol = "-";
+		this.value = 0;
+	}
+
+
+
+	public int getState() {
+		return state;
+	}
+
+	public String getSymbol() {
+		return symbol;
+	}
+	
+	public int getValue() {
+		return value;
+	}
+	
+	public void setSymbol(String symbol) {
+		this.symbol = symbol;
+	}
+	
+	public void setState(int state) {
+		this.state = state;
+	}
+	
+	public void setValue(int value) {
+		this.value = value;
+	}
+
+
+
+	@Override
+	public String toString() {
+		if (symbol == "n")
+			return "[" + value + ":" + state + "]";
+		else
+			return "[" + symbol + ":" + state + "]";
+	}
+	
+	
+	
+	
+	
+}
+
+
+