From 2687704afc028a5e165d0aa21c2074051ff67fc6 Mon Sep 17 00:00:00 2001
From: Rubidium <rubidium@openttd.org>
Date: Wed, 21 Jun 2023 06:35:06 +0200
Subject: [PATCH] Codechange: introduce new type and functions for
 StringParameter backups

---
 src/strings.cpp    | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 src/strings_func.h |  5 +++++
 src/strings_type.h | 30 ++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)

diff --git a/src/strings.cpp b/src/strings.cpp
index e3abf74d5d..fe70915c1c 100644
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -197,6 +197,56 @@ void CopyOutDParam(uint64 *dst, const char **strings, StringID string, int num)
 	}
 }
 
+/**
+ * Copy the parameters from the backup into the global string parameter array.
+ * @param backup The backup to copy from.
+ */
+void CopyInDParam(const span<const StringParameterBackup> backup)
+{
+	for (size_t i = 0; i < backup.size(); i++) {
+		auto &value = backup[i];
+		if (value.string.has_value()) {
+			_global_string_params.SetParam(i, value.string.value());
+		} else {
+			_global_string_params.SetParam(i, value.data);
+		}
+	}
+}
+
+/**
+ * Copy \a num string parameters from the global string parameter array to the \a backup.
+ * @param backup The backup to write to.
+ * @param num Number of string parameters to copy.
+ */
+void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num)
+{
+	backup.resize(num);
+	for (size_t i = 0; i < backup.size(); i++) {
+		backup[i] = _global_string_params.GetParam(i);
+	}
+}
+
+/**
+ * Copy \a num string parameters from the global string parameter array to the \a backup.
+ * @param backup The backup to write to.
+ * @param num Number of string parameters to copy.
+ * @param string The string used to determine where raw strings are and where there are no raw strings.
+ */
+void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num, StringID string)
+{
+	/* Just get the string to extract the type information. */
+	GetString(string);
+
+	backup.resize(num);
+	for (size_t i = 0; i < backup.size(); i++) {
+		if (_global_string_params.GetTypeAtOffset(i) == SCC_RAW_STRING_POINTER) {
+			backup[i] = (const char *)(size_t)_global_string_params.GetParam(i);
+		} else {
+			backup[i] = _global_string_params.GetParam(i);
+		}
+	}
+}
+
 static void StationGetSpecialString(StringBuilder &builder, StationFacility x);
 static void GetSpecialTownNameString(StringBuilder &builder, int ind, uint32 seed);
 static void GetSpecialNameString(StringBuilder &builder, int ind, StringParameters &args);
diff --git a/src/strings_func.h b/src/strings_func.h
index aa726e2435..5e407f9a40 100644
--- a/src/strings_func.h
+++ b/src/strings_func.h
@@ -14,6 +14,7 @@
 #include "string_type.h"
 #include "gfx_type.h"
 #include "core/bitmath_func.hpp"
+#include "core/span_type.hpp"
 #include "vehicle_type.h"
 
 /**
@@ -89,6 +90,10 @@ void CopyInDParam(const uint64 *src, int num);
 void CopyOutDParam(uint64 *dst, int num);
 void CopyOutDParam(uint64 *dst, const char **strings, StringID string, int num);
 
+void CopyInDParam(const span<const StringParameterBackup> backup);
+void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num);
+void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num, StringID string);
+
 uint64_t GetDParam(size_t n);
 
 extern TextDirection _current_text_dir; ///< Text direction of the currently selected language
diff --git a/src/strings_type.h b/src/strings_type.h
index 7ad0c71265..53b2abd48b 100644
--- a/src/strings_type.h
+++ b/src/strings_type.h
@@ -88,4 +88,34 @@ enum SpecialStrings {
 	SPECSTR_PRESIDENT_NAME     = 0x70E7,
 };
 
+/** Data that is to be stored when backing up StringParameters. */
+struct StringParameterBackup {
+	uint64_t data; ///< The data field; valid *when* string has no value.
+	std::optional<std::string> string; ///< The string value.
+
+	/**
+	 * Assign the numeric data with the given value, while clearing the stored string.
+	 * @param data The new value of the data field.
+	 * @return This object.
+	 */
+	StringParameterBackup &operator=(uint64_t data)
+	{
+		this->string.reset();
+		this->data = data;
+		return *this;
+	}
+
+	/**
+	 * Assign a copy of the given string to the string field, while clearing the data field.
+	 * @param string The new value of the string.
+	 * @return This object.
+	 */
+	StringParameterBackup &operator=(const std::string_view string)
+	{
+		this->data = 0;
+		this->string.emplace(string);
+		return *this;
+	}
+};
+
 #endif /* STRINGS_TYPE_H */