diff options
| -rw-r--r-- | absl/strings/str_cat.cc | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/absl/strings/str_cat.cc b/absl/strings/str_cat.cc index 17f42d28..900dc69a 100644 --- a/absl/strings/str_cat.cc +++ b/absl/strings/str_cat.cc @@ -29,6 +29,7 @@ namespace absl { ABSL_NAMESPACE_BEGIN + // ---------------------------------------------------------------------- // StrCat() // This merges the given strings or integers, with no delimiter. This @@ -36,9 +37,10 @@ ABSL_NAMESPACE_BEGIN // of a mix of raw C strings, string_views, strings, and integer values. // ---------------------------------------------------------------------- +namespace { // 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) { +inline 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(); @@ -48,6 +50,13 @@ static char* Append(char* out, const AlphaNum& x) { return after; } +inline void STLStringAppendUninitializedAmortized(std::string* dest, + size_t to_append) { + strings_internal::AppendUninitializedTraits<std::string>::Append(dest, + to_append); +} +} // namespace + std::string StrCat(const AlphaNum& a, const AlphaNum& b) { std::string result; absl::strings_internal::STLStringResizeUninitialized(&result, @@ -122,12 +131,12 @@ std::string CatPieces(std::initializer_list<absl::string_view> pieces) { void AppendPieces(std::string* dest, std::initializer_list<absl::string_view> pieces) { size_t old_size = dest->size(); - size_t total_size = old_size; + size_t to_append = 0; for (absl::string_view piece : pieces) { ASSERT_NO_OVERLAP(*dest, piece); - total_size += piece.size(); + to_append += piece.size(); } - strings_internal::STLStringResizeUninitializedAmortized(dest, total_size); + STLStringAppendUninitializedAmortized(dest, to_append); char* const begin = &(*dest)[0]; char* out = begin + old_size; @@ -146,8 +155,7 @@ void AppendPieces(std::string* dest, void StrAppend(std::string* dest, const AlphaNum& a) { ASSERT_NO_OVERLAP(*dest, a); std::string::size_type old_size = dest->size(); - strings_internal::STLStringResizeUninitializedAmortized(dest, - old_size + a.size()); + STLStringAppendUninitializedAmortized(dest, a.size()); char* const begin = &(*dest)[0]; char* out = begin + old_size; out = Append(out, a); @@ -158,8 +166,7 @@ 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::STLStringResizeUninitializedAmortized( - dest, old_size + a.size() + b.size()); + STLStringAppendUninitializedAmortized(dest, a.size() + b.size()); char* const begin = &(*dest)[0]; char* out = begin + old_size; out = Append(out, a); @@ -173,8 +180,7 @@ void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b, ASSERT_NO_OVERLAP(*dest, b); ASSERT_NO_OVERLAP(*dest, c); std::string::size_type old_size = dest->size(); - strings_internal::STLStringResizeUninitializedAmortized( - dest, old_size + a.size() + b.size() + c.size()); + STLStringAppendUninitializedAmortized(dest, a.size() + b.size() + c.size()); char* const begin = &(*dest)[0]; char* out = begin + old_size; out = Append(out, a); @@ -190,8 +196,8 @@ void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b, ASSERT_NO_OVERLAP(*dest, c); ASSERT_NO_OVERLAP(*dest, d); std::string::size_type old_size = dest->size(); - strings_internal::STLStringResizeUninitializedAmortized( - dest, old_size + a.size() + b.size() + c.size() + d.size()); + STLStringAppendUninitializedAmortized( + dest, a.size() + b.size() + c.size() + d.size()); char* const begin = &(*dest)[0]; char* out = begin + old_size; out = Append(out, a); |