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/*
* 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.
*/
#include "rtc_base/strings/string_builder.h"
#include <stdarg.h>
#include <cstdio>
#include <cstring>
#include "absl/strings/string_view.h"
#include "api/array_view.h"
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_minmax.h"
namespace webrtc {
SimpleStringBuilder::SimpleStringBuilder(ArrayView<char> buffer)
: buffer_(buffer) {
buffer_[0] = '\0';
RTC_DCHECK(IsConsistent());
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(char ch) {
return operator<<(absl::string_view(&ch, 1));
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(absl::string_view str) {
RTC_DCHECK_LT(size_ + str.length(), buffer_.size())
<< "Buffer size was insufficient";
const size_t chars_added = SafeMin(str.length(), buffer_.size() - size_ - 1);
memcpy(&buffer_[size_], str.data(), chars_added);
size_ += chars_added;
buffer_[size_] = '\0';
RTC_DCHECK(IsConsistent());
return *this;
}
// Numeric conversion routines.
//
// We use std::[v]snprintf instead of std::to_string because:
// * std::to_string relies on the current locale for formatting purposes,
// and therefore concurrent calls to std::to_string from multiple threads
// may result in partial serialization of calls
// * snprintf allows us to print the number directly into our buffer.
// * avoid allocating a std::string (potential heap alloc).
// TODO(tommi): Switch to std::to_chars in C++17.
SimpleStringBuilder& SimpleStringBuilder::operator<<(int i) {
return AppendFormat("%d", i);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(unsigned i) {
return AppendFormat("%u", i);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(long i) { // NOLINT
return AppendFormat("%ld", i);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(long long i) { // NOLINT
return AppendFormat("%lld", i);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(
unsigned long i) { // NOLINT
return AppendFormat("%lu", i);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(
unsigned long long i) { // NOLINT
return AppendFormat("%llu", i);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(float f) {
return AppendFormat("%g", f);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(double f) {
return AppendFormat("%g", f);
}
SimpleStringBuilder& SimpleStringBuilder::operator<<(long double f) {
return AppendFormat("%Lg", f);
}
SimpleStringBuilder& SimpleStringBuilder::AppendFormat(const char* fmt, ...) {
va_list args;
va_start(args, fmt);
const int len =
std::vsnprintf(&buffer_[size_], buffer_.size() - size_, fmt, args);
if (len >= 0) {
const size_t chars_added = SafeMin(len, buffer_.size() - 1 - size_);
size_ += chars_added;
RTC_DCHECK_EQ(len, chars_added) << "Buffer size was insufficient";
} else {
// This should never happen, but we're paranoid, so re-write the
// terminator in case vsnprintf() overwrote it.
RTC_DCHECK_NOTREACHED();
buffer_[size_] = '\0';
}
va_end(args);
RTC_DCHECK(IsConsistent());
return *this;
}
StringBuilder& StringBuilder::AppendFormat(const char* fmt, ...) {
va_list args, copy;
va_start(args, fmt);
va_copy(copy, args);
const int predicted_length = std::vsnprintf(nullptr, 0, fmt, copy);
va_end(copy);
RTC_DCHECK_GE(predicted_length, 0);
if (predicted_length > 0) {
const size_t size = str_.size();
str_.resize(size + predicted_length);
// Pass "+ 1" to vsnprintf to include space for the '\0'.
const int actual_length =
std::vsnprintf(&str_[size], predicted_length + 1, fmt, args);
RTC_DCHECK_GE(actual_length, 0);
}
va_end(args);
return *this;
}
} // namespace webrtc
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