Reflect enum type

iguana/enum_reflection.hpp

@@ -0,0 +1,165 @@
+#pragma once
+#include <array>
+#include <string_view>
+
+#include "frozen/string.h"
+#include "frozen/unordered_map.h"
+
+namespace iguana {
+template <typename T> constexpr std::string_view get_raw_name() {
+#ifdef _MSC_VER
+  return __FUNCSIG__;
+#else
+  return __PRETTY_FUNCTION__;
+#endif
+}
+
+template <auto T> constexpr std::string_view get_raw_name() {
+#ifdef _MSC_VER
+  return __FUNCSIG__;
+#else
+  return __PRETTY_FUNCTION__;
+#endif
+}
+
+template <typename T> inline constexpr std::string_view type_string() {
+  constexpr std::string_view sample = get_raw_name<int>();
+  constexpr size_t pos = sample.find("int");
+  constexpr std::string_view str = get_raw_name<T>();
+  constexpr auto next1 = str.rfind(sample[pos + 3]);
+#if defined(_MSC_VER)
+  constexpr auto s1 = str.substr(pos + 6, next1 - pos - 6);
+#else
+  constexpr auto s1 = str.substr(pos, next1 - pos);
+#endif
+  return s1;
+}
+
+template <auto T> inline constexpr std::string_view enum_string() {
+  constexpr std::string_view sample = get_raw_name<int>();
+  constexpr size_t pos = sample.find("int");
+  constexpr std::string_view str = get_raw_name<T>();
+  constexpr auto next1 = str.rfind(sample[pos + 3]);
+#if defined(__clang__) || defined(_MSC_VER)
+  constexpr auto s1 = str.substr(pos, next1 - pos);
+#else
+  constexpr auto s1 = str.substr(pos + 5, next1 - pos - 5);
+#endif
+  return s1;
+}
+
+#if defined(__clang__) && (__clang_major__ >= 17)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wenum-constexpr-conversion"
+#endif
+
+template <typename E, E V> constexpr std::string_view get_raw_name_with_v() {
+#ifdef _MSC_VER
+  return __FUNCSIG__;
+#else
+  return __PRETTY_FUNCTION__;
+#endif
+}
+
+// True means the V is a valid enum value, and the second of the result is the
+// name
+template <typename E, E V>
+constexpr std::pair<bool, std::string_view> try_get_enum_name() {
+  constexpr std::string_view sample_raw_name = get_raw_name_with_v<int, 5>();
+  constexpr size_t pos = sample_raw_name.find("5");
+  constexpr std::string_view enum_raw_name = get_raw_name_with_v<E, V>();
+  constexpr auto enum_end = enum_raw_name.rfind(&sample_raw_name[pos + 1]);
+#ifdef _MSC_VER
+  constexpr auto enum_begin = enum_raw_name.rfind(',', enum_end) + 1;
+#else
+  constexpr auto enum_begin = enum_raw_name.rfind(' ', enum_end) + 1;
+#endif
+  constexpr std::string_view res =
+      enum_raw_name.substr(enum_begin, enum_end - enum_begin);
+
+  constexpr size_t pos_brackets = res.find(')');
+
+  size_t pos_colon = res.find("::");
+  return {pos_brackets == std::string_view::npos,
+          res.substr(pos_colon == std::string_view::npos ? 0 : pos_colon + 2)};
+}
+
+// Enumerate the numbers in a integer sequence to see if they are legal enum
+// value
+template <typename E, std::int64_t... Is>
+constexpr inline auto
+get_enum_arr(const std::integer_sequence<std::int64_t, Is...> &) {
+  constexpr std::size_t N = sizeof...(Is);
+  std::array<std::string_view, N> enum_names = {};
+  std::array<E, N> enum_values = {};
+  std::size_t num = 0;
+  (([&]() {
+     constexpr auto res = try_get_enum_name<E, static_cast<E>(Is)>();
+     if constexpr (res.first) {
+       //  the Is is a valid enum value
+       enum_names[num] = res.second;
+       enum_values[num] = static_cast<E>(Is);
+       ++num;
+     }
+   })(),
+   ...);
+  return std::make_tuple(num, enum_values, enum_names);
+}
+
+template <std::size_t N, const std::array<int, N> &arr, size_t... Is>
+constexpr auto array_to_seq(const std::index_sequence<Is...> &) {
+  return std::integer_sequence<std::int64_t, arr[Is]...>();
+}
+
+// convert array to map
+template <typename E, size_t N, size_t... Is>
+constexpr inline auto
+get_enum_to_str_map(const std::array<std::string_view, N> &enum_names,
+                    const std::array<E, N> &enum_values,
+                    const std::index_sequence<Is...> &) {
+  return frozen::unordered_map<E, frozen::string, sizeof...(Is)>{
+      {enum_values[Is], enum_names[Is]}...};
+}
+
+template <typename E, size_t N, size_t... Is>
+constexpr inline auto
+get_str_to_enum_map(const std::array<std::string_view, N> &enum_names,
+                    const std::array<E, N> &enum_values,
+                    const std::index_sequence<Is...> &) {
+  return frozen::unordered_map<frozen::string, E, sizeof...(Is)>{
+      {enum_names[Is], enum_values[Is]}...};
+}
+
+// the default generic enum_value
+// if the user has not defined a specialization template, this will be called
+template <typename T> struct enum_value {
+  constexpr static std::array<int, 0> value = {};
+};
+
+template <bool str_to_enum, typename E> constexpr inline auto get_enum_map() {
+  constexpr auto &arr = enum_value<E>::value;
+  constexpr auto arr_size = arr.size();
+  if constexpr (arr_size > 0) {
+    // the user has defined a specialization template
+    constexpr auto arr_seq =
+        array_to_seq<arr_size, arr>(std::make_index_sequence<arr_size>());
+    constexpr auto t = get_enum_arr<E>(arr_seq);
+    if constexpr (str_to_enum) {
+      return get_str_to_enum_map<E, arr_size>(
+          std::get<2>(t), std::get<1>(t),
+          std::make_index_sequence<std::get<0>(t)>{});
+    } else {
+      return get_enum_to_str_map<E, arr_size>(
+          std::get<2>(t), std::get<1>(t),
+          std::make_index_sequence<std::get<0>(t)>{});
+    }
+  } else {
+    return false;
+  }
+}
+
+#if defined(__clang__) && (__clang_major__ >= 17)
+#pragma clang diagnostic pop
+#endif
+
+} // namespace iguana

