Unparse AST < O(exp(n))?
问题 Abstract problem description: The way I see it, unparsing means to create a token stream from an AST, which when parsed again produces an equal AST. So parse(unparse(AST)) = AST holds. This is the equal to finding a valid parse tree which would produce the same AST. The language is described by a context free S-attributed grammar using a eBNF variant. So the unparser has to find a valid 'path' through the traversed nodes in which all grammar constraints hold. This bascially means to find a