问题
I am trying to search for fairly complex queries with Lucene.Net like
"inject* needle*" OR "point* thingy"~2
So basically I need wildcards in regular as well as proximity phrases. However, the basic Lucene.Net QueryParser gets rid of these wildcards.
I understand that ComplexPhraseQueryParser would work for that, unfortunately this is not included in Lucene.Net.
Is there any way of constructing queries like this in Lucene.Net?
回答1:
I ended up by actually porting the ComplexPhraseQueryParser from Java to C#. It was a lot easier than expected and was a good excercise for learning C# a bit better.
I have provided the code below in case it is helpfull to anyone else. Please note that it is still very Java-like Code as I am a lot more familiar with Java than I am with C# ;-)
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Ported to C# from Java source at http://grepcode.com/file/repo1.maven.org/maven2/org.apache.lucene/lucene-misc/3.0.3/org/apache/lucene/queryParser/complexPhrase/ComplexPhraseQueryParser.java
using Lucene.Net.Analysis;
using Lucene.Net.Index;
using Lucene.Net.QueryParsers;
using Lucene.Net.Search;
using Lucene.Net.Search.Spans;
using System;
using System.Collections.Generic;
using Version = Lucene.Net.Util.Version;
public class ComplexPhraseQueryParser : QueryParser
{
private List<ComplexPhraseQuery> complexPhrases = null;
private Boolean isPass2ResolvingPhrases;
private ComplexPhraseQuery currentPhraseQuery = null;
public ComplexPhraseQueryParser(Version matchVersion, String f, Analyzer a) : base(matchVersion, f, a) { }
protected override Query GetFieldQuery(String field, String queryText, int slop)
{
ComplexPhraseQuery cpq = new ComplexPhraseQuery(field, queryText, slop);
complexPhrases.Add(cpq); // add to list of phrases to be parsed once
// we
// are through with this pass
return cpq;
}
public override Query Parse(String query)
{
if (isPass2ResolvingPhrases)
{
RewriteMethod oldMethod = MultiTermRewriteMethod;
try
{
// Temporarily force BooleanQuery rewrite so that Parser will
// generate visible
// collection of terms which we can convert into SpanQueries.
// ConstantScoreRewrite mode produces an
// opaque ConstantScoreQuery object which cannot be interrogated for
// terms in the same way a BooleanQuery can.
// QueryParser is not guaranteed threadsafe anyway so this temporary
// state change should not
// present an issue
MultiTermRewriteMethod = MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE;
return base.Parse(query);
}
finally
{
MultiTermRewriteMethod = oldMethod;
}
}
// First pass - parse the top-level query recording any PhraseQuerys
// which will need to be resolved
complexPhrases = new List<ComplexPhraseQuery>();
Query q = base.Parse(query);
// Perform second pass, using this QueryParser to parse any nested
// PhraseQueries with different
// set of syntax restrictions (i.e. all fields must be same)
isPass2ResolvingPhrases = true;
try
{
using (IEnumerator<ComplexPhraseQuery> enumerator = complexPhrases.GetEnumerator())
{
while (enumerator.MoveNext())
{
currentPhraseQuery = enumerator.Current;
currentPhraseQuery.ParsePhraseElements(this);
}
}
}
finally
{
isPass2ResolvingPhrases = false;
}
return q;
}
// There is No "getTermQuery throws ParseException" method to override so
// unfortunately need
// to throw a runtime exception here if a term for another field is embedded
// in phrase query
protected override Query NewTermQuery(Term term)
{
if (isPass2ResolvingPhrases)
{
try
{
CheckPhraseClauseIsForSameField(term.Field);
}
catch (ParseException pe)
{
throw new SystemException("Error parsing complex phrase", pe);
}
}
return base.NewTermQuery(term);
}
// Helper method used to report on any clauses that appear in query syntax
private void CheckPhraseClauseIsForSameField(String field)
{
if (!field.Equals(currentPhraseQuery.Field))
{
throw new ParseException("Cannot have clause for field \"" + field
+ "\" nested in phrase " + " for field \"" + currentPhraseQuery.Field
