Implement Graham, Harrison, Ruzzo (GHR)

[SamyaDaleh]

Improvement of Earley.

Initialize:
_________ beta =>* epsilon
[S -> beta dot gamma, 0, 0]

Scan:
[A -> alpha dot a beta gamma, i, j], [a, j, j+1]
_________ beta =>* epsilon
[A -> alpha a beta dot gamma, i, j+1]

C1:
[A -> alpha dot B beta gamma, i, j], [B -> delta dot, j, k]
_________ i < j < k AND beta =>* epsilon
[A -> alpha B beta dot gamma, i, k]

C2:
[A -> alpha dot B beta gamma, i, i], [C -> delta dot, i, j]
___________ i < j AND B =>* C AND beta =>* epsilon
[A -> alpha B beta dot gamma, i, j]

Pred:
[A -> alpha dot B beta, i, j]
__________ B =>* C gamma AND alpha' =>* epsilon
[C -> alpha' dot beta', j, j]

Source: Sikkel, Parsing Schemata p. 113