for #647 move merger to sharding-core module

/*

 * Copyright 1999-2015 dangdang.com.

 * <p>

 * Licensed 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.

 * </p>

 */

package io.shardingjdbc.core.merger;

import io.shardingjdbc.core.merger.show.ShowCreateTableResultSetMerger;

import io.shardingjdbc.core.merger.show.ShowDatabasesResultSetMerger;

import io.shardingjdbc.core.merger.show.ShowOtherResultSetMerger;

import io.shardingjdbc.core.merger.show.ShowTablesResultSetMerger;

import io.shardingjdbc.core.parsing.parser.dialect.mysql.statement.ShowCreateTableStatement;

import io.shardingjdbc.core.parsing.parser.dialect.mysql.statement.ShowDatabasesStatement;

import io.shardingjdbc.core.parsing.parser.dialect.mysql.statement.ShowTablesStatement;

import io.shardingjdbc.core.parsing.parser.sql.dal.DALStatement;

import io.shardingjdbc.core.rule.ShardingRule;

import lombok.RequiredArgsConstructor;

import java.sql.SQLException;

import java.util.List;

/**

 * DAL result set merge engine.

 *

 * @author zhangliang

 */

@RequiredArgsConstructor

public final class DALMergeEngine implements MergeEngine {

    private final ShardingRule shardingRule;

    private final List<QueryResult> queryResults;

    private final DALStatement dalStatement;

    @Override

    public ResultSetMerger merge() throws SQLException {

        if (dalStatement instanceof ShowDatabasesStatement) {

            return new ShowDatabasesResultSetMerger();

        }

        if (dalStatement instanceof ShowTablesStatement) {

            return new ShowTablesResultSetMerger(shardingRule, queryResults);

        }

        if (dalStatement instanceof ShowCreateTableStatement) {

            return new ShowCreateTableResultSetMerger(shardingRule, queryResults);

        }

        return new ShowOtherResultSetMerger(queryResults.get(0));

    }

}

/*

 * Copyright 1999-2015 dangdang.com.

 * <p>

 * Licensed 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.

 * </p>

 */

package io.shardingjdbc.core.merger;

import io.shardingjdbc.core.constant.DatabaseType;

import io.shardingjdbc.core.merger.groupby.GroupByMemoryResultSetMerger;

import io.shardingjdbc.core.merger.groupby.GroupByStreamResultSetMerger;

import io.shardingjdbc.core.merger.iterator.IteratorStreamResultSetMerger;

import io.shardingjdbc.core.merger.orderby.OrderByStreamResultSetMerger;

import io.shardingjdbc.core.merger.pagination.LimitDecoratorResultSetMerger;

import io.shardingjdbc.core.merger.pagination.RowNumberDecoratorResultSetMerger;

import io.shardingjdbc.core.merger.pagination.TopAndRowNumberDecoratorResultSetMerger;

import io.shardingjdbc.core.parsing.parser.context.limit.Limit;

import io.shardingjdbc.core.parsing.parser.sql.dql.select.SelectStatement;

import io.shardingjdbc.core.util.SQLUtil;

import java.sql.SQLException;

import java.util.List;

import java.util.Map;

import java.util.TreeMap;

/**

 * DQL result set merge engine.

 *

 * @author zhangliang

 */

public final class DQLMergeEngine implements MergeEngine {

    private final List<QueryResult> queryResults;

    private final SelectStatement selectStatement;

    private final Map<String, Integer> columnLabelIndexMap;

    public DQLMergeEngine(final List<QueryResult> queryResults, final SelectStatement selectStatement) throws SQLException {

        this.queryResults = queryResults;

        this.selectStatement = selectStatement;

        columnLabelIndexMap = getColumnLabelIndexMap(queryResults.get(0));

    }

    private Map<String, Integer> getColumnLabelIndexMap(final QueryResult queryResult) throws SQLException {

        Map<String, Integer> result = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);

        for (int i = 1; i <= queryResult.getColumnCount(); i++) {

            result.put(SQLUtil.getExactlyValue(queryResult.getColumnLabel(i)), i);

        }

        return result;

    }

    @Override

    public ResultSetMerger merge() throws SQLException {

        selectStatement.setIndexForItems(columnLabelIndexMap);

        return decorate(build());

    }

    private ResultSetMerger build() throws SQLException {

        if (!selectStatement.getGroupByItems().isEmpty() || !selectStatement.getAggregationSelectItems().isEmpty()) {

            if (selectStatement.isSameGroupByAndOrderByItems()) {

                return new GroupByStreamResultSetMerger(columnLabelIndexMap, queryResults, selectStatement);

