generated from guanyuankai/bonus-edge-proxy
337 lines
11 KiB
C++
337 lines
11 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/strings/str_cat.h"
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#include <assert.h>
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#include <cstddef>
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#include <cstdint>
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#include <cstring>
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#include <initializer_list>
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#include <string>
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#include <type_traits>
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#include "absl/base/config.h"
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#include "absl/base/nullability.h"
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#include "absl/strings/internal/resize_uninitialized.h"
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#include "absl/strings/numbers.h"
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#include "absl/strings/string_view.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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// ----------------------------------------------------------------------
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// StrCat()
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// This merges the given strings or integers, with no delimiter. This
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// is designed to be the fastest possible way to construct a string out
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// of a mix of raw C strings, string_views, strings, and integer values.
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// ----------------------------------------------------------------------
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namespace {
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// Append is merely a version of memcpy that returns the address of the byte
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// after the area just overwritten.
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absl::Nonnull<char*> Append(absl::Nonnull<char*> out, const AlphaNum& x) {
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// memcpy is allowed to overwrite arbitrary memory, so doing this after the
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// call would force an extra fetch of x.size().
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char* after = out + x.size();
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if (x.size() != 0) {
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memcpy(out, x.data(), x.size());
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}
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return after;
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}
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} // namespace
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std::string StrCat(const AlphaNum& a, const AlphaNum& b) {
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std::string result;
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absl::strings_internal::STLStringResizeUninitialized(&result,
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a.size() + b.size());
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char* const begin = &result[0];
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char* out = begin;
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out = Append(out, a);
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out = Append(out, b);
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assert(out == begin + result.size());
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return result;
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}
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std::string StrCat(const AlphaNum& a, const AlphaNum& b, const AlphaNum& c) {
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std::string result;
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strings_internal::STLStringResizeUninitialized(
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&result, a.size() + b.size() + c.size());
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char* const begin = &result[0];
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char* out = begin;
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out = Append(out, a);
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out = Append(out, b);
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out = Append(out, c);
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assert(out == begin + result.size());
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return result;
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}
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std::string StrCat(const AlphaNum& a, const AlphaNum& b, const AlphaNum& c,
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const AlphaNum& d) {
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std::string result;
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strings_internal::STLStringResizeUninitialized(
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&result, a.size() + b.size() + c.size() + d.size());
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char* const begin = &result[0];
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char* out = begin;
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out = Append(out, a);
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out = Append(out, b);
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out = Append(out, c);
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out = Append(out, d);
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assert(out == begin + result.size());
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return result;
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}
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namespace strings_internal {
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// Do not call directly - these are not part of the public API.
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void STLStringAppendUninitializedAmortized(std::string* dest,
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size_t to_append) {
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strings_internal::AppendUninitializedTraits<std::string>::Append(dest,
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to_append);
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}
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template <typename Integer>
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std::enable_if_t<std::is_integral<Integer>::value, std::string> IntegerToString(
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Integer i) {
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std::string str;
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const auto /* either bool or std::false_type */ is_negative =
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absl::numbers_internal::IsNegative(i);
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const uint32_t digits = absl::numbers_internal::Base10Digits(
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absl::numbers_internal::UnsignedAbsoluteValue(i));
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absl::strings_internal::STLStringResizeUninitialized(
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&str, digits + static_cast<uint32_t>(is_negative));
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absl::numbers_internal::FastIntToBufferBackward(i, &str[str.size()], digits);
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return str;
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}
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template <>
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std::string IntegerToString(long i) { // NOLINT
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if (sizeof(i) <= sizeof(int)) {
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return IntegerToString(static_cast<int>(i));
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} else {
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return IntegerToString(static_cast<long long>(i)); // NOLINT
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}
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}
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template <>
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std::string IntegerToString(unsigned long i) { // NOLINT
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if (sizeof(i) <= sizeof(unsigned int)) {
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return IntegerToString(static_cast<unsigned int>(i));
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} else {
