/**
 * 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.
 */

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

PARSER_BEGIN(QueryParser)

package Lucene.Net.QueryParsers;

import java.util.Vector;
import java.io.*;
import java.text.*;
import java.util.*;
import Lucene.Net.Index.Term;
import Lucene.Net.Analysis.*;
import Lucene.Net.Documents.*;
import Lucene.Net.Search.*;
import Lucene.Net.Util.Parameter;

/**
 * This class is generated by JavaCC.  The most important method is
 * {@link #parse(String)}.
 *
 * The syntax for query strings is as follows:
 * A Query is a series of clauses.
 * A clause may be prefixed by:
 * <ul>
 * <li> a plus (<code>+</code>) or a minus (<code>-</code>) sign, indicating
 * that the clause is required or prohibited respectively; or
 * <li> a term followed by a colon, indicating the field to be searched.
 * This enables one to construct queries which search multiple fields.
 * </ul>
 *
 * A clause may be either:
 * <ul>
 * <li> a term, indicating all the documents that contain this term; or
 * <li> a nested query, enclosed in parentheses.  Note that this may be used
 * with a <code>+</code>/<code>-</code> prefix to require any of a set of
 * terms.
 * </ul>
 *
 * Thus, in BNF, the query grammar is:
 * <pre>
 *   Query  ::= ( Clause )*
 *   Clause ::= ["+", "-"] [&lt;TERM&gt; ":"] ( &lt;TERM&gt; | "(" Query ")" )
 * </pre>
 *
 * <p>
 * Examples of appropriately formatted queries can be found in the <a
 * href="http://lucene.apache.org/java/docs/queryparsersyntax.html">query syntax
 * documentation</a>.
 * </p>
 *
 * <p>
 * In {@link RangeQuery}s, QueryParser tries to detect date values, e.g.
 * <tt>date:[6/1/2005 TO 6/4/2005]</tt> produces a range query that searches
 * for "date" fields between 2005-06-01 and 2005-06-04. Note that the format
 * of the accepted input depends on {@link #setLocale(Locale) the locale}.
 * By default a date is converted into a search term using the deprecated
 * {@link DateField} for compatibility reasons.
 * To use the new {@link DateTools} to convert dates, a
 * {@link DateTools.Resolution} has to be set.
 * </p>
 * <p>
 * The date resolution that shall be used for RangeQueries can be set
 * using {@link #setDateResolution(DateTools.Resolution)}
 * or {@link #setDateResolution(String, DateTools.Resolution)}. The former
 * sets the default date resolution for all fields, whereas the latter can
 * be used to set field specific date resolutions. Field specific date
 * resolutions take, if set, precedence over the default date resolution.
 * </p>
 * <p>
 * If you use neither {@link DateField} nor {@link DateTools} in your
 * index, you can create your own
 * query parser that inherits QueryParser and overwrites
 * {@link #getRangeQuery(String, String, String, boolean)} to
 * use a different method for date conversion.
 * </p>
 *
 * <p>Note that QueryParser is <em>not</em> thread-safe.</p>
 *
 * @author Brian Goetz
 * @author Peter Halacsy
 * @author Tatu Saloranta
 */
public class QueryParser {

  private static final int CONJ_NONE   = 0;
  private static final int CONJ_AND    = 1;
  private static final int CONJ_OR     = 2;

  private static final int MOD_NONE    = 0;
  private static final int MOD_NOT     = 10;
  private static final int MOD_REQ     = 11;

  // make it possible to call setDefaultOperator() without accessing 
  // the nested class:
  /** Alternative form of QueryParser.Operator.AND */
  public static final Operator AND_OPERATOR = Operator.AND;
  /** Alternative form of QueryParser.Operator.OR */
  public static final Operator OR_OPERATOR = Operator.OR;

  /** The actual operator that parser uses to combine query terms */
  private Operator operator = OR_OPERATOR;

  boolean lowercaseExpandedTerms = true;
  boolean useOldRangeQuery= false;  
  boolean allowLeadingWildcard = false;

  Analyzer analyzer;
  String field;
  int phraseSlop = 0;
  float fuzzyMinSim = FuzzyQuery.defaultMinSimilarity;
  int fuzzyPrefixLength = FuzzyQuery.defaultPrefixLength;
  Locale locale = Locale.getDefault();

  // the default date resolution
  DateTools.Resolution dateResolution = null;
  // maps field names to date resolutions
  Map fieldToDateResolution = null;

