Remove String on Linux.

18 files changed, 38 insertions, 723 deletions

diff --git a/src/ThemeBuilder/components/StyleRuleSetEditor.cpp b/src/ThemeBuilder/components/StyleRuleSetEditor.cpp
index ccffa591..a4e15fe7 100644
--- a/src/ThemeBuilder/components/StyleRuleSetEditor.cpp
+++ b/src/ThemeBuilder/components/StyleRuleSetEditor.cpp
@@ -1,6 +1,5 @@
 #include "StyleRuleSetEditor.h"
 #include "cru/base/Exception.h"
-#include "cru/base/String.h"
 #include "cru/ui/DeleteLater.h"
 #include "cru/ui/ThemeManager.h"
 #include "cru/ui/controls/FlexLayout.h"
diff --git a/src/ThemeBuilder/components/properties/ThicknessPropertyEditor.cpp b/src/ThemeBuilder/components/properties/ThicknessPropertyEditor.cpp
index 2ee13c06..bd8c64b9 100644
--- a/src/ThemeBuilder/components/properties/ThicknessPropertyEditor.cpp
+++ b/src/ThemeBuilder/components/properties/ThicknessPropertyEditor.cpp
@@ -1,6 +1,5 @@
 #include "ThicknessPropertyEditor.h"
 #include <format>
-#include "cru/base/Format.h"
 #include "cru/ui/mapper/MapperRegistry.h"
 #include "cru/ui/mapper/ThicknessMapper.h"
 
