7.2.1 The standard model of input

In the standard model of input, there is exactly one successful marpa_r_alternative() call immediately previous to every marpa_r_earleme_complete() call. A marpa_r_alternative() call is immediately previous to a marpa_r_earleme_complete() call iff that marpa_r_earleme_complete() call is the first marpa_r_earleme_complete() call after the marpa_r_alternative() call.

Recall that, since the standard model is a basic model, the token length in every successful call to marpa_r_alternative() will be one. For an input of length n, there will be exactly n marpa_r_earleme_complete() calls, and all but the last call to marpa_r_earleme_complete() must be successful.

In the standard model, after a successful call to marpa_r_alternative(), if c is the value of the current earleme before the call,

• the current earleme will remain unchanged and therefore will be c; and
• the furthest earleme will be c+1.

In the standard model, a call to marpa_r_earleme_complete() follows a successful call of marpa_r_alternative(), so that the value of the furthest earleme before the call to marpa_r_earleme_complete() will be c+1, where c is the value of the current earleme. After a successful call to marpa_r_earleme_complete(),

• the current earleme will be advanced to c+1; and
• the furthest earleme will be c+1, and therefore equal to the current earleme.

Recall that, in the basic models of input, the latest earleme is always equal to the current earleme.