Export of internal Abseil changes.

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70f43a482d7d4ae4a255f17ca02b0106653dd600 by Shaindel Schwartz <shaindel@google.com>:

Internal change

PiperOrigin-RevId: 201571193

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93e6e9c2e683158be49d9dd1f5cb1a91d0c0f556 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 201567108

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fbd8ee94fbe9f2448e5adf5e88706f9c8216048f by Juemin Yang <jueminyang@google.com>:

str_format release

PiperOrigin-RevId: 201565129

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387faa301555a8a888c4429df52734aa806dca46 by Abseil Team <absl-team@google.com>:

Adds a defaulted allocator parameter to the size_type constructor of InlinedVector

PiperOrigin-RevId: 201558711

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39b15ea2c68d7129d70cbde7e71af900032595ec by Matt Calabrese <calabrese@google.com>:

Update the variant implementation to eliminate unnecessary checking on alternative access when the index is known or required to be correct.

PiperOrigin-RevId: 201529535

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adab77f1f7bb363aa534297f22aae2b0f08889ea by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 201458388

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a701dc0ba62e3cadf0de14203415b91df4ee8151 by Greg Falcon <gfalcon@google.com>:

Internal cleanup

PiperOrigin-RevId: 201394836

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8a7191410b8f440fdfa27f722ff05e451502ab61 by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 201369269
GitOrigin-RevId: 70f43a482d7d4ae4a255f17ca02b0106653dd600
Change-Id: I8ab073b30b4e27405a3b6da2c826bb4f3f0b9af6