+ "\"");
}
}
protected override Query GetWildcardQuery(String field, String termStr)
{
if (isPass2ResolvingPhrases)
{
CheckPhraseClauseIsForSameField(field);
}
return base.GetWildcardQuery(field, termStr);
}
protected override Query GetRangeQuery(String field, String part1, String part2, Boolean inclusive)
{
if (isPass2ResolvingPhrases)
{
CheckPhraseClauseIsForSameField(field);
}
return base.GetRangeQuery(field, part1, part2, inclusive);
}
protected override Query NewRangeQuery(String field, String part1, String part2,
Boolean inclusive)
{
if (isPass2ResolvingPhrases)
{
// Must use old-style RangeQuery in order to produce a BooleanQuery
// that can be turned into SpanOr clause
TermRangeQuery rangeQuery = new TermRangeQuery(field, part1, part2, inclusive, inclusive, RangeCollator);
rangeQuery.RewriteMethod = MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE;
return rangeQuery;
}
return base.NewRangeQuery(field, part1, part2, inclusive);
}
protected Query GetFuzzyQuery(String field, String termStr, float minSimilarity)
{
if (isPass2ResolvingPhrases)
{
CheckPhraseClauseIsForSameField(field);
}
return base.GetFuzzyQuery(field, termStr, minSimilarity);
}
/*
* Used to handle the query content in between quotes and produced Span-based
* interpretations of the clauses.
*/
class ComplexPhraseQuery : Query
{
public string Field { get; set; }
public string PhrasedQueryStringContents { get; set; }
public int SlopFactor { get; set; }
private Query Contents;
public ComplexPhraseQuery(string Field, string PhrasedQueryStringContents, int SlopFactor)
: base()
{
this.Field = Field;
this.PhrasedQueryStringContents = PhrasedQueryStringContents;
this.SlopFactor = SlopFactor;
}
// Called by ComplexPhraseQueryParser for each phrase after the main
// parse
// thread is through
public void ParsePhraseElements(QueryParser qp)
{
// TODO ensure that field-sensitivity is preserved ie the query
// string below is parsed as
// field+":("+phrasedQueryStringContents+")"
// but this will need code in rewrite to unwrap the first layer of
// boolean query
Contents = qp.Parse(PhrasedQueryStringContents);
}
public override Query Rewrite(IndexReader reader)
{
// ArrayList spanClauses = new ArrayList();
if (Contents is TermQuery)
{
return Contents;
}
// Build a sequence of Span clauses arranged in a SpanNear - child
// clauses can be complex
// Booleans e.g. nots and ors etc
int numNegatives = 0;
if (!(Contents is BooleanQuery))
{
throw new ArgumentException("Unknown query type \""
+ Contents.GetType()
+ "\" found in phrase query string \"" + PhrasedQueryStringContents
+ "\"");
}
BooleanQuery bq = (BooleanQuery)Contents;
BooleanClause[] bclauses = bq.GetClauses();
SpanQuery[] allSpanClauses = new SpanQuery[bclauses.Length];
// For all clauses e.g. one* two~
for (int i = 0; i < bclauses.Length; i++)
{
// HashSet bclauseterms=new HashSet();
Query qc = bclauses[i].Query;
// Rewrite this clause e.g one* becomes (one OR onerous)
qc = qc.Rewrite(reader);
if (bclauses[i].Occur.Equals(Occur.MUST_NOT))
{
numNegatives++;
}
if (qc is BooleanQuery)
{
List<SpanQuery> sc = new List<SpanQuery>();
AddComplexPhraseClause(sc, (BooleanQuery)qc);
if (sc.Count > 0)
{
allSpanClauses[i] = sc[0];
}
else
{
// Insert fake term e.g. phrase query was for "Fred Smithe*" and
// there were no "Smithe*" terms - need to
// prevent match on just "Fred".
allSpanClauses[i] = new SpanTermQuery(new Term(Field,
"Dummy clause because no terms found - must match nothing"));
}
}
else
{
if (qc is TermQuery)
{
TermQuery tq = (TermQuery)qc;
allSpanClauses[i] = new SpanTermQuery(tq.Term);
}
else
{
throw new ArgumentException("Unknown query type \""
+ qc.GetType()
+ "\" found in phrase query string \""
+ PhrasedQueryStringContents + "\"");
}
}
}
if (numNegatives == 0)
{
// The simple case - no negative elements in phrase
return new SpanNearQuery(allSpanClauses, SlopFactor, true);
}
// Complex case - we have mixed positives and negatives in the
// sequence.
