chromium/base/strings/cstring_view.h

// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_STRINGS_CSTRING_VIEW_H_
#define BASE_STRINGS_CSTRING_VIEW_H_

#include <algorithm>
#include <concepts>
#include <cstddef>
#include <iosfwd>
#include <string>
#include <string_view>

#include "base/check.h"
#include "base/compiler_specific.h"
#include "base/containers/checked_iterators.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/numerics/safe_conversions.h"
#include "build/build_config.h"

namespace base {

// A CString is a NUL-terminated character array, which is the C programming
// language representation of a string. This class (and its aliases below)
// provides a non-owning and bounds-safe view of a CString, and can replace all
// use of native pointers (such as `const char*`) for this purpose in C++ code.
//
// The basic_cstring_view class is followed by aliases for the various char
// types:
// * cstring_view provides a view of a `const char*`.
// * u16cstring_view provides a view of a `const char16_t*`.
// * u32cstring_view provides a view of a `const char32_t*`.
// * wcstring_view provides a view of a `const wchar_t*`.
template <class Char>
class basic_cstring_view final { … };

// cstring_view provides a view of a NUL-terminated string. It is a replacement
// for all use of `const char*`, in order to provide bounds checks and prevent
// unsafe pointer usage (otherwise prevented by `-Wunsafe-buffer-usage`).
//
// See basic_cstring_view for more.
cstring_view;

// u16cstring_view provides a view of a NUL-terminated string. It is a
// replacement for all use of `const char16_t*`, in order to provide bounds
// checks and prevent unsafe pointer usage (otherwise prevented by
// `-Wunsafe-buffer-usage`).
//
// See basic_cstring_view for more.
u16cstring_view;

// u32cstring_view provides a view of a NUL-terminated string. It is a
// replacement for all use of `const char32_t*`, in order to provide bounds
// checks and prevent unsafe pointer usage (otherwise prevented by
// `-Wunsafe-buffer-usage`).
//
// See basic_cstring_view for more.
u32cstring_view;

#if BUILDFLAG(IS_WIN)
// wcstring_view provides a view of a NUL-terminated string. It is a
// replacement for all use of `const wchar_t*`, in order to provide bounds
// checks and prevent unsafe pointer usage (otherwise prevented by
// `-Wunsafe-buffer-usage`).
//
// See basic_cstring_view for more.
using wcstring_view = basic_cstring_view<wchar_t>;
#endif

// Writes the contents of the cstring view to the stream.
template <class Char, class Traits>
std::basic_ostream<Char, Traits>& operator<<(
    std::basic_ostream<Char, Traits>& os,
    basic_cstring_view<Char> view) { … }

// Explicitly define PrintTo to avoid gtest printing these as containers
// rather than strings.
inline void PrintTo(cstring_view view, std::ostream* os) { … }

}  // namespace base

hash<base::basic_cstring_view<Char>>;

enable_borrowed_range;

enable_view;

#endif  // BASE_STRINGS_CSTRING_VIEW_H_