io.druid.segment.virtual.ExpressionSelectors.java Source code

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Here is the source code for io.druid.segment.virtual.ExpressionSelectors.java

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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.segment.virtual;

import com.google.common.base.Strings;
import io.druid.math.expr.Expr;
import io.druid.math.expr.ExprEval;
import io.druid.query.extraction.ExtractionFn;
import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
import io.druid.segment.ColumnSelectorFactory;
import io.druid.segment.ColumnValueSelector;
import io.druid.segment.DimensionSelector;

import javax.annotation.Nullable;

public class ExpressionSelectors {
    private ExpressionSelectors() {
        // No instantiation.
    }

    public static ColumnValueSelector makeColumnValueSelector(ColumnSelectorFactory columnSelectorFactory,
            Expr expression) {
        final ExpressionObjectSelector baseSelector = ExpressionObjectSelector.from(columnSelectorFactory,
                expression);
        return new ColumnValueSelector() {
            @Override
            public double getDouble() {
                final ExprEval exprEval = baseSelector.getObject();
                return exprEval.isNull() ? 0.0 : exprEval.asDouble();
            }

            @Override
            public float getFloat() {
                final ExprEval exprEval = baseSelector.getObject();
                return exprEval.isNull() ? 0.0f : (float) exprEval.asDouble();
            }

            @Override
            public long getLong() {
                final ExprEval exprEval = baseSelector.getObject();
                return exprEval.isNull() ? 0L : exprEval.asLong();
            }

            @Nullable
            @Override
            public Object getObject() {
                final ExprEval exprEval = baseSelector.getObject();
                return exprEval.value();
            }

            @Override
            public Class classOfObject() {
                return Object.class;
            }

            @Override
            public void inspectRuntimeShape(RuntimeShapeInspector inspector) {
                inspector.visit("baseSelector", baseSelector);
            }
        };
    }

    public static DimensionSelector makeDimensionSelector(final ColumnSelectorFactory columnSelectorFactory,
            final Expr expression, final ExtractionFn extractionFn) {
        final ExpressionObjectSelector baseSelector = ExpressionObjectSelector.from(columnSelectorFactory,
                expression);

        if (extractionFn == null) {
            class DefaultExpressionDimensionSelector extends BaseSingleValueDimensionSelector {
                @Override
                protected String getValue() {
                    return Strings.emptyToNull(baseSelector.getObject().asString());
                }

                @Override
                public void inspectRuntimeShape(RuntimeShapeInspector inspector) {
                    inspector.visit("baseSelector", baseSelector);
                }
            }
            return new DefaultExpressionDimensionSelector();
        } else {
            class ExtractionExpressionDimensionSelector extends BaseSingleValueDimensionSelector {
                @Override
                protected String getValue() {
                    return extractionFn.apply(Strings.emptyToNull(baseSelector.getObject().asString()));
                }

                @Override
                public void inspectRuntimeShape(RuntimeShapeInspector inspector) {
                    inspector.visit("baseSelector", baseSelector);
                    inspector.visit("extractionFn", extractionFn);
                }
            }
            return new ExtractionExpressionDimensionSelector();
        }
    }
}