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// Copyright 2018-2019 Mozilla
//
// 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
// 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.
use super::ErrorImpl;
use crate::backend::traits::BackendIter;
pub struct IterImpl<'i, C> {
// LMDB semantics dictate that a cursor must be valid for the entire lifetime
// of an iterator. In other words, cursors must not be dropped while an
// iterator built from it is alive. Unfortunately, the LMDB crate API does
// not express this through the type system, so we must enforce it somehow.
#[allow(dead_code)]
cursor: C,
iter: lmdb::Iter<'i>,
}
impl<'i, C> IterImpl<'i, C> {
pub(crate) fn new(
mut cursor: C,
to_iter: impl FnOnce(&mut C) -> lmdb::Iter<'i>,
) -> IterImpl<'i, C> {
let iter = to_iter(&mut cursor);
IterImpl { cursor, iter }
}
}
impl<'i, C> BackendIter<'i> for IterImpl<'i, C> {
type Error = ErrorImpl;
#[allow(clippy::type_complexity)]
fn next(&mut self) -> Option<Result<(&'i [u8], &'i [u8]), Self::Error>> {
self.iter.next().map(|e| e.map_err(ErrorImpl::LmdbError))
}
}