final exam

NAME

1–4 CHARACTERS CODE (if you want your final grade posted)

CSE 756: Final Exam

Monday, June 2, 1:30—3:28
Open Notes, Open Books
The exam consists of four problems
Answers not appearing in designated spaces WILL NOT be graded

Consider the programming language having the following grammar

prog	::=	body
body	::=	body stat
		ϵ
stat	::=	DO body REPEAT
		COPY
		EXIT_0

where the following semantics holds.

COPY. Read a value from the input and print it into the output
DO body REPEAT. Repeatedly execute the body
EXIT_0. Exit the execution of the loop that directly embeds the instruction or the program execution for non-nested cases, if the most recent read value is 0 or no value has been read so far.

Example.

EXIT_0
DO
  COPY
  EXIT_0
  COPY
  EXIT_0
  DO
    EXIT_0
    COPY
    EXIT_0
    COPY
    EXIT_0
  REPEAT
  COPY
  EXIT_0
REPEAT
COPY
EXIT_0

Problem #1 (10 points)

Write a (J)FLEX program that generates a scanner for the language

Problem #2 (10 points)

Write a Bison/CUP program that provides a translation into MINI MACHINE code.

Problem #3 (10 points)

Provide the parsing table for the following LALR(1)-like transition diagram of the grammar. (The cores of the states are identical to those of the LALR(1) diagram. The lookahead symbols are different.)

$||||||||| |||||||||| |||||| |||||| --|prog→ ⋅body,$||- --| bopdry→obg→obdoydy⋅s⋅,t$at,$ ||- -body→ ⋅body stat,$-----body------stat→ ⋅DO body REPEAT,$ -||| →ϵ⋅,$ ||-- -|| → ⋅COP Y,$ |----- ||||I0|||| ----|||→|⋅EXIIT1 _0,$||||---- ---------- COP-Y--- |||||||| ------ ---------- ------ ||DO||||||||| EXIT 0------ stat ---------- ||||||||-||||----- |||||||||| ||||||||| -----|||||-|||||||| ----------||||||||-||||||||| -stat→COP Y⋅,{$,REPEAT|}|- -stat→DObod⋅by→ody⋅boRdEyP stEatA,RTE,{P$,ERAETPEAT }|| -stat→EXIT _0⋅,{$,REP EAT}|- --body→body stat⋅,{$,REPEAT|}|| |||||||| I3 ||-||||-- -||| →ϵ⋅,REPEAT ||-- ||||||-|| I4 ||||||||- |---||||| I5 ||||||||- |||||||| ----- ||||||||||-|I2||-|||||||||| ------ |||-|||| --------- ||||||||| ------ body| - EXIT--0-- stat------ COP Y ------ |||||--||||||DO|||| ------ ---------- stat→DO| body ⋅REP EAT,{$,REPEAT-}------- --| body→body ⋅stat,REP EAT ||- - stat→ ⋅DO body REPEAT,REP EAT -- -||| →→⋅⋅ECXOIPTY_,0R,ERPEEPAETAT |||- |||||||||||I6|||||||||||| | |REP|EAT||||||||||||| -|||||| ||||||| |stat→DO||body REPIE7AT ⋅,{$,REPEAT|}-- |||||||||||||||||$

Problem #4 (10 points)

Determine the LR(0), SLR(1), and LR(1) transition diagrams for the grammar.