Introduce std::string_view into wider use (#14368)

src/script/common/helper.h

@@ -19,6 +19,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
+#include <string_view>
+
 extern "C" {
 #include <lua.h>
 }
@@ -27,23 +29,22 @@ class LuaHelper
 {
 protected:
 	/**
-	 * Read a value using a template type T from Lua State L and index
-	 *
+	 * Read a value using a template type T from Lua state L at index
 	 *
 	 * @tparam T type to read from Lua
 	 * @param L Lua state
-	 * @param index Lua Index to read
+	 * @param index Lua index to read
 	 * @return read value from Lua
 	 */
 	template <typename T>
 	static T readParam(lua_State *L, int index);
 
 	/**
-	 * Read a value using a template type T from Lua State L and index
+	 * Read a value using a template type T from Lua state L at index
 	 *
 	 * @tparam T type to read from Lua
 	 * @param L Lua state
-	 * @param index Lua Index to read
+	 * @param index Lua index to read
 	 * @param default_value default value to apply if nil
 	 * @return read value from Lua or default value if nil
 	 */
@@ -53,3 +54,18 @@ protected:
 		return lua_isnoneornil(L, index) ? default_value : readParam<T>(L, index);
 	}
 };
+
+// (only declared for documentation purposes:)
+
+/**
+ * Read a string from Lua state L at index without copying it.
+ *
+ * Note that the returned string view is only valid as long as the value is on
+ * the stack and has not been modified. Be careful.
+ *
+ * @param L Lua state
+ * @param index Lua index to read
+ * @return string view
+ */
+template <>
+std::string_view LuaHelper::readParam(lua_State *L, int index);