| /* |
| * 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.druid.segment; |
| |
| import org.apache.druid.guice.annotations.PublicApi; |
| import org.apache.druid.query.dimension.DimensionSpec; |
| import org.apache.druid.segment.column.ColumnCapabilities; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * Factory class for MetricSelectors |
| * |
| * @see org.apache.druid.segment.vector.VectorColumnSelectorFactory, the vectorized version |
| */ |
| @PublicApi |
| public interface ColumnSelectorFactory |
| { |
| DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec); |
| |
| /** |
| * Returns ColumnValueSelector corresponding to the given column name, or {@link NilColumnValueSelector} if the |
| * column with such name is absent. |
| */ |
| ColumnValueSelector makeColumnValueSelector(String columnName); |
| |
| /** |
| * Returns capabilities of a particular column, if known. May be null if the column doesn't exist, or if |
| * the column does exist but the capabilities are unknown. The latter is possible with dynamically discovered |
| * columns. |
| * |
| * @param column column name |
| * |
| * @return capabilities, or null |
| */ |
| @Nullable |
| ColumnCapabilities getColumnCapabilities(String column); |
| } |