chromium/third_party/blink/renderer/platform/wtf/text/character_visitor.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_TEXT_CHARACTER_VISITOR_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_TEXT_CHARACTER_VISITOR_H_

namespace WTF {

// Visits the characters of a WTF::String, StringView or compatible type.
//
// Intended to be used with a generic lambda or other functor overloaded to
// handle either LChar* or UChar*. Reduces code duplication in many cases.
// The functor should return the same type in both branches.
//
// Callers should ensure that characters exist (i.e. the string is not null)
// first.
//
// Example:
//
//   if (string.IsNull())
//     return false;
//
//   return WTF::VisitCharacters(string, [&](const auto* chars, unsigned len) {
//     bool contains_space = false;
//     for (unsigned i = 0; i < len; i++)
//       contains_space |= IsASCIISpace(chars[i]);
//     return contains_space;
//   });
//
// This will instantiate the functor for both LChar (8-bit) and UChar (16-bit)
// automatically.
template <typename StringType, typename Functor>
decltype(auto) VisitCharacters(const StringType& string,
                               const Functor& functor) { … }

}  // namespace WTF

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_TEXT_CHARACTER_VISITOR_H_