diff --git a/src/base/CMakeLists.txt b/src/base/CMakeLists.txt
index 685ceb8c..106a03ef 100644
--- a/src/base/CMakeLists.txt
+++ b/src/base/CMakeLists.txt
@@ -2,9 +2,7 @@ add_library(CruBase
 	Base.cpp
 	Buffer.cpp
 	Exception.cpp
-	Format.cpp
 	PropertyTree.cpp
-	String.cpp
 	StringUtil.cpp
 	SubProcess.cpp
 	io/AutoReadStream.cpp
diff --git a/src/base/Format.cpp b/src/base/Format.cpp
deleted file mode 100644
index e442e572..00000000
--- a/src/base/Format.cpp
+++ /dev/null
@@ -1,111 +0,0 @@
-#include "cru/base/Format.h"
-
-namespace cru {
-namespace details {
-FormatToken ParsePlaceHolder(String place_holder_string) {
-  if (place_holder_string.empty()) {
-    return FormatToken::NonePlaceHolder({});
-  }
-
-  if (place_holder_string.StartWith(u":")) {
-    if (place_holder_string.Find(u':', 1) != -1) {
-      throw Exception("Two ':' inside placeholder.");
-    }
-
-    return FormatToken::NonePlaceHolder(place_holder_string.substr(1));
-  }
-  if (IsDigit(place_holder_string[0])) {
-    int position = 0;
-    int index = 0;
-    while (index < place_holder_string.size() &&
-           IsDigit(place_holder_string[index])) {
-      position = position * 10 + place_holder_string[index] - '0';
-      index++;
-    }
-
-    String option;
-
-    if (index != place_holder_string.size()) {
-      if (place_holder_string[index] != ':') {
-        throw Exception("Invalid placeholder in format.");
-      }
-
-      option = place_holder_string.substr(index + 1);
-    }
-
-    return FormatToken::PositionedPlaceHolder(position, std::move(option));
-  }
-
-  auto separator_index = place_holder_string.Find(':');
-  if (separator_index == -1) {
-    return FormatToken::NamedPlaceHolder(place_holder_string, {});
-  } else {
-    return FormatToken::NamedPlaceHolder(
-        place_holder_string.substr(0, separator_index),
-        place_holder_string.substr(separator_index + 1));
-  }
-}
-
-std::vector<FormatToken> ParseToFormatTokenList(StringView str) {
-  std::vector<FormatToken> result;
-
-  auto push_char = [&result](char16_t c) {
-    if (result.empty() || result.back().type == FormatTokenType::PlaceHolder) {
-      result.push_back(FormatToken::Text());
-    }
-    result.back().data.append(c);
-  };
-
-  bool try_to_escape = false;
-  bool is_in_place_holder = false;
-  String place_holder_string;
-
-  for (auto c : str) {
-    if (c == u'{') {
-      if (try_to_escape) {
-        push_char(u'{');
-        try_to_escape = false;
-        is_in_place_holder = false;
-      } else {
-        if (is_in_place_holder) {
-          throw Exception("Invalid format string: '{' inside placeholder.");
-        }
-
-        try_to_escape = true;
-        is_in_place_holder = true;
-      }
-    } else if (c == u'}') {
-      if (is_in_place_holder) {
-        is_in_place_holder = false;
-        result.push_back(ParsePlaceHolder(std::move(place_holder_string)));
-        place_holder_string.clear();
-      } else {
-        push_char(u'}');
-      }
-      try_to_escape = false;
-    } else {
-      if (is_in_place_holder) {
-        place_holder_string.push_back(c);
-      } else {
-        push_char(c);
-      }
-      try_to_escape = false;
-    }
-  }
-  return result;
-}
-
-void FormatAppendFromFormatTokenList(
-    String& current, const std::vector<FormatToken>& format_token_list,
-    Index index) {
-  for (Index i = index; i < static_cast<Index>(format_token_list.size()); i++) {
-    const auto& token = format_token_list[i];
-    if (token.type == FormatTokenType::PlaceHolder) {
-      throw Exception("More placeholder than args.");
-    } else {
-      current += token.data;
-    }
-  }
-}
-}  // namespace details
-}  // namespace cru
diff --git a/src/base/String.cpp b/src/base/String.cpp
deleted file mode 100644
index c96b898d..00000000
--- a/src/base/String.cpp
+++ /dev/null
@@ -1,565 +0,0 @@
-#include "cru/base/String.h"
-
-#include "cru/base/Buffer.h"
-#include "cru/base/Exception.h"
-#include "cru/base/StringUtil.h"
-
-#include <algorithm>
-#include <cstring>
-#include <functional>
-
-#ifdef CRU_PLATFORM_OSX
-#include <CoreFoundation/CoreFoundation.h>
-#endif
-
-namespace cru {
-template <typename C>
-Index GetStrSize(const C* str) {
-  Index i = 0;
-  while (str[i]) {
-    i++;
-  }
-  return i;
-}
-
-String String::FromUtf8(const char* str) {
-  return FromUtf8(str, GetStrSize(str));
-}
-
-String String::FromUtf8(const char* str, Index size) {
-  String result;
-  Utf8CodePointIterator iter(str, size);
-  for (auto cp : iter) {
-    Utf16EncodeCodePointAppend(
-        cp,
-        std::bind(&String::push_back, std::ref(result), std::placeholders::_1));
-  }
-  return result;
-}
-
-String String::FromUtf8(const std::byte* str, Index size) {
