Method lexically_normal

system/lib/libcxx/src/filesystem/path.cpp:160–235

}

path path::lexically_normal() const {
  if (__pn_.empty())
    return *this;

  using PartKindPair = pair<string_view_t, PathPartKind>;
  vector<PartKindPair> Parts;
  // Guess as to how many elements the path has to avoid reallocating.
  Parts.reserve(32);

  // Track the total size of the parts as we collect them. This allows the
  // resulting path to reserve the correct amount of memory.
  size_t NewPathSize = 0;
  auto AddPart       = [&](PathPartKind K, string_view_t P) {
    NewPathSize += P.size();
    Parts.emplace_back(P, K);
  };
  auto LastPartKind = [&]() {
    if (Parts.empty())
      return PK_None;
    return Parts.back().second;
  };

  bool MaybeNeedTrailingSep = false;
  // Build a stack containing the remaining elements of the path, popping off
  // elements which occur before a '..' entry.
  for (auto PP = PathParser::CreateBegin(__pn_); PP; ++PP) {
    auto Part         = *PP;
    PathPartKind Kind = ClassifyPathPart(Part);
    switch (Kind) {
    case PK_Filename:
    case PK_RootSep: {
      // Add all non-dot and non-dot-dot elements to the stack of elements.
      AddPart(Kind, Part);
      MaybeNeedTrailingSep = false;
      break;
    }
    case PK_DotDot: {
      // Only push a ".." element if there are no elements preceding the "..",
      // or if the preceding element is itself "..".
      auto LastKind = LastPartKind();
      if (LastKind == PK_Filename) {
        NewPathSize -= Parts.back().first.size();
        Parts.pop_back();
      } else if (LastKind != PK_RootSep)
        AddPart(PK_DotDot, PATHSTR(".."));
      MaybeNeedTrailingSep = LastKind == PK_Filename;
      break;
    }
    case PK_Dot:
    case PK_TrailingSep: {
      MaybeNeedTrailingSep = true;
      break;
    }
    case PK_None:
      __libcpp_unreachable();
    }
  }
  // [fs.path.generic]p6.8: If the path is empty, add a dot.