...

17 files changed, 241 insertions, 92 deletions

diff --git a/include/cru/common/Exception.hpp b/include/cru/common/Exception.hpp
index 8864f4df..4e5d3a16 100644
--- a/include/cru/common/Exception.hpp
+++ b/include/cru/common/Exception.hpp
@@ -5,7 +5,7 @@ namespace cru {
 class CRU_BASE_API Exception {
  public:
   Exception() = default;
-  Exception(String message) : message_(std::move(message)) {}
+  explicit Exception(String message) : message_(std::move(message)) {}
 
   CRU_DEFAULT_COPY(Exception)
   CRU_DEFAULT_MOVE(Exception)
diff --git a/include/cru/common/HandlerRegistry.hpp b/include/cru/common/HandlerRegistry.hpp
index bd74a9e0..0af97968 100644
--- a/include/cru/common/HandlerRegistry.hpp
+++ b/include/cru/common/HandlerRegistry.hpp
@@ -59,6 +59,7 @@ class HandlerRegistry final {
   int AddHandler(std::function<T> handler) {
     auto id = current_id_++;
     handler_list_.push_back({id, std::move(handler)});
+    return id;
   }
 
   void RemoveHandler(int id) {
diff --git a/include/cru/common/Logger.hpp b/include/cru/common/Logger.hpp
index 239a25cd..5aea5126 100644
--- a/include/cru/common/Logger.hpp
+++ b/include/cru/common/Logger.hpp
@@ -1,10 +1,10 @@
 #pragma once
 #include "Base.hpp"
 
-#include <fmt/format.h>
+#include "String.hpp"
+
 #include <list>
 #include <memory>
-#include <string_view>
 
 namespace cru::log {
 
@@ -13,7 +13,7 @@ enum class LogLevel { Debug, Info, Warn, Error };
 struct CRU_BASE_API ILogSource : virtual Interface {
   // Write the string s. LogLevel is just a helper. It has no effect on the
   // content to write.
-  virtual void Write(LogLevel level, const std::u16string& s) = 0;
+  virtual void Write(LogLevel level, const String& s) = 0;
 };
 
 class CRU_BASE_API Logger : public Object {
@@ -33,8 +33,8 @@ class CRU_BASE_API Logger : public Object {
   void RemoveSource(ILogSource* source);
 
  public:
-  void Log(LogLevel level, std::u16string_view s);
-  void Log(LogLevel level, std::u16string_view tag, std::u16string_view s);
+  void Log(LogLevel level, const String& message);
+  void Log(LogLevel level, const String& tag, const String& message);
 
  private:
   std::list<std::unique_ptr<ILogSource>> sources_;
@@ -45,26 +45,26 @@ template <typename... TArgs>
 void Debug([[maybe_unused]] TArgs&&... args) {
 #ifdef CRU_DEBUG
   Logger::GetInstance()->Log(LogLevel::Debug,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 #endif
 }
 
 template <typename... TArgs>
 void Info(TArgs&&... args) {
   Logger::GetInstance()->Log(LogLevel::Info,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 }
 
 template <typename... TArgs>
 void Warn(TArgs&&... args) {
   Logger::GetInstance()->Log(LogLevel::Warn,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 }
 
 template <typename... TArgs>
 void Error(TArgs&&... args) {
   Logger::GetInstance()->Log(LogLevel::Error,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 }
 
 // TODO: Remove argument evaluation in Debug.
@@ -73,25 +73,25 @@ void TagDebug([[maybe_unused]] std::u16string_view tag,
               [[maybe_unused]] TArgs&&... args) {
 #ifdef CRU_DEBUG
   Logger::GetInstance()->Log(LogLevel::Debug, tag,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 #endif
 }
 
 template <typename... TArgs>
 void TagInfo(std::u16string_view tag, TArgs&&... args) {
   Logger::GetInstance()->Log(LogLevel::Info, tag,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 }
 
 template <typename... TArgs>
 void TagWarn(std::u16string_view tag, TArgs&&... args) {
   Logger::GetInstance()->Log(LogLevel::Warn, tag,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 }
 
 template <typename... TArgs>
 void TagError(std::u16string_view tag, TArgs&&... args) {
   Logger::GetInstance()->Log(LogLevel::Error, tag,
-                             fmt::format(std::forward<TArgs>(args)...));
+                             Format(std::forward<TArgs>(args)...));
 }
 }  // namespace cru::log
diff --git a/include/cru/common/String.hpp b/include/cru/common/String.hpp
index 42143c9d..9443417f 100644
--- a/include/cru/common/String.hpp
+++ b/include/cru/common/String.hpp
@@ -4,8 +4,14 @@
 #include "Range.hpp"
 #include "StringUtil.hpp"
 
