Revised internal search APIs. Changes include:

a. Queries are no longer modified during a search.  This makes
  it possible, e.g., to reuse the same query instance with
  multiple indexes from multiple threads.

  b. Term-expanding queries (e.g. PrefixQuery, WildcardQuery,
  etc.)  now work correctly with MultiSearcher, fixing bugs 12619
  and 12667.

  c. Boosting BooleanQuery's now works, and is supported by the
  query parser (problem reported by Lee Mallabone).  Thus a query
  like "(+foo +bar)^2 +baz" is now supported and equivalent to
  "(+foo^2 +bar^2) +baz".

  d. New method: Query.rewrite(IndexReader).  This permits a
  query to re-write itself as an alternate, more primitive query.
  Most of the term-expanding query classes (PrefixQuery,
  WildcardQuery, etc.) are now implemented using this method.

  e. New method: Searchable.explain(Query q, int doc).  This
  returns an Explanation instance that describes how a particular
  document is scored against a query.  An explanation can be
  displayed as either plain text, with the toString() method, or
  as HTML, with the toHtml() method.  Note that computing an
  explanation is as expensive as executing the query over the
  entire index.  This is intended to be used in developing
  Similarity implementations, and, for good performance, should
  not be displayed with every hit.

  f. Scorer and Weight are public, not package protected.  It now
  possible for someone to write a Scorer implementation that is
  not in the org.apache.lucene.search package.  This is still
  fairly advanced programming, and I don't expect anyone to do
  this anytime soon, but at least now it is possible.

Caution: These are extensive changes and they have not yet been
tested extensively.  Bug reports are appreciated.


git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@149922 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -104,6 +104,45 @@ $Id$
  21. Added getFields(String) and getValues(String) methods.
      (Rasik Pandey via otis)
 
+ 22. Revised internal search APIs.  Changes include:
+
+       a. Queries are no longer modified during a search.  This makes
+       it possible, e.g., to reuse the same query instance with
+       multiple indexes from multiple threads.
+
+       b. Term-expanding queries (e.g. PrefixQuery, WildcardQuery,
+       etc.)  now work correctly with MultiSearcher, fixing bugs 12619
+       and 12667.
+
+       c. Boosting BooleanQuery's now works, and is supported by the
+       query parser (problem reported by Lee Mallabone).  Thus a query
+       like "(+foo +bar)^2 +baz" is now supported and equivalent to
+       "(+foo^2 +bar^2) +baz".
+
+       d. New method: Query.rewrite(IndexReader).  This permits a
+       query to re-write itself as an alternate, more primitive query.
+       Most of the term-expanding query classes (PrefixQuery,
+       WildcardQuery, etc.) are now implemented using this method.
+
+       e. New method: Searchable.explain(Query q, int doc).  This
+       returns an Explanation instance that describes how a particular
+       document is scored against a query.  An explanation can be
+       displayed as either plain text, with the toString() method, or
+       as HTML, with the toHtml() method.  Note that computing an
+       explanation is as expensive as executing the query over the
+       entire index.  This is intended to be used in developing
+       Similarity implementations, and, for good performance, should
+       not be displayed with every hit.
+
+       f. Scorer and Weight are public, not package protected.  It now
+       possible for someone to write a Scorer implementation that is
+       not in the org.apache.lucene.search package.  This is still
+       fairly advanced programming, and I don't expect anyone to do
+       this anytime soon, but at least now it is possible.
+
+     Caution: These are extensive changes and they have not yet been
+     tested extensively.  Bug reports are appreciated.
+
 
   Contributed by Rasik Pandey on 2002-10-09
 1.2 RC6

default.properties

@@ -10,7 +10,7 @@ Name=Lucene
 version=1.3-dev1
 year=2000-2002
 final.name=${name}-${version}
-debug=off
+debug=on
 
 project.name = site
 docs.src =  ./xdocs

src/java/org/apache/lucene/index/Term.java

@@ -116,9 +116,7 @@ public final class Term implements java.io.Serializable {
     text = txt;
   }
 
-  public final String toString() {
+  public final String toString() { return field + ":" + text; }
-    return "Term<" + field + ":" + text + ">";
-  }
   
   private void readObject(java.io.ObjectInputStream in) 
     throws java.io.IOException, ClassNotFoundException

src/java/org/apache/lucene/queryParser/QueryParser.jj

@@ -433,7 +433,7 @@ Query Query(String field) :
 
 Query Clause(String field) : {
   Query q;
-  Token fieldToken=null;
+  Token fieldToken=null, boost=null;
 }
 {
   [
@@ -443,9 +443,17 @@ Query Clause(String field) : {
 
   (
    q=Term(field)
-   | <LPAREN> q=Query(field) <RPAREN>
+   | <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;
     }
 }

src/java/org/apache/lucene/search/BooleanClause.java

@@ -72,4 +72,20 @@ public class BooleanClause implements java.io.Serializable {
     required = r;
     prohibited = p;
   }
+
+  /** Returns true iff <code>o</code> is equal to this. */
+  public boolean equals(Object o) {
+    if (!(o instanceof BooleanClause))
+      return false;
+    BooleanClause other = (BooleanClause)o;
+    return this.query.equals(other.query)
+      && (this.required == other.required)
+      && (this.prohibited == other.prohibited);
+  }
+
+  /** Returns a hash code value for this object.*/
+  public int hashCode() {
+    return query.hashCode() ^ (this.required?1:0) ^ (this.prohibited?2:0);
+  }
+
 }

src/java/org/apache/lucene/search/BooleanQuery.java

@@ -88,60 +88,95 @@ public class BooleanQuery extends Query {
     clauses.addElement(clause);
   }
 
-  void prepare(IndexReader reader) {
+  /** Returns the set of clauses in this query. */
-    for (int i = 0 ; i < clauses.size(); i++) {
+  public BooleanClause[] getClauses() {
-      BooleanClause c = (BooleanClause)clauses.elementAt(i);
+    return (BooleanClause[])clauses.toArray(new BooleanClause[0]);
-      c.query.prepare(reader);
-    }
   }
 
-  float sumOfSquaredWeights(Searcher searcher)
+  private class BooleanWeight implements Weight {
-       throws IOException {
+    private Searcher searcher;
-    float sum = 0.0f;
+    private float norm;
+    private Vector weights = new Vector();
 
-    for (int i = 0 ; i < clauses.size(); i++) {
+    public BooleanWeight(Searcher searcher) {
-      BooleanClause c = (BooleanClause)clauses.elementAt(i);
+      this.searcher = searcher;
-      if (!c.prohibited)
+      for (int i = 0 ; i < clauses.size(); i++) {
-	sum += c.query.sumOfSquaredWeights(searcher); // sum sub-query weights
+        BooleanClause c = (BooleanClause)clauses.elementAt(i);
+        weights.add(c.query.createWeight(searcher));
+      }
+    }
+
+    public Query getQuery() { return BooleanQuery.this; }
+    public float getValue() { return getBoost(); }
+
+    public float sumOfSquaredWeights() throws IOException {
+      float sum = 0.0f;
+      for (int i = 0 ; i < weights.size(); i++) {
+        BooleanClause c = (BooleanClause)clauses.elementAt(i);
+        Weight w = (Weight)weights.elementAt(i);
+        if (!c.prohibited)
+          sum += w.sumOfSquaredWeights();         // sum sub weights
+      }
+      
+      sum *= getBoost() * getBoost();             // boost each sub-weight
+
+      return sum ;
+    }
+
+
+    public void normalize(float norm) {
+      norm *= getBoost();                         // incorporate boost
+      for (int i = 0 ; i < weights.size(); i++) {
+        BooleanClause c = (BooleanClause)clauses.elementAt(i);
+        Weight w = (Weight)weights.elementAt(i);
+        if (!c.prohibited)
+          w.normalize(norm);
+      }
+    }
+
+    public Scorer scorer(IndexReader reader) throws IOException {
+      if (weights.size() == 1) {                  // optimize 1-clause queries
+        BooleanClause c = (BooleanClause)clauses.elementAt(0);
+        Weight w = (Weight)weights.elementAt(0);
+        if (!c.prohibited)			  // just return clause scorer
+          return w.scorer(reader);
+      }
+
+      BooleanScorer result = new BooleanScorer(searcher.getSimilarity());
+
+      for (int i = 0 ; i < weights.size(); i++) {
+        BooleanClause c = (BooleanClause)clauses.elementAt(0);
+        Weight w = (Weight)weights.elementAt(i);
+        Scorer subScorer = w.scorer(reader);
+        if (subScorer != null)
+          result.add(subScorer, c.required, c.prohibited);
+        else if (c.required)
+          return null;
+      }
+
+      return result;
+    }
+
+    public Explanation explain() throws IOException {
+      Explanation result = new Explanation();
+      result.setDescription("boost(" + getQuery() + ")");
+      result.setValue(getBoost());
+      return result;
     }
 
