blob: d095385ab4645d82869f189d64e66d41c137390e [file] [log] [blame]
/*
* Copyright 2018 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef RTC_BASE_STRINGS_STRING_BUILDER_H_
#define RTC_BASE_STRINGS_STRING_BUILDER_H_
#include <cstdio>
#include <cstring>
#include <string>
#include "api/array_view.h"
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_minmax.h"
#include "rtc_base/stringutils.h"
namespace rtc {
// This is a minimalistic string builder class meant to cover the most cases of
// when you might otherwise be tempted to use a stringstream (discouraged for
// anything except logging). It uses a fixed-size buffer provided by the caller
// and concatenates strings and numbers into it, allowing the results to be
// read via |str()|.
class SimpleStringBuilder {
public:
explicit SimpleStringBuilder(rtc::ArrayView<char> buffer);
SimpleStringBuilder(const SimpleStringBuilder&) = delete;
SimpleStringBuilder& operator=(const SimpleStringBuilder&) = delete;
SimpleStringBuilder& operator<<(const char* str);
SimpleStringBuilder& operator<<(char ch);
SimpleStringBuilder& operator<<(const std::string& str);
SimpleStringBuilder& operator<<(int i);
SimpleStringBuilder& operator<<(unsigned i);
SimpleStringBuilder& operator<<(long i); // NOLINT
SimpleStringBuilder& operator<<(long long i); // NOLINT
SimpleStringBuilder& operator<<(unsigned long i); // NOLINT
SimpleStringBuilder& operator<<(unsigned long long i); // NOLINT
SimpleStringBuilder& operator<<(float f);
SimpleStringBuilder& operator<<(double f);
SimpleStringBuilder& operator<<(long double f);
// Returns a pointer to the built string. The name |str()| is borrowed for
// compatibility reasons as we replace usage of stringstream throughout the
// code base.
const char* str() const { return buffer_.data(); }
// Returns the length of the string. The name |size()| is picked for STL
// compatibility reasons.
size_t size() const { return size_; }
// Allows appending a printf style formatted string.
#if defined(__GNUC__)
__attribute__((__format__(__printf__, 2, 3)))
#endif
SimpleStringBuilder&
AppendFormat(const char* fmt, ...);
// An alternate way from operator<<() to append a string. This variant is
// slightly more efficient when the length of the string to append, is known.
SimpleStringBuilder& Append(const char* str, size_t length = SIZE_UNKNOWN);
private:
bool IsConsistent() const {
return size_ <= buffer_.size() - 1 && buffer_[size_] == '\0';
}
// An always-zero-terminated fixed-size buffer that we write to. The fixed
// size allows the buffer to be stack allocated, which helps performance.
// Having a fixed size is furthermore useful to avoid unnecessary resizing
// while building it.
const rtc::ArrayView<char> buffer_;
// Represents the number of characters written to the buffer.
// This does not include the terminating '\0'.
size_t size_ = 0;
};
} // namespace rtc
#endif // RTC_BASE_STRINGS_STRING_BUILDER_H_