  /** The default operator for parsing queries. 
   * Use {@link QueryParser#setDefaultOperator} to change it.
   */
  static public final class Operator extends Parameter {
    private Operator(String name) {
      super(name);
    }
    static public final Operator OR = new Operator("OR");
    static public final Operator AND = new Operator("AND");
  }


  /** Constructs a query parser.
   *  @param f  the default field for query terms.
   *  @param a   used to find terms in the query text.
   */
  public QueryParser(String f, Analyzer a) {
    this(new FastCharStream(new StringReader("")));
    analyzer = a;
    field = f;
  }

  /** Parses a query string, returning a {@link Lucene.Net.Search.Query}.
   *  @param query  the query string to be parsed.
   *  @throws ParseException if the parsing fails
   */
  public Query parse(String query) throws ParseException {
    ReInit(new FastCharStream(new StringReader(query)));
    try {
      return Query(field);
    }
    catch (ParseException tme) {
      // rethrow to include the original query:
      throw new ParseException("Cannot parse '" +query+ "': " + tme.getMessage());
    }
    catch (TokenMgrError tme) {
      throw new ParseException("Cannot parse '" +query+ "': " + tme.getMessage());
    }
    catch (BooleanQuery.TooManyClauses tmc) {
      throw new ParseException("Cannot parse '" +query+ "': too many boolean clauses");
    }
  }
  
   /**
   * @return Returns the analyzer.
   */
  public Analyzer getAnalyzer() {
    return analyzer;
  }
  
  /**
   * @return Returns the field.
   */
  public String getField() {
    return field;
  }
  
   /**
   * Get the minimal similarity for fuzzy queries.
   */
  public float getFuzzyMinSim() {
      return fuzzyMinSim;
  }
  
  /**
   * Set the minimum similarity for fuzzy queries.
   * Default is 0.5f.
   */
  public void setFuzzyMinSim(float fuzzyMinSim) {
      this.fuzzyMinSim = fuzzyMinSim;
  }
  
   /**
   * Get the prefix length for fuzzy queries. 
   * @return Returns the fuzzyPrefixLength.
   */
  public int getFuzzyPrefixLength() {
    return fuzzyPrefixLength;
  }
  
  /**
   * Set the prefix length for fuzzy queries. Default is 0.
   * @param fuzzyPrefixLength The fuzzyPrefixLength to set.
   */
  public void setFuzzyPrefixLength(int fuzzyPrefixLength) {
    this.fuzzyPrefixLength = fuzzyPrefixLength;
  }

  /**
   * Sets the default slop for phrases.  If zero, then exact phrase matches
   * are required.  Default value is zero.
   */
  public void setPhraseSlop(int phraseSlop) {
    this.phraseSlop = phraseSlop;
  }

  /**
   * Gets the default slop for phrases.
   */
  public int getPhraseSlop() {
    return phraseSlop;
  }


  /**
   * Set to <code>true</code> to allow <code>*</code> and <code>?</code> as the first character 
   * of a PrefixQuery and WildcardQuery. Note that this can produce very slow
   * queries on big indexes. Default: false.
   */
  public void setAllowLeadingWildcard(boolean allowLeadingWildcard) {
    this.allowLeadingWildcard = allowLeadingWildcard;
  }

  /**
   * @see #setAllowLeadingWildcard
   */
  public boolean getAllowLeadingWildcard() {
    return allowLeadingWildcard;
  }

  /**
   * Sets the boolean operator of the QueryParser.
   * In default mode (<code>OR_OPERATOR</code>) terms without any modifiers
   * are considered optional: for example <code>capital of Hungary</code> is equal to
   * <code>capital OR of OR Hungary</code>.<br/>
   * In <code>AND_OPERATOR</code> mode terms are considered to be in conjuction: the
   * above mentioned query is parsed as <code>capital AND of AND Hungary</code>
   */
  public void setDefaultOperator(Operator op) {
    this.operator = op;
  }


  /**
   * Gets implicit operator setting, which will be either AND_OPERATOR
   * or OR_OPERATOR.
   */
  public Operator getDefaultOperator() {
    return operator;
  }


  /**
   * Whether terms of wildcard, prefix, fuzzy and range queries are to be automatically
   * lower-cased or not.  Default is <code>true</code>.
   */
  public void setLowercaseExpandedTerms(boolean lowercaseExpandedTerms) {
    this.lowercaseExpandedTerms = lowercaseExpandedTerms;
  }