iguana/json_reader.hpp

@@ -25,7 +25,9 @@ IGUANA_INLINE void parse_escape(U &value, It &&it, It &&end) {
   if (*it == 'u') {
     ++it;
     if (std::distance(it, end) <= 4)
-      throw std::runtime_error(R"(Expected 4 hexadecimal digits)");
+      IGUANA_UNLIKELY {
+        throw std::runtime_error(R"(Expected 4 hexadecimal digits)");
+      }
     auto code_point = parse_unicode_hex4(it);
     encode_utf8(value, code_point);
   } else if (*it == 'n') {
@@ -87,12 +89,6 @@ IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
       std::string_view(&*start, static_cast<size_t>(std::distance(start, it)));
 }
 
-template <typename U, typename It, std::enable_if_t<enum_v<U>, int> = 0>
-IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
-  using T = std::underlying_type_t<std::decay_t<U>>;
-  parse_item(reinterpret_cast<T &>(value), it, end);
-}
-
 template <bool skip = false, typename U, typename It,
           std::enable_if_t<char_v<U>, int> = 0>
 IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
@@ -183,7 +179,7 @@ IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
         IGUANA_UNLIKELY case '\\' : ++it;
         parse_escape(value, it, end);
         break;
-        IGUANA_UNLIKELY case ']' : return;
+        // IGUANA_UNLIKELY case ']' : return;
         IGUANA_UNLIKELY case '"' : ++it;
         return;
         IGUANA_LIKELY default : value.push_back(*it);
@@ -215,6 +211,26 @@ IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
   throw std::runtime_error("Expected \"");
 }
 
+template <typename U, typename It, std::enable_if_t<enum_v<U>, int> = 0>
+IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
+  static constexpr auto str_to_enum = get_enum_map<true, std::decay_t<U>>();
+  if constexpr (bool_v<decltype(str_to_enum)>) {
+    // not defined a specialization template
+    using T = std::underlying_type_t<std::decay_t<U>>;
+    parse_item(reinterpret_cast<T &>(value), it, end);
+  } else {
+    std::string_view enum_names;
+    parse_item(enum_names, it, end);
+    auto it = str_to_enum.find(enum_names);
+    if (it != str_to_enum.end())
+      IGUANA_LIKELY { value = it->second; }
+    else {
+      throw std::runtime_error(std::string(enum_names) +
+                               " missing corresponding value in enum_value");
+    }
+  }
+}
+
 template <typename U, typename It, std::enable_if_t<fixed_array_v<U>, int> = 0>
 IGUANA_INLINE void parse_item(U &value, It &&it, It &&end) {
   using T = std::remove_reference_t<U>;
@@ -632,9 +648,8 @@ inline void parse_object(jobject &result, It &&it, It &&end) {
   skip_ws(it, end);
 