-#include <cstdint>
+#include <algorithm>
+#include <array>
+#include <charconv>
 #include <iterator>
+#include <stdexcept>
+#include <system_error>
+#include <type_traits>
+#include <vector>
 
 namespace cru {
 class CRU_BASE_API String {
@@ -25,6 +31,11 @@ class CRU_BASE_API String {
     return String(str, size);
   }
 
+  // Never use this if you don't know what this mean!
+  static String FromBuffer(std::uint16_t* buffer, Index size, Index capacity) {
+    return String{from_buffer_tag{}, buffer, size, capacity};
+  }
+
 #ifdef CRU_PLATFORM_WINDOWS
   static String FromUtf16(wchar_t* str) { return String(str); }
   static String FromUtf16(wchar_t* str, Index size) {
@@ -69,6 +80,10 @@ class CRU_BASE_API String {
 
   ~String();
 
+ private:
+  struct from_buffer_tag {};
+  String(from_buffer_tag, std::uint16_t* buffer, Index size, Index capacity);
+
  public:
   bool empty() const { return this->size_ == 0; }
   Index size() const { return this->size_; }
@@ -136,12 +151,6 @@ class CRU_BASE_API String {
     return *this;
   }
 
-  String operator+(const String& other) const {
-    String result(*this);
-    result += other;
-    return result;
-  }
-
  public:
   Utf16CodePointIterator CodePointIterator() const {
     return Utf16CodePointIterator(
@@ -163,6 +172,9 @@ class CRU_BASE_API String {
   }
 #endif
 
+  template <typename... T>
+  String Format(T&&... args) const;
+
   std::string ToUtf8() const;
 
   int Compare(const String& other) const;
@@ -178,4 +190,76 @@ class CRU_BASE_API String {
 
 CRU_DEFINE_COMPARE_OPERATORS(String)
 
+inline String operator+(const String& left, const String& right) {
+  String result(left);
+  result += right;
+  return result;
+}
+
+template <typename T, typename = std::enable_if_t<std::is_arithmetic_v<T>>>
+String ToString(T value) {
+  std::array<char, 50> buffer;
+  auto result =
+      std::to_chars(buffer.data(), buffer.data() + buffer.size(), value);
+
+  auto size = result.ptr - buffer.data();
+  auto b = new std::uint16_t[size + 1];
+  b[size] = 0;
+  std::copy(buffer.data(), result.ptr, b);
+  return String::FromBuffer(b, size, size);
+
+  if (result.ec == std::errc{}) {
+  } else {
+    throw std::invalid_argument("Failed to convert value to chars.");
+  }
+}
+
+inline String ToString(String value) { return std::move(value); }
+
+namespace details {
+enum class FormatTokenType { PlaceHolder, Text };
+
+struct FormatToken {
+  FormatTokenType type;
+  String data;
+};
+
+std::vector<FormatToken> ParseToFormatTokenList(const String& str);
+
+void FormatAppendFromFormatTokenList(
+    String& current, const std::vector<FormatToken>& format_token_list,
+    Index index);
+
+template <typename TA, typename... T>
+void FormatAppendFromFormatTokenList(
+    String& current, const std::vector<FormatToken>& format_token_list,
+    Index index, TA&& args0, T&&... args) {
+  for (Index i = index; i < format_token_list.size(); i++) {
+    const auto& token = format_token_list[i];
+    if (token.type == FormatTokenType::PlaceHolder) {
+      current += ToString(std::forward<TA>(args0));
+      FormatAppendFromFormatTokenList(current, format_token_list, i + 1,
+                                      std::forward<T>(args)...);
+    } else {
+      current += token.data;
+    }
+  }
+}
+}  // namespace details
+
+template <typename... T>
+String Format(const String& format, T&&... args) {
+  String result;
+
+  details::FormatAppendFromFormatTokenList(
+      result, details::ParseToFormatTokenList(format), 0,
+      std::forward<T>(args)...);
+
+  return result;
+}
+
+template <typename... T>
+String String::Format(T&&... args) const {
+  return cru::Format(*this, std::forward<T>(args)...);
+}
 }  // namespace cru
diff --git a/include/cru/platform/Check.hpp b/include/cru/platform/Check.hpp
index 9ecd2d1d..5d99aa9c 100644
--- a/include/cru/platform/Check.hpp
+++ b/include/cru/platform/Check.hpp
@@ -2,9 +2,8 @@
 #include "Exception.hpp"
 #include "Resource.hpp"
 