  /**
   * @see #setLowercaseExpandedTerms(boolean)
   */
  public boolean getLowercaseExpandedTerms() {
    return lowercaseExpandedTerms;
  }
  
  /**
   * By default QueryParser uses new ConstantScoreRangeQuery in preference to RangeQuery
   * for range queries. This implementation is generally preferable because it 
   * a) Runs faster b) Does not have the scarcity of range terms unduly influence score 
   * c) avoids any "TooManyBooleanClauses" exception.
   * However, if your application really needs to use the old-fashioned RangeQuery and the above
   * points are not required then set this option to <code>true</code>
   * Default is <code>false</code>.
   */
  public void setUseOldRangeQuery(boolean useOldRangeQuery) {
    this.useOldRangeQuery = useOldRangeQuery;
  }


  /**
   * @see #setUseOldRangeQuery(boolean)
   */
  public boolean getUseOldRangeQuery() {
    return useOldRangeQuery;
  }
  

  /**
   * Set locale used by date range parsing.
   */
  public void setLocale(Locale locale) {
    this.locale = locale;
  }

  /**
   * Returns current locale, allowing access by subclasses.
   */
  public Locale getLocale() {
    return locale;
  }

  /**
   * Sets the default date resolution used by RangeQueries for fields for which no
   * specific date resolutions has been set. Field specific resolutions can be set
   * with {@link #setDateResolution(String, DateTools.Resolution)}.
   *  
   * @param dateResolution the default date resolution to set
   */
  public void setDateResolution(DateTools.Resolution dateResolution) {
    this.dateResolution = dateResolution;
  }
  
  /**
   * Sets the date resolution used by RangeQueries for a specific field.
   *  
   * @param field field for which the date resolution is to be set 
   * @param dateResolution date resolution to set
   */
  public void setDateResolution(String fieldName, DateTools.Resolution dateResolution) {
    if (fieldName == null) {
      throw new IllegalArgumentException("Field cannot be null.");
    }
    
    if (fieldToDateResolution == null) {
      // lazily initialize HashMap
      fieldToDateResolution = new HashMap();
    }
    
    fieldToDateResolution.put(fieldName, dateResolution);
  }

  /**
   * Returns the date resolution that is used by RangeQueries for the given field. 
   * Returns null, if no default or field specific date resolution has been set
   * for the given field.
   *
   */
  public DateTools.Resolution getDateResolution(String fieldName) {
    if (fieldName == null) {
      throw new IllegalArgumentException("Field cannot be null.");
    }
    
    if (fieldToDateResolution == null) {
      // no field specific date resolutions set; return default date resolution instead
      return this.dateResolution;
    }
    
    DateTools.Resolution resolution = (DateTools.Resolution) fieldToDateResolution.get(fieldName);
    if (resolution == null) {
      // no date resolutions set for the given field; return default date resolution instead
      resolution = this.dateResolution;
    }
    
    return resolution;
  }

  protected void addClause(Vector clauses, int conj, int mods, Query q) {
    boolean required, prohibited;

    // If this term is introduced by AND, make the preceding term required,
    // unless it's already prohibited
    if (clauses.size() > 0 && conj == CONJ_AND) {
      BooleanClause c = (BooleanClause) clauses.elementAt(clauses.size()-1);
      if (!c.isProhibited())
        c.setOccur(BooleanClause.Occur.MUST);
    }

    if (clauses.size() > 0 && operator == AND_OPERATOR && conj == CONJ_OR) {
      // If this term is introduced by OR, make the preceding term optional,
      // unless it's prohibited (that means we leave -a OR b but +a OR b-->a OR b)
      // notice if the input is a OR b, first term is parsed as required; without
      // this modification a OR b would parsed as +a OR b
      BooleanClause c = (BooleanClause) clauses.elementAt(clauses.size()-1);
      if (!c.isProhibited())
        c.setOccur(BooleanClause.Occur.SHOULD);
    }

