Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2020 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.expressionevaluator.impl.function.dataaccess;

import java.util.List;

import java.util.Objects;

import org.apache.commons.lang3.Range;

import org.gvsig.expressionevaluator.Codes;

import org.gvsig.expressionevaluator.Expression;

import org.gvsig.expressionevaluator.ExpressionRuntimeException;

import org.gvsig.expressionevaluator.ExpressionUtils;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.impl.DALFunctions;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

import org.gvsig.fmap.dal.DALLocator;

import org.gvsig.fmap.dal.DataManager;

import org.gvsig.fmap.dal.DataStore;

import org.gvsig.fmap.dal.feature.Feature;

import org.gvsig.fmap.dal.feature.FeatureQuery;

import org.gvsig.fmap.dal.feature.FeatureQueryOrder;

import org.gvsig.fmap.dal.feature.FeatureStore;

/**

 *

 * @author jjdelcerro

 */

public class SelectFunction extends AbstractFunction {

  public SelectFunction() {

    super(DALFunctions.GROUP_DATA_ACCESS,

            DALFunctions.FUNCTION_SELECT,

            Range.between(1,5),

            "Returns a list of features of the table by applying the filter, order and limit indicated.\n"+

                    "The syntax is:\n\n"+

                    "SELECT * FROM table WHERE boolean_expression ORDER BY order_column LIMIT limit;\n\n"+

                    "Indicate a filter expression with WHERE, an order or LIMIT is optional.\n"+

                    "The SELECT statement must always end with a semicolon.",

            "SELECT * FROM {{table_name}} WHERE filter ;",

            new String[]{

              "table_name - Name of the table",

              "filter - boolean expression to apply as filter",

              "order_column - the order used to retrieve the features. It is a list of column names separated by a comma. The column name can optionally be followed by ASC or DESC to indicate whether the order should be ascending or descending.",

              "limit - Maximum number of features to return"

            },

            "List",

            true

    );

  }

  @Override

  public boolean isHidden() {

    return false;

  }

  @Override

  public boolean allowConstantFolding() {

    return false;

  }

  @Override

  public boolean allowArgNames() {

    return true;

  }

  @Override

  public boolean useArgumentsInsteadObjects() {

    return true;

  }

  @Override

  public Object call(Interpreter interpreter, Object[] args) throws Exception {

    throw new UnsupportedOperationException();

  }

  @Override

  public Object call(Interpreter interpreter, Codes args) throws Exception {

    String storeName =  (String) getObject(interpreter, args, "TABLE");

    String where = Objects.toString(args.get("WHERE"),null);

    Number limit = (Number) getObject(interpreter, args, "LIMIT");

    FeatureQueryOrder order = null;

    for( int n=0 ; args.contains("ORDER", n); n++) {

      String member = (String) getObject(interpreter, args, "ORDER", n);

      Boolean mode = (Boolean) getObject(interpreter, args, "ORDER_MODE", n);

      if( order == null ) {

        order = new FeatureQueryOrder();

      }

      order.add(member, mode);

    }

    try {

      DataStore store = this.getStore(storeName);

      if (store == null ) {

        throw new ExpressionRuntimeException("Cant locate the store '" + storeName + "' in function '" + DALFunctions.FUNCTION_SELECT + "'.");

      }

      if (!(store instanceof FeatureStore)) {

        throw new ExpressionRuntimeException("The store'" + storeName + "' is not valid for function '" + DALFunctions.FUNCTION_SELECT + "', a FeatureStore is required.");

      }

      FeatureStore featureStore = (FeatureStore) store;

      List<Feature> features;

      if (where == null && order == null && limit==null ) {

        features = featureStore.getFeatures();

      } else {

        FeatureQuery query = featureStore.createFeatureQuery();

        if (where != null) {

          Expression filter = ExpressionUtils.createExpression(where);

          filter.getSymbolTable().addSymbolTable(interpreter.getSymbolTable());

          query.addFilter(filter);

        }

        if (order != null) {

          query.getOrder().copyFrom(order);

        }

        if( limit!=null ) {

          query.setLimit(limit.longValue());

        }

        query.retrievesAllAttributes();

        features = featureStore.getFeatures(query);

      }

      return features;

    } catch (ExpressionRuntimeException ex) {

      throw ex;

    } catch (Exception ex) {

      throw new ExpressionRuntimeException("Problems calling '" + DALFunctions.FUNCTION_SELECT + "' function", ex);

    }

  }

  protected DataStore getStore(String storeName) {

    DataManager dataManager = DALLocator.getDataManager();

    DataStore store = dataManager.getStoresRepository().getStore(storeName);

    return store;

  }

}