Re: eliminating left-recursion

"jackycn" <lojiancn@hotmail.com>
9 Jan 2006 23:50:02 -0500

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Re: eliminating left-recursion lojiancn@hotmail.com (jackycn) (2006-01-09)
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From: "jackycn" <lojiancn@hotmail.com>
Newsgroups: comp.compilers
Date: 9 Jan 2006 23:50:02 -0500
Organization: http://groups.google.com
References: 06-01-01306-01-016
Keywords: parse, LL(1)
Posted-Date: 09 Jan 2006 23:50:02 EST

Please see Louden's 'Compiler Construction, Principles and Practice''s
Chapter 4, section 4.2.3.
CAS2: General immediate left recursion:


Given:
A --> Aa1 | Aa2 | .. | Aan | b1 | b2 | ... |bm
where, none of the b2, b2,...,bm begin with A.
The solution is :
A --> b1A' | b2A' |... |bmA'
A' --> a1A' | a2A' | ... |anA' | epsilon


so , give your's production expression:


d-declarator: ID | d-declarator '[' constant ']' | '(' d-declarator ')'




we can rewrite as


d-declarator : d-declarator '[' constant ']' | '(' d-declarator ')'
| ID


and the solution is:


d-declarator : ID d-declarator' | '(' d-declarator ')' d-declarator'


;
d-declarator' : '[' constant ']' declarator' | epsilon
;


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