| gvSIG desktop 1

package com.hardcode.gdbms.engine.strategies;

import java.util.Comparator;

import java.util.TreeSet;

import com.hardcode.gdbms.driver.exceptions.ReadDriverException;

import com.hardcode.gdbms.engine.data.DataSource;

import com.hardcode.gdbms.engine.data.FieldNameAccessSupport;

import com.hardcode.gdbms.engine.data.persistence.Memento;

import com.hardcode.gdbms.engine.data.persistence.MementoException;

import com.hardcode.gdbms.engine.data.persistence.OperationLayerMemento;

import com.hardcode.gdbms.engine.instruction.EvaluationException;

import com.hardcode.gdbms.engine.instruction.Expression;

import com.hardcode.gdbms.engine.instruction.IncompatibleTypesException;

import com.hardcode.gdbms.engine.internalExceptions.InternalException;

import com.hardcode.gdbms.engine.internalExceptions.InternalExceptionCatcher;

import com.hardcode.gdbms.engine.internalExceptions.InternalExceptionEvent;

import com.hardcode.gdbms.engine.values.BooleanValue;

import com.hardcode.gdbms.engine.values.Value;

import com.hardcode.gdbms.engine.values.ValueCollection;

import com.hardcode.gdbms.engine.values.ValueFactory;

/**

 * DOCUMENT ME!

 *

 * @author Fernando Gonz?lez Cort?s

 */

public class DistinctDataSource extends OperationDataSource {

    private DataSource dataSource;

    private int[] indexes;

    private FieldNameAccessSupport fnaSupport = new FieldNameAccessSupport(this);

    private Expression[] expressions;

    /**

     * Crea un nuevo DistinctDataSource.

     *

     * @param ds DOCUMENT ME!

     * @param expressions DOCUMENT ME!

     */

    public DistinctDataSource(DataSource ds, Expression[] expressions) {

        dataSource = ds;

        this.expressions = expressions;

    }

    /**

     * @see com.hardcode.gdbms.engine.data.DataSource#start()

     */

    public void start() throws ReadDriverException {

        dataSource.start();

    }

    /**

     * @see com.hardcode.gdbms.engine.data.DataSource#stop()

     */

    public void stop() throws ReadDriverException {

        dataSource.stop();

    }

    /**

     * @see com.hardcode.gdbms.engine.data.DataSource#getMemento()

     */

    public Memento getMemento() throws MementoException {

        return new OperationLayerMemento(getName(),

            new Memento[] { dataSource.getMemento() }, getSQL());

    }

    /**

     * @see com.hardcode.gdbms.engine.data.DataSource#getFieldIndexByName(java.lang.String)

     */

    public int getFieldIndexByName(String fieldName) throws ReadDriverException {

        return fnaSupport.getFieldIndexByName(fieldName);

    }

    /**

     * @see com.hardcode.gdbms.engine.data.driver.ReadAccess#getFieldValue(long,

     *      int)

     */

    public Value getFieldValue(long rowIndex, int fieldId)

        throws ReadDriverException {

        return dataSource.getFieldValue(indexes[(int) rowIndex], fieldId);

    }

    /**

     * @see com.hardcode.gdbms.engine.data.driver.ReadAccess#getFieldCount()

     */

    public int getFieldCount() throws ReadDriverException {

        return dataSource.getFieldCount();

    }

    /**

     * @see com.hardcode.gdbms.engine.data.driver.ReadAccess#getFieldName(int)

     */

    public String getFieldName(int fieldId) throws ReadDriverException {

        return dataSource.getFieldName(fieldId);

    }

    /**

     * @see com.hardcode.gdbms.engine.data.driver.ReadAccess#getRowCount()

     */

    public long getRowCount() throws ReadDriverException {

        return indexes.length;

    }

    /**

     * @see com.hardcode.gdbms.engine.data.driver.ReadAccess#getFieldType(int)

     */

    public int getFieldType(int i) throws ReadDriverException {

        return dataSource.getFieldType(i);

    }

    /**

     * DOCUMENT ME!

     * @throws EvaluationException DOCUMENT ME!

     * @throws ReadDriverException TODO

     * @throws RuntimeException DOCUMENT ME!

     */

    public void filter() throws EvaluationException, ReadDriverException {

        int[] idx = new int[(int) dataSource.getRowCount()];

        TreeSet h = new TreeSet(new Comparator() {

                    public int compare(Object o1, Object o2) {

                        try {

                            Value v1 = (Value) o1;

                            Value v2 = (Value) o2;

                            if (((BooleanValue) v1.equals(v2)).getValue()) {

                                return 0;

                            } else {

                                return 1;

                            } 

                        } catch (IncompatibleTypesException e) {

                            InternalExceptionCatcher.callExceptionRaised(new InternalExceptionEvent(DistinctDataSource.this, new InternalException("Internal error calculating distinct clause", e)));

                            return 0;

                        }

                    }

                });

        int index = 0;

        for (int i = 0; i < dataSource.getRowCount(); i++) {

            Value[] values;

            if (expressions == null){

                values = new Value[dataSource.getFieldCount()];

                for (int j = 0; j < values.length; j++) {

                    values[j] = dataSource.getFieldValue(i, j);

                }

            } else {

                values = new Value[expressions.length];

                for (int j = 0; j < values.length; j++) {

                    values[j] = expressions[j].evaluate(i);

                }

            }

            ValueCollection vc = ValueFactory.createValue(values);

            if (!h.contains(vc)) {

                idx[index] = i;

                index++;

                h.add(vc);

            }

        }

        indexes = new int[index];

        System.arraycopy(idx, 0, indexes, 0, index);

    }

        public int getFieldWidth(int i) throws ReadDriverException {

        return dataSource.getFieldType(i);

        }

}