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tdutils/td/utils/ChangesProcessor.h

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <utility>
+
+namespace td {
+
+// Process changes after they are finished in order of addition
+template <class DataT>
+class ChangesProcessor {
+ public:
+  using Id = uint64;
+
+  void clear() {
+    offset_ += data_array_.size();
+    ready_i_ = 0;
+    data_array_.clear();
+  }
+
+  template <class FromDataT>
+  Id add(FromDataT &&data) {
+    auto res = offset_ + data_array_.size();
+    data_array_.emplace_back(std::forward<DataT>(data), false);
+    return static_cast<Id>(res);
+  }
+
+  template <class F>
+  void finish(Id token, F &&func) {
+    size_t pos = static_cast<size_t>(token) - offset_;
+    if (pos >= data_array_.size()) {
+      return;
+    }
+    data_array_[pos].second = true;
+    while (ready_i_ < data_array_.size() && data_array_[ready_i_].second == true) {
+      func(std::move(data_array_[ready_i_].first));
+      ready_i_++;
+    }
+    try_compactify();
+  }
+
+ private:
+  size_t offset_ = 1;
+  size_t ready_i_ = 0;
+  std::vector<std::pair<DataT, bool>> data_array_;
+  void try_compactify() {
+    if (ready_i_ > 5 && ready_i_ * 2 > data_array_.size()) {
+      data_array_.erase(data_array_.begin(), data_array_.begin() + ready_i_);
+      offset_ += ready_i_;
+      ready_i_ = 0;
+    }
+  }
+};
+
+}  // namespace td