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Lucene example source code file (QueryParser.jj)

This example Lucene source code file (QueryParser.jj) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

and, arraylist, arraylist, fieldsquery, fieldsquerylist, io, or, parseexception, parseexception, srndquery, srndquery, string, token, token, util, w

The Lucene QueryParser.jj source code

/**
 * 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.
 */

/* Surround query language parser */

/* Query language operators: OR, AND, NOT, W, N, (, ), ^, *, ?, " and comma */


options {
  STATIC=false;
  JAVA_UNICODE_ESCAPE=true;
  USER_CHAR_STREAM=true;
}

PARSER_BEGIN(QueryParser)

package org.apache.lucene.queryParser.surround.parser;

import java.util.ArrayList;
import java.util.List;
import java.io.StringReader;


import org.apache.lucene.analysis.TokenStream;

import org.apache.lucene.queryParser.surround.query.SrndQuery;
import org.apache.lucene.queryParser.surround.query.FieldsQuery;
import org.apache.lucene.queryParser.surround.query.OrQuery;
import org.apache.lucene.queryParser.surround.query.AndQuery;
import org.apache.lucene.queryParser.surround.query.NotQuery;
import org.apache.lucene.queryParser.surround.query.DistanceQuery;
import org.apache.lucene.queryParser.surround.query.SrndTermQuery;
import org.apache.lucene.queryParser.surround.query.SrndPrefixQuery;
import org.apache.lucene.queryParser.surround.query.SrndTruncQuery;

/**
 * This class is generated by JavaCC.  The only method that clients should need
 * to call is <a href="#parse">parse().
 */

public class QueryParser {
  final int minimumPrefixLength = 3;
  final int minimumCharsInTrunc = 3;
  final String truncationErrorMessage = "Too unrestrictive truncation: ";
  final String boostErrorMessage = "Cannot handle boost value: ";
 
  /* CHECKME: These should be the same as for the tokenizer. How? */
  final char truncator = '*';
  final char anyChar = '?';
  final char quote = '\"';
  final char fieldOperator = ':';
  final char comma = ','; /* prefix list separator */
  final char carat = '^'; /* weight operator */
 
  static public SrndQuery parse(String query) throws ParseException {
    QueryParser parser = new QueryParser();
    return parser.parse2(query);
  }

  public QueryParser() {
    this(new FastCharStream(new StringReader("")));
  }

  public SrndQuery parse2(String query) throws ParseException {
    ReInit(new FastCharStream(new StringReader(query)));
    try {
      return TopSrndQuery();
    } catch (TokenMgrError tme) {
      throw new ParseException(tme.getMessage());
    }
  }
    
  protected SrndQuery getFieldsQuery(
      SrndQuery q, ArrayList<String> fieldNames) {
    /* FIXME: check acceptable subquery: at least one subquery should not be
     * a fields query.
     */
    return new FieldsQuery(q, fieldNames, fieldOperator);
  }
  
  protected SrndQuery getOrQuery(List<SrndQuery> queries, boolean infix, Token orToken) {
    return new OrQuery(queries, infix, orToken.image);
  }

  protected SrndQuery getAndQuery(List<SrndQuery> queries, boolean infix, Token andToken) {
    return new AndQuery( queries, infix, andToken.image);
  }
  
  protected SrndQuery getNotQuery(List<SrndQuery> queries, Token notToken) {
    return new NotQuery( queries, notToken.image);
  }
  
  protected static int getOpDistance(String distanceOp) {
    /* W, 2W, 3W etc -> 1, 2 3, etc. Same for N, 2N ... */
    return distanceOp.length() == 1 
      ? 1
      : Integer.parseInt( distanceOp.substring( 0, distanceOp.length() - 1));
  }
  
  protected static void checkDistanceSubQueries(DistanceQuery distq, String opName)
  throws ParseException {
    String m = distq.distanceSubQueryNotAllowed();
    if (m != null) {
      throw new ParseException("Operator " + opName + ": " + m);
    }
  }
  
  protected SrndQuery getDistanceQuery(
        List<SrndQuery> queries,
        boolean infix,
        Token dToken,
        boolean ordered) throws ParseException {
    DistanceQuery dq = new DistanceQuery(queries,
                                        infix,
                                        getOpDistance(dToken.image),
                                        dToken.image,
                                        ordered);
    checkDistanceSubQueries(dq, dToken.image);
    return dq;
  }

  protected SrndQuery getTermQuery(
        String term, boolean quoted) {
    return new SrndTermQuery(term, quoted);
  }

  protected boolean allowedSuffix(String suffixed) {
    return (suffixed.length() - 1) >= minimumPrefixLength;
  }

  protected SrndQuery getPrefixQuery(
      String prefix, boolean quoted) {
    return new SrndPrefixQuery(prefix, quoted, truncator);
  }
  
  protected boolean allowedTruncation(String truncated) {
    /* At least 3 normal characters needed. */
    int nrNormalChars = 0;
    for (int i = 0; i < truncated.length(); i++) {
      char c = truncated.charAt(i);
      if ((c != truncator) && (c != anyChar)) {
        nrNormalChars++;
      }
    }
    return nrNormalChars >= minimumCharsInTrunc;
  }

  protected SrndQuery getTruncQuery(String truncated) {
    return new SrndTruncQuery(truncated, truncator, anyChar);
  }
}

