/**
* Returns a fulltext query that is a superset of the original one and does not have phrase
* searches.
*
* <p>Negative phrases (which are at AND level) are removed, positive phrases are split into ANDed
* words.
*/
protected static FulltextQuery breakPhrases(FulltextQuery ft) {
FulltextQuery newFt = new FulltextQuery();
if (ft.op == Op.AND || ft.op == Op.OR) {
List<FulltextQuery> newTerms = new LinkedList<FulltextQuery>();
for (FulltextQuery term : ft.terms) {
FulltextQuery broken = breakPhrases(term);
if (broken == null) {
// remove negative phrase
} else if (ft.op == Op.AND && broken.op == Op.AND) {
// associativity (sub-AND hoisting)
newTerms.addAll(broken.terms);
} else {
newTerms.add(broken);
}
}
if (newTerms.size() == 1) {
// single-term parenthesis elimination
newFt = newTerms.get(0);
} else {
newFt.op = ft.op;
newFt.terms = newTerms;
}
} else {
boolean isPhrase = ft.isPhrase();
if (!isPhrase) {
newFt = ft;
} else if (ft.op == Op.WORD) {
// positive phrase
// split it
List<FulltextQuery> newTerms = new LinkedList<FulltextQuery>();
for (String subword : ft.word.split(" ")) {
FulltextQuery sft = new FulltextQuery();
sft.op = Op.WORD;
sft.word = subword;
newTerms.add(sft);
}
newFt.op = Op.AND;
newFt.terms = newTerms;
} else {
// negative phrase
// removed
newFt = null;
}
}
return newFt;
}
/** Removes toplevel ANDed simple words from the query. */
protected static FulltextQuery removeToplevelAndedWords(FulltextQuery ft) {
if (ft.op == Op.OR || ft.op == Op.NOTWORD) {
return ft;
}
if (ft.op == Op.WORD) {
if (ft.isPhrase()) {
return ft;
}
return null;
}
List<FulltextQuery> newTerms = new LinkedList<FulltextQuery>();
for (FulltextQuery term : ft.terms) {
if (term.op == Op.NOTWORD) {
newTerms.add(term);
} else { // Op.WORD
if (term.isPhrase()) {
newTerms.add(term);
}
}
}
if (newTerms.isEmpty()) {
return null;
} else if (newTerms.size() == 1) {
// single-term parenthesis elimination
return newTerms.get(0);
} else {
FulltextQuery newFt = new FulltextQuery();
newFt.op = Op.AND;
newFt.terms = newTerms;
return newFt;
}
}