// Need to return a SpanNotQuery
List<SpanQuery> positiveClauses = new List<SpanQuery>();
for (int j = 0; j < allSpanClauses.Length; j++)
{
if (!bclauses[j].Occur.Equals(Occur.MUST_NOT))
{
positiveClauses.Add(allSpanClauses[j]);
}
}
//SpanQuery[] includeClauses = positiveClauses.ToArray(new SpanQuery[positiveClauses.Count]);
SpanQuery[] includeClauses = positiveClauses.ToArray();
SpanQuery include = null;
if (includeClauses.Length == 1)
{
include = includeClauses[0]; // only one positive clause
}
else
{
// need to increase slop factor based on gaps introduced by
// negatives
include = new SpanNearQuery(includeClauses, SlopFactor + numNegatives,
true);
}
// Use sequence of positive and negative values as the exclude.
SpanNearQuery exclude = new SpanNearQuery(allSpanClauses, SlopFactor,
true);
SpanNotQuery snot = new SpanNotQuery(include, exclude);
return snot;
}
private void AddComplexPhraseClause(List<SpanQuery> spanClauses, BooleanQuery qc)
{
List<SpanQuery> ors = new List<SpanQuery>();
List<SpanQuery> nots = new List<SpanQuery>();
BooleanClause[] bclauses = qc.GetClauses();
// For all clauses e.g. one* two~
for (int i = 0; i < bclauses.Length; i++)
{
Query childQuery = bclauses[i].Query;
// select the list to which we will add these options
List<SpanQuery> chosenList = ors;
if (bclauses[i].Occur == Occur.MUST_NOT)
{
chosenList = nots;
}
if (childQuery is TermQuery)
{
TermQuery tq = (TermQuery)childQuery;
SpanTermQuery stq = new SpanTermQuery(tq.Term);
stq.Boost = tq.Boost;
chosenList.Add(stq);
}
else if (childQuery is BooleanQuery)
{
BooleanQuery cbq = (BooleanQuery)childQuery;
AddComplexPhraseClause(chosenList, cbq);
}
else
{
// TODO alternatively could call extract terms here?
throw new ArgumentException("Unknown query type:"
+ childQuery.GetType());
}
}
if (ors.Count == 0)
{
return;
}
SpanOrQuery soq = new SpanOrQuery(ors.ToArray());
if (nots.Count == 0)
{
spanClauses.Add(soq);
}
else
{
SpanOrQuery snqs = new SpanOrQuery(nots.ToArray());
SpanNotQuery snq = new SpanNotQuery(soq, snqs);
spanClauses.Add(snq);
}
}
public override String ToString(String field)
{
return "\"" + PhrasedQueryStringContents + "\"";
}
public override int GetHashCode()
{
const int prime = 31;
int result = 1;
result = prime * result + ((Field == null) ? 0 : Field.GetHashCode());
result = prime
* result
+ ((PhrasedQueryStringContents == null) ? 0
: PhrasedQueryStringContents.GetHashCode());
result = prime * result + SlopFactor;
return result;
}
public override Boolean Equals(Object obj)
{
if (this == obj)
return true;
if (obj == null)
return false;
if (GetType() != obj.GetType())
return false;
ComplexPhraseQuery other = (ComplexPhraseQuery)obj;
if (Field == null)
{
if (other.Field != null)
return false;
}
else if (!Field.Equals(other.Field))
return false;
if (PhrasedQueryStringContents == null)
{
if (other.PhrasedQueryStringContents != null)
return false;
}
else if (!PhrasedQueryStringContents
.Equals(other.PhrasedQueryStringContents))
return false;
if (SlopFactor != other.SlopFactor)
return false;
return true;
}
}
}
来源：https://stackoverflow.com/questions/28094280/complex-phrases-and-or-complexphrasequeryparser-in-lucene-net