PARSER_END(QueryParser)

/* ***************** */
/* Token Definitions */
/* ***************** */

<*> TOKEN : {
  <#_NUM_CHAR:   ["0"-"9"] >
| <#_TERM_CHAR: /* everything except whitespace and operators */
    ( ~[ " ", "\t", "\n", "\r",
          ",", "?", "*", "(", ")", ":", "^", "\""]
     ) >
| <#_WHITESPACE: ( " " | "\t" | "\n" | "\r" ) >
| <#_STAR:       "*" > /* term truncation */
| <#_ONE_CHAR:   "?" > /* precisely one character in a term */
/* 2..99 prefix for distance operators */
| <#_DISTOP_NUM: ((["2"-"9"](["0"-"9"])?) | ("1" ["0"-"9"]))> 
}

<DEFAULT> SKIP : {
  < <_WHITESPACE>>
}

/* Operator tokens (in increasing order of precedence): */
<DEFAULT> TOKEN :
{
  <OR:        "OR" | "or"> 
| <AND:       "AND" | "and">
| <NOT:       "NOT" | "not">
| <W:         (<_DISTOP_NUM>)? ("W"|"w")>
| <N:         (<_DISTOP_NUM>)? ("N"|"n")>
/* These are excluded in _TERM_CHAR: */
| <LPAREN:    "(">
| <RPAREN:    ")">
| <COMMA:     ",">
| <COLON:     ":">
| <CARAT:     "^"> : Boost
/* Literal non empty term between single quotes,
 * escape quoted quote or backslash by backslash.
 * Evt. truncated.
 */
| <TRUNCQUOTED: "\"" (~["\""])+ "\"" <_STAR>>
| <QUOTED:      "\"" ( (~["\"", "\\"]) | ("\\" ["\\", "\""]))+ "\"">
| <SUFFIXTERM: (<_TERM_CHAR>)+ <_STAR>>
| <TRUNCTERM:  (<_TERM_CHAR>)+
               (<_STAR> | <_ONE_CHAR> )+ /* at least one * or ? */
               (<_TERM_CHAR> | <_STAR>  | <_ONE_CHAR> )*
               >
| <TERM:       (<_TERM_CHAR>)+>
}

<Boost> TOKEN : {
<NUMBER:    (<_NUM_CHAR>)+ ( "." (<_NUM_CHAR>)+ )?> : DEFAULT
}


SrndQuery TopSrndQuery() : {
  SrndQuery q;
}{
  q = FieldsQuery()
  <EOF>
  {return q;}
}


SrndQuery FieldsQuery() : {
  SrndQuery q;
  ArrayList<String> fieldNames;
}{
  fieldNames = OptionalFields()
  q = OrQuery()
  {return (fieldNames == null) ? q : getFieldsQuery(q, fieldNames);}
}


ArrayList<String> OptionalFields() : {
  Token fieldName;
  ArrayList<String> fieldNames = null;
}{
  ( LOOKAHEAD(2) // to the colon
    fieldName = <TERM>
    <COLON> {
      if (fieldNames == null) {
        fieldNames = new ArrayList<String>();
      }
      fieldNames.add(fieldName.image);
    }
  )*
  {return fieldNames;}
}


SrndQuery OrQuery() : {
  SrndQuery q;
  ArrayList<SrndQuery> queries = null;
  Token oprt = null;
}{
  q = AndQuery()
  ( oprt = <OR> { /* keep only last used operator */
      if (queries == null) {
        queries = new ArrayList<SrndQuery>();
        queries.add(q);
      }
    }    
    q = AndQuery() {
      queries.add(q);
    }
  )*
  {return (queries == null) ? q : getOrQuery(queries, true /* infix */, oprt);}
}


SrndQuery AndQuery() : {
  SrndQuery q;
  ArrayList<SrndQuery> queries = null;
  Token oprt = null;
}{
  q = NotQuery()
  ( oprt = <AND> { /* keep only last used operator */
      if (queries == null) {
        queries = new ArrayList<SrndQuery>();
        queries.add(q);
      }
    }
    q = NotQuery() {
      queries.add(q);
    }
  )* 
  {return (queries == null) ? q : getAndQuery(queries, true /* infix */, oprt);}
}