1 files changed, 512 insertions, 0 deletions

diff --git a/absl/strings/str_format.h b/absl/strings/str_format.h
new file mode 100644
index 000000000000..98e0fef4906b
--- /dev/null
+++ b/absl/strings/str_format.h
@@ -0,0 +1,512 @@
+//
+// Copyright 2018 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
+//
+//      http://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.
+//
+// -----------------------------------------------------------------------------
+// File: str_format.h
+// -----------------------------------------------------------------------------
+//
+// The `str_format` library is a typesafe replacement for the family of
+// `printf()` std::string formatting routines within the `<cstdio>` standard library
+// header. Like the `printf` family, the `str_format` uses a "format string" to
+// perform argument substitutions based on types.
+//
+// Example:
+//
+//   std::string s = absl::StrFormat("%s %s You have $%d!", "Hello", name, dollars);
+//
+// The library consists of the following basic utilities:
+//
+//   * `absl::StrFormat()`, a type-safe replacement for `std::sprintf()`, to
+//     write a format std::string to a `string` value.
+//   * `absl::StrAppendFormat()` to append a format std::string to a `string`
+//   * `absl::StreamFormat()` to more efficiently write a format std::string to a
+//     stream, such as`std::cout`.
+//   * `absl::PrintF()`, `absl::FPrintF()` and `absl::SNPrintF()` as
+//     replacements for `std::printf()`, `std::fprintf()` and `std::snprintf()`.
+//
+//     Note: a version of `std::sprintf()` is not supported as it is
+//     generally unsafe due to buffer overflows.
+//
+// Additionally, you can provide a format std::string (and its associated arguments)
+// using one of the following abstractions:
+//
+//   * A `FormatSpec` class template fully encapsulates a format std::string and its
+//     type arguments and is usually provided to `str_format` functions as a
+//     variadic argument of type `FormatSpec<Arg...>`. The `FormatSpec<Args...>`
+//     template is evaluated at compile-time, providing type safety.
+//   * A `ParsedFormat` instance, which encapsulates a specific, pre-compiled
+//     format std::string for a specific set of type(s), and which can be passed
+//     between API boundaries. (The `FormatSpec` type should not be used
+//     directly.)
+//
+// The `str_format` library provides the ability to output its format strings to
+// arbitrary sink types:
+//
+//   * A generic `Format()` function to write outputs to arbitrary sink types,
+//     which must implement a `RawSinkFormat` interface. (See
+//     `str_format_sink.h` for more information.)
+//
+//   * A `FormatUntyped()` function that is similar to `Format()` except it is
+//     loosely typed. `FormatUntyped()` is not a template and does not perform
+//     any compile-time checking of the format std::string; instead, it returns a
+//     boolean from a runtime check.
+//
+// In addition, the `str_format` library provides extension points for
+// augmenting formatting to new types. These extensions are fully documented
+// within the `str_format_extension.h` header file.
+#ifndef ABSL_STRINGS_STR_FORMAT_H_
+#define ABSL_STRINGS_STR_FORMAT_H_
+
+#include <cstdio>
+#include <string>
+
+#include "absl/strings/internal/str_format/arg.h"  // IWYU pragma: export
+#include "absl/strings/internal/str_format/bind.h"  // IWYU pragma: export
+#include "absl/strings/internal/str_format/checker.h"  // IWYU pragma: export
+#include "absl/strings/internal/str_format/extension.h"  // IWYU pragma: export
+#include "absl/strings/internal/str_format/parser.h"  // IWYU pragma: export
+
+namespace absl {
+
+// UntypedFormatSpec
+//
+// A type-erased class that can be used directly within untyped API entry
+// points. An `UntypedFormatSpec` is specifically used as an argument to
+// `FormatUntyped()`.
+//
+// Example:
+//
+//   absl::UntypedFormatSpec format("%d");
+//   std::string out;
+//   CHECK(absl::FormatUntyped(&out, format, {absl::FormatArg(1)}));
+class UntypedFormatSpec {
+ public:
+  UntypedFormatSpec() = delete;
+  UntypedFormatSpec(const UntypedFormatSpec&) = delete;
+  UntypedFormatSpec& operator=(const UntypedFormatSpec&) = delete;
+
+  explicit UntypedFormatSpec(string_view s) : spec_(s) {}
+
+ protected:
+  explicit UntypedFormatSpec(const str_format_internal::ParsedFormatBase* pc)
+      : spec_(pc) {}
+
+ private:
+  friend str_format_internal::UntypedFormatSpecImpl;
+  str_format_internal::UntypedFormatSpecImpl spec_;
+};
+
+// FormatStreamed()
+//
+// Takes a streamable argument and returns an object that can print it
+// with '%s'. Allows printing of types that have an `operator<<` but no
+// intrinsic type support within `StrFormat()` itself.
+//
+// Example:
+//
+//   absl::StrFormat("%s", absl::FormatStreamed(obj));
+template <typename T>
+str_format_internal::StreamedWrapper<T> FormatStreamed(const T& v) {
+  return str_format_internal::StreamedWrapper<T>(v);
+}
+
+// FormatCountCapture
+//
+// This class provides a way to safely wrap `StrFormat()` captures of `%n`
