Codechange: Use std::variant for struct StringParameter

src/strings_internal.h

@@ -14,11 +14,11 @@
 #include "string_func.h"
 #include "core/span_type.hpp"
 
+#include <variant>
+
 /** The data required to format and validate a single parameter of a string. */
 struct StringParameter {
-	uint64_t data; ///< The data of the parameter.
-	const char *string_view; ///< The string value, if it has any.
-	std::unique_ptr<std::string> string; ///< Copied string value, if it has any.
+	std::variant<uint64_t, const char *, std::unique_ptr<std::string>> data; ///< The data of the parameter: integer, non-owning string value, or owned string value.
 	char32_t type; ///< The #StringControlCode to interpret this data with when it's the first parameter, otherwise '\0'.
 };
 
@@ -95,7 +95,12 @@ public:
 	T GetNextParameter()
 	{
 		auto ptr = GetNextParameterPointer();
-		return static_cast<T>(ptr->data);
+
+		if (std::holds_alternative<uint64_t>(ptr->data)) {
+			return static_cast<T>(std::get<uint64_t>(ptr->data));
+		} else {
+			throw std::out_of_range("Trying to read string parameter as integer");
+		}
 	}
 
 	/**
@@ -107,7 +112,14 @@ public:
 	const char *GetNextParameterString()
 	{
 		auto ptr = GetNextParameterPointer();
-		return ptr->string != nullptr ? ptr->string->c_str() : ptr->string_view;
+
+		if (std::holds_alternative<const char *>(ptr->data)) {
+			return std::get<const char *>(ptr->data);
+		} else if (std::holds_alternative<std::unique_ptr<std::string>>(ptr->data)) {
+			return std::get<std::unique_ptr<std::string>>(ptr->data)->c_str();
+		} else {
+			throw std::out_of_range("Trying to read string parameter as integer");
+		}
 	}
 
 	/**
@@ -152,8 +164,6 @@ public:
 	{
 		assert(n < this->parameters.size());
 		this->parameters[n].data = v;
-		this->parameters[n].string.reset();
-		this->parameters[n].string_view = nullptr;
 	}
 
 	template <typename T, std::enable_if_t<std::is_base_of<StrongTypedefBase, T>::value, int> = 0>
@@ -165,9 +175,7 @@ public:
 	void SetParam(size_t n, const char *str)
 	{
 		assert(n < this->parameters.size());
-		this->parameters[n].data = 0;
-		this->parameters[n].string.reset();
-		this->parameters[n].string_view = str;
+		this->parameters[n].data = str;
 	}
 
 	void SetParam(size_t n, const std::string &str) { this->SetParam(n, str.c_str()); }
@@ -175,16 +183,14 @@ public:
 	void SetParam(size_t n, std::string &&str)
 	{
 		assert(n < this->parameters.size());
-		this->parameters[n].data = 0;
-		this->parameters[n].string = std::make_unique<std::string>(std::move(str));
-		this->parameters[n].string_view = nullptr;
+		this->parameters[n].data = std::make_unique<std::string>(std::move(str));
 	}
 
 	uint64_t GetParam(size_t n) const
 	{
 		assert(n < this->parameters.size());
-		assert(this->parameters[n].string_view == nullptr && this->parameters[n].string == nullptr);
-		return this->parameters[n].data;
+		assert(std::holds_alternative<uint64_t>(this->parameters[n].data));
+		return std::get<uint64_t>(this->parameters[n].data);
 	}
 
 	/**
@@ -195,8 +201,14 @@ public:
 	const char *GetParamStr(size_t n) const
 	{
 		assert(n < this->parameters.size());
-		auto &param = this->parameters[n];
-		return param.string != nullptr ? param.string->c_str() : param.string_view;
+
+		if (std::holds_alternative<const char *>(this->parameters[n].data)) {
+			return std::get<const char *>(this->parameters[n].data);
+		} else if (std::holds_alternative<std::unique_ptr<std::string>>(this->parameters[n].data)) {
+			return std::get<std::unique_ptr<std::string>>(this->parameters[n].data)->c_str();
+		} else {
+			return nullptr;
+		}
 	}
 };