/**

 * Copyright 2002-2004 The Apache Software Foundation

 *

 * Licensed 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.

 */

#ifndef _lucene_search_highlight_querytermextractor_

#define _lucene_search_highlight_querytermextractor_

#if defined(_LUCENE_PRAGMA_ONCE)

# pragma once

#endif

#include "CLucene/util/VoidList.h"

#include "CLucene/search/SearchHeader.h"

#include "CLucene/index/IndexReader.h"

#include "CLucene/search/BooleanQuery.h"

#include "CLucene/search/PhraseQuery.h"

#include "CLucene/search/TermQuery.h"

#include "CLucene/highlighter/WeightedTerm.h"

CL_NS_DEF2(search,highlight)

/**

 * Utility class used to extract the terms used in a query, plus any weights.

 * This class will not find terms for MultiTermQuery, RangeQuery and PrefixQuery classes

 * so the caller must pass a rewritten query (see Query.rewrite) to obtain a list of 

 * expanded terms. 

 * 

 */

class QueryTermExtractor

{

	QueryTermExtractor(){

	}

public:

	/**

	 * Extracts all terms texts of a given Query into an array of WeightedTerms

	 *

	 * @param query      Query to extract term texts from

	 * @return an array of the terms used in a query, plus their weights.

	 */

	static WeightedTerm** getTerms(const Query *query);

	/**

	 * Extracts all terms texts of a given Query into an array of WeightedTerms

	 *

	 * @param query      Query to extract term texts from

	 * @param reader used to compute IDF which can be used to a) score selected fragments better 

	 * b) use graded highlights eg chaning intensity of font color

	 * @param fieldName the field on which Inverse Document Frequency (IDF) calculations are based

	 * @return an array of the terms used in a query, plus their weights.

	 */

	 static WeightedTerm** getIdfWeightedTerms(const Query* query, CL_NS(index)::IndexReader* reader, const TCHAR* fieldName);

	/**

	 * Extracts all terms texts of a given Query into an array of WeightedTerms

	 *

	 * @param query      Query to extract term texts from

	 * @param prohibited <code>true</code> to extract "prohibited" terms, too

     * @return an array of the terms used in a query, plus their weights.Memory owned by the caller

     */

	static WeightedTerm** getTerms(const Query * query, bool prohibited);

	static void getTerms(const Query * query, WeightedTermList* terms,bool prohibited);

	static void getTermsFromBooleanQuery(const BooleanQuery * query, WeightedTermList* terms, bool prohibited);

	static void getTermsFromPhraseQuery(const PhraseQuery * query, WeightedTermList* terms);

	static void getTermsFromTermQuery(const TermQuery * query, WeightedTermList* terms);

//	static void getTermsFromSpanNearQuery(SpanNearQuery* query, WeightedTermList* terms);

};

CL_NS_END2

#endif