            } else {

                return new GroupByMemoryResultSetMerger(columnLabelIndexMap, queryResults, selectStatement);

            }

        }

        if (!selectStatement.getOrderByItems().isEmpty()) {

            return new OrderByStreamResultSetMerger(queryResults, selectStatement.getOrderByItems());

        }

        return new IteratorStreamResultSetMerger(queryResults);

    }

    private ResultSetMerger decorate(final ResultSetMerger resultSetMerger) throws SQLException {

        Limit limit = selectStatement.getLimit();

        if (null == limit) {

            return resultSetMerger;

        }

        if (DatabaseType.MySQL == limit.getDatabaseType() || DatabaseType.PostgreSQL == limit.getDatabaseType() || DatabaseType.H2 == limit.getDatabaseType()) {

            return new LimitDecoratorResultSetMerger(resultSetMerger, selectStatement.getLimit());

        }

        if (DatabaseType.Oracle == limit.getDatabaseType()) {

            return new RowNumberDecoratorResultSetMerger(resultSetMerger, selectStatement.getLimit());

        }

        if (DatabaseType.SQLServer == limit.getDatabaseType()) {

            return new TopAndRowNumberDecoratorResultSetMerger(resultSetMerger, selectStatement.getLimit());

        }

        return resultSetMerger;

    }

}

/*

 * Copyright 1999-2015 dangdang.com.

 * <p>

 * Licensed 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.

 * </p>

 */

package io.shardingjdbc.core.merger;

import java.sql.SQLException;

/**

 * result set merge engine.

 *

 * @author zhangliang

 */

public interface MergeEngine {

    /**

     * Merge result sets.

     *

     * @return merged result set.

     * @throws SQLException SQL exception

     */

    ResultSetMerger merge() throws SQLException;

}

/*

 * Copyright 1999-2015 dangdang.com.

 * <p>

 * Licensed 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.

 * </p>

 */

package io.shardingjdbc.core.merger;

import java.sql.SQLException;

/**

 * Query result form database.

 *

 * @author zhangliang

 */

public interface QueryResult extends ResultSetMerger {

    /**

     * Get column count.

     * 

     * @return column count

     * @throws SQLException SQL Exception

     */

    int getColumnCount() throws SQLException;

    /**

     * Get column label.

     * 

     * @param columnIndex column index

     * @return column label

     * @throws SQLException SQL Exception

     */

    String getColumnLabel(int columnIndex) throws SQLException;

}

/*

 * Copyright 1999-2015 dangdang.com.

 * <p>

 * Licensed 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.

 * </p>

 */

package io.shardingjdbc.core.merger;

import java.io.InputStream;

import java.sql.SQLException;

import java.util.Calendar;

/**

 * ResultSet merger interface.

 *

 * @author zhangliang

 */

public interface ResultSetMerger {

    /**

     * iterate next data.

     * 

     * @return has next data

     * @throws SQLException SQL Exception

     */

    boolean next() throws SQLException;

    /**

     * Get data value.

     *

     * @param columnIndex column index

     * @param type class type of data value

     * @return data value

     * @throws SQLException SQL Exception

     */

    Object getValue(int columnIndex, Class<?> type) throws SQLException;

    /**

     * Get data value.

     *

     * @param columnLabel column label

     * @param type class type of data value

     * @return data value

     * @throws SQLException SQL Exception

     */

    Object getValue(String columnLabel, Class<?> type) throws SQLException;

    /**

     * Get calendar value.

     *

     * @param columnIndex column index

     * @param type class type of data value

     * @param calendar calendar

     * @return calendar value

     * @throws SQLException SQL Exception

     */

    Object getCalendarValue(int columnIndex, Class<?> type, Calendar calendar) throws SQLException;

    /**

     * Get calendar value.

     *

     * @param columnLabel column label

     * @param type class type of data value

     * @param calendar calendar

     * @return calendar value

     * @throws SQLException SQL Exception

     */

    Object getCalendarValue(String columnLabel, Class<?> type, Calendar calendar) throws SQLException;

    /**

     * Get InputStream.

     *

     * @param columnIndex column index

     * @param type class type of data value

     * @return InputStream

     * @throws SQLException SQL Exception

     */

    InputStream getInputStream(int columnIndex, String type) throws SQLException;

    /**

     * Get InputStream.

     *

     * @param columnLabel column label

     * @param type class type of data value

     * @return InputStream

     * @throws SQLException SQL Exception

     */

    InputStream getInputStream(String columnLabel, String type) throws SQLException;

    /**

     * Adjust ResultSet is null or not.

     * 

     * @return ResultSet is null or not

     * @throws SQLException SQL Exception

     */

    boolean wasNull() throws SQLException;

}