/*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
* License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is "Simplenlg".
*
* The Initial Developer of the Original Code is Ehud Reiter, Albert Gatt and Dave Westwater.
* Portions created by Ehud Reiter, Albert Gatt and Dave Westwater are Copyright (C) 2010-11 The University of Aberdeen. All Rights Reserved.
*
* Contributor(s): Ehud Reiter, Albert Gatt, Dave Wewstwater, Roman Kutlak, Margaret Mitchell.
*/
package simplenlg.aggregation;
import java.util.List;
import simplenlg.features.Feature;
import simplenlg.features.InternalFeature;
import simplenlg.framework.CoordinatedPhraseElement;
import simplenlg.framework.NLGElement;
import simplenlg.framework.PhraseCategory;
/**
* Implementation of a clausal coordination rule. The rule performs the
* following operations on sentences:
*
* <OL>
* <LI>If the sentences have the same subject, a new sentence is returned with
* that subject, and the VP from the component sentences conjoined. For example
* <I>John kicked the ball.</I> and <I>John sang a song.</I> becomes <I>John
* kicked the ball and sang a song</I>.</LI>
* <LI>If the sentences have the same VP, a new sentence is returned with that
* VP, and the subjects from the component sentences conjoined. For example
* <I>John kicked the ball.</I> and <I>Mary kicked the ball.</I> become <I>John
* and Mary kicked the ball</I>.</LI>
* </OL>
*
* <P>
* These operations only apply to sentences whose front modifiers are identical,
* that is, sentences where, for every pair <code>s1</code> and <code>s2</code>,
* <code>s1.getFrontModifiers().equals(s2.getFrontModifiers())</code>.
*
* <P>
* <STRONG>Note:</STRONG>: it is not recommended to use this rule in addition to
* {@link BackwardConjunctionReductionRule} and/or
* {@link ForwardConjunctionReductionRule}.
*
* @author Albert Gatt, University of Malta & University of Aberdeen
*/
public class ClauseCoordinationRule extends AggregationRule {
/**
* Constructs an instance of the ClauseCoordinationRule
*/
public ClauseCoordinationRule() {
super();
}
/**
* Applies aggregation to two NLGElements e1 and e2, succeeding only if they
* are clauses (that is, e1.getCategory() == e2.getCategory ==
* {@link simplenlg.framework.PhraseCategory#CLAUSE}).
*/
@Override
public NLGElement apply(NLGElement previous, NLGElement next) {
NLGElement aggregated = null;
if (previous.getCategory() == PhraseCategory.CLAUSE
&& next.getCategory() == PhraseCategory.CLAUSE
&& PhraseChecker.nonePassive(previous, next)
&& !PhraseChecker.expletiveSubjects(previous, next)) {
// case 1: identical sentences: remove the current
if (PhraseChecker.sameSentences(previous, next)) {
aggregated = previous;
// case 2: subjects identical: coordinate VPs
} else if (PhraseChecker.sameFrontMods(previous, next)
&& PhraseChecker.sameSubjects(previous, next)
&& PhraseChecker.samePostMods(previous, next)) {
aggregated = this.factory.createClause();
aggregated.setFeature(InternalFeature.SUBJECTS, previous
.getFeatureAsElementList(InternalFeature.SUBJECTS));
aggregated.setFeature(InternalFeature.FRONT_MODIFIERS, previous
.getFeatureAsElement(InternalFeature.FRONT_MODIFIERS));
aggregated.setFeature(Feature.CUE_PHRASE, previous
.getFeatureAsElement(Feature.CUE_PHRASE));
aggregated
.setFeature(
InternalFeature.POSTMODIFIERS,
previous
.getFeatureAsElementList(InternalFeature.POSTMODIFIERS));
NLGElement vp;
// case 2.1: VPs have different arguments but same
// head & mods
if (!PhraseChecker.sameVPArgs(previous, next)
&& PhraseChecker.sameVPHead(previous, next)
&& PhraseChecker.sameVPModifiers(previous, next)) {
NLGElement vp1 = previous
.getFeatureAsElement(InternalFeature.VERB_PHRASE);
vp = this.factory.createVerbPhrase();
vp.setFeature(InternalFeature.HEAD, vp1
.getFeatureAsElement(InternalFeature.HEAD));
vp
.setFeature(
InternalFeature.COMPLEMENTS,
vp1
.getFeatureAsElementList(InternalFeature.COMPLEMENTS));
vp
.setFeature(
InternalFeature.PREMODIFIERS,
vp1
.getFeatureAsElementList(InternalFeature.PREMODIFIERS));
vp
.setFeature(
InternalFeature.POSTMODIFIERS,
vp1
.getFeatureAsElementList(InternalFeature.POSTMODIFIERS));
// case 2.2: just create a coordinate vP
} else {
NLGElement vp1 = previous
.getFeatureAsElement(InternalFeature.VERB_PHRASE);
NLGElement vp2 = next
.getFeatureAsElement(InternalFeature.VERB_PHRASE);
vp = this.factory.createCoordinatedPhrase(vp1, vp2);
// case 2.3: expletive subjects
}
aggregated.setFeature(InternalFeature.VERB_PHRASE, vp);
// case 3: identical VPs: conjoin subjects and front
// modifiers
} else if (PhraseChecker.sameFrontMods(previous, next)
&& PhraseChecker.sameVP(previous, next)
&& PhraseChecker.samePostMods(previous, next)) {
aggregated = this.factory.createClause();
aggregated
.setFeature(
InternalFeature.FRONT_MODIFIERS,
previous
.getFeatureAsElementList(InternalFeature.FRONT_MODIFIERS));
CoordinatedPhraseElement subjects = this.factory
.createCoordinatedPhrase();
subjects.setCategory(PhraseCategory.NOUN_PHRASE);
List<NLGElement> allSubjects = previous
.getFeatureAsElementList(InternalFeature.SUBJECTS);
allSubjects.addAll(next
.getFeatureAsElementList(InternalFeature.SUBJECTS));
for (NLGElement subj : allSubjects) {
subjects.addCoordinate(subj);
}
aggregated.setFeature(InternalFeature.SUBJECTS, subjects);
aggregated
.setFeature(
InternalFeature.POSTMODIFIERS,
previous
.getFeatureAsElementList(InternalFeature.POSTMODIFIERS));
aggregated.setFeature(InternalFeature.VERB_PHRASE, previous
.getFeature(InternalFeature.VERB_PHRASE));
}
}
return aggregated;
}
}