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A module that is everything required to understands Druid Segments
/*
* 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.virtual;
import com.google.common.base.Predicate;
import org.apache.druid.common.config.NullHandling;
import org.apache.druid.math.expr.Evals;
import org.apache.druid.math.expr.ExprEval;
import org.apache.druid.query.extraction.ExtractionFn;
import org.apache.druid.query.filter.DruidPredicateFactory;
import org.apache.druid.query.filter.ValueMatcher;
import org.apache.druid.query.monomorphicprocessing.RuntimeShapeInspector;
import org.apache.druid.segment.ColumnValueSelector;
import org.apache.druid.segment.DimensionSelector;
import org.apache.druid.segment.IdLookup;
import org.apache.druid.segment.data.IndexedInts;
import org.apache.druid.segment.data.RangeIndexedInts;
import org.apache.druid.segment.data.ZeroIndexedInts;
import javax.annotation.Nullable;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;
/**
* Basic multi-value dimension selector for an {@link org.apache.druid.math.expr.Expr} evaluating
* {@link ColumnValueSelector}.
*/
public class ExpressionMultiValueDimensionSelector implements DimensionSelector
{
public static ExpressionMultiValueDimensionSelector fromValueSelector(
ColumnValueSelector baseSelector,
@Nullable ExtractionFn extractionFn
)
{
if (extractionFn != null) {
return new ExtractionMultiValueDimensionSelector(baseSelector, extractionFn);
}
return new ExpressionMultiValueDimensionSelector(baseSelector);
}
protected final ColumnValueSelector baseSelector;
public ExpressionMultiValueDimensionSelector(ColumnValueSelector baseSelector)
{
this.baseSelector = baseSelector;
}
ExprEval getEvaluated()
{
return baseSelector.getObject();
}
@Nullable
String getValue(ExprEval evaluated)
{
assert !evaluated.isArray();
return evaluated.asString();
}
List getArrayAsList(ExprEval evaluated)
{
assert evaluated.isArray();
//noinspection ConstantConditions
return Arrays.stream(evaluated.asArray())
.map(Evals::asString)
.collect(Collectors.toList());
}
@Nullable
String getArrayValue(ExprEval evaluated, int i)
{
return getArrayElement(evaluated, i);
}
@Override
public IndexedInts getRow()
{
ExprEval evaluated = getEvaluated();
if (evaluated.isArray()) {
RangeIndexedInts ints = new RangeIndexedInts();
Object[] evaluatedArray = evaluated.asArray();
ints.setSize(evaluatedArray != null ? evaluatedArray.length : 0);
return ints;
}
return ZeroIndexedInts.instance();
}
@Override
public int getValueCardinality()
{
return CARDINALITY_UNKNOWN;
}
@Nullable
@Override
public String lookupName(int id)
{
ExprEval evaluated = getEvaluated();
if (evaluated.isArray()) {
return getArrayValue(evaluated, id);
}
assert id == 0;
return evaluated.asString();
}
@Override
public ValueMatcher makeValueMatcher(@Nullable String value)
{
return new ValueMatcher()
{
@Override
public boolean matches(boolean includeUnknown)
{
ExprEval evaluated = getEvaluated();
if (evaluated.isArray()) {
List array = getArrayAsList(evaluated);
return array.stream().anyMatch(x -> (includeUnknown && x == null) || Objects.equals(x, value));
}
final String rowValue = getValue(evaluated);
return (includeUnknown && rowValue == null) || Objects.equals(rowValue, value);
}
@Override
public void inspectRuntimeShape(RuntimeShapeInspector inspector)
{
inspector.visit("selector", baseSelector);
}
};
}
@Override
public ValueMatcher makeValueMatcher(DruidPredicateFactory predicateFactory)
{
return new ValueMatcher()
{
@Override
public boolean matches(boolean includeUnknown)
{
ExprEval evaluated = getEvaluated();
final boolean matchNull = includeUnknown && predicateFactory.isNullInputUnknown();
final Predicate predicate = predicateFactory.makeStringPredicate();
if (evaluated.isArray()) {
List array = getArrayAsList(evaluated);
return array.stream().anyMatch(x -> (matchNull && x == null) || predicate.apply(x));
}
final String rowValue = getValue(evaluated);
return (matchNull && rowValue == null) || predicate.apply(rowValue);
}
@Override
public void inspectRuntimeShape(RuntimeShapeInspector inspector)
{
inspector.visit("selector", baseSelector);
inspector.visit("predicate", predicateFactory);
}
};
}
@Override
public void inspectRuntimeShape(RuntimeShapeInspector inspector)
{
inspector.visit("baseSelector", baseSelector);
}
@Override
public boolean nameLookupPossibleInAdvance()
{
return false;
}
@Nullable
@Override
public IdLookup idLookup()
{
return null;
}
@Nullable
@Override
public Object getObject()
{
ExprEval evaluated = getEvaluated();
if (evaluated.isArray()) {
return getArrayAsList(evaluated);
}
return getValue(evaluated);
}
@Override
public Class> classOfObject()
{
return Object.class;
}
/**
* expressions + extractions
*/
static class ExtractionMultiValueDimensionSelector extends ExpressionMultiValueDimensionSelector
{
private final ExtractionFn extractionFn;
private ExtractionMultiValueDimensionSelector(ColumnValueSelector baseSelector, ExtractionFn extractionFn)
{
super(baseSelector);
this.extractionFn = extractionFn;
}
@Override
String getValue(ExprEval evaluated)
{
assert !evaluated.isArray();
return extractionFn.apply(NullHandling.emptyToNullIfNeeded(evaluated.asString()));
}
@Override
List getArrayAsList(ExprEval evaluated)
{
assert evaluated.isArray();
return Arrays.stream(evaluated.asArray())
.map(x -> extractionFn.apply(Evals.asString(x)))
.collect(Collectors.toList());
}
@Override
String getArrayValue(ExprEval evaluated, int i)
{
return extractionFn.apply(ExpressionMultiValueDimensionSelector.getArrayElement(evaluated, i));
}
@Override
public void inspectRuntimeShape(RuntimeShapeInspector inspector)
{
inspector.visit("baseSelector", baseSelector);
inspector.visit("extractionFn", extractionFn);
}
}
@Nullable
private static String getArrayElement(ExprEval eval, int i)
{
final Object[] stringArray = eval.asArray();
if (stringArray == null) {
return null;
}
return Evals.asString(stringArray[i]);
}
}