Change ErrBadEnum to improve the error message

Author: BitoLabs

CHANGELOG.md

@@ -3,7 +3,7 @@ Change log
 
 This project follows [Semantic Versioning](http://semver.org/).
 
-1.1.0 (IN PROGRESS)
+1.1.0 (2025-07-26)
 ==================
 
 ### New features
@@ -13,6 +13,8 @@ This project follows [Semantic Versioning](http://semver.org/).
 
 ### Changes
 
+* Change ErrBadEnum to improve the error message.
+
 ### Fixes
 
 1.0.3 (2025-04-04)

README.md

@@ -43,7 +43,7 @@ Summary of features
 * The input is in UTF-8 format. The string tokens can contain escape sequences with
   [UTF-16 code points].
 * `//` comments are supported. Note that these are not part of the JSON standard.
-* Number values can be fetched as signed integers (32 or 64 bit) or as 64-bit float values.
+* Number values can be fetched as integers (32 or 64 bit) or as 64-bit float values.
 * Exceptions are used to handle the errors. See [error handling].
 * Value validation is easy and doesn't require a JSON schema. See:
     - [Number range checking].

ujson.cpp

@@ -380,7 +380,7 @@ int32_t Str::get_enum_idx(const char* const str_set[], size_t len) const
     for (size_t i = 0; i < len; i++) {
         if (strcmp(str, str_set[i]) == 0) return static_cast<int32_t>(i);
     }
-    throw ErrBadEnum(*this);
+    throw ErrBadEnum(*this, str, str_set, len);
 }
 
 int32_t Arr::get_len() const noexcept
@@ -935,9 +935,6 @@ std::string ErrValue::get_err_str() const
     else if (val_idx >= 0) {
         str += "  value index: " + std::to_string(val_idx) + '\n';
     }
-    if (val_type != vtNone) {
-        str += "  val_type: " + type_to_str(val_type) + '\n';
-    }
     return str;
 }
 
@@ -950,8 +947,11 @@ ErrBadType::ErrBadType(const Val& v, ValType expected) noexcept
 std::string ErrBadType::get_err_str() const
 {
     std::string str = ErrValue::get_err_str();
+    if (val_type != vtNone) {
+        str += "  value type: " + type_to_str(val_type) + '\n';
+    }
     if (expected_type != vtNone) {
-        str += "  expected_type: " + type_to_str(expected_type) + '\n';
+        str += "  expected type: " + type_to_str(expected_type) + '\n';
     }
     return str;
 }
@@ -1001,9 +1001,37 @@ ErrUnknownMember::ErrUnknownMember(const Val& v) noexcept
 {
 }
 
-ErrBadEnum::ErrBadEnum(const Val& v) noexcept
-    : ErrValue("unsupported value", v)
+ErrBadEnum::ErrBadEnum(
+    const Val& v,
+    const char* bad_str,
+    const char* const set[],
+    size_t set_len
+) noexcept
+    : ErrValue("value is not in allowed set", v)
 {
+    this->bad_str = bad_str;
+    for (size_t i = 0; i < set_len; i++) {
+        this->set.push_back(set[i]);
+    }
+}
+
+std::string ErrBadEnum::get_err_str() const
+{
+    std::string str = ErrValue::get_err_str();
+    str += "  bad value: " + bad_str + '\n';
+    if (set.size() > 0) {
+        str += "  allowed set: (";
+        bool first = true;
+        for (auto& s : set) {
+            if (!first) {
+                str += '|';
+            }
+            str += s;
+            first = false;
+        }
+        str += ")\n";
+    }
+    return str;
 }
 
 void Json::clear() noexcept

ujson.h

@@ -4,6 +4,7 @@
 #include <stdexcept>
 #include <string>
 #include <array>
+#include <vector>
 
 namespace ujson {
 
@@ -254,7 +255,15 @@ struct ErrUnknownMember : ErrValue
 
 struct ErrBadEnum : ErrValue
 {
-    explicit ErrBadEnum(const Val& v) noexcept;
+    std::string bad_str;
+    std::vector<std::string> set;
+
+    explicit ErrBadEnum(
+        const Val& v,
+        const char* bad_str,
+        const char* const set[],
+        size_t set_len) noexcept;
+    std::string get_err_str() const override;
 };
 
 }; // namespace ujson