Abstract: On the basis of Earley parsing extended grammars, this paper gives an automatic generation algorithm of a semantic parser for EBNF. Given an extended grammar with embedded semantic routines and an input string, the algorithm outputs the corresponding semantic parser. With the execution of these semantic routines, some work such as type checking, intermediate code generation and optimization can be done, which makes the parsing algorithm

Key words: Earley parsing, extended grammar, operator state machine, semantic routine, parser