Re: [boost] Yacc, lex, and C++

From: James Kanze (kanze_at_[hidden])
Date: 2002-03-03 09:26:32

Douglas Gregor <gregod_at_[hidden]> writes:

    [...]
|>  > The Spirit parser is not what I am looking for, as it is limited
|>  > to recursive-descent parsing, and is hence unsuitable for many
|>  > applications (say, parsing a C++ program).

|>  As Dave Abrahams already mentioned, several of the better C++
|>  parsers uses recursive descent parsing. 

Strictly speaking, this isn't true; you cannot parse C++ using recursive
descent.  Most C++ are based on a hand written recursive descent parsing
strategy, however, because it is easier to break out of the idiom in
special cases and use ad hoc solutions.

|>  This is generally because recursive descent parsers handle context
|>  sensitivity and arbitrary lookahead _much_ better than any
|>  Yacc-based solution. 

Formally, recursive descent doesn't allow arbitrary look ahead at all.
On the other hand, it is far easier to add backtracking to a recursive
descent parser than to any other type -- the results aren't formally
recursive descent, even if the initial analysis and coding are based on
recursive descent.

-- 
James Kanze                                mailto:kanze_at_[hidden]
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