1 files changed, 158 insertions, 0 deletions
diff --git a/protocols/Telegram/tdlib/td/tdutils/td/utils/Span.h b/protocols/Telegram/tdlib/td/tdutils/td/utils/Span.h
new file mode 100644
index 0000000000..877adcf78a
--- /dev/null
+++ b/protocols/Telegram/tdlib/td/tdutils/td/utils/Span.h
@@ -0,0 +1,158 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2022
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#include <array>
+#include <iterator>
+
+namespace td {
+
+namespace detail {
+template <class T, class InnerT>
+class SpanImpl {
+  InnerT *data_{nullptr};
+  size_t size_{0};
+
+ public:
+  SpanImpl() = default;
+  SpanImpl(InnerT *data, size_t size) : data_(data), size_(size) {
+  }
+  SpanImpl(InnerT &data) : SpanImpl(&data, 1) {
+  }
+
+  template <class OtherInnerT>
+  SpanImpl(const SpanImpl<T, OtherInnerT> &other) : SpanImpl(other.data(), other.size()) {
+  }
+
+  template <size_t N>
+  SpanImpl(const std::array<T, N> &arr) : SpanImpl(arr.data(), arr.size()) {
+  }
+  template <size_t N>
+  SpanImpl(std::array<T, N> &arr) : SpanImpl(arr.data(), arr.size()) {
+  }
+  template <size_t N>
+  SpanImpl(const T (&arr)[N]) : SpanImpl(arr, N) {
+  }
+  template <size_t N>
+  SpanImpl(T (&arr)[N]) : SpanImpl(arr, N) {
+  }
+  SpanImpl(const vector<T> &v) : SpanImpl(v.data(), v.size()) {
+  }
+  SpanImpl(vector<T> &v) : SpanImpl(v.data(), v.size()) {
+  }
+
+  template <class OtherInnerT>
+  SpanImpl &operator=(const SpanImpl<T, OtherInnerT> &other) {
+    SpanImpl copy{other};
+    *this = copy;
+  }
+  template <class OtherInnerT>
+  bool operator==(const SpanImpl<T, OtherInnerT> &other) const {
+    if (size() != other.size()) {
+      return false;
+    }
+    for (size_t i = 0; i < size(); i++) {
+      if (!((*this)[i] == other[i])) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  InnerT &operator[](size_t i) {
+    DCHECK(i < size());
+    return data_[i];
+  }
+
+  const InnerT &operator[](size_t i) const {
+    DCHECK(i < size());
+    return data_[i];
+  }
+
+  InnerT &back() {
+    DCHECK(!empty());
+    return data_[size() - 1];
+  }
+
+  const InnerT &back() const {
+    DCHECK(!empty());
+    return data_[size() - 1];
+  }
+
+  InnerT &front() {
+    DCHECK(!empty());
+    return data_[0];
+  }
+
+  const InnerT &front() const {
+    DCHECK(!empty());
+    return data_[0];
+  }
+
+  InnerT *data() const {
+    return data_;
+  }
+
+  InnerT *begin() const {
+    return data_;
+  }
+  InnerT *end() const {
+    return data_ + size_;
+  }
+
+  std::reverse_iterator<InnerT *> rbegin() const {
+    return std::reverse_iterator<InnerT *>(end());
+  }
+  std::reverse_iterator<InnerT *> rend() const {
+    return std::reverse_iterator<InnerT *>(begin());
+  }
+
+  size_t size() const {
+    return size_;
+  }
+  bool empty() const {
+    return size() == 0;
+  }
+
+  SpanImpl &truncate(size_t size) {
+    if (size < size_) {
+      size_ = size;
+    }
+    return *this;
+  }
+
+  SpanImpl substr(size_t offset) const {
+    CHECK(offset <= size_);
+    return SpanImpl(begin() + offset, size_ - offset);
+  }
+  SpanImpl substr(size_t offset, size_t size) const {
+    CHECK(offset <= size_);
+    CHECK(size_ - offset >= size);
+    return SpanImpl(begin() + offset, size);
+  }
+};
+}  // namespace detail
+
+template <class T>
+using Span = detail::SpanImpl<T, const T>;
+
+template <class T>
+using MutableSpan = detail::SpanImpl<T, T>;
+
+template <class T>
+Span<T> as_span(const std::vector<T> &vec) {
+  return Span<T>(vec);
+}
+
+template <class T>
+MutableSpan<T> as_mutable_span(std::vector<T> &vec) {
+  return MutableSpan<T>(vec);
+}
+
+}  // namespace td