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Document number: N3762

Date: 2013-09-01

string_view: a non-owning reference to a string, revision 5

by Jeffrey Yasskin

Excerpt:

References to strings are very common in C++ programs, but often the callee doesn't care about the exact type of the object that owns the data. ...

Google, LLVM, and Bloomberg have independently implemented a string-reference type to encapsulate this kind of argument. string_view is implicitly constructible from const char* and std::string. It provides the const member operations from std::string to ease conversion. This paper follows Chromium and Bloomberg in extending string_view to basic_string_view<charT>, and further extends it to include a traits parameter to match basic_string. We provide typedefs to parallel the 4 basic_string typedefs.

Both Google's and LLVM's string_view types (but not Bloomberg's) extend the interface from std::string to provide some helpful utility functions:

• starts_with
• ends_with
• remove_prefix
• remove_suffix
• split
• trim
• consume_prefix
• count

Versions of std::string operations that take string_view instead also give the standard a way to provide in-place operations on non-null-terminated byte/character sequences:

• hash, as requested by c++std-lib-31935
• In a future addition, numeric conversions