<?php

/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. 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.
 */

declare(strict_types=1);

namespace Elastic\Apm\Impl\Util;

/**
 * Code in this file is part of implementation internals and thus it is not covered by the backward compatibility.
 *
 * @internal
 */
final class IterableUtil
{
    use StaticClassTrait;

    /**
     * @template TValue
     *
     * @param TValue           $headVal
     * @param iterable<TValue> $tail
     *
     * @return iterable<TValue>
     */
    public static function prepend($headVal, iterable $tail): iterable
    {
        yield $headVal;
        yield from $tail;
    }

    /**
     * @template TValue
     *
     * @param TValue[] $inArray
     * @param int      $suffixStartIndex
     *
     * @return iterable<TValue>
     */
    public static function arraySuffix(array $inArray, int $suffixStartIndex): iterable
    {
        foreach (RangeUtil::generateFromToIncluding($suffixStartIndex, count($inArray) - 1) as $index) {
            yield $inArray[$index];
        }
    }
}