Inside Bitcoin

1// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file. See the AUTHORS file for names of contributors.
4
5#include "leveldb/iterator.h"
6
7namespace leveldb {
8
9Iterator::Iterator() {
10  cleanup_head_.function = nullptr;
11  cleanup_head_.next = nullptr;
12}
13
14Iterator::~Iterator() {
15  if (!cleanup_head_.IsEmpty()) {
16    cleanup_head_.Run();
17    for (CleanupNode* node = cleanup_head_.next; node != nullptr;) {
18      node->Run();
19      CleanupNode* next_node = node->next;
20      delete node;
21      node = next_node;
22    }
23  }
24}
25
26void Iterator::RegisterCleanup(CleanupFunction func, void* arg1, void* arg2) {
27  assert(func != nullptr);
28  CleanupNode* node;
29  if (cleanup_head_.IsEmpty()) {
30    node = &cleanup_head_;
31  } else {
32    node = new CleanupNode();
33    node->next = cleanup_head_.next;
34    cleanup_head_.next = node;
35  }
36  node->function = func;
37  node->arg1 = arg1;
38  node->arg2 = arg2;
39}
40
41namespace {
42
43class EmptyIterator : public Iterator {
44 public:
45  EmptyIterator(const Status& s) : status_(s) {}
46  ~EmptyIterator() override = default;
47
48  bool Valid() const override { return false; }
49  void Seek(const Slice& target) override {}
50  void SeekToFirst() override {}
51  void SeekToLast() override {}
52  void Next() override { assert(false); }
53  void Prev() override { assert(false); }
54  Slice key() const override {
55    assert(false);
56    return Slice();
57  }
58  Slice value() const override {
59    assert(false);
60    return Slice();
61  }
62  Status status() const override { return status_; }
63
64 private:
65  Status status_;
66};
67
68}  // anonymous namespace
69
70Iterator* NewEmptyIterator() { return new EmptyIterator(Status::OK()); }
71
72Iterator* NewErrorIterator(const Status& status) {
73  return new EmptyIterator(status);
74}
75
76}  // namespace leveldb
77