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A predictive parser is a recursive descent parser that does not require backtracking. [3] Predictive parsing is possible only for the class of LL( k ) grammars, which are the context-free grammars for which there exists some positive integer k that allows a recursive descent parser to decide which production to use by examining only the next k ...
parboiled is commonly used as an alternative for regular expressions or parser ... complete recursive descent parser with ... Example of a complete Java 6 parser ...
With many levels of precedence, implementing this grammar with a predictive recursive-descent parser can become inefficient. Parsing a number, for example, can require five function calls: one for each non-terminal in the grammar until reaching primary. An operator-precedence parser can do the same more efficiently. [1]
The Spirit Parser Framework is an object oriented recursive descent parser generator framework implemented using template metaprogramming techniques. Expression templates allow users to approximate the syntax of extended Backus–Naur form (EBNF) completely in C++ .
A formal grammar that contains left recursion cannot be parsed by a naive recursive descent parser unless they are converted to a weakly equivalent right-recursive form. . However, recent research demonstrates that it is possible to accommodate left-recursive grammars (along with all other forms of general CFGs) in a more sophisticated top-down parser by use of curta
A TDPL grammar can be viewed as an extremely minimalistic formal representation of a recursive descent parser, in which each of the nonterminals schematically represents a parsing function. Each of these nonterminal-functions takes as its input argument a string to be recognized, and yields one of two possible outcomes:
(For example, upon encountering a variable declaration, user-written code could save the name and type of the variable into an external data structure, so that these could be checked against later variable references detected by the parser.)
The example uses no token look ahead at all and thus is not really helpful to understand the strength of recursive descent parsers. There should at least be a bit of ambiguity in the grammar, otherwise the example is too trivial and - even worse - points the reader into wrong directions.