| /* |
| * 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.cassandra.distributed.api; |
| |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.NoSuchElementException; |
| import java.util.Objects; |
| import java.util.function.Predicate; |
| |
| public final class QueryResults |
| { |
| private static final SimpleQueryResult EMPTY = new SimpleQueryResult(new String[0], null); |
| |
| private QueryResults() {} |
| |
| public static SimpleQueryResult empty() |
| { |
| return EMPTY; |
| } |
| |
| public static QueryResult fromIterator(String[] names, Iterator<Row> iterator) |
| { |
| Objects.requireNonNull(names, "names"); |
| Objects.requireNonNull(iterator, "iterator"); |
| return new IteratorQueryResult(names, iterator); |
| } |
| |
| public static QueryResult fromObjectArrayIterator(String[] names, Iterator<Object[]> iterator) |
| { |
| Row row = new Row(names); |
| return fromIterator(names, new Iterator<Row>() |
| { |
| @Override |
| public boolean hasNext() |
| { |
| return iterator.hasNext(); |
| } |
| |
| @Override |
| public Row next() |
| { |
| row.setResults(iterator.next()); |
| return row; |
| } |
| }); |
| } |
| |
| public static QueryResult filter(QueryResult result, Predicate<Row> fn) |
| { |
| return new FilterQueryResult(result, fn); |
| } |
| |
| public static Builder builder() |
| { |
| return new Builder(); |
| } |
| |
| public static final class Builder |
| { |
| private static final int UNSET = -1; |
| |
| private int numColumns = UNSET; |
| private String[] names; |
| private List<Object[]> results = new ArrayList<>(); |
| |
| public Builder columns(String... columns) |
| { |
| if (columns != null) |
| { |
| if (numColumns == UNSET) |
| numColumns = columns.length; |
| |
| if (numColumns != columns.length) |
| throw new AssertionError("Attempted to add column names with different column count; " + |
| "expected " + numColumns + " columns but given " + Arrays.toString(columns)); |
| } |
| |
| names = columns; |
| return this; |
| } |
| |
| public Builder row(Object... values) |
| { |
| if (numColumns == UNSET) |
| numColumns = values.length; |
| |
| if (numColumns != values.length) |
| throw new AssertionError("Attempted to add row with different column count; " + |
| "expected " + numColumns + " columns but given " + Arrays.toString(values)); |
| results.add(values); |
| return this; |
| } |
| |
| public SimpleQueryResult build() |
| { |
| if (names == null) |
| { |
| if (numColumns == UNSET) |
| return QueryResults.empty(); |
| names = new String[numColumns]; |
| for (int i = 0; i < numColumns; i++) |
| names[i] = "unknown"; |
| } |
| return new SimpleQueryResult(names, results.stream().toArray(Object[][]::new)); |
| } |
| } |
| |
| private static final class IteratorQueryResult implements QueryResult |
| { |
| private final List<String> names; |
| private final Iterator<Row> iterator; |
| |
| private IteratorQueryResult(String[] names, Iterator<Row> iterator) |
| { |
| this(Collections.unmodifiableList(Arrays.asList(names)), iterator); |
| } |
| |
| private IteratorQueryResult(List<String> names, Iterator<Row> iterator) |
| { |
| this.names = names; |
| this.iterator = iterator; |
| } |
| |
| @Override |
| public List<String> names() |
| { |
| return names; |
| } |
| |
| @Override |
| public boolean hasNext() |
| { |
| return iterator.hasNext(); |
| } |
| |
| @Override |
| public Row next() |
| { |
| return iterator.next(); |
| } |
| } |
| |
| private static final class FilterQueryResult implements QueryResult |
| { |
| private final QueryResult delegate; |
| private final Predicate<Row> filter; |
| private Row current; |
| |
| private FilterQueryResult(QueryResult delegate, Predicate<Row> filter) |
| { |
| this.delegate = delegate; |
| this.filter = filter; |
| } |
| |
| @Override |
| public List<String> names() |
| { |
| return delegate.names(); |
| } |
| |
| @Override |
| public boolean hasNext() |
| { |
| while (delegate.hasNext()) |
| { |
| Row row = delegate.next(); |
| if (filter.test(row)) |
| { |
| current = row; |
| return true; |
| } |
| } |
| current = null; |
| return false; |
| } |
| |
| @Override |
| public Row next() |
| { |
| if (current == null) |
| throw new NoSuchElementException(); |
| return current; |
| } |
| } |
| } |