--- /dev/null
+//
+// 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
+//
+// 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.
+//
+// -----------------------------------------------------------------------------
+// File: str_format.h
+// -----------------------------------------------------------------------------
+//
+// The `str_format` library is a typesafe replacement for the family of
+// `printf()` 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. See the `FormatSpec` section
+// below for format string documentation.
+//
+// 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 string to a `string` value.
+// * `absl::StrAppendFormat()` to append a format string to a `string`
+// * `absl::StreamFormat()` to more efficiently write a format 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 string (and its associated arguments)
+// using one of the following abstractions:
+//
+// * A `FormatSpec` class template fully encapsulates a format 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 string for a specific set of type(s), and which can be passed
+// between API boundaries. (The `FormatSpec` type should not be used
+// directly except as an argument type for wrapper functions.)
+//
+// 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 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 string within the
+// `str_format` library. It is a variadic class template that is evaluated at
+// compile-time, according to the format string and arguments that are passed to
+// it.
+//
+// You should not need to manipulate this type directly. You should only name it
+// if you are writing wrapper functions which accept format arguments that will
+// be provided unmodified to functions in this library. Such a wrapper function
+// might be a class method that provides format arguments and/or internally uses
+// the result of formatting.
+//
+// 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 string is
+// valid before use. (See below.)
+//
+// Example:
+//
+// // Provided as a 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 string generally follows the POSIX syntax as used within the POSIX
+// `printf` specification.
+//
+// (See http://pubs.opengroup.org/onlinepubs/9699919799/functions/fprintf.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.
+//
+// Implementation-defined behavior:
+// * A null pointer provided to "%s" or "%p" is output as "(nil)".
+// * A non-null pointer provided to "%p" is output in hex as if by %#x or
+// %#lx.
+//
+// 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", (void*)&value -> "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 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;
+
+// ParsedFormat
+//
+// A `ParsedFormat` is a class template representing a preparsed `FormatSpec`,
+// with template arguments specifying the conversion characters used within the
+// format 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 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 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 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 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 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` string given a format 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 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 string and zero or more arguments. This
+// function is functionally equivalent to `std::printf()` (and type-safe);
+// prefer `absl::PrintF()` over `std::printf()`.
+//
+// Example:
+//
+// std::string_view s = "Ulaanbaatar";
+// absl::PrintF("The capital of Mongolia is %s", 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 string and zero or more arguments. This
+// function is functionally equivalent to `std::fprintf()` (and type-safe);
+// prefer `absl::FPrintF()` over `std::fprintf()`.
+//
+// Example:
+//
+// std::string_view s = "Ulaanbaatar";
+// absl::FPrintF(stdout, "The capital of Mongolia is %s", 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 string and zero or more arguments.
+// This function is functionally equivalent to `std::snprintf()` (and
+// type-safe); prefer `absl::SNPrintF()` over `std::snprintf()`.
+//
+// Example:
+//
+// std::string_view s = "Ulaanbaatar";
+// char output[128];
+// absl::SNPrintF(output, sizeof(output),
+// "The capital of Mongolia is %s", s);
+//
+// Post-condition: output == "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 string to an arbitrary sink object (implementing the
+// `absl::FormatRawSink` interface), using a format string and zero or more
+// additional arguments.
+//
+// By default, `std::string` and `std::ostream` are supported as destination
+// objects.
+//
+// `absl::Format()` is a generic version of `absl::StrFormat(), for custom
+// sinks. The format 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 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
+// 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_
git://repos.xcallymotion.com / motion2.git / blobdiff