Simplify JSON conversion for ValueNone and ValueRegex (#466)

Signed-off-by: Juan Cruz Viotti <[email protected]>

Author: jviotti

src/compiler/compile_json.cc

@@ -2,19 +2,6 @@
 
 #include <variant> // std::visit
 
-namespace sourcemeta::core {
-template <typename T>
-  requires std::is_same_v<T, sourcemeta::blaze::ValueNone>
-auto to_json(const T &) -> JSON {
-  return JSON{nullptr};
-}
-template <typename T>
-  requires std::is_same_v<T, typename sourcemeta::blaze::ValueRegex::first_type>
-auto to_json(const T &) -> JSON {
-  return JSON{nullptr};
-}
-} // namespace sourcemeta::core
-
 namespace sourcemeta::blaze {
 
 auto to_json(const Instruction &instruction) -> sourcemeta::core::JSON {

src/evaluator/include/sourcemeta/blaze/evaluator_value.h

@@ -19,7 +19,11 @@ namespace sourcemeta::blaze {
 
 /// @ingroup evaluator
 /// @brief Represents a compiler step empty value
-struct ValueNone {};
+struct ValueNone {
+  auto to_json() const -> sourcemeta::core::JSON {
+    return sourcemeta::core::JSON{nullptr};
+  }
+};
 
 /// @ingroup evaluator
 /// Represents a compiler step JSON value
@@ -62,7 +66,16 @@ using ValueType = sourcemeta::core::JSON::Type;
 /// original string and the regular expression as standard regular expressions
 /// do not keep a copy of their original value (which we need for serialization
 /// purposes)
-using ValueRegex = std::pair<sourcemeta::core::Regex<ValueString>, std::string>;
+struct ValueRegex {
+  using second_type = ValueString;
+  using first_type = sourcemeta::core::Regex<second_type>;
+  const first_type first;
+  const second_type second;
+
+  auto to_json() const -> sourcemeta::core::JSON {
+    return sourcemeta::core::to_json(this->second);
+  }
+};
 
 /// @ingroup evaluator
 /// Represents a compiler step JSON unsigned integer value

test/compiler/compiler_json_test.cc

@@ -128,7 +128,7 @@ TEST(Compiler_JSON, example_3) {
         "r": 0,
         "v": {
           "t": 9,
-          "v": [ null, "^f" ]
+          "v": "^f"
         },
         "c": []
       }