[#absl-ParsedFormat]
= xref:absl.adoc[absl]::ParsedFormat
:relfileprefix: ../
:mrdocs:

A class template representing a preparsed `FormatSpec`, with template arguments specifying the conversion characters used within the format string.

== Synopsis

Declared in `<absl/strings/str_format.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<auto Conv...>
using ParsedFormat = absl::str_format_internal::ExtendedParsedFormat<absl::str_format_internal::ToFormatConversionCharSet(Conv)...>;
----

== Description

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'> format_string("Welcome to %s, Number %d!"); absl::StrFormat(format_string, "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 ... }

An 'extended' format is also allowed that can specify multiple conversion characters per format argument, using a combination of `absl::FormatConversionCharSet` enum values (logically a set union) via the `|` operator. (Single character‐based arguments are still accepted, but cannot be combined). Some common conversions also have predefined enum values, such as `absl::FormatConversionCharSet::kIntegral`.

Example: // Extended format supports multiple conversion characters per argument, // specified via a combination of `FormatConversionCharSet` enums. using MyFormat = absl::ParsedFormat<absl::FormatConversionCharSet::d | absl::FormatConversionCharSet::x>; MyFormat GetFormat(bool use_hex) { if (use_hex) return MyFormat("foo %x bar"); return MyFormat("foo %d bar"); } // `format` can be used with any value that supports 'd' and 'x', // like `int`. auto format = GetFormat(use_hex); value = StringF(format, i);


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