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Example for CLR Parsing

 

Let us take an example and understand CLR Parsing.

 

Example:

Consider the grammar S → AA

    A → aA/b 

and construct the CLR(1) parser for the given grammar.

Sol: S → AA

        A → aA/b

The augmented grammar is : S’→ .S,S

S → AA

A → aA/b

Closure (I) = S’ → .S,$

S → .AA, $

A → .aA, a/b

A → .b, a/b

 

 

Goto (Io, $) = I1 

S1 → S.,$

Goto (Io, A) = I2 

         S→ A.A,$

         A→ .aA,$

         A → .b, $

Goto (Io,a) = I3

        A → a.A, a/b

        A →  .aA, a/b

        A →  .b, a/b

Goto (I3, b) = I8 

        A → b., a/b

Goto (I3, a) = I3

        A → a.A, a/b

        A → .aA, a/b

        A → .b, a/b

Goto (I3, b) = I4 

        A → b., a/b

 

Goto (Io, b) = I4 

A → b, a/b

Goto (I4, A) = I5 

         S → AA., $

Goto (I2, a) = I6 

         A → a.A, $

         A → .aA, $

         A →  .b/$

Goto (I2, b) = I7

         A → b, $    

Goto (I0, A) = I9 

         A → aA. $

Goto (I0, a) = I6

         A→ a.A, $

         A → .aA, $

         A → .b, $

Goto (I0, b) = I7 

         A→ b., $

 

Reference Link

Example for CLR Parsing