CS536 Homework 6 Solution

Question 1:

1. 1. The shortest input that can be parsed is: NAME IDNUM EOF
   2. The parse tree is:
      
2. 1. The shortest sequence of tokens that would stump tha parser is: NAME IDNUM INTLIT
   2. The parse tree is:
      
   3. The parser cannot choose between these two rules:

      grades → oneGrade
      grades → oneGrade COMMA grades

3. The rules with a common prefix are the ones with grades on the left. Here are the transformed rules:

   grades → oneGrade grades'
   grades' → ε | COMMA grades

4. The rules with immediate left recursion are the ones with stars on the left. Here are the transformed rules:

   stars → STAR stars'
   stars' → STAR stars' | ε

Question 2:

Nonterminal X	FIRST(X)	FOLLOW(X)
program	{	EOF
stmts	ID, if, ε	}
stmt	ID, if	}, ID, if
exp	ID	;, )
tail	+, -, ε	;, )