-    return sum;
   }
 
-  void normalize(float norm) {
+  protected Weight createWeight(Searcher searcher) {
-    for (int i = 0 ; i < clauses.size(); i++) {
+    return new BooleanWeight(searcher);
-      BooleanClause c = (BooleanClause)clauses.elementAt(i);
-      if (!c.prohibited)
-	c.query.normalize(norm);
-    }
-  }
-
-  Scorer scorer(IndexReader reader, Similarity similarity)
-       throws IOException {
-
-    if (clauses.size() == 1) {			  // optimize 1-term queries
-      BooleanClause c = (BooleanClause)clauses.elementAt(0);
-      if (!c.prohibited)			  // just return term scorer
-	return c.query.scorer(reader, similarity);
-    }
-
-    BooleanScorer result = new BooleanScorer(similarity);
-
-    for (int i = 0 ; i < clauses.size(); i++) {
-      BooleanClause c = (BooleanClause)clauses.elementAt(i);
-      Scorer subScorer = c.query.scorer(reader, similarity);
-      if (subScorer != null)
-	result.add(subScorer, c.required, c.prohibited);
-      else if (c.required)
-	return null;
-    }
-
-    return result;
   }
 
   /** Prints a user-readable version of this query. */
   public String toString(String field) {
     StringBuffer buffer = new StringBuffer();
+    if (getBoost() > 1.0) {
+      buffer.append("(");
+    }
+
     for (int i = 0 ; i < clauses.size(); i++) {
       BooleanClause c = (BooleanClause)clauses.elementAt(i);
       if (c.prohibited)
@@ -160,7 +195,27 @@ public class BooleanQuery extends Query {
       if (i != clauses.size()-1)
 	buffer.append(" ");
     }
+
+    if (getBoost() > 1.0) {
+      buffer.append(")^");
+      buffer.append(getBoost());
+    }
+
     return buffer.toString();
   }
 
+  /** Returns true iff <code>o</code> is equal to this. */
+  public boolean equals(Object o) {
+    if (!(o instanceof BooleanQuery))
+      return false;
+    BooleanQuery other = (BooleanQuery)o;
+    return (this.getBoost() == other.getBoost())
+      &&  this.clauses.equals(other.clauses);
+  }
+
+  /** Returns a hash code value for this object.*/
+  public int hashCode() {
+    return Float.floatToIntBits(getBoost()) ^ clauses.hashCode();
+  }
+
 }

src/java/org/apache/lucene/search/BooleanScorer.java

@@ -117,10 +117,11 @@ final class BooleanScorer extends Scorer {
   private final void computeCoordFactors() throws IOException {
     coordFactors = new float[maxCoord];
     for (int i = 0; i < maxCoord; i++)
-      coordFactors[i] = getSimilarity().coord(i, maxCoord);
+      coordFactors[i] = getSimilarity().coord(i, maxCoord-1);
   }
 
-  final void score(HitCollector results, int maxDoc) throws IOException {
+  public final void score(HitCollector results, int maxDoc)
+    throws IOException {
     if (coordFactors == null)
       computeCoordFactors();
 
@@ -205,4 +206,43 @@ final class BooleanScorer extends Scorer {
       }
     }
   }
+
+  public Explanation explain(int doc) throws IOException {
+    Explanation sumExpl = new Explanation();
+    sumExpl.setDescription("sum of:");
+    int coord = 0;
+    float sum = 0.0f;
+    for (SubScorer s = scorers; s != null; s = s.next) {
+      Explanation e = s.scorer.explain(doc);
+      if (e.getValue() > 0) {
+        if (!s.prohibited) {
+          sumExpl.addDetail(e);
+          sum += e.getValue();
+          coord++;
+        } else {
+          return new Explanation(0.0f, "match prohibited");
+        }
+      } else if (s.required) {
+        return new Explanation(0.0f, "match required");
+      }
+    }
+    sumExpl.setValue(sum);
+
+    if (coord == 1)                               // only one clause matched
+      sumExpl = sumExpl.getDetails()[0];          // eliminate wrapper
+
+    float coordFactor = getSimilarity().coord(coord, maxCoord-1);
+    if (coordFactor == 1.0f)                      // coord is no-op
+      return sumExpl;                             // eliminate wrapper
+    else {
+      Explanation result = new Explanation();
+      result.setDescription("product of:");
+      result.addDetail(sumExpl);
+      result.addDetail(new Explanation(coordFactor,
+                                       "coord("+coord+"/"+(maxCoord-1)+")"));
+      result.setValue(sum*coordFactor);
+      return result;
+    }
+  }
+
 }

src/java/org/apache/lucene/search/ExactPhraseScorer.java

@@ -61,9 +61,9 @@ import org.apache.lucene.index.*;
 
 final class ExactPhraseScorer extends PhraseScorer {
 
-  ExactPhraseScorer(TermPositions[] tps, Similarity similarity,
+  ExactPhraseScorer(Weight weight, TermPositions[] tps, Similarity similarity,
-                    byte[] norms, float weight) throws IOException {
+                    byte[] norms) throws IOException {
-    super(tps, similarity, norms, weight);
+    super(weight, tps, similarity, norms);
   }
 
   protected final float phraseFreq() throws IOException {

src/java/org/apache/lucene/search/Explanation.java

@@ -0,0 +1,145 @@
+package org.apache.lucene.search;
+
+/* ====================================================================
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2003 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Apache" and "Apache Software Foundation" and
+ *    "Apache Lucene" must not be used to endorse or promote products
+ *    derived from this software without prior written permission. For
+ *    written permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache",
+ *    "Apache Lucene", nor may "Apache" appear in their name, without
+ *    prior written permission of the Apache Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+import java.util.ArrayList;
+
+/** Expert: Describes the score computation for document and query. */
+public class Explanation implements java.io.Serializable {
+  private float value;                            // the value of this node
+  private String description;                     // what it represents
+  private ArrayList details;                      // sub-explanations
+
+  public Explanation() {}
+
+  public Explanation(float value, String description) {
+    this.value = value;
+    this.description = description;
+  }
+
+  /** The value assigned to this explanation node. */
+  public float getValue() { return value; }
+  /** Sets the value assigned to this explanation node. */
+  public void setValue(float value) { this.value = value; }
+
+  /** A description of this explanation node. */
+  public String getDescription() { return description; }
+  /** Sets the description of this explanation node. */
+  public void setDescription(String description) {
+    this.description = description;
+  }
+
+  /** The sub-nodes of this explanation node. */
+  public Explanation[] getDetails() {
+    if (details == null)
+      return null;
+    return (Explanation[])details.toArray(new Explanation[0]);
+  }
+
+  /** Adds a sub-node to this explanation node. */
+  public void addDetail(Explanation detail) {
+    if (details == null)
+      details = new ArrayList();
+    details.add(detail);
+  }
+
+  /** Render an explanation as HTML. */
+  public String toString() {
+    return toString(0);
+  }
+  private String toString(int depth) {
+    StringBuffer buffer = new StringBuffer();
+    for (int i = 0; i < depth; i++) {
+      buffer.append("  ");
+    }
+    buffer.append(getValue());
+    buffer.append(" = ");
+    buffer.append(getDescription());
+    buffer.append("\n");
+
+    Explanation[] details = getDetails();
+    if (details != null) {
+      for (int i = 0 ; i < details.length; i++) {
+        buffer.append(details[i].toString(depth+1));
+      }
+    }
+
+    return buffer.toString();
+  }
+
+
+  /** Render an explanation as HTML. */
+  public String toHtml() {
+    StringBuffer buffer = new StringBuffer();
+    buffer.append("<ul>\n");
+
+    buffer.append("<li>");
+    buffer.append(getValue());
+    buffer.append(" = ");
+    buffer.append(getDescription());
+    buffer.append("</li>\n");
+
+    Explanation[] details = getDetails();
+    if (details != null) {
+      for (int i = 0 ; i < details.length; i++) {
+        buffer.append(details[i].toHtml());
+      }
+    }
+
+    buffer.append("</ul>\n");
+
+    return buffer.toString();
+  }
+}

src/java/org/apache/lucene/search/FuzzyQuery.java

@@ -60,20 +60,15 @@ import java.io.IOException;
 
 /** Implements the fuzzy search query */
 public final class FuzzyQuery extends MultiTermQuery {
-    private Term fuzzyTerm;
+  public FuzzyQuery(Term term) {
+    super(term);
+  }
     
-    public FuzzyQuery(Term term) {
+  protected FilteredTermEnum getEnum(IndexReader reader) throws IOException {
-        super(term);
+    return new FuzzyTermEnum(reader, getTerm());
-        fuzzyTerm = term;
+  }
-    }
     