    // We might have been passed a null query; the term might have been
    // filtered away by the analyzer.
    if (q == null)
      return;

    if (operator == OR_OPERATOR) {
      // We set REQUIRED if we're introduced by AND or +; PROHIBITED if
      // introduced by NOT or -; make sure not to set both.
      prohibited = (mods == MOD_NOT);
      required = (mods == MOD_REQ);
      if (conj == CONJ_AND && !prohibited) {
        required = true;
      }
    } else {
      // We set PROHIBITED if we're introduced by NOT or -; We set REQUIRED
      // if not PROHIBITED and not introduced by OR
      prohibited = (mods == MOD_NOT);
      required   = (!prohibited && conj != CONJ_OR);
    }
    if (required && !prohibited)
      clauses.addElement(new BooleanClause(q, BooleanClause.Occur.MUST));
    else if (!required && !prohibited)
      clauses.addElement(new BooleanClause(q, BooleanClause.Occur.SHOULD));
    else if (!required && prohibited)
      clauses.addElement(new BooleanClause(q, BooleanClause.Occur.MUST_NOT));
    else
      throw new RuntimeException("Clause cannot be both required and prohibited");
  }


  /**
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getFieldQuery(String field, String queryText)  throws ParseException {
    // Use the analyzer to get all the tokens, and then build a TermQuery,
    // PhraseQuery, or nothing based on the term count

    TokenStream source = analyzer.tokenStream(field, new StringReader(queryText));
    Vector v = new Vector();
    Lucene.Net.Analysis.Token t;
    int positionCount = 0;
    boolean severalTokensAtSamePosition = false;

    while (true) {
      try {
        t = source.next();
      }
      catch (IOException e) {
        t = null;
      }
      if (t == null)
        break;
      v.addElement(t);
      if (t.getPositionIncrement() != 0)
        positionCount += t.getPositionIncrement();
      else
        severalTokensAtSamePosition = true;
    }
    try {
      source.close();
    }
    catch (IOException e) {
      // ignore
    }

    if (v.size() == 0)
      return null;
    else if (v.size() == 1) {
      t = (Lucene.Net.Analysis.Token) v.elementAt(0);
      return new TermQuery(new Term(field, t.termText()));
    } else {
      if (severalTokensAtSamePosition) {
        if (positionCount == 1) {
          // no phrase query:
          BooleanQuery q = new BooleanQuery(true);
          for (int i = 0; i < v.size(); i++) {
            t = (Lucene.Net.Analysis.Token) v.elementAt(i);
            TermQuery currentQuery = new TermQuery(
                new Term(field, t.termText()));
            q.add(currentQuery, BooleanClause.Occur.SHOULD);
          }
          return q;
        }
        else {
          // phrase query:
          MultiPhraseQuery mpq = new MultiPhraseQuery();
          mpq.setSlop(phraseSlop);          
          List multiTerms = new ArrayList();
          for (int i = 0; i < v.size(); i++) {
            t = (Lucene.Net.Analysis.Token) v.elementAt(i);
            if (t.getPositionIncrement() == 1 && multiTerms.size() > 0) {
              mpq.add((Term[])multiTerms.toArray(new Term[0]));
              multiTerms.clear();
            }
            multiTerms.add(new Term(field, t.termText()));
          }
          mpq.add((Term[])multiTerms.toArray(new Term[0]));
          return mpq;
        }
      }
      else {
        PhraseQuery q = new PhraseQuery();
        q.setSlop(phraseSlop);
        for (int i = 0; i < v.size(); i++) {
          q.add(new Term(field, ((Lucene.Net.Analysis.Token) 
              v.elementAt(i)).termText()));

        }
        return q;
      }
    }
  }


  /**
   * Base implementation delegates to {@link #getFieldQuery(String,String)}.
   * This method may be overridden, for example, to return
   * a SpanNearQuery instead of a PhraseQuery.
   *
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getFieldQuery(String field, String queryText, int slop) 
  	throws ParseException {
    Query query = getFieldQuery(field, queryText);

    if (query instanceof PhraseQuery) {
      ((PhraseQuery) query).setSlop(slop);
    }
    if (query instanceof MultiPhraseQuery) {
      ((MultiPhraseQuery) query).setSlop(slop);
    }

    return query;
  }


  /**
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getRangeQuery(String field,
                                String part1,
                                String part2,
                                boolean inclusive) throws ParseException
  {
    if (lowercaseExpandedTerms) {
      part1 = part1.toLowerCase();
      part2 = part2.toLowerCase();
    }
    try {
      DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT, locale);
      df.setLenient(true);
      Date d1 = df.parse(part1);
      Date d2 = df.parse(part2);
      if (inclusive) {
        // The user can only specify the date, not the time, so make sure
        // the time is set to the latest possible time of that date to really
        // include all documents:
        Calendar cal = Calendar.getInstance(locale);
        cal.setTime(d2);
        cal.set(Calendar.HOUR_OF_DAY, 23);
        cal.set(Calendar.MINUTE, 59);
        cal.set(Calendar.SECOND, 59);
        cal.set(Calendar.MILLISECOND, 999);
        d2 = cal.getTime();
      }
      DateTools.Resolution resolution = getDateResolution(field);
      if (resolution == null) {
        // no default or field specific date resolution has been set,
        // use deprecated DateField to maintain compatibilty with
        // pre-1.9 Lucene versions.
        part1 = DateField.dateToString(d1);
        part2 = DateField.dateToString(d2);
      } else {
        part1 = DateTools.dateToString(d1, resolution);
        part2 = DateTools.dateToString(d2, resolution);
      }
    }
    catch (Exception e) { }