-  return String::FromUtf8(reinterpret_cast<const char*>(str), size);
-}
-
-String String::FromUtf8(const Buffer& buffer) {
-  return String::FromUtf8(buffer.GetUsedBeginPtr(), buffer.GetUsedSize());
-}
-
-String String::FromStdPath(const std::filesystem::path& path) {
-  return String::FromUtf8(path.string());
-}
-
-namespace {
-char16_t kEmptyBuffer[1] = {0};
-}
-
-String::String()
-    : buffer_(kEmptyBuffer),
-      size_(0), capacity_(0) {}
-
-String::String(const_pointer str) : String(str, GetStrSize(str)) {}
-
-String::String(const_pointer str, Index size) {
-  this->buffer_ = new value_type[size + 1];
-  std::memcpy(this->buffer_, str, size * sizeof(char16_t));
-  this->buffer_[size] = 0;
-  this->size_ = size;
-  this->capacity_ = size;
-}
-
-String::String(size_type size, value_type ch) : String() {
-  reserve(size);
-  for (Index i = 0; i < size; i++) {
-    append(ch);
-  }
-}
-
-String::String(std::initializer_list<char16_t> l)
-    : String(l.begin(), l.size()) {}
-
-#ifdef CRU_PLATFORM_WINDOWS
-String::String(const wchar_t* str) : String(str, GetStrSize(str)) {}
-String::String(const wchar_t* str, Index size)
-    : String(reinterpret_cast<const char16_t*>(str), size) {}
-#endif
-
-String::String(const String& other) {
-  if (other.size_ == 0) {
-    this->buffer_ = kEmptyBuffer;
-    this->size_ = this->capacity_ = 0;
-    return;
-  }
-  this->buffer_ = new value_type[other.size_ + 1];
-  std::memcpy(this->buffer_, other.buffer_, other.size_ * sizeof(value_type));
-  this->buffer_[other.size_] = 0;
-  this->size_ = other.size_;
-  this->capacity_ = other.size_;
-}
-
-String::String(String&& other) noexcept {
-  this->buffer_ = other.buffer_;
-  this->size_ = other.size_;
-  this->capacity_ = other.capacity_;
-  other.buffer_ = kEmptyBuffer;
-  other.size_ = 0;
-  other.capacity_ = 0;
-}
-
-String& String::operator=(const String& other) {
-  if (this != &other) {
-    if (this->buffer_ != kEmptyBuffer) {
-      delete[] this->buffer_;
-    }
-
-    if (other.buffer_ == kEmptyBuffer) {
-      this->buffer_ = kEmptyBuffer;
-      this->size_ = 0;
-      this->capacity_ = 0;
-    } else {
-      this->buffer_ = new value_type[other.size_ + 1];
-      std::memcpy(this->buffer_, other.buffer_,
-                  other.size_ * sizeof(value_type));
-      this->buffer_[other.size_] = 0;
-      this->size_ = other.size_;
-      this->capacity_ = other.size_;
-    }
-  }
-  return *this;
-}
-
-String& String::operator=(String&& other) noexcept {
-  if (this != &other) {
-    if (this->buffer_ != kEmptyBuffer) {
-      delete[] this->buffer_;
-    }
-
-    this->buffer_ = other.buffer_;
-    this->size_ = other.size_;
-    this->capacity_ = other.capacity_;
-    other.buffer_ = kEmptyBuffer;
-    other.size_ = 0;
-    other.capacity_ = 0;
-  }
-  return *this;
-}
-
-String::~String() {
-  if (this->buffer_ != kEmptyBuffer) {
-    delete[] this->buffer_;
-  }
-}
-
-String::String(from_buffer_tag, pointer buffer, Index size, Index capacity)
-    : buffer_(buffer), size_(size), capacity_(capacity) {}
-
-void String::clear() { resize(0); }
-
-void String::resize(Index new_size) {
-  Expects(new_size >= 0);
-
-  if (new_size == size_) return;
-
-  if (new_size < size_) {
-    size_ = new_size;
-    buffer_[size_] = 0;
-  } else {
-    reserve(new_size);
-    std::memset(buffer_ + size_, 0, sizeof(value_type) * (new_size - size_));
-    buffer_[new_size] = 0;
-    size_ = new_size;
-  }
-}
-
-void String::shrink_to_fit() {
-  if (capacity_ == size_) return;
-  if (size_ == 0) {
-    delete[] buffer_;
-    buffer_ = kEmptyBuffer;
-    size_ = 0;
-    capacity_ = 0;
-  } else {
-    auto new_buffer = new value_type[size_ + 1];
-    std::memcpy(new_buffer, buffer_, sizeof(value_type) * size_);
-    delete[] buffer_;
-    buffer_ = new_buffer;
-    capacity_ = size_;
-  }
-}
-
-void String::reserve(Index new_capacity) {
-  Expects(new_capacity >= 0);
-  if (new_capacity <= this->capacity_) return;
-  if (new_capacity > 0) {
-    pointer new_buffer = new value_type[new_capacity + 1];
-    if (this->buffer_ != kEmptyBuffer) {
-      memcpy(new_buffer, this->buffer_, this->size_ * sizeof(value_type));
-      delete[] this->buffer_;
-    }
-    new_buffer[this->size_] = 0;
-    this->buffer_ = new_buffer;
-    this->capacity_ = new_capacity;
-  }
-}
-
-String::iterator String::insert(const_iterator pos, const_iterator str,
-                                Index size) {
-  Expects(pos >= cbegin() && pos <= cend());
-
-  std::vector<value_type> backup_buffer;
-  if (str >= buffer_ && str < buffer_ + size_) {
-    backup_buffer.resize(size);
-    std::copy(str, str + size, backup_buffer.begin());