+// conversions, which denote the number of characters written by a formatting
+// operation to this point, into an integer value.
+//
+// This wrapper is designed to allow safe usage of `%n` within `StrFormat(); in
+// the `printf()` family of functions, `%n` is not safe to use, as the `int *`
+// buffer can be used to capture arbitrary data.
+//
+// Example:
+//
+//   int n = 0;
+//   std::string s = absl::StrFormat("%s%d%n", "hello", 123,
+//                   absl::FormatCountCapture(&n));
+//   EXPECT_EQ(8, n);
+class FormatCountCapture {
+ public:
+  explicit FormatCountCapture(int* p) : p_(p) {}
+
+ private:
+  // FormatCountCaptureHelper is used to define FormatConvertImpl() for this
+  // class.
+  friend struct str_format_internal::FormatCountCaptureHelper;
+  // Unused() is here because of the false positive from -Wunused-private-field
+  // p_ is used in the templated function of the friend FormatCountCaptureHelper
+  // class.
+  int* Unused() { return p_; }
+  int* p_;
+};
+
+// FormatSpec
+//
+// The `FormatSpec` type defines the makeup of a format std::string within the
+// `str_format` library. You should not need to use or manipulate this type
+// directly. A `FormatSpec` is a variadic class template that is evaluated at
+// compile-time, according to the format std::string and arguments that are passed
+// to it.
+//
+// For a `FormatSpec` to be valid at compile-time, it must be provided as
+// either:
+//
+// * A `constexpr` literal or `absl::string_view`, which is how it most often
+//   used.
+// * A `ParsedFormat` instantiation, which ensures the format std::string is
+//   valid before use. (See below.)
+//
+// Example:
+//
+//   // Provided as a std::string literal.
+//   absl::StrFormat("Welcome to %s, Number %d!", "The Village", 6);
+//
+//   // Provided as a constexpr absl::string_view.
+//   constexpr absl::string_view formatString = "Welcome to %s, Number %d!";
+//   absl::StrFormat(formatString, "The Village", 6);
+//
+//   // Provided as a pre-compiled ParsedFormat object.
+//   // Note that this example is useful only for illustration purposes.
+//   absl::ParsedFormat<'s', 'd'> formatString("Welcome to %s, Number %d!");
+//   absl::StrFormat(formatString, "TheVillage", 6);
+//
+// A format std::string generally follows the POSIX syntax as used within the POSIX
+// `printf` specification.
+//
+// (See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html.)
+//
+// In specific, the `FormatSpec` supports the following type specifiers:
+//   * `c` for characters
+//   * `s` for strings
+//   * `d` or `i` for integers
+//   * `o` for unsigned integer conversions into octal
+//   * `x` or `X` for unsigned integer conversions into hex
+//   * `u` for unsigned integers
+//   * `f` or `F` for floating point values into decimal notation
+//   * `e` or `E` for floating point values into exponential notation
+//   * `a` or `A` for floating point values into hex exponential notation
+//   * `g` or `G` for floating point values into decimal or exponential
+//     notation based on their precision
+//   * `p` for pointer address values
+//   * `n` for the special case of writing out the number of characters
+//     written to this point. The resulting value must be captured within an
+//     `absl::FormatCountCapture` type.
+//
+// NOTE: `o`, `x\X` and `u` will convert signed values to their unsigned
+// counterpart before formatting.
+//
+// Examples:
+//     "%c", 'a'                -> "a"
+//     "%c", 32                 -> " "
+//     "%s", "C"                -> "C"
+//     "%s", std::string("C++") -> "C++"
+//     "%d", -10                -> "-10"
+//     "%o", 10                 -> "12"
+//     "%x", 16                 -> "10"
+//     "%f", 123456789          -> "123456789.000000"
+//     "%e", .01                -> "1.00000e-2"
+//     "%a", -3.0               -> "-0x1.8p+1"
+//     "%g", .01                -> "1e-2"
+//     "%p", *int               -> "0x7ffdeb6ad2a4"
+//
+//     int n = 0;
+//     std::string s = absl::StrFormat(
+//         "%s%d%n", "hello", 123, absl::FormatCountCapture(&n));
+//     EXPECT_EQ(8, n);
+//
+// The `FormatSpec` intrinsically supports all of these fundamental C++ types:
+//
+// *   Characters: `char`, `signed char`, `unsigned char`
+// *   Integers: `int`, `short`, `unsigned short`, `unsigned`, `long`,
+//         `unsigned long`, `long long`, `unsigned long long`
+// *   Floating-point: `float`, `double`, `long double`
+//
+// However, in the `str_format` library, a format conversion specifies a broader
+// C++ conceptual category instead of an exact type. For example, `%s` binds to
+// any std::string-like argument, so `std::string`, `absl::string_view`, and
+// `const char*` are all accepted. Likewise, `%d` accepts any integer-like
+// argument, etc.
+
+template <typename... Args>
+using FormatSpec =
+    typename str_format_internal::FormatSpecDeductionBarrier<Args...>::type;
+
+using absl::str_format_internal::ExtendedParsedFormat;
+
+// ParsedFormat
+//
