test: update test codes to v4

tests/to_json.cpp

@@ -0,0 +1,161 @@
+
+#include <iomanip>
+#include <iostream>
+#include <string>
+
+#include <toml.hpp>
+#include <nlohmann/json.hpp>
+
+#include <cmath>
+
+#ifdef TOML11_TO_JSON_USE_V1_1_0
+#  define TOML11_TO_JSON_SPEC toml::spec::v(1, 1, 0)
+#else
+#  define TOML11_TO_JSON_SPEC toml::spec::v(1, 0, 0)
+#endif
+
+template<typename Value = toml::value>
+struct json_converter
+{
+    using value_type = Value;
+    using boolean_type         = typename value_type::boolean_type        ;
+    using integer_type         = typename value_type::integer_type        ;
+    using floating_type        = typename value_type::floating_type       ;
+    using string_type          = typename value_type::string_type         ;
+    using local_time_type      = typename value_type::local_time_type     ;
+    using local_date_type      = typename value_type::local_date_type     ;
+    using local_datetime_type  = typename value_type::local_datetime_type ;
+    using offset_datetime_type = typename value_type::offset_datetime_type;
+    using array_type           = typename value_type::array_type          ;
+    using table_type           = typename value_type::table_type          ;
+
+    nlohmann::json operator()(boolean_type v)
+    {
+        nlohmann::json j;
+        j["type"] = "bool";
+        if(v)
+        {
+            j["value"] = "true";
+        }
+        else
+        {
+            j["value"] = "false";
+        }
+        return j;
+    }
+    nlohmann::json operator()(integer_type v)
+    {
+        nlohmann::json j;
+        j["type"] = "integer";
+        j["value"] = std::to_string(v);
+        return j;
+    }
+    nlohmann::json operator()(floating_type v)
+    {
+        std::ostringstream oss;
+        oss << std::setprecision(16);
+        // if we set the precision as max_digit, 1.1 will be 1.1000000000000001.
+        // But toml-test does not allow 1.1000000000000001.
+        if(std::isnan(v) && std::signbit(v))
+        {
+            // toml-test does not allow negative NaN represented in "-nan" because
+            // there are languages that does not distinguish nan and -nan.
+            // But toml11 keeps sign from input. To resolve this difference,
+            // we convert -nan to nan here.
+            v = std::numeric_limits<floating_type>::quiet_NaN();
+        }
+        oss << v;
+
+        nlohmann::json j;
+        j["type"] = "float";
+        j["value"] = oss.str();
+        return j;
+    }
+    nlohmann::json operator()(const string_type& v)
+    {
+        nlohmann::json j;
+        j["type"] = "string";
+        j["value"] = v;
+        return j;
+    }
+    nlohmann::json operator()(const toml::local_time& v)
+    {
+        nlohmann::json j;
+        j["type"] = "time-local";
+        j["value"] = toml::to_string(v);
+        return j;
+    }
+    nlohmann::json operator()(const toml::local_date& v)
+    {
+        nlohmann::json j;
+        j["type"] = "date-local";
+        j["value"] = toml::to_string(v);
+        return j;
+    }
+    nlohmann::json operator()(const toml::local_datetime& v)
+    {
+        nlohmann::json j;
+        j["type"] = "datetime-local";
+        j["value"] = toml::to_string(v);
+        return j;
+    }
+    nlohmann::json operator()(const toml::offset_datetime& v)
+    {
+        nlohmann::json j;
+        j["type"] = "datetime";
+        j["value"] = toml::to_string(v);
+        return j;
+    }
+    nlohmann::json operator()(const toml::array& v)
+    {
+        nlohmann::json j = nlohmann::json::array();
+        for(const auto& elem : v)
+        {
+            j.push_back(toml::visit(*this, elem));
+        }
+        return j;
+    }
+    nlohmann::json operator()(const toml::table& v)
+    {
+        nlohmann::json j = nlohmann::json::object();
+        for(const auto& kv : v)
+        {
+            j[kv.first] = toml::visit(*this, kv.second);
+        }
+        return j;
+    }
+};
+
+int main(int argc, char** argv)
+{
+    try
+    {
+        if(argc == 2)
+        {
+            const std::string fname(argv[1]);
+            const auto data = toml::parse(fname, TOML11_TO_JSON_SPEC);
+            std::cout << toml::visit(json_converter<>(), data);
+            return 0;
+        }
+        else
+        {
+            std::vector<unsigned char> buf;
+            std::cin.peek();
+
+            while(!std::cin.eof())
+            {
+                buf.push_back(static_cast<unsigned char>(std::cin.get()));
+                std::cin.peek();
+            }
+
+            const auto data = toml::parse(buf, "cin", TOML11_TO_JSON_SPEC);
+            std::cout << toml::visit(json_converter<>(), data);
+            return 0;
+        }
+    }
+    catch(const std::exception& err)
+    {
+        std::cout << "what(): " << err.what() << std::endl;
+        return 1;
+    }
+}