    if(useOldRangeQuery)
    {
	    return new RangeQuery(new Term(field, part1),
                          new Term(field, part2),
                          inclusive);
    }
    else
    {
      return new ConstantScoreRangeQuery(field,part1,part2,inclusive,inclusive);
    }
  }

  /**
   * Factory method for generating query, given a set of clauses.
   * By default creates a boolean query composed of clauses passed in.
   *
   * Can be overridden by extending classes, to modify query being
   * returned.
   *
   * @param clauses Vector that contains {@link BooleanClause} instances
   *    to join.
   *
   * @return Resulting {@link Query} object.
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getBooleanQuery(Vector clauses) throws ParseException {
    return getBooleanQuery(clauses, false);
  }

  /**
   * Factory method for generating query, given a set of clauses.
   * By default creates a boolean query composed of clauses passed in.
   *
   * Can be overridden by extending classes, to modify query being
   * returned.
   *
   * @param clauses Vector that contains {@link BooleanClause} instances
   *    to join.
   * @param disableCoord true if coord scoring should be disabled.
   *
   * @return Resulting {@link Query} object.
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getBooleanQuery(Vector clauses, boolean disableCoord)
    throws ParseException
  {
    BooleanQuery query = new BooleanQuery(disableCoord);
    for (int i = 0; i < clauses.size(); i++) {
  query.add((BooleanClause)clauses.elementAt(i));
    }
    return query;
  }

  /**
   * Factory method for generating a query. Called when parser
   * parses an input term token that contains one or more wildcard
   * characters (? and *), but is not a prefix term token (one
   * that has just a single * character at the end)
   *<p>
   * Depending on settings, prefix term may be lower-cased
   * automatically. It will not go through the default Analyzer,
   * however, since normal Analyzers are unlikely to work properly
   * with wildcard templates.
   *<p>
   * Can be overridden by extending classes, to provide custom handling for
   * wildcard queries, which may be necessary due to missing analyzer calls.
   *
   * @param field Name of the field query will use.
   * @param termStr Term token that contains one or more wild card
   *   characters (? or *), but is not simple prefix term
   *
   * @return Resulting {@link Query} built for the term
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getWildcardQuery(String field, String termStr) throws ParseException
  {
    if ("*".equals(field)) {
      if ("*".equals(termStr)) return new MatchAllDocsQuery();
    }
    if (!allowLeadingWildcard && (termStr.startsWith("*") || termStr.startsWith("?")))
      throw new ParseException("'*' or '?' not allowed as first character in WildcardQuery");
    if (lowercaseExpandedTerms) {
      termStr = termStr.toLowerCase();
    }
    Term t = new Term(field, termStr);
    return new WildcardQuery(t);
  }

  /**
   * Factory method for generating a query (similar to
   * {@link #getWildcardQuery}). Called when parser parses an input term
   * token that uses prefix notation; that is, contains a single '*' wildcard
   * character as its last character. Since this is a special case
   * of generic wildcard term, and such a query can be optimized easily,
   * this usually results in a different query object.
   *<p>
   * Depending on settings, a prefix term may be lower-cased
   * automatically. It will not go through the default Analyzer,
   * however, since normal Analyzers are unlikely to work properly
   * with wildcard templates.
   *<p>
   * Can be overridden by extending classes, to provide custom handling for
   * wild card queries, which may be necessary due to missing analyzer calls.
   *
   * @param field Name of the field query will use.
   * @param termStr Term token to use for building term for the query
   *    (<b>without</b> trailing '*' character!)
   *
   * @return Resulting {@link Query} built for the term
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getPrefixQuery(String field, String termStr) throws ParseException
  {
    if (!allowLeadingWildcard && termStr.startsWith("*"))
      throw new ParseException("'*' not allowed as first character in PrefixQuery");
    if (lowercaseExpandedTerms) {
      termStr = termStr.toLowerCase();
    }
    Term t = new Term(field, termStr);
    return new PrefixQuery(t);
  }

