1 /**

     2  * Copyright 2002-2004 The Apache Software Foundation

     3  *

     4  * Licensed under the Apache License, Version 2.0 (the "License");

     5  * you may not use this file except in compliance with the License.

     6  * You may obtain a copy of the License at

     7  *

     8  *     http://www.apache.org/licenses/LICENSE-2.0

     9  *

    10  * Unless required by applicable law or agreed to in writing, software

    11  * distributed under the License is distributed on an "AS IS" BASIS,

    12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    13  * See the License for the specific language governing permissions and

    14  * limitations under the License.

    15  */

    16 #ifndef _lucene_search_highlight_querytermextractor_

    17 #define _lucene_search_highlight_querytermextractor_

    18 

    19 #if defined(_LUCENE_PRAGMA_ONCE)

    20 # pragma once

    21 #endif

    22 

    23 #include "CLucene/util/VoidList.h"

    24 #include "CLucene/search/SearchHeader.h"

    25 #include "CLucene/index/IndexReader.h"

    26 #include "CLucene/search/BooleanQuery.h"

    27 #include "CLucene/search/PhraseQuery.h"

    28 #include "CLucene/search/TermQuery.h"

    29 #include "CLucene/highlighter/WeightedTerm.h"

    30 

    31 CL_NS_DEF2(search,highlight)

    32 

    33 /**

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

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

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

    37  * expanded terms. 

    38  * 

    39  */

    40 class QueryTermExtractor

    41 {

    42 	QueryTermExtractor(){

    43 	}

    44 public:

    45 

    46 	/**

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

    48 	 *

    49 	 * @param query      Query to extract term texts from

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

    51 	 */

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

    53 

    54 	/**

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

    56 	 *

    57 	 * @param query      Query to extract term texts from

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

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

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

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

    62 	 */

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

    64 

    65 	/**

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

    67 	 *

    68 	 * @param query      Query to extract term texts from

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

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

    71      */

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

    73 

    74 

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

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

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

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

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

    80 };

    81 

    82 CL_NS_END2

    83 

    84 

    85 

    86 #endif