diff options
Diffstat (limited to 'absl/strings/str_cat.h')
-rw-r--r-- | absl/strings/str_cat.h | 98 |
1 files changed, 83 insertions, 15 deletions
diff --git a/absl/strings/str_cat.h b/absl/strings/str_cat.h index 730b4d8c..d5f71ff0 100644 --- a/absl/strings/str_cat.h +++ b/absl/strings/str_cat.h @@ -87,13 +87,16 @@ #ifndef ABSL_STRINGS_STR_CAT_H_ #define ABSL_STRINGS_STR_CAT_H_ +#include <algorithm> #include <array> #include <cstdint> +#include <cstring> #include <string> #include <type_traits> #include <utility> #include <vector> +#include "absl/base/attributes.h" #include "absl/base/port.h" #include "absl/strings/internal/has_absl_stringify.h" #include "absl/strings/internal/stringify_sink.h" @@ -201,6 +204,27 @@ struct Hex { explicit Hex(Pointee* v, PadSpec spec = absl::kNoPad) : Hex(spec, reinterpret_cast<uintptr_t>(v)) {} + template <typename S> + friend void AbslStringify(S& sink, Hex hex) { + static_assert( + numbers_internal::kFastToBufferSize >= 32, + "This function only works when output buffer >= 32 bytes long"); + char buffer[numbers_internal::kFastToBufferSize]; + char* const end = &buffer[numbers_internal::kFastToBufferSize]; + auto real_width = + absl::numbers_internal::FastHexToBufferZeroPad16(hex.value, end - 16); + if (real_width >= hex.width) { + sink.Append(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); + sink.Append(absl::string_view(end - hex.width, hex.width)); + } + } + private: Hex(PadSpec spec, uint64_t v) : value(v), @@ -235,6 +259,38 @@ struct Dec { : spec - absl::kZeroPad2 + 2), fill(spec >= absl::kSpacePad2 ? ' ' : '0'), neg(v < 0) {} + + template <typename S> + friend void AbslStringify(S& sink, Dec dec) { + assert(dec.width <= numbers_internal::kFastToBufferSize); + char buffer[numbers_internal::kFastToBufferSize]; + char* const end = &buffer[numbers_internal::kFastToBufferSize]; + char* const minfill = end - dec.width; + char* writer = end; + uint64_t val = dec.value; + while (val > 9) { + *--writer = '0' + (val % 10); + val /= 10; + } + *--writer = '0' + static_cast<char>(val); + if (dec.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 (dec.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 = '-'; + } + + sink.Append(absl::string_view(writer, static_cast<size_t>(end - writer))); + } }; // ----------------------------------------------------------------------------- @@ -282,28 +338,30 @@ class AlphaNum { AlphaNum(double f) // NOLINT(runtime/explicit) : piece_(digits_, numbers_internal::SixDigitsToBuffer(f, digits_)) {} - AlphaNum(Hex hex); // NOLINT(runtime/explicit) - AlphaNum(Dec dec); // NOLINT(runtime/explicit) - template <size_t size> AlphaNum( // NOLINT(runtime/explicit) - const strings_internal::AlphaNumBuffer<size>& buf) + const strings_internal::AlphaNumBuffer<size>& buf + ABSL_ATTRIBUTE_LIFETIME_BOUND) : piece_(&buf.data[0], buf.size) {} - AlphaNum(const char* c_str) // NOLINT(runtime/explicit) - : piece_(NullSafeStringView(c_str)) {} // NOLINT(runtime/explicit) - AlphaNum(absl::string_view pc) : piece_(pc) {} // NOLINT(runtime/explicit) + AlphaNum(const char* c_str // NOLINT(runtime/explicit) + ABSL_ATTRIBUTE_LIFETIME_BOUND) + : piece_(NullSafeStringView(c_str)) {} + AlphaNum(absl::string_view pc // NOLINT(runtime/explicit) + ABSL_ATTRIBUTE_LIFETIME_BOUND) + : piece_(pc) {} template <typename T, typename = typename std::enable_if< strings_internal::HasAbslStringify<T>::value>::type> - AlphaNum( // NOLINT(runtime/explicit) - const T& v, // NOLINT(runtime/explicit) - strings_internal::StringifySink&& sink = {}) // NOLINT(runtime/explicit) + AlphaNum( // NOLINT(runtime/explicit) + const T& v ABSL_ATTRIBUTE_LIFETIME_BOUND, + strings_internal::StringifySink&& sink ABSL_ATTRIBUTE_LIFETIME_BOUND = {}) : piece_(strings_internal::ExtractStringification(sink, v)) {} template <typename Allocator> AlphaNum( // NOLINT(runtime/explicit) - const std::basic_string<char, std::char_traits<char>, Allocator>& str) + const std::basic_string<char, std::char_traits<char>, Allocator>& str + ABSL_ATTRIBUTE_LIFETIME_BOUND) : piece_(str) {} // Use string literals ":" instead of character literals ':'. @@ -316,14 +374,24 @@ class AlphaNum { const char* data() const { return piece_.data(); } absl::string_view Piece() const { return piece_; } - // Normal enums are already handled by the integer formatters. - // This overload matches only scoped enums. + // Match unscoped enums. Use integral promotion so that a `char`-backed + // enum becomes a wider integral type AlphaNum will accept. template <typename T, typename = typename std::enable_if< - std::is_enum<T>{} && !std::is_convertible<T, int>{} && + std::is_enum<T>{} && std::is_convertible<T, int>{} && !strings_internal::HasAbslStringify<T>::value>::type> AlphaNum(T e) // NOLINT(runtime/explicit) - : AlphaNum(static_cast<typename std::underlying_type<T>::type>(e)) {} + : AlphaNum(+e) {} + + // This overload matches scoped enums. We must explicitly cast to the + // underlying type, but use integral promotion for the same reason as above. + template <typename T, + typename std::enable_if< + std::is_enum<T>{} && !std::is_convertible<T, int>{} && + !strings_internal::HasAbslStringify<T>::value, + char*>::type = nullptr> + AlphaNum(T e) // NOLINT(runtime/explicit) + : AlphaNum(+static_cast<typename std::underlying_type<T>::type>(e)) {} // vector<bool>::reference and const_reference require special help to // convert to `AlphaNum` because it requires two user defined conversions. |