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return IntegerToString(static_cast<unsigned long long>(i)); // NOLINT
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}
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}
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template <typename Float>
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std::enable_if_t<std::is_floating_point<Float>::value, std::string>
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FloatToString(Float f) {
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std::string result;
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strings_internal::STLStringResizeUninitialized(
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&result, numbers_internal::kSixDigitsToBufferSize);
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char* start = &result[0];
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result.erase(numbers_internal::SixDigitsToBuffer(f, start));
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return result;
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}
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std::string SingleArgStrCat(int x) { return IntegerToString(x); }
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std::string SingleArgStrCat(unsigned int x) { return IntegerToString(x); }
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// NOLINTNEXTLINE
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std::string SingleArgStrCat(long x) { return IntegerToString(x); }
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// NOLINTNEXTLINE
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std::string SingleArgStrCat(unsigned long x) { return IntegerToString(x); }
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// NOLINTNEXTLINE
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std::string SingleArgStrCat(long long x) { return IntegerToString(x); }
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// NOLINTNEXTLINE
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std::string SingleArgStrCat(unsigned long long x) { return IntegerToString(x); }
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std::string SingleArgStrCat(float x) { return FloatToString(x); }
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std::string SingleArgStrCat(double x) { return FloatToString(x); }
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template <class Integer>
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std::enable_if_t<std::is_integral<Integer>::value, void> AppendIntegerToString(
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std::string& str, Integer i) {
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const auto /* either bool or std::false_type */ is_negative =
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absl::numbers_internal::IsNegative(i);
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const uint32_t digits = absl::numbers_internal::Base10Digits(
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absl::numbers_internal::UnsignedAbsoluteValue(i));
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absl::strings_internal::STLStringAppendUninitializedAmortized(
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&str, digits + static_cast<uint32_t>(is_negative));
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absl::numbers_internal::FastIntToBufferBackward(i, &str[str.size()], digits);
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}
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template <>
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void AppendIntegerToString(std::string& str, long i) { // NOLINT
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if (sizeof(i) <= sizeof(int)) {
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return AppendIntegerToString(str, static_cast<int>(i));
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} else {
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return AppendIntegerToString(str, static_cast<long long>(i)); // NOLINT
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}
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}
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template <>
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void AppendIntegerToString(std::string& str,
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unsigned long i) { // NOLINT
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if (sizeof(i) <= sizeof(unsigned int)) {
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return AppendIntegerToString(str, static_cast<unsigned int>(i));
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} else {
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return AppendIntegerToString(str,
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static_cast<unsigned long long>(i)); // NOLINT
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}
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}
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// `SingleArgStrAppend` overloads are defined here for the same reasons as with
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// `SingleArgStrCat` above.
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void SingleArgStrAppend(std::string& str, int x) {
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return AppendIntegerToString(str, x);
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}
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void SingleArgStrAppend(std::string& str, unsigned int x) {
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return AppendIntegerToString(str, x);
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}
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// NOLINTNEXTLINE
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void SingleArgStrAppend(std::string& str, long x) {
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return AppendIntegerToString(str, x);
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}
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// NOLINTNEXTLINE
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void SingleArgStrAppend(std::string& str, unsigned long x) {
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return AppendIntegerToString(str, x);
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}
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// NOLINTNEXTLINE
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void SingleArgStrAppend(std::string& str, long long x) {
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return AppendIntegerToString(str, x);
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}
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// NOLINTNEXTLINE
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void SingleArgStrAppend(std::string& str, unsigned long long x) {
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return AppendIntegerToString(str, x);
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}
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std::string CatPieces(std::initializer_list<absl::string_view> pieces) {
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std::string result;
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size_t total_size = 0;
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for (absl::string_view piece : pieces) total_size += piece.size();
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strings_internal::STLStringResizeUninitialized(&result, total_size);
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char* const begin = &result[0];
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char* out = begin;
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for (absl::string_view piece : pieces) {
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const size_t this_size = piece.size();
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if (this_size != 0) {
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memcpy(out, piece.data(), this_size);
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out += this_size;
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}
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}
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assert(out == begin + result.size());
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return result;
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}
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// It's possible to call StrAppend with an absl::string_view that is itself a
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// fragment of the string we're appending to. However the results of this are
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// random. Therefore, check for this in debug mode. Use unsigned math so we
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// only have to do one comparison. Note, there's an exception case: appending an
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// empty string is always allowed.
