I implemented this for my qsol query parser: myhardshadow.com/qsol
Uses a modified SpanNotQuery that takes another parameter saying how
many times the span can cross the specified marker. Index a special
paragraph marker with your text to delimit paragraphs and then the
rest is easy.
- Mark
public class SpanWithinQuery extends SpanQuery {
private SpanQuery include;
private SpanQuery exclude;
private int proximity;
/** Construct a SpanWithinQuery matching spans from
<code>include</code> which
* overlap with spans from <code>exclude</code> up to
<code>proximity</code> times.*/
public SpanWithinQuery(SpanQuery include, SpanQuery exclude, int
proximity) {
this.include = include;
this.exclude = exclude;
this.proximity = proximity;
if (!include.getField().equals(exclude.getField())) {
throw new IllegalArgumentException("Clauses must have same
field.");
}
}
/** Return the SpanQuery whose matches are filtered. */
public SpanQuery getInclude() {
return include;
}
/** Return the SpanQuery whose matches must not overlap those
returned. */
public SpanQuery getExclude() {
return exclude;
}
public String getField() {
return include.getField();
}
/** Returns a collection of all terms matched by this query.
* @deprecated use extractTerms instead
* @see #extractTerms(Set)
*/
public Collection getTerms() {
return include.getTerms();
}
public void extractTerms(Set terms) {
include.extractTerms(terms);
}
public String toString(String field) {
StringBuffer buffer = new StringBuffer();
buffer.append("spanWithin(");
buffer.append(include.toString(field));
buffer.append(", ");
buffer.append(proximity + " ,");
buffer.append(exclude.toString(field));
buffer.append(")");
buffer.append(ToStringUtils.boost(getBoost()));
return buffer.toString();
}
public Spans getSpans(final IndexReader reader) throws IOException {
return new Spans() {
private Spans includeSpans = include.getSpans(reader);
private boolean moreInclude = true;
private Spans excludeSpans = exclude.getSpans(reader);
private boolean moreExclude = true;
public boolean next() throws IOException {
if (moreInclude) { // move to next include
moreInclude = includeSpans.next();
}
while (moreInclude && moreExclude) {
if (includeSpans.doc() > excludeSpans.doc()) {
// skip exclude
moreExclude =
excludeSpans.skipTo(includeSpans.doc());
}
int count = 0;
while (moreExclude // while exclude is before
&&(includeSpans.doc() ==
excludeSpans.doc())) {
if ((!(excludeSpans.end() <=
includeSpans.start()))) {
count += 1;
if (count > proximity) {
break;
}
}
moreExclude = excludeSpans.next(); //
increment exclude
}
if (!moreExclude // if no intersection
||(includeSpans.doc() !=
excludeSpans.doc()) ||
(includeSpans.end() <=
excludeSpans.start())) {
break; // we found a match
}
moreInclude = includeSpans.next(); //
intersected: keep scanning
}
return moreInclude;
}
public boolean skipTo(int target) throws IOException {
if (moreInclude) { // skip include
moreInclude = includeSpans.skipTo(target);
}
if (!moreInclude) {
return false;
}
if (moreExclude // skip exclude
&&(includeSpans.doc() >
excludeSpans.doc())) {
moreExclude =
excludeSpans.skipTo(includeSpans.doc());
}
int count = 0;
while (moreExclude // while exclude is before
&&(includeSpans.doc() ==
excludeSpans.doc())) {
if ((!(excludeSpans.end() <=
includeSpans.start()))) {
count += 1;
if (count > proximity) {
break;
}
}
moreExclude = excludeSpans.next(); //
increment exclude
}
if (!moreExclude // if no intersection
||(includeSpans.doc() !=
excludeSpans.doc()) ||
(includeSpans.end() <=
excludeSpans.start())) {
return true; // we found a match
}
boolean returnboolean = next();
return returnboolean; // scan to next match
}
public int doc() {
return includeSpans.doc();
}
public int start() {
return includeSpans.start();
}
public int end() {
return includeSpans.end();
}
public String toString() {
return "spans(" + SpanWithinQuery.this.toString()
+ ")";
}
};
}
public Query rewrite(IndexReader reader) throws IOException {
SpanWithinQuery clone = null;
SpanQuery rewrittenInclude = (SpanQuery) include.rewrite(reader);
if (rewrittenInclude != include) {
clone = (SpanWithinQuery) this.clone();
clone.include = rewrittenInclude;
}
SpanQuery rewrittenExclude = (SpanQuery) exclude.rewrite(reader);
if (rewrittenExclude != exclude) {
if (clone == null) {
clone = (SpanWithinQuery) this.clone();
}
clone.exclude = rewrittenExclude;
}
if (clone != null) {
return clone; // some clauses rewrote
} else {
return this; // no clauses rewrote
}
}
/** Returns true iff <code>o</code> is equal to this. */
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof SpanWithinQuery)) {
return false;
}
SpanWithinQuery other = (SpanWithinQuery) o;
return this.include.equals(other.include) &&
this.exclude.equals(other.exclude) &&
(this.getBoost() == other.getBoost()) && (proximity ==
other.proximity);
}
public int hashCode() {
int h = include.hashCode();
h = (h << 1) | (h >>> 31); // rotate left
h ^= exclude.hashCode();
h = (h << 1) | (h >>> 31); // rotate left
h ^= Float.floatToRawIntBits(getBoost());
h ^= proximity;
return h;
}
}
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