mojo leveldb: Add an iteration interface.

components/leveldb/public/cpp/remote_iterator.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/leveldb/public/cpp/remote_iterator.h"
+
+#include "components/leveldb/public/cpp/util.h"
+
+namespace leveldb {
+
+RemoteIterator::RemoteIterator(LevelDBDatabase* database, uint64_t iterator_id)
+    : database_(database),
+      iterator_id_(iterator_id),
+      valid_(false),
+      status_(DatabaseError::OK) {}
+
+RemoteIterator::~RemoteIterator() {
+  database_->ReleaseIterator(iterator_id_);
+}
+
+bool RemoteIterator::Valid() const {
+  return valid_;
+}
+
+void RemoteIterator::SeekToFirst() {
+  database_->IteratorSeekToFirst(iterator_id_, &valid_, &status_, &key_,
+                                 &value_);
+}
+
+void RemoteIterator::SeekToLast() {
+  database_->IteratorSeekToLast(iterator_id_, &valid_, &status_, &key_,
+                                &value_);
+}
+
+void RemoteIterator::Seek(const Slice& target) {
+  database_->IteratorSeek(iterator_id_, GetArrayFor(target), &valid_, &status_,
+                          &key_, &value_);
+}
+
+void RemoteIterator::Next() {
+  database_->IteratorNext(iterator_id_, &valid_, &status_, &key_, &value_);
+}
+
+void RemoteIterator::Prev() {
+  database_->IteratorPrev(iterator_id_, &valid_, &status_, &key_, &value_);
+}
+
+Slice RemoteIterator::key() const {
+  return GetSliceFor(key_);
+}
+
+Slice RemoteIterator::value() const {
+  return GetSliceFor(value_);
+}
+
+Status RemoteIterator::status() const {
+  return DatabaseErrorToStatus(status_, GetSliceFor(key_), GetSliceFor(value_));
+}
+
+}  // namespace leveldb