-    final void prepare(IndexReader reader) {
+  public String toString(String field) {
-        try {
+    return super.toString(field) + '~';
-            setEnum(new FuzzyTermEnum(reader, fuzzyTerm));
+  }
-        } catch (IOException e) {}
-    }
-    
-    public String toString(String field) {
-        return super.toString(field) + '~';
-    }
 }

src/java/org/apache/lucene/search/Hits.java

@@ -93,8 +93,8 @@ public final class Hits {
     ScoreDoc[] scoreDocs = topDocs.scoreDocs;
 
     float scoreNorm = 1.0f;
-    if (length > 0 && scoreDocs[0].score > 1.0f)
+//     if (length > 0 && scoreDocs[0].score > 1.0f)
-      scoreNorm = 1.0f / scoreDocs[0].score;
+//       scoreNorm = 1.0f / scoreDocs[0].score;
 
     int end = scoreDocs.length < length ? scoreDocs.length : length;
     for (int i = hitDocs.size(); i < end; i++)

src/java/org/apache/lucene/search/IndexSearcher.java

@@ -122,7 +122,7 @@ public class IndexSearcher extends Searcher implements Searchable {
    */
   public TopDocs search(Query query, Filter filter, final int nDocs)
        throws IOException {
-    Scorer scorer = Query.scorer(query, this, reader);
+    Scorer scorer = query.weight(this).scorer(reader);
     if (scorer == null)
       return new TopDocs(0, new ScoreDoc[0]);
 
@@ -181,10 +181,25 @@ public class IndexSearcher extends Searcher implements Searchable {
 	};
     }
 
-    Scorer scorer = Query.scorer(query, this, reader);
+    Scorer scorer = query.weight(this).scorer(reader);
     if (scorer == null)
       return;
     scorer.score(collector, reader.maxDoc());
   }
 
+  /** */
+  public Query rewrite(Query original) throws IOException {
+    Query query = original;
+    for (Query rewrittenQuery = query.rewrite(reader); rewrittenQuery != query;
+         rewrittenQuery = query.rewrite(reader)) {
+      query = rewrittenQuery;
+    }
+    return query;
+  }
+
+  /** */
+  public Explanation explain(Query query, int doc) throws IOException {
+    return query.weight(this).scorer(reader).explain(doc);
+  }
+
 }

src/java/org/apache/lucene/search/MultiSearcher.java

@@ -203,4 +203,21 @@ public class MultiSearcher extends Searcher implements Searchable {
 
     }
   }
+  
+  /** */
+  public Query rewrite(Query original) throws IOException {
+    Query[] queries = new Query[searchables.length];
+    for (int i = 0; i < searchables.length; i++) {
+      queries[i] = searchables[i].rewrite(original);
+    }
+    return original.combine(queries);
+  }
+
+
+  /** */
+  public Explanation explain(Query query, int doc) throws IOException {
+    int i = subSearcher(doc);			  // find searcher index
+    return searchables[i].explain(query,doc-starts[i]); // dispatch to searcher
+  }
+
 }

src/java/org/apache/lucene/search/MultiTermQuery.java

@@ -73,81 +73,55 @@ import org.apache.lucene.index.TermEnum;
  * <code>MultiTermQuery</code> to provide {@link WildcardTermEnum} and
  * {@link FuzzyTermEnum}, respectively.
  */
-public class MultiTermQuery extends Query {
+public abstract class MultiTermQuery extends Query {
     private Term term;
-    private FilteredTermEnum enum;
-    private BooleanQuery query;
-    
-    /** Enable or disable lucene style toString(field) format */
-    private static boolean LUCENE_STYLE_TOSTRING = false;
     
     /** Constructs a query for terms matching <code>term</code>. */
     public MultiTermQuery(Term term) {
         this.term = term;
     }
     
-    /** Set the TermEnum to be used */
+    /** Returns the pattern term. */
-    protected void setEnum(FilteredTermEnum enum) {
+    public Term getTerm() { return term; }
-        this.enum = enum;
+
+    /** Construct the enumeration to be used, expanding the pattern term. */
+    protected abstract FilteredTermEnum getEnum(IndexReader reader)
+      throws IOException;
+    
+    public Query rewrite(IndexReader reader) throws IOException {
+      FilteredTermEnum enum = getEnum(reader);
+      BooleanQuery query = new BooleanQuery();
+      try {
+        do {
+          Term t = enum.term();
+          if (t != null) {
+            TermQuery tq = new TermQuery(t);      // found a match
+            tq.setBoost(getBoost() * enum.difference()); // set the boost
+            query.add(tq, false, false);          // add to query
+          }
+        } while (enum.next());
+      } finally {
+        enum.close();
+      }
+      return query;
     }
     
-    final float sumOfSquaredWeights(Searcher searcher) throws IOException {
+    public Query combine(Query[] queries) {
-        return getQuery().sumOfSquaredWeights(searcher);
+      return Query.mergeBooleanQueries(queries);
     }
 
-    final void normalize(float norm) {
-        try {
-            getQuery().normalize(norm);
-        } catch (IOException e) {
-            throw new RuntimeException(e.toString());
-        }
-    }
-    
-    final Scorer scorer(IndexReader reader, Similarity similarity)
-      throws IOException {
-      return getQuery().scorer(reader, similarity);
-    }
-    
-    private final BooleanQuery getQuery() throws IOException {
-        if (query == null) {
-            BooleanQuery q = new BooleanQuery();
-            try {
-                do {
-                    Term t = enum.term();
-                    if (t != null) {
-                        TermQuery tq = new TermQuery(t);	// found a match
-                        tq.setBoost(boost * enum.difference()); // set the boost
-                        q.add(tq, false, false);		// add to q
-                    }
-                } while (enum.next());
-            } finally {
-                enum.close();
-            }
-            query = q;
-        }
-        return query;
-    }
 
     /** Prints a user-readable version of this query. */
     public String toString(String field) {
-        if (!LUCENE_STYLE_TOSTRING) {
-            Query q = null;
-            try {
-                q = getQuery();
-            } catch (Exception e) {}
-            if (q != null) {
-                return "(" + q.toString(field) + ")";
-            }
-        }
         StringBuffer buffer = new StringBuffer();
         if (!term.field().equals(field)) {
             buffer.append(term.field());
             buffer.append(":");
         }
         buffer.append(term.text());
-        if (boost != 1.0f) {
+        if (getBoost() != 1.0f) {
             buffer.append("^");
-            buffer.append(Float.toString(boost));
+            buffer.append(Float.toString(getBoost()));
         }
         return buffer.toString();
     }

src/java/org/apache/lucene/search/PhrasePrefixQuery.java

@@ -62,6 +62,7 @@ import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.MultipleTermPositions;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermPositions;
+import org.apache.lucene.index.TermDocs;
 import org.apache.lucene.search.Query;
 
 /**
@@ -75,180 +76,177 @@ import org.apache.lucene.search.Query;
  * @author Anders Nielsen
  * @version 1.0
  */
-public class PhrasePrefixQuery
+public class PhrasePrefixQuery extends Query {
-    extends Query
+  private String field;
-{
+  private ArrayList termArrays = new ArrayList();
-    private String _field;
-    private ArrayList _termArrays = new ArrayList();
 
-    private float _idf = 0.0f;
+  private float idf = 0.0f;
-    private float _weight = 0.0f;
+  private float weight = 0.0f;
 
-    private int _slop = 0;
+  private int slop = 0;
 
-    /**
+  /* Sets the phrase slop for this query.
-     * Creates a new <code>PhrasePrefixQuery</code> instance.
+   * @see PhraseQuery#setSlop(int)
-     *
+   */
-     */
+  public void setSlop(int s) { slop = s; }
-    public PhrasePrefixQuery()
+
-    {
+  /* Sets the phrase slop for this query.
+   * @see PhraseQuery#getSlop()
+   */
+  public int getSlop() { return slop; }
+
+  /* Add a single term at the next position in the phrase.
+   * @see PhraseQuery#add(Term)
+   */
+  public void add(Term term) { add(new Term[]{term}); }
+
+  /* Add multiple terms at the next position in the phrase.  Any of the terms
+   * may match.
+   *
+   * @see PhraseQuery#add(Term)
+   */
+  public void add(Term[] terms) {
+    if (termArrays.size() == 0)
+      field = terms[0].field();
+    
+    for (int i=0; i<terms.length; i++) {
+      if (terms[i].field() != field) {
+        throw new IllegalArgumentException
+          ("All phrase terms must be in the same field (" + field + "): "
+           + terms[i]);
+      }
     }
 
-    /**
+    termArrays.add(terms);
-     * Describe <code>setSlop</code> method here.
+  }
-     *
+
-     * @param s an <code>int</code> value
+  private class PhrasePrefixWeight implements Weight {
-     */
+    private Searcher searcher;
-    public void setSlop(int s)
+    private float value;
-    {
+    private float idf;
-	_slop = s;
+    private float queryNorm;
+
+    public PhrasePrefixWeight(Searcher searcher) {
+      this.searcher = searcher;
     }
 
