Deriving a Parser from EBNF

To derive a parser from a context-free grammar written in EBNF style:

• Introduce one function void A() for each non-terminal A
• The task of A() is to recognize sub-sentences derived from A, or issue an error if no A was found.
• Translate all regular expressions on the right-hand-side of productions as before, but
  • every occurrence of a non-terminal B maps to B()
  • Recursion in the grammar translates naturally to recursion in the parser.
• This technique of writing parsers is called parsing by recursive descent or predictive parsing .