// Copyright 2015 PingCAP, Inc.
//
// 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
//
//     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,
// See the License for the specific language governing permissions and
// limitations under the License.

package kv

import "github.com/juju/errors"

// NextUntil applies FnKeyCmp to each entry of the iterator until meets some condition.
// It will stop when fn returns true, or iterator is invalid or an error occurs.
func NextUntil(it Iterator, fn FnKeyCmp) error {
	var err error
	for it.Valid() && !fn(it.Key()) {
		err = it.Next()
		if err != nil {
			return errors.Trace(err)
		}
	}
	return nil
}