-    /**
+    public Query getQuery() { return PhrasePrefixQuery.this; }
-     * Describe <code>getSlop</code> method here.
+    public float getValue() { return value; }
-     *
+
-     * @return an <code>int</code> value
+    public float sumOfSquaredWeights() throws IOException {
-     */
+      Iterator i = termArrays.iterator();
-    public int getSlop()
+      while (i.hasNext()) {
-    {
+        Term[] terms = (Term[])i.next();
-	return _slop;
+        for (int j=0; j<terms.length; j++)
+          idf += searcher.getSimilarity().idf(terms[j], searcher);
+      }
+
+      value = idf * getBoost();
+      return value * value;
     }
 
-    /**
+    public void normalize(float norm) {
-     * Describe <code>add</code> method here.
+      queryNorm = norm;
-     *
+      queryNorm *= idf;                           // factor from document
-     * @param term a <code>Term</code> value
+      value *= queryNorm;                         // normalize for query
-     */
-    public void add(Term term)
-    {
-	add(new Term[]{term});
     }
 
-    /**
+    public Scorer scorer(IndexReader reader) throws IOException {
-     * Describe <code>add</code> method here.
+      if (termArrays.size() == 0)                  // optimize zero-term case
-     *
+        return null;
-     * @param terms a <code>Term[]</code> value
-     */
-    public void add(Term[] terms)
-    {
-	if (_termArrays.size() == 0)
-	    _field = terms[0].field();
     
-      	for (int i=0; i<terms.length; i++)
+      if (termArrays.size() == 1) {                // optimize one-term case
-	{
+        Term[] terms = (Term[])termArrays.get(0);
-	    if (terms[i].field() != _field)
-	    {
-		throw new IllegalArgumentException(
-		    "All phrase terms must be in the same field (" + _field + "): "
-		    + terms[i]);
-	    }
-	}
       
-	_termArrays.add(terms);
+        BooleanScorer bos = new BooleanScorer(searcher.getSimilarity());
+        for (int i=0; i<terms.length; i++) {
+          TermDocs docs = reader.termDocs(terms[i]);
+          if (docs != null)
+            bos.add(new TermScorer(this, docs, searcher.getSimilarity(),
+                                   reader.norms(field)), false, false);
+        }
+      
+        return bos;
+      }
+
+      TermPositions[] tps = new TermPositions[termArrays.size()];
+      for (int i=0; i<tps.length; i++) {
+        Term[] terms = (Term[])termArrays.get(i);
+      
+        TermPositions p;
+        if (terms.length > 1)
+          p = new MultipleTermPositions(reader, terms);
+        else
+          p = reader.termPositions(terms[0]);
+      
+        if (p == null)
+          return null;
+      
+        tps[i] = p;
+      }
+    
+      if (slop == 0)
+        return new ExactPhraseScorer(this, tps, searcher.getSimilarity(),
+                                     reader.norms(field));
+      else
+        return new SloppyPhraseScorer(this, tps, searcher.getSimilarity(),
+                                      slop, reader.norms(field));
     }
     
-    Scorer scorer(IndexReader reader, Similarity similarity)
+    public Explanation explain() throws IOException {
-	throws IOException
+      Query q = getQuery();
-    {
-    	if (_termArrays.size() == 0)  // optimize zero-term case
-	    return null;
 
-	if (_termArrays.size() == 1)  // optimize one-term case
+      Explanation result = new Explanation();
-	{
+      result.setDescription("weight(" + getQuery() + "), product of:");
-	    Term[] terms = (Term[])_termArrays.get(0);
 
-	    BooleanQuery boq = new BooleanQuery();
+      Explanation boostExpl = new Explanation(getBoost(), "boost");
-	    for (int i=0; i<terms.length; i++)
+      if (getBoost() != 1.0f)
-		boq.add(new TermQuery(terms[i]), false, false);
+        result.addDetail(boostExpl);
       
-	    return boq.scorer(reader, similarity);
+      Explanation idfExpl = new Explanation(idf, "idf");
-    	}
+      result.addDetail(idfExpl);
       
-    	TermPositions[] tps = new TermPositions[_termArrays.size()];
+      Explanation normExpl = new Explanation(queryNorm, "queryNorm");
-	for (int i=0; i<tps.length; i++)
+      result.addDetail(normExpl);
-	{
-	    Term[] terms = (Term[])_termArrays.get(i);
 
-	    TermPositions p;
+      result.setValue(boostExpl.getValue() *
-	    if (terms.length > 1)
+                      idfExpl.getValue() *
-		p = new MultipleTermPositions(reader, terms);
+                      normExpl.getValue());
-	    else
-		p = reader.termPositions(terms[0]);
 
-	    if (p == null)
+      return result;
-		return null;
+    }
+  }
 
-	    tps[i] = p;
+  protected Weight createWeight(Searcher searcher) {
-	}
+    return new PhrasePrefixWeight(searcher);
+  }
 
-	if (_slop == 0)
+  /** Prints a user-readable version of this query. */
-	    return new ExactPhraseScorer(tps, similarity,
+  public final String toString(String f) {
-                                         reader.norms(_field), _weight);
+    StringBuffer buffer = new StringBuffer();
-	else
+    if (!field.equals(f)) {
-	    return new SloppyPhraseScorer(tps, similarity, _slop,
+      buffer.append(field);
-                                          reader.norms(_field), _weight);
+      buffer.append(":");
     }
 
-    float sumOfSquaredWeights(Searcher searcher)
+    buffer.append("\"");
-	throws IOException
+    Iterator i = termArrays.iterator();
-    {
+    while (i.hasNext()) {
-	Iterator i = _termArrays.iterator();
+      Term[] terms = (Term[])i.next();
-	while (i.hasNext())
+      buffer.append(terms[0].text() + (terms.length > 0 ? "*" : ""));
-	{
+    }
-	    Term[] terms = (Term[])i.next();
+    buffer.append("\"");
-	    for (int j=0; j<terms.length; j++)
-		_idf += searcher.getSimilarity().idf(terms[j], searcher);
-	}
 
-	_weight = _idf * boost;
+    if (slop != 0) {
-	return _weight * _weight;
+      buffer.append("~");
+      buffer.append(slop);
     }
 
-    void normalize(float norm)
+    if (getBoost() != 1.0f) {
-    {
+      buffer.append("^");
-	_weight *= norm;
+      buffer.append(Float.toString(getBoost()));
-	_weight *= _idf;
     }
 
-    /**
+    return buffer.toString();
-     * Describe <code>toString</code> method here.
+  }
-     *
-     * This method assumes that the first term in a array of terms is the
-     * prefix for the whole array. That might not necessarily be so.
-     *
-     * @param f a <code>String</code> value
-     * @return a <code>String</code> value
-     */
-    public final String toString(String f)
-    {
-	StringBuffer buffer = new StringBuffer();
-	if (!_field.equals(f))
-	{
-	    buffer.append(_field);
-	    buffer.append(":");
-	}
-
-	buffer.append("\"");
-	Iterator i = _termArrays.iterator();
-	while (i.hasNext())
-	{
-	    Term[] terms = (Term[])i.next();
-	    buffer.append(terms[0].text() + (terms.length > 0 ? "*" : ""));
-	}
-	buffer.append("\"");
-
-	if (_slop != 0)
-	{
-	    buffer.append("~");
-	    buffer.append(_slop);
-	}
-
-	if (boost != 1.0f)
-	{
-	    buffer.append("^");
-	    buffer.append(Float.toString(boost));
-	}
-
-	return buffer.toString();
-    }
 }

src/java/org/apache/lucene/search/PhraseQuery.java

@@ -68,15 +68,10 @@ import org.apache.lucene.index.IndexReader;
 public class PhraseQuery extends Query {
   private String field;
   private Vector terms = new Vector();
-  private float idf = 0.0f;
-  private float weight = 0.0f;
-
   private int slop = 0;
 
-
   /** Constructs an empty phrase query. */
-  public PhraseQuery() {
+  public PhraseQuery() {}
-  }
 
   /** Sets the number of other words permitted between words in query phrase.
     If zero, then this is an exact phrase search.  For larger values this works
@@ -107,48 +102,103 @@ public class PhraseQuery extends Query {
     terms.addElement(term);
   }
 
-  final float sumOfSquaredWeights(Searcher searcher) throws IOException {
+  /** Returns the set of terms in this phrase. */
-    idf = searcher.getSimilarity().idf(terms, searcher);
+  public Term[] getTerms() {
-    weight = idf * boost;
+    return (Term[])terms.toArray(new Term[0]);
-    return weight * weight;			  // square term weights
   }
 
-  final void normalize(float norm) {
+  private class PhraseWeight implements Weight {
-    weight *= norm;				  // normalize for query
+    private Searcher searcher;
-    weight *= idf;				  // factor from document
+    private float value;
-  }
+    private float idf;
+    private float queryNorm;
 