  
   /**
   * Factory method for generating a query (similar to
   * {@link #getWildcardQuery}). Called when parser parses
   * an input term token that has the fuzzy suffix (~) appended.
   *
   * @param field Name of the field query will use.
   * @param termStr Term token to use for building term for the query
   *
   * @return Resulting {@link Query} built for the term
   * @exception ParseException throw in overridden method to disallow
   */
  protected Query getFuzzyQuery(String field, String termStr, float minSimilarity) throws ParseException
  {
    if (lowercaseExpandedTerms) {
      termStr = termStr.toLowerCase();
    }
    Term t = new Term(field, termStr);
    return new FuzzyQuery(t, minSimilarity, fuzzyPrefixLength);
  }

  /**
   * Returns a String where the escape char has been
   * removed, or kept only once if there was a double escape.
   * 
   * Supports escaped unicode characters, e. g. translates
   * <code>\u0041</code> to <code>A</code>.
   * 
   */
  private String discardEscapeChar(String input) throws ParseException {
    // Create char array to hold unescaped char sequence
    char[] output = new char[input.length()];
      
    // The length of the output can be less than the input
    // due to discarded escape chars. This variable holds
    // the actual length of the output
    int length = 0;
      
    // We remember whether the last processed character was 
    // an escape character
    boolean lastCharWasEscapeChar = false;
      
    // The multiplier the current unicode digit must be multiplied with.
    // E. g. the first digit must be multiplied with 16^3, the second with 16^2...
    int codePointMultiplier = 0;
      
    // Used to calculate the codepoint of the escaped unicode character
    int codePoint = 0;
      
    for (int i = 0; i < input.length(); i++) {
      char curChar = input.charAt(i);
      if (codePointMultiplier > 0) {
        codePoint += hexToInt(curChar) * codePointMultiplier;
        codePointMultiplier >>>= 4;
        if (codePointMultiplier == 0) {
          output[length++] = (char)codePoint;
          codePoint = 0;
        }
      } else if (lastCharWasEscapeChar) {
        if (curChar == 'u') {
          // found an escaped unicode character
          codePointMultiplier = 16 * 16 * 16;
        } else { 
          // this character was escaped
          output[length] = curChar;    
          length++;
        }
        lastCharWasEscapeChar = false;
      } else {
        if (curChar == '\\') {
          lastCharWasEscapeChar = true;
        } else {
          output[length] = curChar;
          length++;
        }
      }
    }
      
    if (codePointMultiplier > 0) {
      throw new ParseException("Truncated unicode escape sequence.");
    }
    
    if (lastCharWasEscapeChar) {
      throw new ParseException("Term can not end with escape character.");
    }
      
    return new String(output, 0, length);
  }
  
  /** Returns the numeric value of the hexadecimal character */
  private static final int hexToInt(char c) throws ParseException {
    if ('0' <= c && c <= '9') {
      return c - '0';
    } else if ('a' <= c && c <= 'f'){
      return c - 'a' + 10;
    } else if ('A' <= c && c <= 'F') {
      return c - 'A' + 10;
    } else {
      throw new ParseException("None-hex character in unicode escape sequence: " + c);
    }
  }
  
  /**
   * Returns a String where those characters that QueryParser
   * expects to be escaped are escaped by a preceding <code>\</code>.
   */
  public static String escape(String s) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < s.length(); i++) {
      char c = s.charAt(i);
      // NOTE: keep this in sync with _ESCAPED_CHAR below!
      if (c == '\\' || c == '+' || c == '-' || c == '!' || c == '(' || c == ')' || c == ':'
        || c == '^' || c == '[' || c == ']' || c == '\"' || c == '{' || c == '}' || c == '~'
        || c == '*' || c == '?') {
        sb.append('\\');
      }
      sb.append(c);
    }
    return sb.toString();
  }

  /**
   * Command line tool to test QueryParser, using {@link Lucene.Net.Analysis.SimpleAnalyzer}.
   * Usage:<br>
   * <code>java Lucene.Net.QueryParsers.QueryParser &lt;input&gt;</code>
   */
  public static void main(String[] args) throws Exception {
    if (args.length == 0) {
      System.out.println("Usage: java Lucene.Net.QueryParsers.QueryParser <input>");
      System.exit(0);
    }
    QueryParser qp = new QueryParser("field",
                           new Lucene.Net.Analysis.SimpleAnalyzer());
    Query q = qp.parse(args[0]);
    System.out.println(q.toString("field"));
  }
}