   while (true) {
-    if (it == end) {
-      break;
-    }
+    if (it == end)
+      IGUANA_UNLIKELY { throw std::runtime_error("Expected }"); }
     std::string key;
     detail::parse_item(key, it, end);
 

iguana/json_util.hpp

@@ -5,6 +5,7 @@
 
 #include "define.h"
 #include "detail/charconv.h"
+#include "enum_reflection.hpp"
 #include "reflection.hpp"
 #include "value.hpp"
 #include <filesystem>

iguana/json_writer.hpp

@@ -109,7 +109,22 @@ IGUANA_INLINE void render_json_value(Stream &ss, T &&t) {
 
 template <typename Stream, typename T, std::enable_if_t<enum_v<T>, int> = 0>
 IGUANA_INLINE void render_json_value(Stream &ss, T val) {
-  render_json_value(ss, static_cast<std::underlying_type_t<T>>(val));
+  static constexpr auto enum_to_str = get_enum_map<false, std::decay_t<T>>();
+  if constexpr (bool_v<decltype(enum_to_str)>) {
+    render_json_value(ss, static_cast<std::underlying_type_t<T>>(val));
+  } else {
+    auto it = enum_to_str.find(val);
+    if (it != enum_to_str.end())
+      IGUANA_LIKELY {
+        auto str = it->second;
+        render_json_value(ss, std::string_view(str.data(), str.size()));
+      }
+    else {
+      throw std::runtime_error(
+          std::to_string(static_cast<std::underlying_type_t<T>>(val)) +
+          " is a missing value in enum_value");
+    }
+  }
 }
 
 template <typename Stream, typename T>

test/test.cpp

@@ -766,6 +766,80 @@ TEST_CASE("check some types") {
                 value_type{std::in_place_index_t<1>{}, &point_t::y});
 }
 
+enum class Status { STOP = 10, START };
+namespace iguana {
+template <> struct enum_value<Status> {
+  constexpr static std::array<int, 1> value = {10};
+};
+} // namespace iguana
+TEST_CASE("test exception") {
+  {
+    std::string str = R"({"\u8001": "name"})";
+    std::unordered_map<std::string_view, std::string> mp;
+    iguana::from_json(mp, str);
+    CHECK(mp["老"] == "name");
+  }
+  {
+    std::string str = R"({"a": "\)";
+    std::unordered_map<std::string, std::string> mp;
+    CHECK_THROWS(iguana::from_json(mp, str));
+  }
+  {
+    std::string str = R"({"a": "\u8")";
+    std::unordered_map<std::string, std::string> mp;
+    CHECK_THROWS(iguana::from_json(mp, str));
+  }
+  {
+    std::string str = R"([10, d5])";
+    std::deque<char> char_q(str.begin(), str.end());
+    std::vector<int> arr;
+    CHECK_THROWS(iguana::from_json(arr, char_q));
+  }
+  {
+    std::string str = R"({"a": "\)";
+    std::unordered_map<std::string, char> mp;
+    CHECK_THROWS(iguana::from_json(mp, str));
+  }
+  {
+    std::string str = R"({"a: "\")";
+    std::unordered_map<std::string, std::string_view> mp;
+    CHECK_THROWS(iguana::from_json(mp, str));
+  }
+  {
+    std::string str = R"(bb)";
+    iguana::jvalue val;
+    CHECK_THROWS(iguana::parse(val, str.begin(), str.end()));
+  }
+  {
+    // THREW exception: duplicated key a
+    std::string str = R"({"a": "b", "a": "c"})";
+    iguana::jvalue val;
+    CHECK_THROWS(iguana::parse(val, str.begin(), str.end()));
+  }
+  {
+    std::string str = R"({"a": "c",)";
+    iguana::jvalue val;
+    CHECK_THROWS(iguana::parse(val, str.begin(), str.end()));
+  }
+  {
+    std::string str = R"(
+{
+  "a": "START",
+  "b": "STOP",
+}
+  )";
+    std::unordered_map<std::string, Status> mp;
+    CHECK_THROWS(iguana::from_json(mp, str));
+  }
+  {
+    std::unordered_map<std::string, Status> mp;
+    mp["a"] = Status::START;
+    mp["b"] = Status::STOP;
+    std::string ss;
+    CHECK_THROWS(iguana::to_json(mp, ss));
+  }
+}
+
 // doctest comments
 // 'function' : must be 'attribute' - see issue #182
 DOCTEST_MSVC_SUPPRESS_WARNING_WITH_PUSH(4007)