org.springframework.data.cassandra.core.EntityQueryUtils Maven / Gradle / Ivy
Show all versions of spring-data-cassandra Show documentation
/*
* Copyright 2016-2020 the original author or authors.
*
* Licensed 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
*
* https://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.springframework.data.cassandra.core;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.springframework.data.cassandra.core.cql.RowMapper;
import org.springframework.data.cassandra.core.query.CassandraPageRequest;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Slice;
import org.springframework.data.domain.SliceImpl;
import org.springframework.lang.Nullable;
import com.datastax.oss.driver.api.core.CqlIdentifier;
import com.datastax.oss.driver.api.core.cql.AsyncResultSet;
import com.datastax.oss.driver.api.core.cql.ResultSet;
import com.datastax.oss.driver.api.core.cql.Row;
import com.datastax.oss.driver.api.core.cql.SimpleStatement;
import com.datastax.oss.driver.api.core.cql.Statement;
/**
* Simple utility class for working with the QueryBuilder API using mapped entities.
*
* Only intended for internal use.
*
* @author Mark Paluch
* @since 2.0
*/
class EntityQueryUtils {
private static final Pattern FROM_REGEX = Pattern.compile(" FROM ([\"]?[\\w]*[\\\\.]?[\\w]*[\"]?)[\\s]?",
Pattern.CASE_INSENSITIVE);
/**
* Read a {@link Slice} of data from the {@link ResultSet} for a {@link Pageable}.
*
* @param resultSet must not be {@literal null}.
* @param mapper must not be {@literal null}.
* @param page
* @param pageSize
* @return the resulting {@link Slice}.
*/
static Slice readSlice(ResultSet resultSet, RowMapper mapper, int page, int pageSize) {
int toRead = resultSet.getAvailableWithoutFetching();
return readSlice(() -> limit(resultSet.iterator(), toRead), resultSet.getExecutionInfo().getPagingState(), mapper,
page, pageSize);
}
/**
* Read a {@link Slice} of data from the {@link ResultSet} for a {@link Pageable}.
*
* @param resultSet must not be {@literal null}.
* @param mapper must not be {@literal null}.
* @param page
* @param pageSize
* @return the resulting {@link Slice}.
* @since 3.0
*/
static Slice readSlice(AsyncResultSet resultSet, RowMapper mapper, int page, int pageSize) {
return readSlice(() -> limit(resultSet.currentPage().iterator(), resultSet.remaining()),
resultSet.getExecutionInfo().getPagingState(), mapper, page, pageSize);
}
/**
* Read a {@link Slice} of data from the {@link Iterable} of {@link Row}s for a {@link Pageable}.
*
* @param rows must not be {@literal null}.
* @param pagingState
* @param mapper must not be {@literal null}.
* @param page
* @param pageSize
* @return the resulting {@link Slice}.
* @since 2.1
*/
static Slice readSlice(Iterable rows, @Nullable ByteBuffer pagingState, RowMapper mapper, int page,
int pageSize) {
List result = new ArrayList<>(pageSize);
Iterator iterator = rows.iterator();
int index = 0;
while (iterator.hasNext()) {
T element = mapper.mapRow(iterator.next(), index++);
result.add(element);
}
CassandraPageRequest pageRequest = CassandraPageRequest.of(PageRequest.of(page, pageSize), pagingState);
return new SliceImpl<>(result, pageRequest, pagingState != null);
}
/**
* Extract the table name from a {@link Statement}.
*
* @param statement
* @return
* @since 2.1
*/
static CqlIdentifier getTableName(Statement statement) {
String cql = statement instanceof SimpleStatement ? ((SimpleStatement) statement).getQuery() : statement.toString();
Matcher matcher = FROM_REGEX.matcher(cql);
if (matcher.find()) {
String cqlTableName = matcher.group(1);
int separator = cqlTableName.indexOf('.');
if (separator != -1) {
cqlTableName = cqlTableName.substring(separator + 1);
}
if (cqlTableName.startsWith("\"") || cqlTableName.endsWith("\"")) {
return CqlIdentifier.fromCql(cqlTableName.substring(separator + 1));
}
return CqlIdentifier.fromInternal(cqlTableName);
}
return CqlIdentifier.fromCql("unknown");
}
/**
* Returns a view containing the first {@code limitSize} elements of {@code iterator}. If {@code
* iterator} contains fewer than {@code limitSize} elements, the returned view contains all of its elements. The
* returned iterator supports {@code remove()} if {@code iterator} does.
*
* @param iterator the iterator to limit
* @param limitSize the maximum number of elements in the returned iterator
* @throws IllegalArgumentException if {@code limitSize} is negative
* @since 3.0
*/
private static Iterator limit(Iterator iterator, int limitSize) {
return new Iterator() {
private int count;
@Override
public boolean hasNext() {
return count < limitSize && iterator.hasNext();
}
@Override
public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
count++;
return iterator.next();
}
@Override
public void remove() {
iterator.remove();
}
};
}
}