7.1.1 The traditional input model

In traditional Earley parsers, the concept of location is very simple. Locations are numbered from 0 to n, where n is the length of the input. Every location has an Earley set, and vice versa. Location 0 is the start location. Every location after the start location has exactly one input token associated with it.

Some applications do not fit this traditional input model — natural language processing requires ambiguous tokens, for example. Libmarpa allows a wide variety of alternative input models.