Add TinyString: SLE_STR compatible c-string wrapper

projects/openttd_vs140.vcxproj

@@ -784,6 +784,7 @@
     <ClInclude Include="..\src\core\smallstack_type.hpp" />
     <ClInclude Include="..\src\core\smallvec_type.hpp" />
     <ClInclude Include="..\src\core\string_compare_type.hpp" />
+    <ClInclude Include="..\src\core\tinystring_type.hpp" />
     <ClCompile Include="..\src\aircraft_gui.cpp" />
     <ClCompile Include="..\src\airport_gui.cpp" />
     <ClCompile Include="..\src\autoreplace_gui.cpp" />

projects/openttd_vs140.vcxproj.filters

@@ -1449,6 +1449,9 @@
     <ClInclude Include="..\src\core\string_compare_type.hpp">
       <Filter>Core Source Code</Filter>
     </ClInclude>
+    <ClInclude Include="..\src\core\tinystring_type.hpp">
+      <Filter>Core Source Code</Filter>
+    </ClInclude>
     <ClCompile Include="..\src\aircraft_gui.cpp">
       <Filter>GUI Source Code</Filter>
     </ClCompile>

projects/openttd_vs141.vcxproj

@@ -784,6 +784,7 @@
     <ClInclude Include="..\src\core\smallstack_type.hpp" />
     <ClInclude Include="..\src\core\smallvec_type.hpp" />
     <ClInclude Include="..\src\core\string_compare_type.hpp" />
+    <ClInclude Include="..\src\core\tinystring_type.hpp" />
     <ClCompile Include="..\src\aircraft_gui.cpp" />
     <ClCompile Include="..\src\airport_gui.cpp" />
     <ClCompile Include="..\src\autoreplace_gui.cpp" />

projects/openttd_vs141.vcxproj.filters

@@ -1449,6 +1449,9 @@
     <ClInclude Include="..\src\core\string_compare_type.hpp">
       <Filter>Core Source Code</Filter>
     </ClInclude>
+    <ClInclude Include="..\src\core\tinystring_type.hpp">
+      <Filter>Core Source Code</Filter>
+    </ClInclude>
     <ClCompile Include="..\src\aircraft_gui.cpp">
       <Filter>GUI Source Code</Filter>
     </ClCompile>

projects/openttd_vs142.vcxproj

@@ -784,6 +784,7 @@
     <ClInclude Include="..\src\core\smallstack_type.hpp" />
     <ClInclude Include="..\src\core\smallvec_type.hpp" />
     <ClInclude Include="..\src\core\string_compare_type.hpp" />
+    <ClInclude Include="..\src\core\tinystring_type.hpp" />
     <ClCompile Include="..\src\aircraft_gui.cpp" />
     <ClCompile Include="..\src\airport_gui.cpp" />
     <ClCompile Include="..\src\autoreplace_gui.cpp" />

projects/openttd_vs142.vcxproj.filters

@@ -1449,6 +1449,9 @@
     <ClInclude Include="..\src\core\string_compare_type.hpp">
       <Filter>Core Source Code</Filter>
     </ClInclude>
+    <ClInclude Include="..\src\core\tinystring_type.hpp">
+      <Filter>Core Source Code</Filter>
+    </ClInclude>
     <ClCompile Include="..\src\aircraft_gui.cpp">
       <Filter>GUI Source Code</Filter>
     </ClCompile>

source.list

@@ -489,6 +489,7 @@ core/smallmatrix_type.hpp
 core/smallstack_type.hpp
 core/smallvec_type.hpp
 core/string_compare_type.hpp
+core/tinystring_type.hpp
 
 # GUI Source Code
 aircraft_gui.cpp

src/core/tinystring_type.hpp

@@ -0,0 +1,111 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file tinystring_type.hpp Functions related to the allocation of memory */
+
+#ifndef TINYSTRING_TYPE_HPP
+#define TINYSTRING_TYPE_HPP
+
+#include "../string_func.h"
+#include <cstddef>
+#include <cstring>
+#include <string>
+
+/**
+ * An SLE_STR compatible tiny c-string wrapper class.
+ *
+ * This is intended for the cases where the string is almost always empty,
+ * and the space overhead of std::string is undesirable.
+ */
+class TinyString {
+	char *storage = nullptr;
+
+public:
+	inline TinyString()
+	{
+		static_assert(offsetof(TinyString, storage) == 0, "offsetof(TinyString, storage) must be 0");
+	}
+
+	inline TinyString(const TinyString &other)
+	{
+		if (other.storage != nullptr) this->storage = stredup(other.storage);
+	}
+
+	inline TinyString(TinyString &&other) noexcept
+	{
+		this->storage = other.storage;
+		other.storage = nullptr;
+	}
+
+	inline TinyString(const std::string &other) noexcept
+	{
+		if (!other.empty()) this->storage = stredup(other.c_str());
+	}
+
+	inline TinyString(const char *str) noexcept
+	{
+		if (str != nullptr && *str != 0) this->storage = stredup(str);
+	}
+
+	inline void clear()
+	{
+		if (this->storage != nullptr) {
+			free(this->storage);
+			this->storage = nullptr;
+		}
+	}
+
+	inline ~TinyString()
+	{
+		if (this->storage != nullptr) free(this->storage);
+	}
+
+	inline TinyString &operator=(const TinyString &other)
+	{
+		this->clear();
+		if (other.storage != nullptr) this->storage = stredup(other.storage);
+		return *this;
+	}
+
+	inline TinyString &operator=(TinyString &&other) noexcept
+	{
+		this->clear();
+		if (other.storage != nullptr) {
+			this->storage = other.storage;
+			other.storage = nullptr;
+		}
+		return *this;
+	}
+
+	inline TinyString &operator=(const std::string &other)
+	{
+		this->clear();
+		if (!other.empty()) this->storage = stredup(other.c_str());
+		return *this;
+	}
+
+	inline TinyString &operator=(const char *str)
+	{
+		this->clear();
+		if (str != nullptr && *str != 0) this->storage = stredup(str);
+		return *this;
+	}
+
+	inline bool operator==(const char *str) const
+	{
+		if (str == nullptr) return this->empty();
+		if (this->storage == nullptr) return *str == 0;
+		return strcmp(this->storage, str) == 0;
+	}
+
+	inline bool empty() const { return this->storage == nullptr || *this->storage == 0; }
+	inline const char *c_str() const { return this->storage; }
+	inline const char *data() const { return this->storage; }
+};
+
+
+#endif /* TINYSTRING_TYPE_HPP */