diff --git a/src/java/org/apache/solr/common/params/ModifiableSolrParams.java b/src/java/org/apache/solr/common/params/ModifiableSolrParams.java
new file mode 100644
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+++ b/src/java/org/apache/solr/common/params/ModifiableSolrParams.java
@@ -0,0 +1,187 @@
+/**
+ * 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.
+ */
+
+package org.apache.solr.common.params;
+
+import java.io.IOException;
+import java.net.URLEncoder;
+import java.util.LinkedHashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+
+
+/**
+ * This class is similar to MultiMapSolrParams except you can edit the 
+ * parameters after it is initialized.  It has helper functions to set/add
+ * integer and boolean param values.
+ * 
+ * @author ryan
+ * @since solr 1.3
+ */
+public class ModifiableSolrParams extends SolrParams 
+{
+  private Map<String,String[]> vals;
+  
+  public ModifiableSolrParams()
+  {
+    // LinkedHashMap so params show up in CGI in the same order as they are entered
+    vals = new LinkedHashMap<String, String[]>();
+  }
+  
+  public ModifiableSolrParams( Map<String,String[]> v )
+  {
+    vals = v;
+  }
+
+  //----------------------------------------------------------------
+  //----------------------------------------------------------------
+
+  /**
+   * Replace any existing parameter with the given name.  if val==null remove key from params completely.
+   */
+  public void set( String name, String ... val ) {
+    if (val==null || (val.length==1 && val[0]==null)) {
+      vals.remove(name);
+    } else {
+      vals.put( name, val );
+    }
+  }
+  
+  public void set( String name, int val ) {
+    set( name, String.valueOf(val) );
+  }
+  
+  public void set( String name, boolean val ) {
+    set( name, String.valueOf(val) );
+  }
+
+  /**
+   * Add the given values to any existing name
+   */
+  public void add( String name, String ... val ) {
+    String[] old = vals.get( name );
+    if( old != null ) {
+      int i =0;
+      if( val == null || val.length < 1 ) {
+        String[] both = new String[old.length+1];
+        for( String v : old ) {
+          both[i++] = v;
+        }
+        both[i++] = null;
+        vals.put( name, both );
+      }
+      else {
+        String[] both = new String[old.length+val.length];
+        for( String v : old ) {
+          both[i++] = v;
+        }
+        for( String v : val ) {
+          both[i++] = v;
+        }
+        vals.put( name, both );
+      }
+    }
+    else {
+      vals.put( name, val );
+    }
+  }
+  
+  /**
+   * remove a field at the given name
+   */
+  public String[] remove( String name )
+  {
+    return vals.remove( name );
+  }
+  
+  /** 
+   * remove the given value for the given name
+   * 
+   * @return true if the item was removed, false if null or not present
+   */
+  public boolean remove(String name, String value) {
+     String[] tmp = vals.get(name);
+     if (tmp==null) return false;
+     for (int i=0; i<tmp.length; i++) {
+       if (tmp[i].equals(value)) {
+         String[] tmp2 = new String[tmp.length-1];
+         if (tmp2.length==0) {
+           tmp2 = null;
+           remove(name);
+         } else {
+           System.arraycopy(tmp, 0, tmp2, 0, i);
+           System.arraycopy(tmp, i+1, tmp2, i, tmp.length-i-1);
+           set(name, tmp2);
+         }
+         return true;
+       }
+     }
+     return false;
+  }
+
+  //----------------------------------------------------------------
+  //----------------------------------------------------------------
+
+  @Override
+  public String get(String param) {
+    String[] v = vals.get( param );
+    if( v!= null && v.length > 0 ) {
+      return v[0];
+    }
+    return null;
+  }
+
+  @Override
+  public Iterator<String> getParameterNamesIterator() {
+    return vals.keySet().iterator();
+  }
+  
+  public Set<String> getParameterNames() {
+    return vals.keySet();
+  }
+
+  @Override
+  public String[] getParams(String param) {
+    return vals.get( param );
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder(128);
+    try {
+      boolean first=true;
+
+      for (Map.Entry<String,String[]> entry : vals.entrySet()) {
+        String key = entry.getKey();
+        String[] valarr = entry.getValue();
+        for (String val : valarr) {
+          if (!first) sb.append('&');
+          first=false;
+          sb.append(key);
+          sb.append('=');
+          if( val != null ) {
+            sb.append( URLEncoder.encode( val, "UTF-8" ) );
+          }
+        }
+      }
+    }
+    catch (IOException e) {throw new RuntimeException(e);}  // can't happen
+
+    return sb.toString();
+  }
+}