On 12/18/2013 11:27 AM, Goubier Thierry wrote:

Le 18/12/2013 11:15, Nicolas Anquetil a écrit :

ben there is nothing magic about PPCompositeParser, it is a parser like
all the other one
and if you call rules without consuming any input + have a loop in the
rule calls, then there will be a infinite loop

Yes and no. Some parsers can't handle left-recursion in rules (petit parser? LL parsers can't), some parsers don't have any problem with left recursion (LR parsers like SmaCC).

I meant PPCompositeParser within PetitParser
All parsers PPParsers behave more or less the same way when we come to this.
If other can't handle correctly left-recursion ther eis no reasonnable reason to hope that PPCompositeParser composite parser will do.

Moreover, being a recursive descent parser, PetitParser naturally can't handle left recursivity

In this case, you will need to convert the grammar to a right recursive one, for example like this (which is more or less the same thing I believe):

ClassOrInterfaceType: ClassType "/ InterfaceType -- this option is useless here as it is equal to ClassType"

ClassType: TypeDeclSpecifier

TypeDeclSpecifier: TypeName { . TypeDeclSpecifier }

TypeName: Identifier TypeArgumentsopt

InterfaceType: TypeDeclSpecifier, TypeArgumentsopt

Some of the rules are not really needed, but that way it sticks closer to the reference grammar

nicolas

-- 
Nicolas Anquetil -- RMod research team (Inria)