-  final Scorer scorer(IndexReader reader, Similarity similarity)
+    public PhraseWeight(Searcher searcher) {
-    throws IOException {
+      this.searcher = searcher;
-    if (terms.size() == 0)			  // optimize zero-term case
-      return null;
-    if (terms.size() == 1) {			  // optimize one-term case
-      Term term = (Term)terms.elementAt(0);
-      TermDocs docs = reader.termDocs(term);
-      if (docs == null)
-	return null;
-      return new TermScorer(docs, similarity,
-                            reader.norms(term.field()), weight);
     }
 
-    TermPositions[] tps = new TermPositions[terms.size()];
+    public Query getQuery() { return PhraseQuery.this; }
-    for (int i = 0; i < terms.size(); i++) {
+    public float getValue() { return value; }
-      TermPositions p = reader.termPositions((Term)terms.elementAt(i));
+
-      if (p == null)
+    public float sumOfSquaredWeights() throws IOException {
-	return null;
+      idf = searcher.getSimilarity().idf(terms, searcher);
-      tps[i] = p;
+      value = idf * getBoost();
+      return value * value;			  // square term weights
     }
 
-    if (slop == 0)				  // optimize exact case
+    public void normalize(float norm) {
-      return new ExactPhraseScorer(tps, similarity,
+      queryNorm = norm;
-                                   reader.norms(field), weight);
+      queryNorm *= idf;                           // factor from document
-    else
+      value *= queryNorm;                         // normalize for query
-      return
+    }
-	new SloppyPhraseScorer(tps, similarity, slop,
-                               reader.norms(field), weight);
 
+    public Scorer scorer(IndexReader reader) throws IOException {
+      if (terms.size() == 0)			  // optimize zero-term case
+        return null;
+      if (terms.size() == 1) {			  // optimize one-term case
+        Term term = (Term)terms.elementAt(0);
+        TermDocs docs = reader.termDocs(term);
+        if (docs == null)
+          return null;
+        return new TermScorer(this, docs, searcher.getSimilarity(),
+                              reader.norms(term.field()));
+      }
+
+      TermPositions[] tps = new TermPositions[terms.size()];
+      for (int i = 0; i < terms.size(); i++) {
+        TermPositions p = reader.termPositions((Term)terms.elementAt(i));
+        if (p == null)
+          return null;
+        tps[i] = p;
+      }
+
+      if (slop == 0)				  // optimize exact case
+        return new ExactPhraseScorer(this, tps, searcher.getSimilarity(),
+                                     reader.norms(field));
+      else
+        return
+          new SloppyPhraseScorer(this, tps, searcher.getSimilarity(), slop,
+                                 reader.norms(field));
+      
+    }
+
+    public Explanation explain() throws IOException {
+      Query q = getQuery();
+
+      Explanation result = new Explanation();
+      result.setDescription("weight(" + getQuery() + "), product of:");
+
+      Explanation boostExpl = new Explanation(getBoost(), "boost");
+      if (getBoost() != 1.0f)
+        result.addDetail(boostExpl);
+      
+      StringBuffer docFreqs = new StringBuffer();
+      for (int i = 0; i < terms.size(); i++) {
+        if (i != 0) docFreqs.append(" ");
+        docFreqs.append(((Term)terms.elementAt(i)).text());
+        docFreqs.append("=");
+        docFreqs.append(searcher.docFreq((Term)terms.elementAt(i)));
+      }
+      Explanation idfExpl =
+        new Explanation(idf, "idf(" + field + ": " + docFreqs + ")");
+      result.addDetail(idfExpl);
+      
+      Explanation normExpl = new Explanation(queryNorm, "queryNorm");
+      result.addDetail(normExpl);
+
+      result.setValue(boostExpl.getValue() *
+                      idfExpl.getValue() *
+                      normExpl.getValue());
+
+      return result;
+    }
   }
 
+  protected Weight createWeight(Searcher searcher) {
+    return new PhraseWeight(searcher);
+  }
+
+
   /** Prints a user-readable version of this query. */
   public String toString(String f) {
     StringBuffer buffer = new StringBuffer();
@@ -170,11 +220,29 @@ public class PhraseQuery extends Query {
       buffer.append(slop);
     }
 
-    if (boost != 1.0f) {
+    if (getBoost() != 1.0f) {
       buffer.append("^");
-      buffer.append(Float.toString(boost));
+      buffer.append(Float.toString(getBoost()));
     }
 
     return buffer.toString();
   }
+
+  /** Returns true iff <code>o</code> is equal to this. */
+  public boolean equals(Object o) {
+    if (!(o instanceof PhraseQuery))
+      return false;
+    PhraseQuery other = (PhraseQuery)o;
+    return (this.getBoost() == other.getBoost())
+      && (this.slop == other.slop)
+      &&  this.terms.equals(other.terms);
+  }
+
+  /** Returns a hash code value for this object.*/
+  public int hashCode() {
+    return Float.floatToIntBits(getBoost())
+      ^ Float.floatToIntBits(slop)
+      ^ terms.hashCode();
+  }
+
 }

src/java/org/apache/lucene/search/PhraseScorer.java

@@ -60,17 +60,21 @@ import org.apache.lucene.util.*;
 import org.apache.lucene.index.*;
 
 abstract class PhraseScorer extends Scorer {
+  private Weight weight;
   protected byte[] norms;
-  protected float weight;
+  protected float value;
 
   protected PhraseQueue pq;
   protected PhrasePositions first, last;
 
-  PhraseScorer(TermPositions[] tps, Similarity similarity,
+  private float freq;
-               byte[] norms, float weight) throws IOException {
+
+  PhraseScorer(Weight weight, TermPositions[] tps, Similarity similarity,
+               byte[] norms) throws IOException {
     super(similarity);
     this.norms = norms;
     this.weight = weight;
+    this.value = weight.getValue();
 
     // use PQ to build a sorted list of PhrasePositions
     pq = new PhraseQueue(tps.length);
@@ -79,7 +83,7 @@ abstract class PhraseScorer extends Scorer {
     pqToList();
   }
 
-  final void score(HitCollector results, int end) throws IOException {
+  public final void score(HitCollector results, int end) throws IOException {
     Similarity similarity = getSimilarity();
     while (last.doc < end) {			  // find doc w/ all the terms
       while (first.doc < last.doc) {		  // scan forward in first
@@ -92,10 +96,10 @@ abstract class PhraseScorer extends Scorer {
       }
 
       // found doc with all terms
-      float freq = phraseFreq();		  // check for phrase
+      freq = phraseFreq();                        // check for phrase
 
       if (freq > 0.0) {
-	float score = similarity.tf(freq)*weight; // compute score
+	float score = similarity.tf(freq)*value;  // compute score
 	score *= Similarity.decodeNorm(norms[first.doc]); // normalize
 	results.collect(first.doc, score);	  // add to results
       }
@@ -124,4 +128,37 @@ abstract class PhraseScorer extends Scorer {
     first = first.next;
     last.next = null;
   }
+
+  public Explanation explain(final int doc) throws IOException {
+    Explanation result = new Explanation();
+    PhraseQuery query = (PhraseQuery)weight.getQuery();
+
+    result.setDescription("phraseScore(" + query + "), product of:");
+    
+    Explanation weightExplanation = weight.explain();
+    result.addDetail(weightExplanation);
+
+    Explanation tfExplanation = new Explanation();
+    score(new HitCollector() {
+        public final void collect(int d, float score) {}
+      }, doc+1);
+
+    float phraseFreq = (first.doc == doc) ? freq : 0.0f;
+    tfExplanation.setValue(getSimilarity().tf(phraseFreq));
+    tfExplanation.setDescription("tf(phraseFreq=" + phraseFreq + ")");
+    result.addDetail(tfExplanation);
+    
+    Explanation normExplanation = new Explanation();
+    normExplanation.setValue(Similarity.decodeNorm(norms[doc]));
+    String field = query.getTerms()[0].field();
+    normExplanation.setDescription("norm(field="+field + ", doc="+doc + ")");
+    result.addDetail(normExplanation);
+
+    result.setValue(weightExplanation.getValue() *
+                    tfExplanation.getValue() *
+                    normExplanation.getValue());
+    
+    return result;
+  }
+
 }

src/java/org/apache/lucene/search/PrefixQuery.java

@@ -63,65 +63,41 @@ import org.apache.lucene.index.IndexReader;
 /** A Query that matches documents containing terms with a specified prefix. */
 public class PrefixQuery extends Query {
   private Term prefix;
-  private IndexReader reader;
-  private BooleanQuery query;
 
   /** Constructs a query for terms starting with <code>prefix</code>. */
   public PrefixQuery(Term prefix) {
     this.prefix = prefix;
-    this.reader = reader;
   }
 