-    str = backup_buffer.data();
-  }
-
-  Index index = pos - cbegin();
-
-  Index new_size = size_ + size;
-  if (new_size > capacity_) {
-    auto new_capacity = capacity_;
-    if (new_capacity == 0) {
-      new_capacity = new_size;
-    } else {
-      while (new_capacity < new_size) {
-        new_capacity *= 2;
-      }
-    }
-
-    this->reserve(new_capacity);
-  }
-
-  std::memmove(begin() + index + size, begin() + index,
-               (size_ - index) * sizeof(value_type));
-  std::memcpy(begin() + index, str, size * sizeof(value_type));
-
-  buffer_[new_size] = 0;
-  size_ = new_size;
-
-  return begin() + new_size;
-}
-
-String::iterator String::erase(const_iterator start, const_iterator end) {
-  Expects(buffer_ <= start && start <= end && end <= buffer_ + size_);
-
-  Index new_size = size_ - (end - start);
-
-  auto s = const_cast<iterator>(start);
-  auto e = const_cast<iterator>(end);
-
-  std::memmove(s, e, (cend() - end) * sizeof(value_type));
-  this->size_ = new_size;
-  this->buffer_[new_size] = 0;
-
-  return s;
-}
-
-String& String::operator+=(StringView other) {
-  append(other);
-  return *this;
-}
-
-StringView String::View() const { return *this; }
-
-Index String::Find(value_type value, Index start) const {
-  return View().Find(value, start);
-}
-
-std::vector<String> String::Split(value_type separator,
-                                  bool remove_space_line) const {
-  return View().Split(separator, remove_space_line);
-}
-
-std::vector<String> String::SplitToLines(bool remove_space_line) const {
-  return View().SplitToLines(remove_space_line);
-}
-
-bool String::StartWith(StringView str) const { return View().StartWith(str); }
-
-bool String::EndWith(StringView str) const { return View().EndWith(str); }
-
-std::string String::ToUtf8() const { return View().ToUtf8(); }
-
-Buffer String::ToUtf8Buffer(bool end_zero) const {
-  return View().ToUtf8Buffer();
-}
-
-String& String::TrimStart() {
-  if (size_ == 0) return *this;
-
-  auto start = begin();
-  while (start != end() && IsWhitespace(*start)) {
-    ++start;
-  }
-
-  if (start == end()) {
-    clear();
-  } else {
-    erase(begin(), start);
-  }
-
-  return *this;
-}
-
-String& String::TrimEnd() {
-  if (size_ == 0) return *this;
-  while (size_ > 0 && IsWhitespace(buffer_[size_ - 1])) {
-    size_--;
-  }
-
-  return *this;
-}
-
-String& String::Trim() {
-  TrimStart();
-  TrimEnd();
-  return *this;
-}
-
-void String::AppendCodePoint(CodePoint code_point) {
-  if (!Utf16EncodeCodePointAppend(
-          code_point,
-          std::bind(&String::push_back, this, std::placeholders::_1))) {
-    throw TextEncodeException("Code point out of range.");
-  }
-}
-
-Index String::IndexFromCodeUnitToCodePoint(Index code_unit_index) const {
-  return View().IndexFromCodeUnitToCodePoint(code_unit_index);
-}
-
-Index String::IndexFromCodePointToCodeUnit(Index code_point_index) const {
-  return View().IndexFromCodePointToCodeUnit(code_point_index);
-}
-
-Range String::RangeFromCodeUnitToCodePoint(Range code_unit_range) const {
-  return View().RangeFromCodeUnitToCodePoint(code_unit_range);
-}
-
-Range String::RangeFromCodePointToCodeUnit(Range code_point_range) const {
-  return View().RangeFromCodePointToCodeUnit(code_point_range);
-}
-
-std::ostream& operator<<(std::ostream& os, const String& value) {
-  os << value.ToUtf8();
-  return os;
-}
-
-namespace {
-inline int Compare(char16_t left, char16_t right) {
-  if (left < right) return -1;
-  if (left > right) return 1;
-  return 0;
-}
-
-inline int CaseInsensitiveCompare(char16_t left, char16_t right) {
-  return Compare(ToLower(left), ToLower(right));
-}
-}  // namespace
-
-int String::Compare(const String& other) const { return View().Compare(other); }
-int String::CaseInsensitiveCompare(const String& other) const {
-  return View().CaseInsensitiveCompare(other);
-}
-
-int StringView::Compare(const StringView& other) const {
-  const_iterator i1 = cbegin();
-  const_iterator i2 = other.cbegin();
-
-  const_iterator end1 = cend();
-  const_iterator end2 = other.cend();
-
-  while (i1 != end1 && i2 != end2) {
-    int r = cru::Compare(*i1, *i2);
-    if (r != 0) return r;
-    i1++;
-    i2++;
-  }
-
-  if (i1 == end1) {
-    if (i2 == end2) {
-      return 0;
-    } else {
-      return -1;
-    }
-  } else {
-    return 1;
-  }
-}
-
-int StringView::CaseInsensitiveCompare(const StringView& other) const {
-  const_iterator i1 = cbegin();
-  const_iterator i2 = other.cbegin();
-
-  const_iterator end1 = cend();
-  const_iterator end2 = other.cend();
-
-  while (i1 != end1 && i2 != end2) {
-    int r = cru::CaseInsensitiveCompare(*i1, *i2);
-    if (r != 0) return r;
-    i1++;