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#define ASSERT_NO_OVERLAP(dest, src) \
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assert(((src).size() == 0) || \
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(uintptr_t((src).data() - (dest).data()) > uintptr_t((dest).size())))
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void AppendPieces(absl::Nonnull<std::string*> dest,
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std::initializer_list<absl::string_view> pieces) {
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size_t old_size = dest->size();
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size_t to_append = 0;
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for (absl::string_view piece : pieces) {
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ASSERT_NO_OVERLAP(*dest, piece);
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to_append += piece.size();
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}
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strings_internal::STLStringAppendUninitializedAmortized(dest, to_append);
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char* const begin = &(*dest)[0];
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char* out = begin + old_size;
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for (absl::string_view piece : pieces) {
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const size_t this_size = piece.size();
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if (this_size != 0) {
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memcpy(out, piece.data(), this_size);
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out += this_size;
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}
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}
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assert(out == begin + dest->size());
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}
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} // namespace strings_internal
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void StrAppend(absl::Nonnull<std::string*> dest, const AlphaNum& a) {
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ASSERT_NO_OVERLAP(*dest, a);
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std::string::size_type old_size = dest->size();
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strings_internal::STLStringAppendUninitializedAmortized(dest, a.size());
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char* const begin = &(*dest)[0];
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char* out = begin + old_size;
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out = Append(out, a);
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assert(out == begin + dest->size());
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}
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void StrAppend(absl::Nonnull<std::string*> dest, const AlphaNum& a,
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const AlphaNum& b) {
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ASSERT_NO_OVERLAP(*dest, a);
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ASSERT_NO_OVERLAP(*dest, b);
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std::string::size_type old_size = dest->size();
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strings_internal::STLStringAppendUninitializedAmortized(dest,
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a.size() + b.size());
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char* const begin = &(*dest)[0];
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char* out = begin + old_size;
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out = Append(out, a);
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out = Append(out, b);
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assert(out == begin + dest->size());
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}
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void StrAppend(absl::Nonnull<std::string*> dest, const AlphaNum& a,
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const AlphaNum& b, const AlphaNum& c) {
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ASSERT_NO_OVERLAP(*dest, a);
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ASSERT_NO_OVERLAP(*dest, b);
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ASSERT_NO_OVERLAP(*dest, c);
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std::string::size_type old_size = dest->size();
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strings_internal::STLStringAppendUninitializedAmortized(
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dest, a.size() + b.size() + c.size());
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char* const begin = &(*dest)[0];
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char* out = begin + old_size;
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out = Append(out, a);
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out = Append(out, b);
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out = Append(out, c);
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assert(out == begin + dest->size());
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}
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void StrAppend(absl::Nonnull<std::string*> dest, const AlphaNum& a,
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const AlphaNum& b, const AlphaNum& c, const AlphaNum& d) {
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ASSERT_NO_OVERLAP(*dest, a);
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ASSERT_NO_OVERLAP(*dest, b);
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ASSERT_NO_OVERLAP(*dest, c);
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ASSERT_NO_OVERLAP(*dest, d);
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std::string::size_type old_size = dest->size();
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strings_internal::STLStringAppendUninitializedAmortized(
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dest, a.size() + b.size() + c.size() + d.size());
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char* const begin = &(*dest)[0];
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char* out = begin + old_size;
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out = Append(out, a);
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out = Append(out, b);
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out = Append(out, c);
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out = Append(out, d);
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assert(out == begin + dest->size());
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}
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ABSL_NAMESPACE_END
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} // namespace absl
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