-  final void prepare(IndexReader reader) {
+  public Query rewrite(IndexReader reader) throws IOException {
-    this.query = null;
+    BooleanQuery query = new BooleanQuery();
-    this.reader = reader;
+    TermEnum enum = reader.terms(prefix);
-  }
-
-  final float sumOfSquaredWeights(Searcher searcher)
-    throws IOException {
-    return getQuery().sumOfSquaredWeights(searcher);
-  }
-
-  void normalize(float norm) {
     try {
-      getQuery().normalize(norm);
+      String prefixText = prefix.text();
-    } catch (IOException e) {
+      String prefixField = prefix.field();
-      throw new RuntimeException(e.toString());
+      do {
-    }
+        Term term = enum.term();
-  }
+        if (term != null &&
-
+            term.text().startsWith(prefixText) &&
-  Scorer scorer(IndexReader reader, Similarity similarity) throws IOException {
+            term.field() == prefixField) {
-    return getQuery().scorer(reader, similarity);
+          TermQuery tq = new TermQuery(term);	  // found a match
-  }
+          tq.setBoost(getBoost());                // set the boost
-
+          query.add(tq, false, false);		  // add to query
-  private BooleanQuery getQuery() throws IOException {
+          //System.out.println("added " + term);
-    if (query == null) {
+        } else {
-      BooleanQuery q = new BooleanQuery();
+          break;
-      TermEnum enum = reader.terms(prefix);
+        }
-      try {
+      } while (enum.next());
-	String prefixText = prefix.text();
+    } finally {
-	String prefixField = prefix.field();
+      enum.close();
-	do {
-	  Term term = enum.term();
-	  if (term != null &&
-	      term.text().startsWith(prefixText) &&
-	      term.field() == prefixField) {
-	    TermQuery tq = new TermQuery(term);	  // found a match
-	    tq.setBoost(boost);			  // set the boost
-	    q.add(tq, false, false);		  // add to q
-	    //System.out.println("added " + term);
-	  } else {
-	    break;
-	  }
-	} while (enum.next());
-      } finally {
-	enum.close();
-      }
-      query = q;
     }
     return query;
   }
 
+  public Query combine(Query[] queries) {
+    return Query.mergeBooleanQueries(queries);
+  }
+
   /** Prints a user-readable version of this query. */
   public String toString(String field) {
     StringBuffer buffer = new StringBuffer();
@@ -131,9 +107,9 @@ public class PrefixQuery extends Query {
     }
     buffer.append(prefix.text());
     buffer.append('*');
-    if (boost != 1.0f) {
+    if (getBoost() != 1.0f) {
       buffer.append("^");
-      buffer.append(Float.toString(boost));
+      buffer.append(Float.toString(getBoost()));
     }
     return buffer.toString();
   }

src/java/org/apache/lucene/search/Query.java

@@ -55,8 +55,10 @@ package org.apache.lucene.search;
  */
 
 import java.io.IOException;
-import java.util.Hashtable;
+
-import org.apache.lucene.document.Document;
+import java.util.HashSet;
+import java.util.Iterator;
+
 import org.apache.lucene.index.IndexReader;
 
 /** The abstract base class for queries.
@@ -76,52 +78,93 @@ import org.apache.lucene.index.IndexReader;
     <li>{@link org.apache.lucene.queryParser.QueryParser QueryParser}
     </ul>
 */
-public abstract class Query implements java.io.Serializable
+public abstract class Query implements java.io.Serializable {
-{
+  private float boost = 1.0f;                     // query boost factor
-    // query boost factor
-    protected float boost = 1.0f;
 
-    // query weighting
+  /** Sets the boost for this query clause to <code>b</code>.  Documents
-    abstract float sumOfSquaredWeights(Searcher searcher) throws IOException;
+   * matching this clause will (in addition to the normal weightings) have
-    abstract void normalize(float norm);
+   * their score multiplied by <code>b</code>.
+   */
+  public void setBoost(float b) { boost = b; }
 
-    // query evaluation
+  /** Gets the boost for this clause.  Documents matching
-    abstract Scorer scorer(IndexReader reader, Similarity similarity)
+   * this clause will (in addition to the normal weightings) have their score
-      throws IOException;
+   * multiplied by <code>b</code>.   The boost is 1.0 by default.
+   */
+  public float getBoost() { return boost; }
 
-    void prepare(IndexReader reader) {}
+  /** Prints a query to a string, with <code>field</code> as the default field
+   * for terms.  <p>The representation used is one that is readable by {@link
+   * org.apache.lucene.queryParser.QueryParser QueryParser} (although, if the
+   * query was created by the parser, the printed representation may not be
+   * exactly what was parsed).
+   */
+  public abstract String toString(String field);
 
-    static Scorer scorer(Query query, Searcher searcher, IndexReader reader)
+  /** Prints a query to a string. */
-      throws IOException {
+  public String toString() {
-      Similarity similarity = searcher.getSimilarity();
+    return toString("");
-      query.prepare(reader);
+  }
-      float sum = query.sumOfSquaredWeights(searcher);
+
-      float norm = similarity.queryNorm(sum);
+  /** Expert: Constructs an appropriate Weight implementation for this query.
-      query.normalize(norm);
+   *
-      return query.scorer(reader, similarity);
+   * <p>Only implemented by primitive queries, which re-write to themselves.
+   */
+  protected Weight createWeight(Searcher searcher) {
+    throw new UnsupportedOperationException();
+  }
+  
+  /** Expert: Constructs an initializes a Weight for a top-level query. */
+  public Weight weight(Searcher searcher)
+    throws IOException {
+    Query query = searcher.rewrite(this);
+    Weight weight = query.createWeight(searcher);
+    float sum = weight.sumOfSquaredWeights();
+    float norm = searcher.getSimilarity().queryNorm(sum);
+    weight.normalize(norm);
+    return weight;
+  }
+
+  /** Expert: called to re-write queries into primitive queries.
+   *
+   * <p>Only implemented by derived queries, with no {@link
+   * #createWeight(Searcher)} implementatation..
+   */
+  public Query rewrite(IndexReader reader) throws IOException {
+    return this;
+  }
+
+  /** Expert: called when re-writing queries under MultiSearcher.
+   *
+   * <p>Only implemented by derived queries, with no {@link
+   * #createWeight(Searcher)} implementatation..
+   */
+  public Query combine(Query[] queries) {
+    throw new UnsupportedOperationException();
+  }
+
+
+  /** Expert: merges the clauses of a set of BooleanQuery's into a single
+   * BooleanQuery.
+   *
+   *<p>A utility for use by {@link #combine(Query[])} implementations.
+   */
+  public static Query mergeBooleanQueries(Query[] queries) {
+    HashSet allClauses = new HashSet();
+    for (int i = 0; i < queries.length; i++) {
+      BooleanClause[] clauses = ((BooleanQuery)queries[i]).getClauses();
+      for (int j = 0; j < clauses.length; j++) {
+        allClauses.add(clauses[j]);
+      }
     }
 
-    /**
+    BooleanQuery result = new BooleanQuery();
-     * Sets the boost for this term to <code>b</code>.  Documents containing
+    Iterator i = allClauses.iterator();
-     * this term will (in addition to the normal weightings) have their score
+    while (i.hasNext()) {
-     * multiplied by <code>b</code>.
+      result.add((BooleanClause)i.next());
-     */
+    }
-    public void setBoost(float b) { boost = b; }
+    return result;
+  }
 
-    /**
-     * Gets the boost for this term.  Documents containing
-     * this term will (in addition to the normal weightings) have their score
-     * multiplied by <code>b</code>.   The boost is 1.0 by default.
-     */
-    public float getBoost() { return boost; }
 
-    /**
-     * Prints a query to a string, with <code>field</code> as the default field
-     * for terms.
-     * <p>The representation used is one that is readable by
-     * {@link org.apache.lucene.queryParser.QueryParser QueryParser}
-     * (although, if the query was created by the parser, the printed
-     * representation may not be exactly what was parsed).
-     */
-    public abstract String toString(String field);
 }

src/java/org/apache/lucene/search/RangeQuery.java

@@ -66,8 +66,6 @@ public class RangeQuery extends Query
     private Term lowerTerm;
     private Term upperTerm;
     private boolean inclusive;
-    private IndexReader reader;
-    private BooleanQuery query;
     
     /** Constructs a query selecting all terms greater than 
      * <code>lowerTerm</code> but less than <code>upperTerm</code>.
@@ -90,96 +88,56 @@ public class RangeQuery extends Query
         this.inclusive = inclusive;
     }
 