-    i2++;
-  }
-
-  if (i1 == end1) {
-    if (i2 == end2) {
-      return 0;
-    } else {
-      return -1;
-    }
-  } else {
-    return 1;
-  }
-}
-
-StringView StringView::substr(Index pos) {
-  Expects(pos >= 0 && pos < size_);
-  return StringView(ptr_ + pos, size_ - pos);
-}
-
-StringView StringView::substr(Index pos, Index size) {
-  Expects(pos >= 0 && pos < size_);
-
-  return StringView(ptr_ + pos, std::min(size, size_ - pos));
-}
-
-Index StringView::Find(value_type value, Index start) const {
-  Expects(start >= 0 && start <= size_);
-
-  for (Index i = start; i < size_; ++i) {
-    if (ptr_[i] == value) return i;
-  }
-  return -1;
-}
-
-std::vector<String> StringView::Split(value_type separator,
-                                      bool remove_space_line) const {
-  std::vector<String> result;
-
-  if (size_ == 0) return result;
-
-  Index line_start = 0;
-  Index line_end = 0;
-  while (line_end < size_) {
-    if (ptr_[line_end] == separator) {
-      if (remove_space_line) {
-        bool add = false;
-        for (Index i = line_start; i < line_end; i++) {
-          if (!IsWhitespace(ptr_[i])) {
-            add = true;
-            break;
-          }
-        }
-        if (add) result.emplace_back(begin() + line_start, begin() + line_end);
-      } else {
-        result.emplace_back(begin() + line_start, begin() + line_end);
-      }
-      line_start = line_end + 1;
-      line_end = line_start;
-    } else {
-      line_end++;
-    }
-  }
-
-  if (remove_space_line) {
-    bool add = false;
-    for (Index i = line_start; i < size_; i++) {
-      if (!IsWhitespace(ptr_[i])) {
-        add = true;
-        break;
-      }
-    }
-    if (add) result.emplace_back(begin() + line_start, begin() + size_);
-  } else {
-    result.emplace_back(begin() + line_start, begin() + size_);
-  }
-
-  return result;
-}
-
-std::vector<String> StringView::SplitToLines(bool remove_space_line) const {
-  return Split(u'\n', remove_space_line);
-}
-
-bool StringView::StartWith(StringView str) const {
-  if (str.size() > size_) return false;
-  return std::memcmp(str.data(), ptr_, str.size()) == 0;
-}
-
-bool StringView::EndWith(StringView str) const {
-  if (str.size() > size_) return false;
-  return std::memcmp(str.data(), ptr_ + size_ - str.size(), str.size()) == 0;
-}
-
-Index StringView::IndexFromCodeUnitToCodePoint(Index code_unit_index) const {
-  auto iter = CodePointIterator();
-  Index result = 0;
-  while (iter.GetPosition() < code_unit_index && !iter.IsPastEnd()) {
-    ++iter;
-    ++result;
-  }
-  return result;
-}
-
-Index StringView::IndexFromCodePointToCodeUnit(Index code_point_index) const {
-  auto iter = CodePointIterator();
-  Index cpi = 0;
-  while (cpi < code_point_index && !iter.IsPastEnd()) {
-    ++iter;
-    ++cpi;
-  }
-  return iter.GetPosition();
-}
-
-Range StringView::RangeFromCodeUnitToCodePoint(Range code_unit_range) const {
-  return Range::FromTwoSides(
-      IndexFromCodeUnitToCodePoint(code_unit_range.GetStart()),
-      IndexFromCodeUnitToCodePoint(code_unit_range.GetEnd()));
-}
-
-Range StringView::RangeFromCodePointToCodeUnit(Range code_point_range) const {
-  return Range::FromTwoSides(
-      IndexFromCodePointToCodeUnit(code_point_range.GetStart()),
-      IndexFromCodePointToCodeUnit(code_point_range.GetEnd()));
-}
-
-std::string StringView::ToUtf8() const {
-  std::string result;
-  for (auto cp : CodePointIterator()) {
-    Utf8EncodeCodePointAppend(
-        cp, std::bind(&std::string::push_back, std::ref(result),
-                      std::placeholders::_1));
-  }
-  return result;
-}
-
-Buffer StringView::ToUtf8Buffer(bool end_zero) const {
-  const Index grow_step = 10;
-  Buffer buffer(grow_step);  // Maybe another init value is more reasonable.
-  auto push_back = [&buffer](char c) {
-    if (buffer.IsUsedReachEnd()) {
-      buffer.ResizeBuffer(buffer.GetBufferSize() + grow_step, true);
-    }
-    buffer.PushBack(static_cast<std::byte>(c));
-  };
-  for (auto cp : CodePointIterator()) {
-    Utf8EncodeCodePointAppend(cp, push_back);
-  }
-  if (end_zero) {
-    push_back(0);
-  }
-  return buffer;
-}
-
-String ToLower(StringView s) {
-  String result;
-  for (auto c : s) result.push_back(ToLower(c));
-  return result;
-}
-
-String ToUpper(StringView s) {
-  String result;
-  for (auto c : s) result.push_back(ToUpper(c));
-  return result;
-}
-
-}  // namespace cru
diff --git a/src/platform/graphics/direct2d/Font.cpp b/src/platform/graphics/direct2d/Font.cpp
index b1c03751..34bb2ea5 100644
--- a/src/platform/graphics/direct2d/Font.cpp
+++ b/src/platform/graphics/direct2d/Font.cpp
@@ -1,6 +1,5 @@
 #include "cru/platform/graphics/direct2d/Font.h"
 
