diff options
Diffstat (limited to 'absl/strings/str_cat.h')
-rw-r--r-- | absl/strings/str_cat.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/absl/strings/str_cat.h b/absl/strings/str_cat.h index 6ee88f14..8a63be0d 100644 --- a/absl/strings/str_cat.h +++ b/absl/strings/str_cat.h @@ -77,6 +77,43 @@ struct AlphaNumBuffer { size_t size; }; +//------------------------------------------------------------------------------ +// StrCat Extension +//------------------------------------------------------------------------------ +// +// AbslStringify() +// +// A simple customization API for formatting user-defined types using +// absl::StrCat(). The API relies on detecting an overload in the +// user-defined type's namespace of a free (non-member) `AbslStringify()` +// function as a friend definition with the following signature: +// +// template <typename Sink> +// void AbslStringify(Sink& sink, const X& value); +// +// An `AbslStringify()` overload for a type should only be declared in the same +// file and namespace as said type. +// +// Note that AbslStringify() also supports use with absl::StrFormat(). +// +// Example: +// +// struct Point { +// // To add formatting support to `Point`, we simply need to add a free +// // (non-member) function `AbslStringify()`. This method specifies how +// // Point should be printed when absl::StrCat() is called on it. You can add +// // such a free function using a friend declaration within the body of the +// // class. The sink parameter is a templated type to avoid requiring +// // dependencies. +// template <typename Sink> friend void AbslStringify(Sink& +// sink, const Point& p) { +// absl::Format(&sink, "(%v, %v)", p.x, p.y); +// } +// +// int x; +// int y; +// }; + class StringifySink { public: void Append(size_t count, char ch); |