PARSER_END(QueryParser)

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

<*> TOKEN : {
  <#_NUM_CHAR:   ["0"-"9"] >
// NOTE: keep this in sync with escape(String) above!
| <#_ESCAPED_CHAR: "\\" [ "\\", "+", "-", "!", "(", ")", ":", "^",
                          "[", "]", "\"", "{", "}", "~", "*", "?" ] >
| <#_TERM_START_CHAR: ( ~[ " ", "\t", "\n", "\r", "+", "-", "!", "(", ")", ":", "^",
                           "[", "]", "\"", "{", "}", "~", "*", "?" ]
                       | <_ESCAPED_CHAR> ) >
| <#_TERM_CHAR: ( <_TERM_START_CHAR> | <_ESCAPED_CHAR> | "-" | "+" ) >
| <#_WHITESPACE: ( " " | "\t" | "\n" | "\r") >
}

<DEFAULT, RangeIn, RangeEx> SKIP : {
  < <_WHITESPACE>>
}

<DEFAULT> TOKEN : {
  <AND:       ("AND" | "&&") >
| <OR:        ("OR" | "||") >
| <NOT:       ("NOT" | "!") >
| <PLUS:      "+" >
| <MINUS:     "-" >
| <LPAREN:    "(" >
| <RPAREN:    ")" >
| <COLON:     ":" >
| <STAR:      "*" >
| <CARAT:     "^" > : Boost
| <QUOTED:     "\"" (~["\""] | "\\\"")+ "\"">
| <TERM:      <_TERM_START_CHAR> (<_TERM_CHAR>)*  >
| <FUZZY_SLOP:     "~" ( (<_NUM_CHAR>)+ ( "." (<_NUM_CHAR>)+ )? )? >
| <PREFIXTERM:  (<_TERM_START_CHAR> | "*") (<_TERM_CHAR>)* "*" >
| <WILDTERM:  (<_TERM_START_CHAR> | [ "*", "?" ]) (<_TERM_CHAR> | ( [ "*", "?" ] ))* >
| <RANGEIN_START: "[" > : RangeIn
| <RANGEEX_START: "{" > : RangeEx
}

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

<RangeIn> TOKEN : {
<RANGEIN_TO: "TO">
| <RANGEIN_END: "]"> : DEFAULT
| <RANGEIN_QUOTED: "\"" (~["\""] | "\\\"")+ "\"">
| <RANGEIN_GOOP: (~[ " ", "]" ])+ >
}

<RangeEx> TOKEN : {
<RANGEEX_TO: "TO">
| <RANGEEX_END: "}"> : DEFAULT
| <RANGEEX_QUOTED: "\"" (~["\""] | "\\\"")+ "\"">
| <RANGEEX_GOOP: (~[ " ", "}" ])+ >
}

// *   Query  ::= ( Clause )*
// *   Clause ::= ["+", "-"] [<TERM> ":"] ( <TERM> | "(" Query ")" )

int Conjunction() : {
  int ret = CONJ_NONE;
}
{
  [
    <AND> { ret = CONJ_AND; }
    | <OR>  { ret = CONJ_OR; }
  ]
  { return ret; }
}

int Modifiers() : {
  int ret = MOD_NONE;
}
{
  [
     <PLUS> { ret = MOD_REQ; }
     | <MINUS> { ret = MOD_NOT; }
     | <NOT> { ret = MOD_NOT; }
  ]
  { return ret; }
}

Query Query(String field) :
{
  Vector clauses = new Vector();
  Query q, firstQuery=null;
  int conj, mods;
}
{
  mods=Modifiers() q=Clause(field)
  {
    addClause(clauses, CONJ_NONE, mods, q);
    if (mods == MOD_NONE)
        firstQuery=q;
  }
  (
    conj=Conjunction() mods=Modifiers() q=Clause(field)
    { addClause(clauses, conj, mods, q); }
  )*
    {
      if (clauses.size() == 1 && firstQuery != null)
        return firstQuery;
      else {
  return getBooleanQuery(clauses);
      }
    }
}

Query Clause(String field) : {
  Query q;
  Token fieldToken=null, boost=null;
}
{
  [
    LOOKAHEAD(2)
    (
    fieldToken=<TERM> <COLON> {field=discardEscapeChar(fieldToken.image);}
    | <STAR> <COLON> {field="*";}
    )
  ]

  (
   q=Term(field)
   | <LPAREN> q=Query(field) <RPAREN> (<CARAT> boost=<NUMBER>)?