-#include "cru/base/Format.h"
 #include "cru/platform/graphics/direct2d/Exception.h"
 #include "cru/platform/graphics/direct2d/Factory.h"
 
diff --git a/src/ui/ThemeManager.cpp b/src/ui/ThemeManager.cpp
index 0f4daeb7..14da3ef8 100644
--- a/src/ui/ThemeManager.cpp
+++ b/src/ui/ThemeManager.cpp
@@ -20,7 +20,7 @@ ThemeManager::ThemeManager() {
   }
 
   PrependThemeResourceDictionary(
-      ThemeResourceDictionary::FromFile(String::FromStdPath(resourses_file)));
+      ThemeResourceDictionary::FromFile(resourses_file));
 }
 
 ThemeManager::~ThemeManager() {}
@@ -44,7 +44,7 @@ void ThemeManager::PrependThemeResourceDictionary(
 }
 
 std::string ThemeManager::GetResourceString(std::string_view key) {
-  return GetResource<String>(key).ToUtf8();
+  return GetResource<std::string>(key);
 }
 
 std::shared_ptr<platform::graphics::IBrush> ThemeManager::GetResourceBrush(
diff --git a/src/ui/ThemeResourceDictionary.cpp b/src/ui/ThemeResourceDictionary.cpp
index f76bdde8..587a14c5 100644
--- a/src/ui/ThemeResourceDictionary.cpp
+++ b/src/ui/ThemeResourceDictionary.cpp
@@ -8,8 +8,8 @@
 namespace cru::ui {
 
 std::unique_ptr<ThemeResourceDictionary> ThemeResourceDictionary::FromFile(
-    const String& file_path) {
-  io::CFileStream stream(file_path.ToUtf8().c_str(), "r");
+    std::filesystem::path file_path) {
+  io::CFileStream stream(file_path.c_str(), "r");
   auto xml_string = stream.ReadToEndAsUtf8String();
   auto parser = xml::XmlParser(xml_string);
   return std::make_unique<ThemeResourceDictionary>(parser.Parse(), false);
diff --git a/src/ui/document/DocumentElementType.cpp b/src/ui/document/DocumentElementType.cpp
index d548b494..ed076169 100644
--- a/src/ui/document/DocumentElementType.cpp
+++ b/src/ui/document/DocumentElementType.cpp
@@ -5,17 +5,17 @@
 
 namespace cru::ui::document {
 DocumentElementType::DocumentElementType(
-    String name, std::vector<DocumentElementType*> parents)
+    std::string name, std::vector<DocumentElementType*> parents)
     : name_(std::move(name)), parents_(std::move(parents)) {}
 
 DocumentElementType::~DocumentElementType() {}
 
 DocumentElementType* const DocumentElementTypes::kBaseElementType =
-    new DocumentElementType(u"Base", {});
+    new DocumentElementType("Base", {});
 
 DocumentElementType* const DocumentElementTypes::kRootElementType =
-    new DocumentElementType(u"Root", {kBaseElementType});
+    new DocumentElementType("Root", {kBaseElementType});
 
 DocumentElementType* const DocumentElementTypes::kTextElementType =
-    new DocumentElementType(u"Text", {kBaseElementType});
+    new DocumentElementType("Text", {kBaseElementType});
 }  // namespace cru::ui::document
diff --git a/src/ui/document/TextDocumentElement.cpp b/src/ui/document/TextDocumentElement.cpp
index 1ba39849..52cfac5a 100644
--- a/src/ui/document/TextDocumentElement.cpp
+++ b/src/ui/document/TextDocumentElement.cpp
@@ -1,10 +1,9 @@
 #include "cru/ui/document/TextDocumentElement.h"
-#include "cru/base/String.h"
 #include "cru/ui/document/DocumentElement.h"
 #include "cru/ui/document/DocumentElementType.h"
 
 namespace cru::ui::document {
-TextDocumentElement::TextDocumentElement(String text, TextStyle style,
+TextDocumentElement::TextDocumentElement(std::string text, TextStyle style,
                                          IDocumentLink* link)
     : DocumentElement(DocumentElementTypes::kTextElementType),
       text_(std::move(text)),
@@ -13,5 +12,5 @@ TextDocumentElement::TextDocumentElement(String text, TextStyle style,
 
 TextDocumentElement::~TextDocumentElement() {}
 
-void TextDocumentElement::SetText(String text) { text_ = std::move(text); }
+void TextDocumentElement::SetText(std::string text) { text_ = std::move(text); }
 }  // namespace cru::ui::document
diff --git a/src/ui/host/RoutedEventDispatch.h b/src/ui/host/RoutedEventDispatch.h
index 98042841..0729d176 100644
--- a/src/ui/host/RoutedEventDispatch.h
+++ b/src/ui/host/RoutedEventDispatch.h
@@ -23,7 +23,7 @@ namespace cru::ui::host {
 // as the rest arguments.
 template <typename EventArgs, typename... Args>
 void DispatchEvent(
-    const String& event_name, controls::Control* const original_sender,
+    const std::string& event_name, controls::Control* const original_sender,
     events::RoutedEvent<EventArgs>* (controls::Control::*event_ptr)(),
     controls::Control* const last_receiver, Args&&... args) {
   constexpr auto kLogTag = "DispatchEvent";
@@ -37,7 +37,7 @@ void DispatchEvent(
       CRU_LOG_TAG_DEBUG(
           "Routed event {} no need to dispatch (original_sender == "
           "last_receiver). Original sender is {}.",
-          event_name.ToUtf8(), original_sender->GetControlType().ToUtf8());
+          event_name, original_sender->GetControlType());
     return;
   }
 
