LL Parser

- LL -

LL ( ) − −( )

LR ( ) − ( ) − − SLR LALR LR ...

LL (1/3) S → aBcd B → bc →b abcd −

LL (2/3) A=Ax|y A = y A' A' = x A' | ε

LL (3/3) A A A A

LL (3/3) A A’ A’ A’ ε

LL (3/3) LL − − T E’ ) T’ E’ $ (i + i) * i $

LL (3/3) E→E T E T T T→T F T F F F→ E i num

LL (3/3) 2 E → TE’ E’ → TE‘ TE‘ ε T’ → FT‘ FT’ ε F→ E i num

LL (3/3) DIRECTOR − FIRST FOLLOW DIRECTOR FIRST FOLLOW

LL (3/3) FIRST FIRST(α) − α ε FIRST α a α∈T, α⇒a… α α a ε a ∈ FIRST(α) ε ∈ FIRST(α) FIRST F , i, num

LL (3/3) FOLLOW FOLLOW(A) − A ε , S ⇒…Aa… FOLLOW A a a∈T∪ S A a $ a∈F () F F , , , , ,

LL (3/3) DIRECTOR , − a DIRECTOR A,α , − A A→α a DIRECTOR A,α DIRECTOR − A,β , LL( ) DIRECTOR A,α − a a∈T,a∈FIRST α ε α⇒ε a∈FOLLOW(A)

LL (3/3) DIRECTOR 2 A A α α a εa a ∈ FIRST(α) ε a⇒ε

LL (3/3) DIRECTOR 3 DIRECTOR(F, E ) FIRST( E ) ε − DIRECTOR(F,i) FIRST( ) ε {i} − DIRECTOR(F,num) FIRST num ε num − able[A,α] A→α a∈DIRECTOR(A,α)

LR − FIRST FOLLOW DIRECTOR −

http://fxp.hp.infoseek.co.jp/arti/parser.html −

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by Yasunori Mahata on Dec 12, 2007