-    final void prepare(IndexReader reader)
+    public Query rewrite(IndexReader reader) throws IOException {
-    {
+      BooleanQuery query = new BooleanQuery();
-        this.query = null;
+      // if we have a lowerTerm, start there. otherwise, start at beginning
-        this.reader = reader;
+      if (lowerTerm == null) lowerTerm = new Term(getField(), "");
-    }
+      TermEnum enum = reader.terms(lowerTerm);
-    
+      try {
-    final float sumOfSquaredWeights(Searcher searcher) throws IOException
+        String lowerText = null;
-    {
+        String field;
-        return getQuery().sumOfSquaredWeights(searcher);
+        boolean checkLower = false;
-    }
+          if (!inclusive) {             // make adjustments to set to exclusive
-    
+            if (lowerTerm != null) {
-    void normalize(float norm)
+              lowerText = lowerTerm.text();
-    {
+              checkLower = true;
-        try
-        {
-            getQuery().normalize(norm);
-        } 
-        catch (IOException e)
-        {
-            throw new RuntimeException(e.toString());
-        }
-    }
-    
-    Scorer scorer(IndexReader reader, Similarity similarity) throws IOException
-    {
-        return getQuery().scorer(reader, similarity);
-    }
-    
-    private BooleanQuery getQuery() throws IOException
-    {
-        if (query == null)
-        {
-            BooleanQuery q = new BooleanQuery();
-            // if we have a lowerTerm, start there. otherwise, start at beginning
-            if (lowerTerm == null) lowerTerm = new Term(getField(), "");
-            TermEnum enum = reader.terms(lowerTerm);
-            try
-            {
-                String lowerText = null;
-                String field;
-                boolean checkLower = false;
-                if (!inclusive) // make adjustments to set to exclusive
-                {
-                    if (lowerTerm != null)
-                    {
-                        lowerText = lowerTerm.text();
-                        checkLower = true;
-                    }
-                    if (upperTerm != null)
-                    {
-                        // set upperTerm to an actual term in the index
-                        TermEnum uppEnum = reader.terms(upperTerm);
-                        upperTerm = uppEnum.term();
-                    }
-                }
-                String testField = getField();
-                do
-                {
-                    Term term = enum.term();
-                    if (term != null && term.field() == testField)
-                    {
-                        if (!checkLower || term.text().compareTo(lowerText) > 0) 
-                        {
-                            checkLower = false;
-                            if (upperTerm != null)
-                            {
-                                int compare = upperTerm.compareTo(term);
-                                /* if beyond the upper term, or is exclusive and
-                                 * this is equal to the upper term, break out */
-                                if ((compare < 0) || (!inclusive && compare == 0)) break;
-                            }
-                            TermQuery tq = new TermQuery(term);	  // found a match
-                            tq.setBoost(boost);               // set the boost
-                            q.add(tq, false, false);		  // add to q
-                        }
-                    } 
-                    else
-                    {
-                        break;
-                    }
-                }
-                while (enum.next());
             }
-            finally
+            if (upperTerm != null) {
-            {
+              // set upperTerm to an actual term in the index
-                enum.close();
+              TermEnum uppEnum = reader.terms(upperTerm);
+              upperTerm = uppEnum.term();
             }
-            query = q;
+          }
-        }
+          String testField = getField();
-        return query;
+          do {
+            Term term = enum.term();
+            if (term != null && term.field() == testField) {
+              if (!checkLower || term.text().compareTo(lowerText) > 0) {
+                checkLower = false;
+                if (upperTerm != null) {
+                  int compare = upperTerm.compareTo(term);
+                  /* if beyond the upper term, or is exclusive and
+                   * this is equal to the upper term, break out */
+                  if ((compare < 0) || (!inclusive && compare == 0)) break;
+                }
+                TermQuery tq = new TermQuery(term); // found a match
+                tq.setBoost(getBoost());          // set the boost
+                query.add(tq, false, false); // add to query
+              }
+            } 
+            else {
+              break;
+            }
+          }
+          while (enum.next());
+      } finally {
+        enum.close();
+      }
+      return query;
+    }
+    
+    public Query combine(Query[] queries) {
+      return Query.mergeBooleanQueries(queries);
     }
 
     private String getField()
@@ -201,10 +159,10 @@ public class RangeQuery extends Query
         buffer.append("-");
         buffer.append(upperTerm != null ? upperTerm.text() : "null");
         buffer.append(inclusive ? "]" : "}");
-        if (boost != 1.0f)
+        if (getBoost() != 1.0f)
         {
             buffer.append("^");
-            buffer.append(Float.toString(boost));
+            buffer.append(Float.toString(getBoost()));
         }
         return buffer.toString();
     }

src/java/org/apache/lucene/search/RemoteSearchable.java

@@ -102,6 +102,14 @@ public class RemoteSearchable
     return local.doc(i);
   }
 
+  public Query rewrite(Query original) throws IOException {
+    return local.rewrite(original);
+  }
+
+  public Explanation explain(Query query, int doc) throws IOException {
+    return local.explain(query, doc);
+  }
+
   /** Exports a searcher for the index in args[0] named
    * "//localhost/Searchable". */
   public static void main(String args[]) throws Exception {

src/java/org/apache/lucene/search/Scorer.java

@@ -56,16 +56,27 @@ package org.apache.lucene.search;
 
 import java.io.IOException;
 
-abstract class Scorer {
+/** Expert: Implements scoring for a class of queries. */
+public abstract class Scorer {
   private Similarity similarity;
 
+  /** Constructs a Scorer. */
   protected Scorer(Similarity similarity) {
     this.similarity = similarity;
   }
 
+  /** Returns the Similarity implementation used by this scorer. */
   public Similarity getSimilarity() {
     return this.similarity;
   }
 
-  abstract void score(HitCollector hc, int maxDoc) throws IOException;
+  /** Scores hits and passes them to a collector.  Stops at the last document
+   * before <code>maxDoc</code>.  If called repeatedly, will restart at point
+   * where it last left off.
+   */
+  public abstract void score(HitCollector hc, int maxDoc) throws IOException;
+
+  /** Returns an explanation of the score for <code>doc</code>. */
+  public abstract Explanation explain(int doc) throws IOException;
+
 }

src/java/org/apache/lucene/search/Searchable.java

@@ -112,4 +112,12 @@ public interface Searchable extends java.rmi.Remote {
    * @see IndexReader#document(int).
    */
   Document doc(int i) throws IOException;
+
+  /** */
+  Query rewrite(Query query) throws IOException;
+
+  /** */
+  Explanation explain(Query query, int doc) throws IOException;
+
+
 }

src/java/org/apache/lucene/search/SloppyPhraseScorer.java

@@ -62,9 +62,9 @@ import org.apache.lucene.index.*;
 final class SloppyPhraseScorer extends PhraseScorer {
   private int slop;
 
-  SloppyPhraseScorer(TermPositions[] tps, Similarity similarity,
+  SloppyPhraseScorer(Weight weight, TermPositions[] tps, Similarity similarity,
-                     int slop, byte[] norms, float weight) throws IOException {
+                     int slop, byte[] norms) throws IOException {
-    super(tps, similarity, norms, weight);
+    super(weight, tps, similarity, norms);
     this.slop = slop;
   }
 

src/java/org/apache/lucene/search/TermQuery.java

@@ -64,34 +64,77 @@ import org.apache.lucene.index.IndexReader;
   */
 public class TermQuery extends Query {
   private Term term;
-  private float idf = 0.0f;
+
-  private float weight = 0.0f;
+  private class TermWeight implements Weight {
+    private Searcher searcher;
+    private float value;
+    private float idf;
+    private float queryNorm;
+
+    public TermWeight(Searcher searcher) {
+      this.searcher = searcher;
+    }
+
+    public Query getQuery() { return TermQuery.this; }
+    public float getValue() { return value; }
+
+    public float sumOfSquaredWeights() throws IOException {
+      idf = searcher.getSimilarity().idf(term, searcher);
+      value = idf * getBoost();
+      return value * value;			  // square term weights
+    }
+
+    public void normalize(float norm) {
+      queryNorm = norm;
+      queryNorm *= idf;                           // factor from document
+      value *= queryNorm;                         // normalize for query
+    }
+
+    public Scorer scorer(IndexReader reader) throws IOException {
+      TermDocs termDocs = reader.termDocs(term);
+      
+      if (termDocs == null)
+        return null;
+      
+      return new TermScorer(this, termDocs, searcher.getSimilarity(),
+                            reader.norms(term.field()));
+    }
+
+    public Explanation explain() throws IOException {
+      Query q = getQuery();
+
+      Explanation result = new Explanation();
+      result.setDescription("weight(" + getQuery() + "), product of:");
+
+      Explanation boostExpl = new Explanation(getBoost(), "boost");
+      if (getBoost() != 1.0f)
+        result.addDetail(boostExpl);
+      
+      Explanation idfExpl =
+        new Explanation(idf, "idf(docFreq=" + searcher.docFreq(term) + ")");
+      result.addDetail(idfExpl);
+      
+      Explanation normExpl = new Explanation(queryNorm,"queryNorm");
+      result.addDetail(normExpl);
+
+      result.setValue(boostExpl.getValue() *
+                      idfExpl.getValue() *
+                      normExpl.getValue());
+
+      return result;
+    }
+  }
 
