com.hazelcast.jet.sql.impl.ExpressionUtil Maven / Gradle / Ivy
/*
* Copyright 2024 Hazelcast Inc.
*
* Licensed under the Hazelcast Community License (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://hazelcast.com/hazelcast-community-license
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.jet.sql.impl;
import com.hazelcast.function.ComparatorEx;
import com.hazelcast.function.FunctionEx;
import com.hazelcast.jet.sql.impl.opt.FieldCollation;
import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;
import com.hazelcast.sql.impl.expression.Expression;
import com.hazelcast.sql.impl.expression.ExpressionEvalContext;
import com.hazelcast.sql.impl.row.JetSqlRow;
import com.hazelcast.sql.impl.row.Row;
import com.hazelcast.shaded.org.apache.calcite.rel.RelFieldCollation.Direction;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public final class ExpressionUtil {
private ExpressionUtil() {
}
public static ComparatorEx comparisonFn(
@Nonnull List fieldCollationList
) {
return new SqlRowComparator(fieldCollationList);
}
public static class SqlRowComparator implements IdentifiedDataSerializable, ComparatorEx {
private static final long serialVersionUID = 1L;
private List fieldCollationList;
public SqlRowComparator() {
}
public SqlRowComparator(List fieldCollationList) {
this.fieldCollationList = fieldCollationList;
}
@Override
public int compareEx(JetSqlRow row1, JetSqlRow row2) {
// Comparison of row values:
// - Compare the rows according to field collations starting from left to right.
// - If one of the field comparison returns the non-zero value, then return it.
// - Otherwise, the rows are equal according to field collations, then return 0.
for (FieldCollation fieldCollation : fieldCollationList) {
// For each collation:
// - Get collation index and use it to fetch values from the rows.
// - Get direction (ASCENDING, DESCENDING)
// - Comparison of field values:
// - If both of them are NULL, then result is 0.
// - Otherwise, if one of them is NULL, then return:
// - result is -1 if LHS is NULL.
// - result is 1 if RHS is NULL.
// - Return the result if ASCENDING
// Return the reverted result if DESCENDING
int index = fieldCollation.getIndex();
Comparable o1 = (Comparable) row1.get(index);
Object o2 = row2.get(index);
Direction direction = fieldCollation.getDirection();
int result;
if (o1 == o2) {
result = 0;
} else if (o1 == null) {
result = -1;
} else if (o2 == null) {
result = 1;
} else {
result = o1.compareTo(o2);
}
if (direction.isDescending()) {
if (result < 0) {
result = 1;
} else if (result > 0) {
result = -1;
}
}
if (result != 0) {
return result;
}
}
return 0;
}
@Override
public void writeData(ObjectDataOutput out) throws IOException {
out.writeInt(fieldCollationList.size());
for (FieldCollation fieldCollation : fieldCollationList) {
out.writeObject(fieldCollation);
}
}
@Override
public void readData(ObjectDataInput in) throws IOException {
int size = in.readInt();
fieldCollationList = new ArrayList<>(size);
for (int i = 0; i < size; i++) {
fieldCollationList.add(in.readObject());
}
}
@Override
public int getFactoryId() {
return JetSqlSerializerHook.F_ID;
}
@Override
public int getClassId() {
return JetSqlSerializerHook.SQL_ROW_COMPARATOR;
}
}
public static FunctionEx projectionFn(
@Nonnull List> projections,
@Nonnull ExpressionEvalContext context
) {
return row0 -> projection(projections, context, row0.getRow());
}
public static FunctionEx calcFn(
@Nonnull List> projections,
@Nonnull Expression predicate,
@Nonnull ExpressionEvalContext context
) {
return row0 -> projection(predicate, projections, row0.getRow(), context);
}
/**
* Concatenates {@code leftRow} and {@code rightRow} into one, evaluates
* the {@code predicate} on it, and if the predicate passed, returns the
* joined row; returns {@code null} if the predicate didn't pass.
*/
@Nullable
public static JetSqlRow join(
@Nonnull JetSqlRow leftRow,
@Nonnull JetSqlRow rightRow,
@Nonnull Expression predicate,
@Nonnull ExpressionEvalContext context
) {
Object[] joined = Arrays.copyOf(leftRow.getValues(), leftRow.getFieldCount() + rightRow.getFieldCount());
System.arraycopy(rightRow.getValues(), 0, joined, leftRow.getFieldCount(), rightRow.getFieldCount());
JetSqlRow result = new JetSqlRow(context.getSerializationService(), joined);
Row row = result.getRow();
return Boolean.TRUE.equals(evaluate(predicate, row, context)) ? result : null;
}
/**
* Evaluate projection&predicate for multiple rows.
*/
@Nonnull
public static List evaluate(
@Nullable Expression predicate,
@Nullable List> projection,
@Nonnull Stream rows,
@Nonnull ExpressionEvalContext context
) {
return rows
.map(row -> evaluate(predicate, projection, row, context))
.filter(Objects::nonNull)
.collect(Collectors.toList());
}
/**
* Evaluate projection&predicate for a single row. Returns {@code null} if
* the row is rejected by the predicate.
*/
@Nullable
public static JetSqlRow evaluate(
@Nullable Expression predicate,
@Nullable List> projection,
@Nonnull JetSqlRow values,
@Nonnull ExpressionEvalContext context
) {
Row row = values.getRow();
if (predicate != null && !Boolean.TRUE.equals(evaluate(predicate, row, context))) {
return null;
}
if (projection == null) {
return values;
}
return projection(projection, context, row);
}
/**
* Projection with optional filter predicate for a single row. Returns {@code null} if
* the row is rejected by the predicate.
*/
@Nullable
public static JetSqlRow projection(
@Nullable Expression predicate,
@Nonnull List> projections,
@Nonnull Row row,
@Nonnull ExpressionEvalContext context
) {
if (predicate != null && !Boolean.TRUE.equals(evaluate(predicate, row, context))) {
return null;
}
return projection(projections, context, row);
}
private static JetSqlRow projection(
@Nonnull List> projections,
@Nonnull ExpressionEvalContext context,
@Nonnull Row row
) {
Object[] result = new Object[projections.size()];
for (int i = 0; i < projections.size(); i++) {
result[i] = evaluate(projections.get(i), row, context);
}
return new JetSqlRow(context.getSerializationService(), result);
}
public static Object evaluate(
@Nonnull Expression expression,
@Nonnull Row row,
@Nonnull ExpressionEvalContext context
) {
return expression.evalTop(row, context);
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy