Index: src/java/org/apache/lucene/search/BooleanQuery.java
===================================================================
--- src/java/org/apache/lucene/search/BooleanQuery.java	(revision 330921)
+++ src/java/org/apache/lucene/search/BooleanQuery.java	(working copy)
@@ -105,6 +105,41 @@
     return result;
   }
 
+  /**
+   * Specifies a minimum number of the optional BooleanClauses
+   * which must be satisifed.
+   *
+   * <p>
+   * By default no optional clauses are neccessary for a match
+   * (unless there are no required clauses).  If this method is used,
+   * then the specified numebr of clauses is required.
+   * </p>
+   * <p>
+   * Use of this method is totally independant of specifying that
+   * any specific clauses are required (or prohibited).  This number will
+   * only be compared against the number of matching optional clauses.
+   * </p>
+   * <p>
+   * EXPERT NOTE: Using this method will force the use of BooleanWeight2,
+   * regardless of wether setUseScorer14(true) has been called.
+   * </p>
+   *
+   * @param min the number of optional clauses that must match
+   * @see #setUseScorer14
+   */
+  public void setMinimumNumberShouldMatch(int min) {
+    this.minNrShouldMatch = min;
+  }
+  protected int minNrShouldMatch = 0;
+
+  /**
+   * Gets the minimum number of the optional BooleanClauses
+   * which must be satisifed.
+   */
+  public int getMinimumNumberShouldMatch() {
+    return minNrShouldMatch;
+  }
+
   /** Adds a clause to a boolean query.  Clauses may be:
    * <ul>
    * <li><code>required</code> which means that documents which <i>do not</i>
@@ -297,7 +332,8 @@
      *          and scores documents in document number order.
      */
     public Scorer scorer(IndexReader reader) throws IOException {
-      BooleanScorer2 result = new BooleanScorer2(similarity);
+      BooleanScorer2 result = new BooleanScorer2(similarity,
+                                                 minNrShouldMatch);
 
       for (int i = 0 ; i < weights.size(); i++) {
         BooleanClause c = (BooleanClause)clauses.elementAt(i);
@@ -325,6 +361,12 @@
   }
 
   protected Weight createWeight(Searcher searcher) throws IOException {
+
+    if (0 < minNrShouldMatch) {
+      // :TODO: should we throw an exception if getUseScorer14 ?
+      return new BooleanWeight2(searcher);
+    }
+
     return getUseScorer14() ? (Weight) new BooleanWeight(searcher)
                             : (Weight) new BooleanWeight2(searcher);
   }
@@ -380,7 +422,8 @@
   /** Prints a user-readable version of this query. */
   public String toString(String field) {
     StringBuffer buffer = new StringBuffer();
-    if (getBoost() != 1.0) {
+    boolean needParens=(getBoost() != 1.0) || (BooleanQuery.getMaxClauseCount()>0) ;
+    if (needParens) {
       buffer.append("(");
     }
 
@@ -403,8 +446,17 @@
         buffer.append(" ");
     }
 
-    if (getBoost() != 1.0) {
+    if (needParens) {
       buffer.append(")");
+    }
+
+    if (getMinimumNumberShouldMatch()>0) {
+      buffer.append('~');
+      buffer.append(getMinimumNumberShouldMatch());
+    }
+
+    if (getBoost() != 1.0f)
+    {
       buffer.append(ToStringUtils.boost(getBoost()));
     }