NATIONAL OPEN UNIVERSITY OF NIGERIA

UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
JULY 2017 EXAMINATION

COURSE CODE:                                                                              CIT445

COURSE TITLE:                                                                             Principles and Techniques of Compilers

TIME ALLOWED:                                                                          3 Hours

INSTRUCTIONS:                                                                            Answer question 1 and any four (4) questions

1.With the aid of illustrative diagram describe the phases of a compiler       14marks

b. Consider the grammar G below:

          G: E→E +T/T

           T→ T* F/F

           F→(E) / i

Generate the non-left recursive version of the grammar                                    5marks

c. Explain what is meant by the term Viable Prefix?                                              3marks

2. What are the benefits of LR parsing?                                                                   4marks

b. List the commn techniques for building tables for an “LR” parser stating the characteristic of each?         6marks

c. Consider the grammar,

       G: E → E + T│ T

       T → T * F │F

       F → (E) │ i

What is the augemented grammar for this grammar                                               2marks

3. Briefly describe the operation performed by the shift-reduce parser                6marks

b. State three of the uses of formal languages                                                               3marks

c. Why do we need a translator                                                                                        3 marks

4. What is a translator?                                                                                                     2marks

b. Consider the grammar,

              G: S→ a│ aS │ bS

Find the LR (0) items for this grammar                                                                             10marks

5. Enumerate the functions performed by the lexical analyser                                    4marks

b. Enumerate any three of the errors which can be detected during lexical analysis          6marks

6. Define formal language?                                                                                                            3marks

b. Find FOLLOW of all the nonterminal symbols in the non-left recursive version of the grammar         9marks.