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>
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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