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diff --git a/third_party/abseil-cpp/absl/strings/str_cat.cc b/third_party/abseil-cpp/absl/strings/str_cat.cc
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+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/str_cat.h"
+
+#include <assert.h>
+
+#include <algorithm>
+#include <cstdint>
+#include <cstring>
+
+#include "absl/strings/ascii.h"
+#include "absl/strings/internal/resize_uninitialized.h"
+#include "absl/strings/numbers.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+AlphaNum::AlphaNum(Hex hex) {
+ static_assert(numbers_internal::kFastToBufferSize >= 32,
+ "This function only works when output buffer >= 32 bytes long");
+ char* const end = &digits_[numbers_internal::kFastToBufferSize];
+ auto real_width =
+ absl::numbers_internal::FastHexToBufferZeroPad16(hex.value, end - 16);
+ if (real_width >= hex.width) {
+ piece_ = absl::string_view(end - real_width, real_width);
+ } else {
+ // Pad first 16 chars because FastHexToBufferZeroPad16 pads only to 16 and
+ // max pad width can be up to 20.
+ std::memset(end - 32, hex.fill, 16);
+ // Patch up everything else up to the real_width.
+ std::memset(end - real_width - 16, hex.fill, 16);
+ piece_ = absl::string_view(end - hex.width, hex.width);
+ }
+}
+
+AlphaNum::AlphaNum(Dec dec) {
+ assert(dec.width <= numbers_internal::kFastToBufferSize);
+ char* const end = &digits_[numbers_internal::kFastToBufferSize];
+ char* const minfill = end - dec.width;
+ char* writer = end;
+ uint64_t value = dec.value;
+ bool neg = dec.neg;
+ while (value > 9) {
+ *--writer = '0' + (value % 10);
+ value /= 10;
+ }
+ *--writer = '0' + value;
+ if (neg) *--writer = '-';
+
+ ptrdiff_t fillers = writer - minfill;
+ if (fillers > 0) {
+ // Tricky: if the fill character is ' ', then it's <fill><+/-><digits>
+ // But...: if the fill character is '0', then it's <+/-><fill><digits>
+ bool add_sign_again = false;
+ if (neg && dec.fill == '0') { // If filling with '0',
+ ++writer; // ignore the sign we just added
+ add_sign_again = true; // and re-add the sign later.
+ }
+ writer -= fillers;
+ std::fill_n(writer, fillers, dec.fill);
+ if (add_sign_again) *--writer = '-';
+ }
+
+ piece_ = absl::string_view(writer, end - writer);
+}
+
+// ----------------------------------------------------------------------
+// StrCat()
+// This merges the given strings or integers, with no delimiter. This
+// is designed to be the fastest possible way to construct a string out
+// of a mix of raw C strings, string_views, strings, and integer values.
+// ----------------------------------------------------------------------
+
+// Append is merely a version of memcpy that returns the address of the byte
+// after the area just overwritten.
+static char* Append(char* out, const AlphaNum& x) {
+ // memcpy is allowed to overwrite arbitrary memory, so doing this after the
+ // call would force an extra fetch of x.size().
+ char* after = out + x.size();
+ if (x.size() != 0) {
+ memcpy(out, x.data(), x.size());
+ }
+ return after;
+}
+
+std::string StrCat(const AlphaNum& a, const AlphaNum& b) {
+ std::string result;
+ absl::strings_internal::STLStringResizeUninitialized(&result,
+ a.size() + b.size());
+ char* const begin = &result[0];
+ char* out = begin;
+ out = Append(out, a);
+ out = Append(out, b);
+ assert(out == begin + result.size());
+ return result;
+}
+
+std::string StrCat(const AlphaNum& a, const AlphaNum& b, const AlphaNum& c) {
+ std::string result;
+ strings_internal::STLStringResizeUninitialized(
+ &result, a.size() + b.size() + c.size());
+ char* const begin = &result[0];
+ char* out = begin;
+ out = Append(out, a);
+ out = Append(out, b);
+ out = Append(out, c);
+ assert(out == begin + result.size());
+ return result;
+}
+
+std::string StrCat(const AlphaNum& a, const AlphaNum& b, const AlphaNum& c,
+ const AlphaNum& d) {
+ std::string result;
+ strings_internal::STLStringResizeUninitialized(
+ &result, a.size() + b.size() + c.size() + d.size());
+ char* const begin = &result[0];
+ char* out = begin;
+ out = Append(out, a);
+ out = Append(out, b);
+ out = Append(out, c);
+ out = Append(out, d);
+ assert(out == begin + result.size());
+ return result;
+}
+
+namespace strings_internal {
+
+// Do not call directly - these are not part of the public API.