  )
    {
      if (boost != null) {
        float f = (float)1.0;
  try {
    f = Float.valueOf(boost.image).floatValue();
          q.setBoost(f);
  } catch (Exception ignored) { }
      }
      return q;
    }
}


Query Term(String field) : {
  Token term, boost=null, fuzzySlop=null, goop1, goop2;
  boolean prefix = false;
  boolean wildcard = false;
  boolean fuzzy = false;
  boolean rangein = false;
  Query q;
}
{
  (
     (
       term=<TERM>
       | term=<STAR> { wildcard=true; }
       | term=<PREFIXTERM> { prefix=true; }
       | term=<WILDTERM> { wildcard=true; }
       | term=<NUMBER>
     )
     [ fuzzySlop=<FUZZY_SLOP> { fuzzy=true; } ]
     [ <CARAT> boost=<NUMBER> [ fuzzySlop=<FUZZY_SLOP> { fuzzy=true; } ] ]
     {
       String termImage=discardEscapeChar(term.image);
       if (wildcard) {
       q = getWildcardQuery(field, termImage);
       } else if (prefix) {
         q = getPrefixQuery(field,
           discardEscapeChar(term.image.substring
          (0, term.image.length()-1)));
       } else if (fuzzy) {
       	  float fms = fuzzyMinSim;
       	  try {
            fms = Float.valueOf(fuzzySlop.image.substring(1)).floatValue();
       	  } catch (Exception ignored) { }
       	 if(fms < 0.0f || fms > 1.0f){
       	   throw new ParseException("Minimum similarity for a FuzzyQuery has to be between 0.0f and 1.0f !");
       	 }
       	 q = getFuzzyQuery(field, termImage,fms);
       } else {
         q = getFieldQuery(field, termImage);
       }
     }
     | ( <RANGEIN_START> ( goop1=<RANGEIN_GOOP>|goop1=<RANGEIN_QUOTED> )
         [ <RANGEIN_TO> ] ( goop2=<RANGEIN_GOOP>|goop2=<RANGEIN_QUOTED> )
         <RANGEIN_END> )
       [ <CARAT> boost=<NUMBER> ]
        {
          if (goop1.kind == RANGEIN_QUOTED) {
            goop1.image = goop1.image.substring(1, goop1.image.length()-1);
          }
          if (goop2.kind == RANGEIN_QUOTED) {
            goop2.image = goop2.image.substring(1, goop2.image.length()-1);
          }
          q = getRangeQuery(field, discardEscapeChar(goop1.image), discardEscapeChar(goop2.image), true);
        }
     | ( <RANGEEX_START> ( goop1=<RANGEEX_GOOP>|goop1=<RANGEEX_QUOTED> )
         [ <RANGEEX_TO> ] ( goop2=<RANGEEX_GOOP>|goop2=<RANGEEX_QUOTED> )
         <RANGEEX_END> )
       [ <CARAT> boost=<NUMBER> ]
        {
          if (goop1.kind == RANGEEX_QUOTED) {
            goop1.image = goop1.image.substring(1, goop1.image.length()-1);
          }
          if (goop2.kind == RANGEEX_QUOTED) {
            goop2.image = goop2.image.substring(1, goop2.image.length()-1);
          }

          q = getRangeQuery(field, discardEscapeChar(goop1.image), discardEscapeChar(goop2.image), false);
        }
     | term=<QUOTED>
       [ fuzzySlop=<FUZZY_SLOP> ]
       [ <CARAT> boost=<NUMBER> ]
       {
         int s = phraseSlop;

         if (fuzzySlop != null) {
           try {
             s = Float.valueOf(fuzzySlop.image.substring(1)).intValue();
           }
           catch (Exception ignored) { }
         }
         q = getFieldQuery(field, discardEscapeChar(term.image.substring(1, term.image.length()-1)), s);
       }
  )
  {
    if (boost != null) {
      float f = (float) 1.0;
      try {
        f = Float.valueOf(boost.image).floatValue();
      }
      catch (Exception ignored) {
    /* Should this be handled somehow? (defaults to "no boost", if
     * boost number is invalid)
     */
      }

      // avoid boosting null queries, such as those caused by stop words
      if (q != null) {
        q.setBoost(f);
      }
    }
    return q;
  }
}