@@ -55,15 +55,15 @@ void DispatchEvent(
 
   if constexpr (debug_flags::routed_event) {
     std::string log = "Dispatch routed event ";
-    log += event_name.ToUtf8();
+    log += event_name;
     log += ". Path (parent first): ";
     auto i = receive_list.crbegin();
     const auto end = --receive_list.crend();
     for (; i != end; ++i) {
-      log += i->Resolve()->GetControlType().ToUtf8();
+      log += i->Resolve()->GetControlType();
       log += " -> ";
     }
-    log += i->Resolve()->GetControlType().ToUtf8();
+    log += i->Resolve()->GetControlType();
     CRU_LOG_TAG_DEBUG("{}", log);
   }
 
diff --git a/src/ui/host/WindowHost.cpp b/src/ui/host/WindowHost.cpp
index 88e8cc87..4c707772 100644
--- a/src/ui/host/WindowHost.cpp
+++ b/src/ui/host/WindowHost.cpp
@@ -21,8 +21,7 @@ using platform::gui::INativeWindow;
 using platform::gui::IUiApplication;
 
 namespace event_names {
-#define CRU_DEFINE_EVENT_NAME(name) \
-  constexpr const char16_t* name = CRU_MAKE_UNICODE_LITERAL(name);
+#define CRU_DEFINE_EVENT_NAME(name) constexpr const char* name = #name;
 
 CRU_DEFINE_EVENT_NAME(LoseFocus)
 CRU_DEFINE_EVENT_NAME(GainFocus)
diff --git a/src/ui/mapper/FontMapper.cpp b/src/ui/mapper/FontMapper.cpp
index a0dcdd9f..ebf7c27c 100644
--- a/src/ui/mapper/FontMapper.cpp
+++ b/src/ui/mapper/FontMapper.cpp
@@ -1,6 +1,5 @@
 #include "cru/ui/mapper/FontMapper.h"
 #include "../Helper.h"
-#include "cru/base/String.h"
 #include "cru/base/StringUtil.h"
 #include "cru/platform/graphics/Factory.h"
 
diff --git a/src/ui/mapper/StringMapper.cpp b/src/ui/mapper/StringMapper.cpp
index 5914da17..6f6b4546 100644
--- a/src/ui/mapper/StringMapper.cpp
+++ b/src/ui/mapper/StringMapper.cpp
@@ -1,19 +1,18 @@
 #include "cru/ui/mapper/StringMapper.h"
 #include "cru/xml/XmlNode.h"
-#include "cru/base/String.h"
 
 namespace cru::ui::mapper {
 StringMapper::StringMapper() { SetAllowedTags({"String"}); }
 
 StringMapper::~StringMapper() {}
 
-String StringMapper::DoMapFromString(std::string str) {
-  return String::FromUtf8(str);
+std::string StringMapper::DoMapFromString(std::string str) {
+  return std::move(str);
 }
 
-String StringMapper::DoMapFromXml(xml::XmlElementNode* node) {
+std::string StringMapper::DoMapFromXml(xml::XmlElementNode* node) {
   auto value_attr = node->GetOptionalAttributeValueCaseInsensitive("value");
-  if (value_attr) return String::FromUtf8(*value_attr);
+  if (value_attr) return *value_attr;
   return {};
 }
 }  // namespace cru::ui::mapper
diff --git a/src/ui/render/BorderRenderObject.cpp b/src/ui/render/BorderRenderObject.cpp
index 957cf9bb..5c4bc22c 100644
--- a/src/ui/render/BorderRenderObject.cpp
+++ b/src/ui/render/BorderRenderObject.cpp
@@ -244,5 +244,5 @@ void BorderRenderObject::RecreateGeometry() {
   builder.reset();
 }
 
-String BorderRenderObject::GetName() const { return u"BorderRenderObject"; }
+std::string BorderRenderObject::GetName() const { return "BorderRenderObject"; }
 }  // namespace cru::ui::render
diff --git a/src/ui/render/FlexLayoutRenderObject.cpp b/src/ui/render/FlexLayoutRenderObject.cpp
index efc98602..53193867 100644
--- a/src/ui/render/FlexLayoutRenderObject.cpp
+++ b/src/ui/render/FlexLayoutRenderObject.cpp
@@ -4,12 +4,11 @@
 #include "cru/ui/render/LayoutHelper.h"
 
