danbikel.parser
Interface Shift

All Known Implementing Classes:

BaseNPAwareShifter, DefaultShifter

public interface Shift

Methods used for the construction of prior states in the Markov process of creating modifier nonterminals. Currently, prior state is stored in a previous modifier list (a SexpList object) and a previous modifier head-word list (a WordList object), so the methods here are used to "shift" a new modifier to the head of these lists, losing the last element of the list (which was the least-recently-generated previous modifier). In the decoder, these previous modifier lists are constructed, so there are two "skip" methods that indicate whether to skip over certain previously-generated modifiers in the construction of these lists.

Implementation note: In the future, the Markov process of generating modifiers will be implemented in a cleaner fashion, by introducing a special State object, which implementors of this interface will manipulate. In other words, this interface will serve to specify a transition function, allowing greater flexibility in the experimentation with different notions of history in the Markov process.

Method Summary

void	shift(TrainerEvent event, SexpList list, Sexp prevMod) Shifts the previously-generated modifier label into the history.
void	shift(TrainerEvent event, WordList wordList, Word prevWord) Shifts the previously-generated modifier head word into the history.
boolean	skip(Item item, Sexp prevMod) Returns whether the previously-generated modifier should be skipped when constructing a history for the specified chart item.
boolean	skip(Item item, Word prevWord) Returns whether the previously-generated modifier head word should be skipped when constructing a history for the specified chart item.

Method Detail

shift

void shift(TrainerEvent event,
           SexpList list,
           Sexp prevMod)

Shifts the previously-generated modifier label into the history.

Parameters:

event - the TrainerEvent whose history is to be updated

list - the current history of previously-generated modifiers

prevMod - the previously-generated modifier

shift

void shift(TrainerEvent event,
           WordList wordList,
           Word prevWord)

Shifts the previously-generated modifier head word into the history.

Parameters:

event - the TrainerEvent whose history is to be updated

wordList - the current history of previously-generated modifier head words

prevWord - the head word of the previously-generated modifier

skip

boolean skip(Item item,
             Sexp prevMod)

Returns whether the previously-generated modifier should be skipped when constructing a history for the specified chart item.

Parameters:

item - the CKYItem object whose history is being constructed

prevMod - the previously-generated modifier

Returns:

whether or not to skip the specified previous modifier when constructing the modifier history for the specified chart item

skip

boolean skip(Item item,
             Word prevWord)

Returns whether the previously-generated modifier head word should be skipped when constructing a history for the specified chart item.

Parameters:

item - the CKYItem object whose history is being constructed

prevWord - the head word of the previously-generated modifier

Returns:

whether or not to skip the specified previous modifier's head word when constructing the modifier head word history for the specified chart item