-#include "cru/common/StringUtil.hpp"
+#include "cru/common/String.hpp"
 
-#include <fmt/format.h>
 #include <memory>
 #include <type_traits>
 
@@ -15,10 +14,10 @@ TTarget* CheckPlatform(IPlatformResource* resource,
   Expects(resource);
   const auto result = dynamic_cast<TTarget*>(resource);
   if (result == nullptr) {
-    throw UnsupportPlatformException(String::FromUtf8(fmt::format(
-        "Try to convert resource to target platform failed. Platform id of "
+    throw UnsupportPlatformException(Format(
+        u"Try to convert resource to target platform failed. Platform id of "
         "resource to convert: {} . Target platform id: {} .",
-        resource->GetPlatformId().ToUtf8(), target_platform.ToUtf8())));
+        resource->GetPlatformId(), target_platform));
   }
   return result;
 }
@@ -31,10 +30,10 @@ std::shared_ptr<TTarget> CheckPlatform(const std::shared_ptr<TSource>& resource,
   Expects(resource);
   const auto result = std::dynamic_pointer_cast<TTarget>(resource);
   if (result == nullptr) {
-    throw UnsupportPlatformException(String::FromUtf8(fmt::format(
-        "Try to convert resource to target platform failed. Platform id of "
+    throw UnsupportPlatformException(Format(
+        u"Try to convert resource to target platform failed. Platform id of "
         "resource to convert: {} . Target platform id: {} .",
-        resource->GetPlatformId().ToUtf8(), target_platform.ToUtf8())));
+        resource->GetPlatformId(), target_platform));
   }
   return result;
 }
diff --git a/include/cru/platform/GraphBase.hpp b/include/cru/platform/GraphBase.hpp
index cc0ffcc7..2cfc9cc4 100644
--- a/include/cru/platform/GraphBase.hpp
+++ b/include/cru/platform/GraphBase.hpp
@@ -4,8 +4,8 @@
 #include "Color.hpp"
 #include "cru/common/Format.hpp"
 #include "cru/common/Range.hpp"
+#include "cru/common/String.hpp"
 
-#include <fmt/core.h>
 #include <cstdint>
 #include <limits>
 #include <optional>
@@ -20,8 +20,8 @@ struct Point final {
   constexpr Point(const float x, const float y) : x(x), y(y) {}
   explicit constexpr Point(const Size& size);
 
-  std::u16string ToDebugString() const {
-    return fmt::format(u"({}, {})", ToUtf16String(x), ToUtf16String(y));
+  String ToDebugString() const {
+    return Format(u"({}, {})", ToUtf16String(x), ToUtf16String(y));
   }
 
   constexpr Point& operator+=(const Point& other) {
@@ -62,9 +62,8 @@ struct Size final {
                 std::numeric_limits<float>::max()};
   }
 
-  std::u16string ToDebugString() const {
-    return fmt::format(u"({}, {})", ToUtf16String(width),
-                       ToUtf16String(height));
+  String ToDebugString() const {
+    return Format(u"({}, {})", ToUtf16String(width), ToUtf16String(height));
   }
 
   float width = 0;
diff --git a/include/cru/platform/gui/InputMethod.hpp b/include/cru/platform/gui/InputMethod.hpp
index 9b07959c..c259e63c 100644
--- a/include/cru/platform/gui/InputMethod.hpp
+++ b/include/cru/platform/gui/InputMethod.hpp
@@ -3,7 +3,6 @@
 
 #include "cru/common/Event.hpp"
 
-#include <fmt/format.h>
 #include <memory>
 #include <vector>
 
@@ -54,28 +53,28 @@ struct IInputMethodContext : virtual IPlatformResource {
 };
 }  // namespace cru::platform::gui
 