 #include <algorithm>
-#include <functional>
 #include <type_traits>
 
 namespace cru::ui::render {
-String FlexLayoutRenderObject::GetName() const {
-  return u"FlexLayoutRenderObject";
+std::string FlexLayoutRenderObject::GetName() const {
+  return "FlexLayoutRenderObject";
 }
 
 struct tag_horizontal_t {};
diff --git a/src/ui/render/RenderObject.cpp b/src/ui/render/RenderObject.cpp
index 521e88c2..d10fd897 100644
--- a/src/ui/render/RenderObject.cpp
+++ b/src/ui/render/RenderObject.cpp
@@ -119,16 +119,17 @@ void RenderObject::Measure(const MeasureRequirement& requirement,
       preferred_size.OverrideBy(preferred_size_);
 
   if constexpr (cru::ui::debug_flags::layout) {
-    CRU_LOG_TAG_DEBUG("{} Measure begins :\nrequirement: {}\npreferred size: {}",
-                  this->GetDebugPathInTree().ToUtf8(), requirement.ToDebugString().ToUtf8(),
-                  preferred_size.ToDebugString().ToUtf8());
+    CRU_LOG_TAG_DEBUG(
+        "{} Measure begins :\nrequirement: {}\npreferred size: {}",
+        this->GetDebugPathInTree(), requirement.ToDebugString(),
+        preferred_size.ToDebugString());
   }
 
   desired_size_ = OnMeasureCore(merged_requirement, merged_preferred_size);
 
   if constexpr (cru::ui::debug_flags::layout) {
     CRU_LOG_TAG_DEBUG("{} Measure ends :\nresult size: {}",
-                  this->GetDebugPathInTree().ToUtf8(), desired_size_);
+                      this->GetDebugPathInTree(), desired_size_);
   }
 
   Ensures(desired_size_.width >= 0);
@@ -145,7 +146,7 @@ Size RenderObject::Measure1(const BoxConstraint& constraint) {
 void RenderObject::Layout(const Point& offset) {
   if constexpr (cru::ui::debug_flags::layout) {
     CRU_LOG_TAG_DEBUG("{} Layout :\noffset: {} size: {}",
-                  this->GetDebugPathInTree().ToUtf8(), offset, desired_size_);
+                      this->GetDebugPathInTree(), offset, desired_size_);
   }
   offset_ = offset;
   size_ = desired_size_;
@@ -193,13 +194,13 @@ Size RenderObject::OnMeasureCore1(const BoxConstraint& constraint) {
   if (space_size.width > merged_constraint.max.width) {
     space_size.width = merged_constraint.max.width;
     CRU_LOG_TAG_WARN("{} space width is over constraint.max.width",
-                 this->GetDebugPathInTree().ToUtf8());
+                     this->GetDebugPathInTree());
   }
 
   if (space_size.height > merged_constraint.max.height) {
     space_size.height = merged_constraint.max.height;
     CRU_LOG_TAG_WARN("{} space height is over constraint.max.height",
-                 this->GetDebugPathInTree().ToUtf8());
+                     this->GetDebugPathInTree());
   }
 
   BoxConstraint content_constraint{merged_constraint.max - space_size,
@@ -284,20 +285,20 @@ void RenderObject::InvalidatePaint() {
   }
 }
 
-String kUnamedName(u"UNNAMED");
-String RenderObject::GetName() const { return kUnamedName; }
+std::string kUnamedName("UNNAMED");
+std::string RenderObject::GetName() const { return kUnamedName; }
 
-String RenderObject::GetDebugPathInTree() const {
-  std::vector<String> chain;
+std::string RenderObject::GetDebugPathInTree() const {
+  std::vector<std::string> chain;
   const RenderObject* parent = this;
   while (parent != nullptr) {
     chain.push_back(parent->GetName());
     parent = parent->GetParent();
   }
 
-  String result(chain.back());
+  std::string result(chain.back());
   for (auto iter = chain.crbegin() + 1; iter != chain.crend(); ++iter) {
-    result += u" -> ";
+    result += " -> ";
     result += *iter;
   }
 
diff --git a/src/ui/style/StyleRule.cpp b/src/ui/style/StyleRule.cpp
index ce823537..8b9b0a56 100644
--- a/src/ui/style/StyleRule.cpp
+++ b/src/ui/style/StyleRule.cpp
@@ -2,7 +2,7 @@
 
 namespace cru::ui::style {
 StyleRule::StyleRule(ClonablePtr<Condition> condition,
-                     ClonablePtr<Styler> styler, String name)
+                     ClonablePtr<Styler> styler, std::string name)
     : condition_(std::move(condition)),
       styler_(std::move(styler)),
       name_(std::move(name)) {}