   /** Constructs a query for the term <code>t</code>. */
   public TermQuery(Term t) {
     term = t;
   }
 
-  final float sumOfSquaredWeights(Searcher searcher) throws IOException {
+  /** Returns the term of this query. */
-    idf = searcher.getSimilarity().idf(term, searcher);
+  public Term getTerm() { return term; };
-    weight = idf * boost;
-    return weight * weight;			  // square term weights
-  }
 
-  final void normalize(float norm) {
+  protected Weight createWeight(Searcher searcher) {
-    weight *= norm;				  // normalize for query
+    return new TermWeight(searcher);
-    weight *= idf;				  // factor from document
-  }
-
-  Scorer scorer(IndexReader reader, Similarity similarity)
-       throws IOException {
-    TermDocs termDocs = reader.termDocs(term);
-
-    if (termDocs == null)
-      return null;
-    
-    return new TermScorer(termDocs, similarity,
-                          reader.norms(term.field()), weight);
   }
 
   /** Prints a user-readable version of this query. */
@@ -102,10 +145,25 @@ public class TermQuery extends Query {
       buffer.append(":");
     }
     buffer.append(term.text());
-    if (boost != 1.0f) {
+    if (getBoost() != 1.0f) {
       buffer.append("^");
-      buffer.append(Float.toString(boost));
+      buffer.append(Float.toString(getBoost()));
     }
     return buffer.toString();
   }
+
+  /** Returns true iff <code>o</code> is equal to this. */
+  public boolean equals(Object o) {
+    if (!(o instanceof TermQuery))
+      return false;
+    TermQuery other = (TermQuery)o;
+    return (this.getBoost() == other.getBoost())
+      && this.term.equals(other.term);
+  }
+
+  /** Returns a hash code value for this object.*/
+  public int hashCode() {
+    return Float.floatToIntBits(getBoost()) ^ term.hashCode();
+  }
+
 }

src/java/org/apache/lucene/search/TermScorer.java

@@ -55,12 +55,14 @@ package org.apache.lucene.search;
  */
 
 import java.io.IOException;
+import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermDocs;
 
 final class TermScorer extends Scorer {
+  private Weight weight;
   private TermDocs termDocs;
   private byte[] norms;
-  private float weight;
+  private float weightValue;
   private int doc;
 
   private final int[] docs = new int[32];	  // buffered doc numbers
@@ -71,15 +73,16 @@ final class TermScorer extends Scorer {
   private static final int SCORE_CACHE_SIZE = 32;
   private float[] scoreCache = new float[SCORE_CACHE_SIZE];
 
-  TermScorer(TermDocs td, Similarity similarity, byte[] norms, float weight)
+  TermScorer(Weight weight, TermDocs td, Similarity similarity,
-    throws IOException {
+             byte[] norms) throws IOException {
     super(similarity);
+    this.weight = weight;
     this.termDocs = td;
     this.norms = norms;
-    this.weight = weight;
+    this.weightValue = weight.getValue();
 
     for (int i = 0; i < SCORE_CACHE_SIZE; i++)
-      scoreCache[i] = getSimilarity().tf(i) * weight;
+      scoreCache[i] = getSimilarity().tf(i) * weightValue;
 
     pointerMax = termDocs.read(docs, freqs);	  // fill buffers
 
@@ -91,7 +94,7 @@ final class TermScorer extends Scorer {
     }
   }
 
-  final void score(HitCollector c, final int end) throws IOException {
+  public final void score(HitCollector c, final int end) throws IOException {
     int d = doc;				  // cache doc in local
     Similarity similarity = getSimilarity();      // cache sim in local
     while (d < end) {				  // for docs in window
@@ -99,7 +102,7 @@ final class TermScorer extends Scorer {
       float score =				  // compute tf(f)*weight
 	f < SCORE_CACHE_SIZE			  // check cache
 	 ? scoreCache[f]			  // cache hit
-	 : similarity.tf(f)*weight;		  // cache miss
+	 : similarity.tf(f)*weightValue;          // cache miss
 
       score *= Similarity.decodeNorm(norms[d]);	  // normalize for field
 
@@ -119,4 +122,45 @@ final class TermScorer extends Scorer {
     }
     doc = d;					  // flush cache
   }
+
+  public Explanation explain(int doc) throws IOException {
+    Explanation result = new Explanation();
+    TermQuery query = (TermQuery)weight.getQuery();
+
+    result.setDescription("termScore(" + query + "), product of:");
+    
+    Explanation weightExplanation = weight.explain();
+    result.addDetail(weightExplanation);
+
+    Explanation tfExplanation = new Explanation();
+    int tf = 0;
+    while (pointer < pointerMax) {
+      if (docs[pointer] == doc)
+        tf = freqs[pointer];
+      pointer++;
+    }
+    if (tf == 0) {
+      while (termDocs.next()) {
+        if (termDocs.doc() == doc) {
+          tf = termDocs.freq();
+        }
+      }
+    }
+    termDocs.close();
+    tfExplanation.setValue(getSimilarity().tf(tf));
+    tfExplanation.setDescription("tf(termFreq("+query.getTerm()+")="+tf+")");
+    result.addDetail(tfExplanation);
+    
+    Explanation normExplanation = new Explanation();
+    normExplanation.setValue(Similarity.decodeNorm(norms[doc]));
+    String field = query.getTerm().field();
+    normExplanation.setDescription("norm(field="+field + ", doc="+doc + ")");
+    result.addDetail(normExplanation);
+
+    result.setValue(weightExplanation.getValue() *
+                    tfExplanation.getValue() *
+                    normExplanation.getValue());
+    
+    return result;
+  }
 }

src/java/org/apache/lucene/search/Weight.java

@@ -0,0 +1,88 @@
+package org.apache.lucene.search;
+
+/* ====================================================================
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2003 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Apache" and "Apache Software Foundation" and
+ *    "Apache Lucene" must not be used to endorse or promote products
+ *    derived from this software without prior written permission. For
+ *    written permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache",
+ *    "Apache Lucene", nor may "Apache" appear in their name, without
+ *    prior written permission of the Apache Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+import java.io.IOException;
+
+import org.apache.lucene.index.IndexReader;
+
+/** Expert: Calculate query weights and build query scorers.
+ *
+ * <p>A Weight is constructed by a query, given a Searcher ({@link
+ * Query#createWeight(Searcher)}).  The {@link #sumOfSquaredWeights()} method
+ * is then called on the top-level query to compute the query normalization
+ * factor (@link Similarity#queryNorm(float)}).  This factor is then passed to
+ * {@link #normalize(float)}.  At this point the weighting is complete and a
+ * scorer may be constructed by calling {@link #scorer(IndexReader)}.
+ */
+public interface Weight extends java.io.Serializable {
+  /** The query that this concerns. */
+  Query getQuery();
+
+  /** The weight for this query. */
+  float getValue();
+
+  /** The sum of squared weights of contained query clauses. */
+  float sumOfSquaredWeights() throws IOException;
+
+  /** Assigns the query normalization factor to this. */
+  void normalize(float norm);
+
+  /** Constructs a scorer for this. */
+  Scorer scorer(IndexReader reader) throws IOException;
+
+  /** An explanation of this weight computation. */
+  Explanation explain() throws IOException;
+}

src/java/org/apache/lucene/search/WildcardQuery.java

@@ -60,17 +60,12 @@ import java.io.IOException;
 
 /** Implements the wildcard search query */
 public class WildcardQuery extends MultiTermQuery {
-    private Term wildcardTerm;
+  public WildcardQuery(Term term) {
+    super(term);
+  }
 
-    public WildcardQuery(Term term) {
+  protected FilteredTermEnum getEnum(IndexReader reader) throws IOException {
-        super(term);
+    return new WildcardTermEnum(reader, getTerm());
-        wildcardTerm = term;
+  }
-    }
-
-    final void prepare(IndexReader reader) {
-        try {
-            setEnum(new WildcardTermEnum(reader, wildcardTerm));
-        } catch (IOException e) {}
-    }
     
 }

src/test/org/apache/lucene/queryParser/TestQueryParser.java

@@ -190,6 +190,8 @@ public class TestQueryParser extends TestCase {
 	assertTrue(getQuery("\"hello there\"", null) instanceof PhraseQuery);
 
 	assertQueryEquals("germ term^2.0", null, "germ term^2.0");
+	assertQueryEquals("(term)^2.0", null, "term^2.0");
+	assertQueryEquals("(germ term)^2.0", null, "(germ term)^2.0");
 	assertQueryEquals("term^2.0", null, "term^2.0");
 	assertQueryEquals("term^2", null, "term^2.0");
 	assertQueryEquals("\"germ term\"^2.0", null, "\"germ term\"^2.0");