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tdutils/td/utils/StringBuilder.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 "td/utils/Slice.h"
+#include "td/utils/StackAllocator.h"
+
+#include <cstdlib>
+#include <memory>
+#include <type_traits>
+
+namespace td {
+
+class StringBuilder {
+ public:
+  explicit StringBuilder(MutableSlice slice, bool use_buffer = false);
+
+  void clear() {
+    current_ptr_ = begin_ptr_;
+    error_flag_ = false;
+  }
+
+  MutableCSlice as_cslice() {
+    if (current_ptr_ >= end_ptr_ + reserved_size) {
+      std::abort();  // shouldn't happen
+    }
+    *current_ptr_ = 0;
+    return MutableCSlice(begin_ptr_, current_ptr_);
+  }
+
+  bool is_error() const {
+    return error_flag_;
+  }
+
+  StringBuilder &operator<<(const char *str) {
+    return *this << Slice(str);
+  }
+
+  StringBuilder &operator<<(const wchar_t *str) = delete;
+
+  StringBuilder &operator<<(Slice slice);
+
+  StringBuilder &operator<<(bool b) {
+    return *this << (b ? Slice("true") : Slice("false"));
+  }
+
+  StringBuilder &operator<<(char c) {
+    if (unlikely(!reserve())) {
+      return on_error();
+    }
+    *current_ptr_++ = c;
+    return *this;
+  }
+
+  StringBuilder &operator<<(unsigned char c) {
+    return *this << static_cast<unsigned int>(c);
+  }
+
+  StringBuilder &operator<<(signed char c) {
+    return *this << static_cast<int>(c);
+  }
+
+  StringBuilder &operator<<(int x);
+
+  StringBuilder &operator<<(unsigned int x);
+
+  StringBuilder &operator<<(long int x);
+
+  StringBuilder &operator<<(long unsigned int x);
+
+  StringBuilder &operator<<(long long int x);
+
+  StringBuilder &operator<<(long long unsigned int x);
+
+  struct FixedDouble {
+    double d;
+    int precision;
+
+    FixedDouble(double d, int precision) : d(d), precision(precision) {
+    }
+  };
+  StringBuilder &operator<<(FixedDouble x);
+
+  StringBuilder &operator<<(double x) {
+    return *this << FixedDouble(x, 6);
+  }
+
+  StringBuilder &operator<<(const void *ptr);
+
+  template <class T>
+  StringBuilder &operator<<(const T *ptr) {
+    return *this << static_cast<const void *>(ptr);
+  }
+
+ private:
+  char *begin_ptr_;
+  char *current_ptr_;
+  char *end_ptr_;
+  bool error_flag_ = false;
+  bool use_buffer_ = false;
+  std::unique_ptr<char[]> buffer_;
+  static constexpr size_t reserved_size = 30;
+
+  StringBuilder &on_error() {
+    error_flag_ = true;
+    return *this;
+  }
+
+  bool reserve() {
+    if (end_ptr_ > current_ptr_) {
+      return true;
+    }
+    return reserve_inner(reserved_size);
+  }
+  bool reserve(size_t size) {
+    if (end_ptr_ > current_ptr_ && static_cast<size_t>(end_ptr_ - current_ptr_) >= size) {
+      return true;
+    }
+    return reserve_inner(size);
+  }
+  bool reserve_inner(size_t size);
+};
+
+template <class T>
+std::enable_if_t<std::is_arithmetic<T>::value, string> to_string(const T &x) {
+  const size_t buf_size = 1000;
+  auto buf = StackAllocator::alloc(buf_size);
+  StringBuilder sb(buf.as_slice());
+  sb << x;
+  return sb.as_cslice().str();
+}
+
+}  // namespace td