+// A `ParsedFormat` is a class template representing a preparsed `FormatSpec`,
+// with template arguments specifying the conversion characters used within the
+// format std::string. Such characters must be valid format type specifiers, and
+// these type specifiers are checked at compile-time.
+//
+// Instances of `ParsedFormat` can be created, copied, and reused to speed up
+// formatting loops. A `ParsedFormat` may either be constructed statically, or
+// dynamically through its `New()` factory function, which only constructs a
+// runtime object if the format is valid at that time.
+//
+// Example:
+//
+//   // Verified at compile time.
+//   absl::ParsedFormat<'s', 'd'> formatString("Welcome to %s, Number %d!");
+//   absl::StrFormat(formatString, "TheVillage", 6);
+//
+//   // Verified at runtime.
+//   auto format_runtime = absl::ParsedFormat<'d'>::New(format_string);
+//   if (format_runtime) {
+//     value = absl::StrFormat(*format_runtime, i);
+//   } else {
+//     ... error case ...
+//   }
+template <char... Conv>
+using ParsedFormat = str_format_internal::ExtendedParsedFormat<
+    str_format_internal::ConversionCharToConv(Conv)...>;
+
+// StrFormat()
+//
+// Returns a `string` given a `printf()`-style format std::string and zero or more
+// additional arguments. Use it as you would `sprintf()`. `StrFormat()` is the
+// primary formatting function within the `str_format` library, and should be
+// used in most cases where you need type-safe conversion of types into
+// formatted strings.
+//
+// The format std::string generally consists of ordinary character data along with
+// one or more format conversion specifiers (denoted by the `%` character).
+// Ordinary character data is returned unchanged into the result std::string, while
+// each conversion specification performs a type substitution from
+// `StrFormat()`'s other arguments. See the comments for `FormatSpec` for full
+// information on the makeup of this format std::string.
+//
+// Example:
+//
+//   std::string s = absl::StrFormat(
+//       "Welcome to %s, Number %d!", "The Village", 6);
+//   EXPECT_EQ("Welcome to The Village, Number 6!", s);
+//
+// Returns an empty std::string in case of error.
+template <typename... Args>
+ABSL_MUST_USE_RESULT std::string StrFormat(const FormatSpec<Args...>& format,
+                                      const Args&... args) {
+  return str_format_internal::FormatPack(
+      str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// StrAppendFormat()
+//
+// Appends to a `dst` std::string given a format std::string, and zero or more additional
+// arguments, returning `*dst` as a convenience for chaining purposes. Appends
+// nothing in case of error (but possibly alters its capacity).
+//
+// Example:
+//
+//   std::string orig("For example PI is approximately ");
+//   std::cout << StrAppendFormat(&orig, "%12.6f", 3.14);
+template <typename... Args>
+std::string& StrAppendFormat(std::string* dst, const FormatSpec<Args...>& format,
+                        const Args&... args) {
+  return str_format_internal::AppendPack(
+      dst, str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// StreamFormat()
+//
+// Writes to an output stream given a format std::string and zero or more arguments,
+// generally in a manner that is more efficient than streaming the result of
+// `absl:: StrFormat()`. The returned object must be streamed before the full
+// expression ends.
+//
+// Example:
+//
+//   std::cout << StreamFormat("%12.6f", 3.14);
+template <typename... Args>
+ABSL_MUST_USE_RESULT str_format_internal::Streamable StreamFormat(
+    const FormatSpec<Args...>& format, const Args&... args) {
+  return str_format_internal::Streamable(
+      str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// PrintF()
+//
+// Writes to stdout given a format std::string and zero or more arguments. This
+// function is functionally equivalent to `std::print()` (and type-safe); prefer
+// `absl::PrintF()` over `std::printf()`.
+//
+// Example:
+//
+//   std::string_view s = "Ulaanbaatar";
+//   absl::PrintF("The capital of Mongolia is: %s \n", s);
+//
+//   Outputs: "The capital of Mongolia is Ulaanbaatar"
+//
+template <typename... Args>
+int PrintF(const FormatSpec<Args...>& format, const Args&... args) {
+  return str_format_internal::FprintF(
+      stdout, str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// FPrintF()
+//
+// Writes to a file given a format std::string and zero or more arguments. This
+// function is functionally equivalent to `std::fprint()` (and type-safe);
+// prefer `absl::FPrintF()` over `std::fprintf()`.
+//
+// Example:
+//
+//   std::string_view s = "Ulaanbaatar";
+//   absl::FPrintF("The capital of Mongolia is: %s \n", s);
+//
+//   Outputs: "The capital of Mongolia is Ulaanbaatar"
+//
+template <typename... Args>
+int FPrintF(std::FILE* output, const FormatSpec<Args...>& format,
+            const Args&... args) {
+  return str_format_internal::FprintF(
+      output, str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// SNPrintF()
+//