-template <>
-struct fmt::formatter<cru::platform::gui::CompositionText, char16_t>
-    : fmt::formatter<std::u16string_view, char16_t> {
-  auto parse(fmt::basic_format_parse_context<char16_t>& ctx) {
-    return fmt::formatter<std::u16string_view, char16_t>::parse(ctx);
-  }
-
-  template <typename FormatContext>
-  auto format(const cru::platform::gui::CompositionText& ct,
-              FormatContext& ctx) {
-    auto output = ctx.out();
-    output = format_to(output, u"text: {}\n", ct.text);
-    output = format_to(output, u"clauses:\n");
-    for (gsl::index i = 0; i < static_cast<gsl::index>(ct.clauses.size());
-         i++) {
-      const auto& clause = ct.clauses[i];
-      output =
-          format_to(output, u"\t{}. start: {} end: {}{}\n", i, clause.start,
-                    clause.end, clause.target ? u" target" : u"");
-    }
-    output = format_to(output, u"selection: position: {} count: {}",
-                       ct.selection.position, ct.selection.count);
-    return output;
-  }
-};
+// template <>
+// struct fmt::formatter<cru::platform::gui::CompositionText, char16_t>
+//     : fmt::formatter<std::u16string_view, char16_t> {
+//   auto parse(fmt::basic_format_parse_context<char16_t>& ctx) {
+//     return fmt::formatter<std::u16string_view, char16_t>::parse(ctx);
+//   }
+
+//   template <typename FormatContext>
+//   auto format(const cru::platform::gui::CompositionText& ct,
+//               FormatContext& ctx) {
+//     auto output = ctx.out();
+//     output = format_to(output, u"text: {}\n", ct.text);
+//     output = format_to(output, u"clauses:\n");
+//     for (gsl::index i = 0; i < static_cast<gsl::index>(ct.clauses.size());
+//          i++) {
+//       const auto& clause = ct.clauses[i];
+//       output =
+//           format_to(output, u"\t{}. start: {} end: {}{}\n", i, clause.start,
+//                     clause.end, clause.target ? u" target" : u"");
+//     }
+//     output = format_to(output, u"selection: position: {} count: {}",
+//                        ct.selection.position, ct.selection.count);
+//     return output;
+//   }
+// };
diff --git a/include/cru/ui/render/MeasureRequirement.hpp b/include/cru/ui/render/MeasureRequirement.hpp
index 6a0c6952..ff9dd6e3 100644
--- a/include/cru/ui/render/MeasureRequirement.hpp
+++ b/include/cru/ui/render/MeasureRequirement.hpp
@@ -1,9 +1,8 @@
 #pragma once
 #include "Base.hpp"
 
-#include "cru/common/Format.hpp"
+#include "cru/common/String.hpp"
 
-#include <fmt/core.h>
 #include <algorithm>
 #include <limits>
 #include <string>
@@ -169,9 +168,8 @@ struct MeasureSize {
     };
   }
 
-  std::u16string ToDebugString() const {
-    return fmt::format(u"({}, {})", width.ToDebugString(),
-                       height.ToDebugString());
+  String ToDebugString() const {
+    return Format(u"({}, {})", width.ToDebugString(), height.ToDebugString());
   }
 
   constexpr static MeasureSize NotSpecified() {
@@ -240,9 +238,9 @@ struct MeasureRequirement {
     return result;
   }
 
-  std::u16string ToDebugString() const {
-    return fmt::format(u"{{min: {}, max: {}}}", min.ToDebugString(),
-                       max.ToDebugString());
+  String ToDebugString() const {
+    return Format(u"{{min: {}, max: {}}}", min.ToDebugString(),
+                  max.ToDebugString());
   }
 
   constexpr static MeasureRequirement Merge(const MeasureRequirement& left,
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 1056a763..e1642da2 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -30,5 +30,4 @@ else()
 endif()
 
 find_package(Microsoft.GSL CONFIG REQUIRED)
-find_package(fmt CONFIG REQUIRED)
-target_link_libraries(cru_base PUBLIC Microsoft.GSL::GSL fmt::fmt)
+target_link_libraries(cru_base PUBLIC Microsoft.GSL::GSL)
diff --git a/src/common/Logger.cpp b/src/common/Logger.cpp
index af1dd692..e77e8a85 100644
--- a/src/common/Logger.cpp
+++ b/src/common/Logger.cpp
@@ -30,7 +30,7 @@ void Logger::RemoveSource(ILogSource *source) {
 }
 
 namespace {
-std::u16string_view LogLevelToString(LogLevel level) {
+String LogLevelToString(LogLevel level) {
   switch (level) {
     case LogLevel::Debug:
       return u"DEBUG";
@@ -45,36 +45,35 @@ std::u16string_view LogLevelToString(LogLevel level) {
   }
 }
 
-std::u16string GetLogTime() {
+String GetLogTime() {
   auto time = std::time(nullptr);
   auto calendar = std::localtime(&time);
-  return fmt::format(u"{}:{}:{}", calendar->tm_hour, calendar->tm_min,
-                     calendar->tm_sec);
+  return Format(u"{}:{}:{}", calendar->tm_hour, calendar->tm_min,
+                calendar->tm_sec);
 }
 }  // namespace
 
