Mailing List Archive

I'm not sure if my last email has dropped through the cracks, so I'm
reposting it just in case it has.

Thanks for your insights in advance,
Chris
----- Original Message -----
From: Christian Meunier
To: lucene-dev@jakarta.apache.org
Sent: Wednesday, May 15, 2002 7:32 PM
Subject: Filter abstract class / Why there is no getter method for the field "Field" ?


Hi all,

i am using lucene since few months and i dont understand why the abstract class does not provide a getter method like

abstract public String getField();

To my knowledge, a filter is always applied to a field ( DateFilter has a field "Field" ).
In my application , i defined a simple FilterField class:

FieldFilter.java
------------------------------------------------------------------------------------------------------------------------------------------------------------------
import java.util.BitSet;
import java.io.IOException;

import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.IndexReader;

public class FieldFilter extends org.apache.lucene.search.Filter
{

private String field;
private String value;
private Term searchTerm;

public FieldFilter(String field, String value)
{
this.field = field;
this.value = value;
searchTerm = new Term(field, value);
}

public String getField()
{
return field;
}

public BitSet bits(IndexReader reader) throws IOException
{
BitSet bits = new BitSet(reader.maxDoc());
TermDocs matchingDocs = reader.termDocs(searchTerm);
try
{
while(matchingDocs.next())
{
bits.set(matchingDocs.doc());
}
}
catch (Exception e) { /* ignore */ }
finally
{
if (matchingDocs != null)
{
matchingDocs.close();
}
}
return bits;
}
}
------------------------------------------------------------------------------------------------------------------------------------------------------------------

I then coded a class which handle multiple filters (FieldFilter, DateFilter,....) at once


MultiFilter.java
------------------------------------------------------------------------------------------------------------------------------------------------------------------
import java.util.Hashtable;
import java.util.BitSet;
import java.util.ArrayList;
import java.io.IOException;

import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Filter;

public class MultiFilter extends org.apache.lucene.search.Filter
{
private ArrayList filterList;

public MultiFilter()
{
filterList = new ArrayList();
}

public MultiFilter(int initialCapacity)
{
filterList = new ArrayList(initialCapacity);
}

public String getField()
{
return null;
}


public void add(Filter filter)
{
filterList.add(filter);
}

public BitSet bits(IndexReader reader) throws IOException
{
int filterListSize = filterList.size();

if (filterListSize > 0)
{
Hashtable filters = new Hashtable();
int pos=0;
for (int i=0; i<filterListSize; i++)
{
if(!filters.containsKey( ((Filter)filterList.get(i)).getField()))
{
filters.put(((Filter)filterList.get(i)).getField(),""+pos);
pos++;
}

}

BitSet [] tab_bits = new BitSet[filters.size()];
for (int i=0; i<filterListSize; i++)
{
if(tab_bits[Integer.parseInt((String)filters.get(((Filter)filterList.get(i)).getField()))]==null)
tab_bits[Integer.parseInt((String)filters.get(((Filter)filterList.get(i)).getField()))] = ((Filter)filterList.get(i)).bits(reader);
else
tab_bits[Integer.parseInt((String)filters.get(((Filter)filterList.get(i)).getField()))].or(((Filter)filterList.get(i)).bits(reader));
}

for(int i=1;i<tab_bits.length;i++)
tab_bits[0].and(tab_bits[i]);

return tab_bits[0];
}
else
{
return new BitSet(reader.maxDoc());
}
}
}
------------------------------------------------------------------------------------------------------------------------------------------------------------------

As you can see, it's mandatory that the Filter class specify a getFilter method so such MultiFilter can work.

Could it be possible to add this getter to the Filter class ?

Thanks in advance for your feedback
Christian Meunier