142 lines
4.2 KiB
C++
142 lines
4.2 KiB
C++
/*
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* Copyright 2018 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "rtc_base/strings/string_builder.h"
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#include <stdarg.h>
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#include <cstdio>
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#include <cstring>
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#include "rtc_base/checks.h"
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#include "rtc_base/numerics/safe_minmax.h"
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namespace rtc {
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SimpleStringBuilder::SimpleStringBuilder(rtc::ArrayView<char> buffer)
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: buffer_(buffer) {
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buffer_[0] = '\0';
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RTC_DCHECK(IsConsistent());
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(const char* str) {
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return Append(str, strlen(str));
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(char ch) {
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return Append(&ch, 1);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(const std::string& str) {
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return Append(str.c_str(), str.length());
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}
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// Numeric conversion routines.
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//
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// We use std::[v]snprintf instead of std::to_string because:
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// * std::to_string relies on the current locale for formatting purposes,
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// and therefore concurrent calls to std::to_string from multiple threads
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// may result in partial serialization of calls
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// * snprintf allows us to print the number directly into our buffer.
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// * avoid allocating a std::string (potential heap alloc).
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// TODO(tommi): Switch to std::to_chars in C++17.
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SimpleStringBuilder& SimpleStringBuilder::operator<<(int i) {
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return AppendFormat("%d", i);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(unsigned i) {
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return AppendFormat("%u", i);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(long i) { // NOLINT
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return AppendFormat("%ld", i);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(long long i) { // NOLINT
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return AppendFormat("%lld", i);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(
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unsigned long i) { // NOLINT
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return AppendFormat("%lu", i);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(
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unsigned long long i) { // NOLINT
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return AppendFormat("%llu", i);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(float f) {
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return AppendFormat("%g", f);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(double f) {
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return AppendFormat("%g", f);
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}
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SimpleStringBuilder& SimpleStringBuilder::operator<<(long double f) {
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return AppendFormat("%Lg", f);
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}
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SimpleStringBuilder& SimpleStringBuilder::AppendFormat(const char* fmt, ...) {
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va_list args;
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va_start(args, fmt);
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const int len =
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std::vsnprintf(&buffer_[size_], buffer_.size() - size_, fmt, args);
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if (len >= 0) {
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const size_t chars_added = rtc::SafeMin(len, buffer_.size() - 1 - size_);
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size_ += chars_added;
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RTC_DCHECK_EQ(len, chars_added) << "Buffer size was insufficient";
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} else {
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// This should never happen, but we're paranoid, so re-write the
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// terminator in case vsnprintf() overwrote it.
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RTC_NOTREACHED();
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buffer_[size_] = '\0';
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}
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va_end(args);
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RTC_DCHECK(IsConsistent());
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return *this;
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}
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SimpleStringBuilder& SimpleStringBuilder::Append(const char* str,
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size_t length) {
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RTC_DCHECK_LT(size_ + length, buffer_.size())
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<< "Buffer size was insufficient";
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const size_t chars_added = rtc::SafeMin(length, buffer_.size() - size_ - 1);
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memcpy(&buffer_[size_], str, chars_added);
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size_ += chars_added;
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buffer_[size_] = '\0';
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RTC_DCHECK(IsConsistent());
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return *this;
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}
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StringBuilder& StringBuilder::AppendFormat(const char* fmt, ...) {
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va_list args, copy;
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va_start(args, fmt);
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va_copy(copy, args);
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const int predicted_length = std::vsnprintf(nullptr, 0, fmt, copy);
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va_end(copy);
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RTC_DCHECK_GE(predicted_length, 0);
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if (predicted_length > 0) {
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const size_t size = str_.size();
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str_.resize(size + predicted_length);
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// Pass "+ 1" to vsnprintf to include space for the '\0'.
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const int actual_length =
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std::vsnprintf(&str_[size], predicted_length + 1, fmt, args);
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RTC_DCHECK_GE(actual_length, 0);
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}
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va_end(args);
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return *this;
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}
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} // namespace rtc
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