SrndQuery NotQuery() : {
  SrndQuery q;
  ArrayList<SrndQuery> queries = null;
  Token oprt = null;
}{
  q = NQuery()
  ( oprt = <NOT>  { /* keep only last used operator */
      if (queries == null) {
        queries = new ArrayList<SrndQuery>();
        queries.add(q);
      }
    }
    q = NQuery() {
      queries.add(q);
    }
  )*
  {return (queries == null) ? q : getNotQuery(queries, oprt);}
}


SrndQuery NQuery() : {
  SrndQuery q;
  ArrayList<SrndQuery> queries;
  Token dt;
}{
  q = WQuery()
  ( dt = <N> {
      queries = new ArrayList<SrndQuery>();
      queries.add(q); /* left associative */
    }
    q = WQuery() {
      queries.add(q);
      q = getDistanceQuery(queries, true /* infix */, dt, false /* not ordered */); 
    }
  )* 
  {return q;}
}


SrndQuery WQuery() : {
  SrndQuery q;
  ArrayList<SrndQuery> queries;
  Token wt;
}{
  q = PrimaryQuery()
  ( wt = <W> {
      queries = new ArrayList<SrndQuery>();
      queries.add(q); /* left associative */
    }
    q = PrimaryQuery() {
      queries.add(q); 
      q = getDistanceQuery(queries, true /* infix */, wt, true /* ordered */); 
    }
  )* 
  {return q;}
}


SrndQuery PrimaryQuery() : { /* bracketed weighted query or weighted term */
  SrndQuery q;
}{
  ( <LPAREN> q = FieldsQuery() 
  | q = PrefixOperatorQuery()
  | q = SimpleTerm()
  )
  OptionalWeights(q)
  {return q;}
}


SrndQuery PrefixOperatorQuery() : {
  Token oprt;
  List<SrndQuery> queries;
}{
  ( oprt = <OR> /* prefix OR */
    queries = FieldsQueryList()
    {return getOrQuery(queries, false /* not infix */, oprt);}
      
  | oprt = <AND> /* prefix AND */
    queries = FieldsQueryList()
    {return getAndQuery(queries, false /* not infix */, oprt);}
  
  | oprt = <N> /* prefix N */
    queries = FieldsQueryList()
    {return getDistanceQuery(queries, false /* not infix */, oprt, false /* not ordered */);}
    
  | oprt = <W> /* prefix W */
    queries = FieldsQueryList()
    {return getDistanceQuery(queries, false  /* not infix */, oprt, true /* ordered */);}
  )
}


List<SrndQuery> FieldsQueryList() : {
  SrndQuery q;
  ArrayList<SrndQuery> queries = new ArrayList();
}{
  <LPAREN>
  q = FieldsQuery() {queries.add(q);}
  (<COMMA> q = FieldsQuery() {queries.add(q);})+
  <RPAREN>
  {return queries;}
}


SrndQuery SimpleTerm() : {
  Token term;
}{
  ( term=<TERM>
    {return getTermQuery(term.image, false /* not quoted */);}
      
  | term=<QUOTED>
    {return getTermQuery(term.image.substring(1, term.image.length()-1), true /* quoted */);}
      
  | term=<SUFFIXTERM> { /* ending in * */
      if (! allowedSuffix(term.image)) {
        throw new ParseException(truncationErrorMessage + term.image);
      }
      return getPrefixQuery(term.image.substring(0, term.image.length()-1), false /* not quoted */);
    }
      
  | term=<TRUNCTERM> { /* with at least one * or ? */
      if (! allowedTruncation(term.image)) {
        throw new ParseException(truncationErrorMessage + term.image);
      }
      return getTruncQuery(term.image);
    }
      
  | term=<TRUNCQUOTED> { /* eg. "9b-b,m"* */
      if ((term.image.length() - 3) < minimumPrefixLength) {
        throw new ParseException(truncationErrorMessage + term.image);
      }
      return getPrefixQuery(term.image.substring(1, term.image.length()-2), true /* quoted */);
    }
  )
}


void OptionalWeights(SrndQuery q) : {
  Token weight=null;
}{
  ( <CARAT> weight= {
      float f;
      try {
        f = Float.valueOf(weight.image).floatValue();
      } catch (Exception floatExc) {
        throw new ParseException(boostErrorMessage + weight.image + " (" + floatExc + ")");
      }
      if (f <= 0.0) {
        throw new ParseException(boostErrorMessage + weight.image);
      }      
      q.setWeight(f * q.getWeight()); /* left associative, fwiw */
    }
  )*
}

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