+// Writes to a sized buffer given a format std::string and zero or more arguments.
+// This function is functionally equivalent to `std::snprint()` (and type-safe);
+// prefer `absl::SNPrintF()` over `std::snprintf()`.
+//
+// Example:
+//
+//   std::string_view s = "Ulaanbaatar";
+//   absl::FPrintF("The capital of Mongolia is: %s \n", s);
+//
+//   Outputs: "The capital of Mongolia is Ulaanbaatar"
+//
+template <typename... Args>
+int SNPrintF(char* output, std::size_t size, const FormatSpec<Args...>& format,
+             const Args&... args) {
+  return str_format_internal::SnprintF(
+      output, size, str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// -----------------------------------------------------------------------------
+// Custom Output Formatting Functions
+// -----------------------------------------------------------------------------
+
+// FormatRawSink
+//
+// FormatRawSink is a type erased wrapper around arbitrary sink objects
+// specifically used as an argument to `Format()`.
+// FormatRawSink does not own the passed sink object. The passed object must
+// outlive the FormatRawSink.
+class FormatRawSink {
+ public:
+  // Implicitly convert from any type that provides the hook function as
+  // described above.
+  template <typename T,
+            typename = typename std::enable_if<std::is_constructible<
+                str_format_internal::FormatRawSinkImpl, T*>::value>::type>
+  FormatRawSink(T* raw)  // NOLINT
+      : sink_(raw) {}
+
+ private:
+  friend str_format_internal::FormatRawSinkImpl;
+  str_format_internal::FormatRawSinkImpl sink_;
+};
+
+// Format()
+//
+// Writes a formatted std::string to an arbitrary sink object (implementing the
+// `absl::FormatRawSink` interface), using a format std::string and zero or more
+// additional arguments.
+//
+// By default, `string` and `std::ostream` are supported as destination objects.
+//
+// `absl::Format()` is a generic version of `absl::StrFormat(), for custom
+// sinks. The format std::string, like format strings for `StrFormat()`, is checked
+// at compile-time.
+//
+// On failure, this function returns `false` and the state of the sink is
+// unspecified.
+template <typename... Args>
+bool Format(FormatRawSink raw_sink, const FormatSpec<Args...>& format,
+            const Args&... args) {
+  return str_format_internal::FormatUntyped(
+      str_format_internal::FormatRawSinkImpl::Extract(raw_sink),
+      str_format_internal::UntypedFormatSpecImpl::Extract(format),
+      {str_format_internal::FormatArgImpl(args)...});
+}
+
+// FormatArg
+//
+// A type-erased handle to a format argument specifically used as an argument to
+// `FormatUntyped()`. You may construct `FormatArg` by passing
+// reference-to-const of any printable type. `FormatArg` is both copyable and
+// assignable. The source data must outlive the `FormatArg` instance. See
+// example below.
+//
+using FormatArg = str_format_internal::FormatArgImpl;
+
+// FormatUntyped()
+//
+// Writes a formatted std::string to an arbitrary sink object (implementing the
+// `absl::FormatRawSink` interface), using an `UntypedFormatSpec` and zero or
+// more additional arguments.
+//
+// This function acts as the most generic formatting function in the
+// `str_format` library. The caller provides a raw sink, an unchecked format
+// std::string, and (usually) a runtime specified list of arguments; no compile-time
+// checking of formatting is performed within this function. As a result, a
+// caller should check the return value to verify that no error occurred.
+// On failure, this function returns `false` and the state of the sink is
+// unspecified.
+//
+// The arguments are provided in an `absl::Span<const absl::FormatArg>`.
+// Each `absl::FormatArg` object binds to a single argument and keeps a
+// reference to it. The values used to create the `FormatArg` objects must
+// outlive this function call. (See `str_format_arg.h` for information on
+// the `FormatArg` class.)_
+//
+// Example:
+//
+//   std::optional<std::string> FormatDynamic(const std::string& in_format,
+//                                       const vector<std::string>& in_args) {
+//     std::string out;
+//     std::vector<absl::FormatArg> args;
+//     for (const auto& v : in_args) {
+//       // It is important that 'v' is a reference to the objects in in_args.
+//       // The values we pass to FormatArg must outlive the call to
+//       // FormatUntyped.
+//       args.emplace_back(v);
+//     }
+//     absl::UntypedFormatSpec format(in_format);
+//     if (!absl::FormatUntyped(&out, format, args)) {
+//       return std::nullopt;
+//     }
+//     return std::move(out);
+//   }
+//
+ABSL_MUST_USE_RESULT inline bool FormatUntyped(
+    FormatRawSink raw_sink, const UntypedFormatSpec& format,
+    absl::Span<const FormatArg> args) {
+  return str_format_internal::FormatUntyped(
+      str_format_internal::FormatRawSinkImpl::Extract(raw_sink),
+      str_format_internal::UntypedFormatSpecImpl::Extract(format), args);
+}
+
+}  // namespace absl
+#endif  // ABSL_STRINGS_STR_FORMAT_H_