-void Logger::Log(LogLevel level, std::u16string_view s) {
+void Logger::Log(LogLevel level, const String &message) {
 #ifndef CRU_DEBUG
   if (level == LogLevel::Debug) {
     return;
   }
 #endif
   for (const auto &source : sources_) {
-    source->Write(level, fmt::format(u"[{}] {}: {}\n", GetLogTime(),
-                                     LogLevelToString(level), s));
+    source->Write(level, Format(u"[{}] {}: {}\n", GetLogTime(),
+                                LogLevelToString(level), message));
   }
 }
 
-void Logger::Log(LogLevel level, std::u16string_view tag,
-                 std::u16string_view s) {
+void Logger::Log(LogLevel level, const String &tag, const String &message) {
 #ifndef CRU_DEBUG
   if (level == LogLevel::Debug) {
     return;
   }
 #endif
   for (const auto &source : sources_) {
-    source->Write(level, fmt::format(u"[{}] {} {}: {}\n", GetLogTime(),
-                                     LogLevelToString(level), tag, s));
+    source->Write(level, Format(u"[{}] {} {}: {}\n", GetLogTime(),
+                                LogLevelToString(level), tag, message));
   }
 }
 }  // namespace cru::log
diff --git a/src/common/String.cpp b/src/common/String.cpp
index e9acf984..94eb8f27 100644
--- a/src/common/String.cpp
+++ b/src/common/String.cpp
@@ -101,6 +101,10 @@ String::~String() {
   }
 }
 
+String::String(from_buffer_tag, std::uint16_t* buffer, Index size,
+               Index capacity)
+    : buffer_(buffer), size_(size), capacity_(capacity) {}
+
 void String::resize(Index new_size) {
   Expects(new_size >= 0);
 
@@ -137,7 +141,7 @@ void String::reserve(Index new_capacity) {
   }
 }
 
-String::iterator String::insert(const_iterator pos, std::uint16_t* str,
+String::iterator String::insert(const_iterator pos, const std::uint16_t* str,
                                 Index size) {
   Index new_size = size_ + size;
   if (new_size > capacity_) {
@@ -239,4 +243,54 @@ int String::Compare(const String& other) const {
   }
 }
 
+namespace details {
+std::vector<FormatToken> ParseToFormatTokenList(const String& str) {
+  std::vector<FormatToken> result;
+
+  auto push_char = [&result](std::uint16_t c) {
+    if (result.empty() || result.back().type == FormatTokenType::PlaceHolder) {
+      result.push_back(FormatToken{FormatTokenType::Text, String{}});
+    }
+    result.back().data.append(c);
+  };
+
+  bool last_is_left_bracket = false;
+  for (auto c : str) {
+    if (c == u'{') {
+      if (last_is_left_bracket) {
+        push_char(u'{');
+        last_is_left_bracket = false;
+      } else {
+        last_is_left_bracket = true;
+      }
+    } else if (c == u'}') {
+      if (last_is_left_bracket) {
+        result.push_back(FormatToken{FormatTokenType::PlaceHolder, String{}});
+      }
+      last_is_left_bracket = false;
+    } else {
+      if (last_is_left_bracket) {
+        push_char(u'{');
+      }
+      push_char(c);
+      last_is_left_bracket = false;
+    }
+  }
+  return result;
+}
+
+void FormatAppendFromFormatTokenList(
+    String& current, const std::vector<FormatToken>& format_token_list,
+    Index index) {
+  for (Index i = index; i < format_token_list.size(); i++) {
+    const auto& token = format_token_list[i];
+    if (token.type == FormatTokenType::PlaceHolder) {
+      current += u"{}";
+    } else {
+      current += token.data;
+    }
+  }
+}
+}  // namespace details
+
 }  // namespace cru
diff --git a/src/osx/graphics/quartz/CMakeLists.txt b/src/osx/graphics/quartz/CMakeLists.txt
index c6bb29cb..868a3ee2 100644
--- a/src/osx/graphics/quartz/CMakeLists.txt
+++ b/src/osx/graphics/quartz/CMakeLists.txt
@@ -20,6 +20,6 @@ target_sources(cru_osx_graphics_quartz PUBLIC
 	${CRU_OSX_GRAPHICS_NATIVE_INCLUDE_DIR}/Resource.hpp
 	${CRU_OSX_GRAPHICS_NATIVE_INCLUDE_DIR}/TextLayout.hpp
 )
-target_link_libraries(cru_osx_graphics_quartz PUBLIC cocoa)
+target_link_libraries(cru_osx_graphics_quartz PUBLIC quartz)
 target_link_libraries(cru_osx_graphics_quartz PUBLIC cru_osx_base cru_platform_graphics)
 
