10 消除左递归

Posted 2020-11-29 hvyan

1.将以下文法消除左递归，并分析符号串 i*i+i  

(1)E -> E+T | T

　　E -> TE‘  

　　E‘ -> +TE‘|ε

(2)T -> T*F | F

　　T -> FT‘

       T‘ -> *F|ε

(3)F -> (E) | i

 

 

2.P101练习7（2）（3）文法改写，并分别求FIRST集、FOLLOW集，和SELECT集

(2)

A -> aABe|a

B -> Bb|d

First(A)={a,e}

First(B)={b,d}

 

 

 (3)

S -> Aa|b

A ->SB

B ->ab

First(S) = {a,b,ab}

First(A) = {a,b,ab}

First(B) = {ab}

 

3.求以下文法的FIRST集、FOLLOW集和SELECT集。

S->Ap
A->a |ε
A->cA

A->aA

First(S) = {a,ε,c}

First(A) = {a,ε,c}

 

S->Ap
S->Bq
A->a
A->cA
B->b
B->dB

First(S) = {a,c,b,d}

First(A) = {a,c}

Fitst(B) = {d,b}