1 files changed, 154 insertions, 0 deletions
diff --git a/include/cru/base/Format.h b/include/cru/base/Format.h
new file mode 100644
index 00000000..d5c5ed99
--- /dev/null
+++ b/include/cru/base/Format.h
@@ -0,0 +1,154 @@
+#pragma once
+
+#include "Exception.h"
+#include "String.h"
+
+#include <cassert>
+#include <cstdio>
+#include <type_traits>
+#include <vector>
+
+namespace cru {
+inline String ToString(bool value) {
+  return value ? String(u"true") : String(u"false");
+}
+
+template <typename T>
+inline constexpr std::nullptr_t kPrintfFormatSpecifierOfType = nullptr;
+
+#define CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(type, specifier) \
+  template <>                                                       \
+  inline constexpr const char* kPrintfFormatSpecifierOfType<type> = specifier;
+
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(signed char, "%c")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(unsigned char, "%c")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(signed short, "%hd")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(unsigned short, "%hu")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(signed int, "%d")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(unsigned int, "%u")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(signed long, "%ld")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(unsigned long, "%lu")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(signed long long, "%lld")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(unsigned long long, "%llu")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(float, "%f")
+CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE(double, "%f")
+
+#undef CRU_DEFINE_PRINTF_FORMAT_SPECIFIER_OF_TYPE
+
+template <typename T>
+std::enable_if_t<
+    !std::is_null_pointer_v<decltype(kPrintfFormatSpecifierOfType<T>)>, String>
+ToString(T value) {
+  auto size = std::snprintf(nullptr, 0, kPrintfFormatSpecifierOfType<T>, value);
+  assert(size > 0);
+  std::vector<char> buffer(size + 1);
+  size = std::snprintf(buffer.data(), size + 1, kPrintfFormatSpecifierOfType<T>,
+                       value);
+  assert(size > 0);
+  return String::FromUtf8(buffer.data(), size);
+}
+
+template <typename T>
+String ToString(const T& value, StringView option) {
+  CRU_UNUSED(option)
+  return ToString(value);
+}
+
+inline String ToString(String value) { return value; }
+
+namespace details {
+enum class FormatTokenType { PlaceHolder, Text };
+enum class FormatPlaceHolderType { None, Positioned, Named };
+
+struct FormatToken {
+  static FormatToken Text() {
+    return FormatToken{FormatTokenType::Text, {}, {}, 0, {}, {}};
+  }
+
+  static FormatToken NonePlaceHolder(String option) {
+    return FormatToken(FormatTokenType::PlaceHolder, {},
+                       FormatPlaceHolderType::None, 0, {}, std::move(option));
+  }
+
+  static FormatToken PositionedPlaceHolder(int position, String option) {
+    return FormatToken(FormatTokenType::PlaceHolder, {},
+                       FormatPlaceHolderType::Positioned, position, {},
+                       std::move(option));
+  }
+
+  static FormatToken NamedPlaceHolder(String name, String option) {
+    return FormatToken(FormatTokenType::PlaceHolder, {},
+                       FormatPlaceHolderType::Named, 0, std::move(name),
+                       std::move(option));
+  }
+
+  FormatToken(FormatTokenType type, String data,
+              FormatPlaceHolderType place_holder_type,
+              int place_holder_position, String place_holder_name,
+              String place_holder_option)
+      : type(type),
+        data(std::move(data)),
+        place_holder_type(place_holder_type),
+        place_holder_position(place_holder_position),
+        place_holder_name(std::move(place_holder_name)),
+        place_holder_option(std::move(place_holder_option)) {}
+
+  CRU_DEFAULT_COPY(FormatToken)
+  CRU_DEFAULT_MOVE(FormatToken)
+
+  CRU_DEFAULT_DESTRUCTOR(FormatToken)
+
+  FormatTokenType type;
+  String data;
+  FormatPlaceHolderType place_holder_type;
+  int place_holder_position;
+  String place_holder_name;
+  String place_holder_option;
+};
+
+std::vector<FormatToken> CRU_BASE_API ParseToFormatTokenList(StringView str);
+
+void CRU_BASE_API 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 < static_cast<Index>(format_token_list.size()); i++) {
+    const auto& token = format_token_list[i];
+    if (token.type == FormatTokenType::PlaceHolder) {
+      if (token.place_holder_type == FormatPlaceHolderType::None) {
+        current += ToString(std::forward<TA>(args0), token.place_holder_option);
+        FormatAppendFromFormatTokenList(current, format_token_list, i + 1,
+                                        std::forward<T>(args)...);
+
+        return;
+      } else {
+        throw Exception(
+            u"Currently do not support positional or named place holder.");
+      }
+    } else {
+      current += token.data;
+    }
+  }
+}
+}  // namespace details
+
+template <typename... T>
+String Format(StringView 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