diff --git a/src/parse/Grammar.cpp b/src/parse/Grammar.cpp
index 95c65e99..34eb2dd4 100644
--- a/src/parse/Grammar.cpp
+++ b/src/parse/Grammar.cpp
@@ -122,8 +122,6 @@ Grammar::GenerateLeftProductionMap() const {
 }
 
 void Grammar::EliminateLeftRecursions() {
-  // TODO: Use a better name.
-
   auto nonterminals = nonterminals_;
   for (int i = 0; i < nonterminals.size(); i++) {
     auto ni = nonterminals[i];
@@ -148,6 +146,7 @@ void Grammar::EliminateLeftRecursions() {
             auto new_right = right;
             new_right.insert(new_right.cbegin(), jp->GetRight().cbegin(),
                              jp->GetRight().cend());
+            // TODO: What should this name be.
             CreateProduction(u"", ni, std::move(new_right));
           }
         }
@@ -167,22 +166,29 @@ void Grammar::EliminateLeftRecursions() {
       }
     }
 
-    auto ni_h = CreateNonterminal(u"");
+    auto ni_h = CreateNonterminal(ni->GetName() +
+                                  u" (Eliminate Left Recursion Helper)");
 
     for (auto p : i_nr_ps) {
       auto right = p->GetRight();
       right.push_back(ni_h);
-      CreateProduction(u"", ni, std::move(right));
+      CreateProduction(p->GetName() + u" (Eliminate Left Recursion Of " +
+                           ni->GetName() + u")",
+                       ni, std::move(right));
     }
 
     for (auto p : i_r_ps) {
       auto right = p->GetRight();
       right.erase(right.cbegin());
       right.push_back(ni_h);
-      CreateProduction(u"", ni_h, std::move(right));
+      CreateProduction(p->GetName() + u" (Eliminate Left Recursion Of " +
+                           ni->GetName() + u")",
+                       ni_h, std::move(right));
     }
 
-    CreateProduction(u"", ni_h, std::vector<Symbol*>{});
+    CreateProduction(u"Empty Production (Eliminate Left Recursion Of " +
+                         ni->GetName() + u")",
+                     ni_h, std::vector<Symbol*>{});
 
     for (auto p : i_r_ps) {
       RemoveProduction(p);
@@ -193,4 +199,6 @@ void Grammar::EliminateLeftRecursions() {
     }
   }
 }
+
+void Grammar::LeftFactor() {}
 }  // namespace cru::parse
diff --git a/src/platform/Color.cpp b/src/platform/Color.cpp
index fe512715..c4cc511b 100644
--- a/src/platform/Color.cpp
+++ b/src/platform/Color.cpp
@@ -6,7 +6,6 @@
 #include <stdexcept>
 #include <string>
 #include <string_view>
-#include "fmt/core.h"
 
 namespace cru::platform {
 std::string Color::ToUtf8String() const {
diff --git a/test/common/CMakeLists.txt b/test/common/CMakeLists.txt
index c1fd078d..730607d2 100644
--- a/test/common/CMakeLists.txt
+++ b/test/common/CMakeLists.txt
@@ -1,4 +1,6 @@
 add_executable(cru_base_test
+	HandlerRegistryTest.cpp
+	StringTest.cpp
 	StringUtilTest.cpp
 )
 target_link_libraries(cru_base_test PRIVATE cru_base cru_test_base)
diff --git a/test/common/StringTest.cpp b/test/common/StringTest.cpp
new file mode 100644
index 00000000..1200a60b
--- /dev/null
+++ b/test/common/StringTest.cpp
@@ -0,0 +1,9 @@
+#include "cru/common/String.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(String, Format) {
+  using cru::Format;
+
+  ASSERT_EQ(Format(u"{} + {} = {}", 123, 321, 444), u"123 + 321 = 444");
+}
diff --git a/vcpkg.json b/vcpkg.json
index 4d97e3fb..cd113520 100644
--- a/vcpkg.json
+++ b/vcpkg.json
@@ -4,7 +4,6 @@
   "version": "0.0.1",
   "dependencies": [
     "ms-gsl",
-    "fmt",
     "gtest",
     "boost-property-tree",
     "boost-functional"