L Rparser Edos

LR Parsers Canonical Collection LR

LR Parser 1 ,[object Object],[object Object],S T A C K Prg Ejem1 ; Real X2 Fig. 6.2 Aho, Ullman. “Principles of Compiler Design” pág. 199 Parsing Table eof …

Driver Routine ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Shift ,[object Object],[object Object],[object Object]

Reduce ,[object Object],[object Object],[object Object],[object Object],[object Object]

How to construct a simple LR 2 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],IBID. Fig. 6.5 pág. 207

Example: G is a grammar with start symbol E E  E + T E  T T  T/F T  F F  (E) F  id

G’ is the augmented grammar with a new start symbol E’ E’  E E  E + T E  T T  T/F T  F F  (E) F  id Blue nucleous

Closure(E’) E’  ♥E Blue nucleous

Closure(E) E’  ♥E E  ♥ E + T E  ♥ T

Closure(T) E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F

Closure(F) E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id

State 1 E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id

State 2=GoTo(1,E) E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T

State 3 =GoTo(1,T) E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F

State 4=GoTo(1,F) E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥

State 5: from state 1 with ( E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥ F  (♥E) E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id

State 6:from state1 with id E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥ F  (♥E) E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id F  id ♥

States 1,2 ,3,4,5,6 E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥ F  (♥E) E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id F  id ♥

States 7,8,9 E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥ F  (♥E) E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id F  id ♥ E’  E+♥T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id T’  T/♥F F  ♥ (E) F  ♥ id F  (E♥) E  E♥+T

States 10,11,12 E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥ F  (♥E) E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id F  id ♥ E’  E+♥T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id T’  T/♥F F  ♥ (E) F  ♥ id F  (E♥) E  E♥+T E’  E+T♥ T  T ♥ /F T’  T/F♥ F  (E)♥

States 1,2,3,4,... 12 E’  ♥E E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id E’  E♥ E  E♥ + T E’  T♥ T  T♥ /F T  F ♥ F  (♥E) E  ♥ E + T E  ♥ T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id F  id ♥ E’  E+♥T T  ♥ T/F T  ♥ F F  ♥ (E) F  ♥ id T’  T/♥F F  ♥ (E) F  ♥ id F  (E♥) E  E♥+T E’  E+T♥ T  T ♥ /F T’  T/F♥ F  (E)♥

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