Make PluginInterface::GetHeaderVersion() return an optional

While the value could actually be NaN, that's also what esplugin uses to
signal that the version could not be found, and either way a NaN value
is useless.

include/loot/plugin_interface.h

@@ -48,10 +48,10 @@ public:
   /**
    * Get the value of the version field in the HEDR subrecord of the plugin's
    * TES4 record.
-   * @return The value of the version field, or NaN if the field could not be
-   *         found.
+   * @return The value of the version field, or an empty optional if that value
+   *         is NaN or could not be found.
    */
-  virtual float GetHeaderVersion() const = 0;
+  virtual std::optional<float> GetHeaderVersion() const = 0;
 
   /**
    * Get the plugin's version number from its description field.

src/api/plugin.cpp

@@ -90,14 +90,19 @@ Plugin::Plugin(const GameType gameType,
 
 std::string Plugin::GetName() const { return name_; }
 
-float Plugin::GetHeaderVersion() const {
+std::optional<float> Plugin::GetHeaderVersion() const {
   float version;
+
   auto ret = esp_plugin_header_version(esPlugin.get(), &version);
   if (ret != ESP_OK) {
     throw FileAccessError(name_ +
                           " : esplugin error code: " + std::to_string(ret));
   }
 
+  if (std::isnan(version)) {
+    return std::nullopt;
+  }
+
   return version;
 }
 

src/api/plugin.h

@@ -49,7 +49,7 @@ public:
          const bool headerOnly);
 
   std::string GetName() const;
-  float GetHeaderVersion() const;
+  std::optional<float> GetHeaderVersion() const;
   std::optional<std::string> GetVersion() const;
   std::vector<std::string> GetMasters() const;
   std::vector<Tag> GetBashTags() const;

src/tests/api/internals/plugin_test.h

@@ -140,7 +140,7 @@ private:
 class OtherPluginType : public PluginInterface {
 public:
   std::string GetName() const { return ""; }
-  float GetHeaderVersion() const { return 0.0f; }
+  std::optional<float> GetHeaderVersion() const { return 0.0f; }
   std::optional<std::string> GetVersion() const { return std::nullopt; }
   std::vector<std::string> GetMasters() const {
     return std::vector<std::string>();
@@ -189,11 +189,11 @@ TEST_P(PluginTest, loadingHeaderOnlyShouldReadHeaderData) {
   EXPECT_EQ("5.0", plugin.GetVersion());
 
   if (GetParam() == GameType::tes3) {
-    EXPECT_FLOAT_EQ(1.2f, plugin.GetHeaderVersion());
+    EXPECT_FLOAT_EQ(1.2f, plugin.GetHeaderVersion().value());
   } else if (GetParam() == GameType::tes4) {
-    EXPECT_FLOAT_EQ(0.8f, plugin.GetHeaderVersion());
+    EXPECT_FLOAT_EQ(0.8f, plugin.GetHeaderVersion().value());
   } else {
-    EXPECT_FLOAT_EQ(0.94f, plugin.GetHeaderVersion());
+    EXPECT_FLOAT_EQ(0.94f, plugin.GetHeaderVersion().value());
   }
 }
 
@@ -215,11 +215,11 @@ TEST_P(PluginTest, loadingWholePluginShouldReadHeaderData) {
   EXPECT_EQ("5.0", plugin.GetVersion());
 
   if (GetParam() == GameType::tes3) {
-    EXPECT_FLOAT_EQ(1.2f, plugin.GetHeaderVersion());
+    EXPECT_FLOAT_EQ(1.2f, plugin.GetHeaderVersion().value());
   } else if (GetParam() == GameType::tes4) {
-    EXPECT_FLOAT_EQ(0.8f, plugin.GetHeaderVersion());
+    EXPECT_FLOAT_EQ(0.8f, plugin.GetHeaderVersion().value());
   } else {
-    EXPECT_FLOAT_EQ(0.94f, plugin.GetHeaderVersion());
+    EXPECT_FLOAT_EQ(0.94f, plugin.GetHeaderVersion().value());
   }
 }