+std::string CatPieces(std::initializer_list<absl::string_view> pieces) {
+ std::string result;
+ size_t total_size = 0;
+ for (const absl::string_view piece : pieces) total_size += piece.size();
+ strings_internal::STLStringResizeUninitialized(&result, total_size);
+
+ char* const begin = &result[0];
+ char* out = begin;
+ for (const absl::string_view piece : pieces) {
+ const size_t this_size = piece.size();
+ if (this_size != 0) {
+ memcpy(out, piece.data(), this_size);
+ out += this_size;
+ }
+ }
+ assert(out == begin + result.size());
+ return result;
+}
+
+// It's possible to call StrAppend with an absl::string_view that is itself a
+// fragment of the string we're appending to. However the results of this are
+// random. Therefore, check for this in debug mode. Use unsigned math so we
+// only have to do one comparison. Note, there's an exception case: appending an
+// empty string is always allowed.
+#define ASSERT_NO_OVERLAP(dest, src) \
+ assert(((src).size() == 0) || \
+ (uintptr_t((src).data() - (dest).data()) > uintptr_t((dest).size())))
+
+void AppendPieces(std::string* dest,
+ std::initializer_list<absl::string_view> pieces) {
+ size_t old_size = dest->size();
+ size_t total_size = old_size;
+ for (const absl::string_view piece : pieces) {
+ ASSERT_NO_OVERLAP(*dest, piece);
+ total_size += piece.size();
+ }
+ strings_internal::STLStringResizeUninitialized(dest, total_size);
+
+ char* const begin = &(*dest)[0];
+ char* out = begin + old_size;
+ for (const absl::string_view piece : pieces) {
+ const size_t this_size = piece.size();
+ if (this_size != 0) {
+ memcpy(out, piece.data(), this_size);
+ out += this_size;
+ }
+ }
+ assert(out == begin + dest->size());
+}
+
+} // namespace strings_internal
+
+void StrAppend(std::string* dest, const AlphaNum& a) {
+ ASSERT_NO_OVERLAP(*dest, a);
+ dest->append(a.data(), a.size());
+}
+
+void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b) {
+ ASSERT_NO_OVERLAP(*dest, a);
+ ASSERT_NO_OVERLAP(*dest, b);
+ std::string::size_type old_size = dest->size();
+ strings_internal::STLStringResizeUninitialized(
+ dest, old_size + a.size() + b.size());
+ char* const begin = &(*dest)[0];
+ char* out = begin + old_size;
+ out = Append(out, a);
+ out = Append(out, b);
+ assert(out == begin + dest->size());
+}
+
+void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b,
+ const AlphaNum& c) {
+ ASSERT_NO_OVERLAP(*dest, a);
+ ASSERT_NO_OVERLAP(*dest, b);
+ ASSERT_NO_OVERLAP(*dest, c);
+ std::string::size_type old_size = dest->size();
+ strings_internal::STLStringResizeUninitialized(
+ dest, old_size + a.size() + b.size() + c.size());
+ char* const begin = &(*dest)[0];
+ char* out = begin + old_size;
+ out = Append(out, a);
+ out = Append(out, b);
+ out = Append(out, c);
+ assert(out == begin + dest->size());
+}
+
+void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b,
+ const AlphaNum& c, const AlphaNum& d) {
+ ASSERT_NO_OVERLAP(*dest, a);
+ ASSERT_NO_OVERLAP(*dest, b);
+ ASSERT_NO_OVERLAP(*dest, c);
+ ASSERT_NO_OVERLAP(*dest, d);
+ std::string::size_type old_size = dest->size();
+ strings_internal::STLStringResizeUninitialized(
+ dest, old_size + a.size() + b.size() + c.size() + d.size());
+ char* const begin = &(*dest)[0];
+ char* out = begin + old_size;
+ out = Append(out, a);
+ out = Append(out, b);
+ out = Append(out, c);
+ out = Append(out, d);
+ assert(out == begin + dest->size());
+}
+
+ABSL_NAMESPACE_END
+} // namespace absl
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