org.h2.expression.aggregate.AggregateDataCollecting Maven / Gradle / Ivy
/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.expression.aggregate;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.TreeSet;
import org.h2.api.ErrorCode;
import org.h2.engine.Database;
import org.h2.message.DbException;
import org.h2.value.Value;
import org.h2.value.ValueNull;
/**
* Data stored while calculating an aggregate that needs collecting of all
* values or a distinct aggregate.
*
*
* NULL values are not collected. {@link #getValue(Database, int)}
* method returns {@code null}. Use {@link #getArray()} for instances of this
* class instead.
*
*/
class AggregateDataCollecting extends AggregateData implements Iterable {
private final boolean distinct;
Collection values;
private Value shared;
/**
* Creates new instance of data for collecting aggregates.
*
* @param distinct if distinct is used
*/
AggregateDataCollecting(boolean distinct) {
this.distinct = distinct;
}
@Override
void add(Database database, Value v) {
if (v == ValueNull.INSTANCE) {
return;
}
Collection c = values;
if (c == null) {
values = c = distinct ? new TreeSet<>(database.getCompareMode()) : new ArrayList();
}
c.add(v);
}
@Override
Value getValue(Database database, int dataType) {
return null;
}
/**
* Returns the count of values.
*
* @return the count of values
*/
int getCount() {
return values != null ? values.size() : 0;
}
/**
* Returns array with values or {@code null}.
*
* @return array with values or {@code null}
*/
Value[] getArray() {
Collection values = this.values;
if (values == null) {
return null;
}
return values.toArray(new Value[0]);
}
@Override
public Iterator iterator() {
return values != null ? values.iterator() : Collections.emptyIterator();
}
/**
* Sets value of a shared argument.
*
* @param shared the shared value
*/
void setSharedArgument(Value shared) {
if (this.shared == null) {
this.shared = shared;
} else if (!this.shared.equals(shared)) {
throw DbException.get(ErrorCode.INVALID_VALUE_2, "Inverse distribution function argument",
this.shared.getTraceSQL() + "<>" + shared.getTraceSQL());
}
}
/**
* Returns value of a shared argument.
*
* @return value of a shared argument
*/
Value getSharedArgument() {
return shared;
}
}