cz.cuni.mff.ksi.jinfer.basicigg.expansion
Class ExpansionHelper

java.lang.Object
  cz.cuni.mff.ksi.jinfer.basicigg.expansion.ExpansionHelper

public final class ExpansionHelper
extends Object

A few useful functions for complex regexp expansion. Library class.

Method Summary

static <T> List<List<T>>	applyInterval(List<List<T>> input, RegexpInterval ri) Applies the regexp interval on the set of words.
static <T> Regexp<T>	getEmptyConcat() Returns an empty, immutable concatenation with interval "once".

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

applyInterval

public static <T> List<List<T>> applyInterval(List<List<T>> input,
                                              RegexpInterval ri)

Applies the regexp interval on the set of words. For this function, word is a List of its letters (see type parameter). The actual list of generated words depends on the interval in following way:

• "once": result is the original set of words.
• Optional (?): result is the original set of words + an empty word.
• Kleene cross (+): for each original word W, the result contains W and WWW (concatenation of 3 W's).
• Kleene star (*): result is an empty word + what would Kleene cross generate.
• Interval ({m, n}): for each original word W, the result contains a concatenation of m W's and a concatenation of n W's.

Type Parameters:

T - Type of the letters of words in this function.

Parameters:

input - List of words (lists of letters) to be processed.

ri - Regexp interval to be applied on the words.

Returns:

List of resulting words.

getEmptyConcat

public static <T> Regexp<T> getEmptyConcat()

Returns an empty, immutable concatenation with interval "once".