CS 132 Fall 2004, Midterm Solution
==================================

Question 1
----------
A ::= y D
D ::= x D | epsilon
                            parsing table
   First  Follow  Nullable    x   y   $
A   {y}    {$}       No       -   yD  -
D   {x}    {$}      Yes       xD  -   epsilon 
   

Question 2
----------
   First  Follow  Nullable
A   {y,z}  {x,$}    Yes
B   {y}    {y,z}    Yes
C   {y,z}  {x,$}     No

The grammar is NOT LL(1) because:
   B is nullable and y is in both First(B ::= yAx) and Follow(B)


Question 3
----------
Here is a sketch of the Java code:

   void A() {
      B();
      if ( token == 'r' ) { get-next-token(); }
      else { error(); }
      if ( token != EOF ) error();
   }
   
   void B() {
      if ( token == 'y' ) { get-next-token(); }
      else { error(); }
      C();
   }
   
   void C() {
      if ( token == 'r' ) { get-next-token(); }
      else {
          if ( token == 'y' ) { 
             B();
             if ( token == 'r' ) { get-next-token(); }
             else { error(); }
          }
          else error();
      }
   }