Replace with a value from hashtable

Question

Is it possible to do replace with a value from a hashtable when using Regex replace, depending on the string that Regex finds? I don't really know how to explain it good, so here's my code: string data_location; static Hashtable main;

 void Start ()
 {
     // Start with importing language files
     main = new Hashtable ();
     data_location = Application.dataPath + "/data/language/EN/";
     
     StreamReader main_file = new StreamReader (data_location + "main.txt");
     string main_language = main_file.ReadToEnd ();
     string[] main_language_lines = main_language.Split ('\n');
     
     foreach (string line in main_language_lines)
     {
         // Save every line
         if (line != "")
         {
             // Add the strings to the hashtable after processing them
             string pattern = "{([A-z0-9_]+)}";
             
             string[] line_content = line.Split ('|');
             main.Add (line_content[0], Regex.Replace (line_content[1].Replace ("\\n", "\n"), pattern, (string) main["$1"]));
         }
     }
 }

And here's the content of the file being imported:

 GAME_NAME|Derpflerpia
 VERSION|{GAME_NAME} PreAlpha v0.1
 WELCOME|Welcome to {GAME_NAME}!
 WELCOME_TEXT|{GAME_NAME} is still a WIP. Expect many derps and stoff.\n\nControls:\nW - Move forward\nA - Move left\nS - Move backwards\nD - Move right\nQ - Show current quests\nE - Teleport to the cave\nI - Open inventory\nP - Pause\nEsc - Close game\nEnter - Close this window
 BACKPACK|Backpack
 PAUSED|Paused
 QUESTS|Quests

The problem lies in this line: main.Add (line_content[0], Regex.Replace (line_content[1].Replace ("\\n", "\n"), pattern, (string) main["$1"]));

If I replace it to this it works: main.Add (line_content[0], Regex.Replace (line_content[1].Replace ("\\n", "\n"), pattern, (string) main["GAME_NAME"]));

But then it will not work in future cases with other strings, so any suggestions how I should do?

Sorry about bad explanations

Answer 1

I'll start from different problem: you create StreamReader without closing or disposing it. You should either call Close/Dispose, or just use using keyword to automatically handle disposing

 using(StreamReader sr = new StreamReader(path))
 {
     // read the data
 }

You can use File.ReadAllLines as well, which has an advantage over StreamReader.ReadToEnd, because it returns array of lines.

As to your question: it doesn't work, because substitution ($1 here) must be passed directly to the Replace method. When you do main["$1"], substitution is not used, and you're just trying to get a value with key "$1" from hashtable. I suggest the following solution:

 Dictionary<string, string> main = new Dictionary<string, string>(); // I suggest using Dictionary, because it is strongly typed and doesn't require any casting to string, like you did in your code
 
 string pattern = @"\{([A-z0-9_]+)\}"; // this should be outside of foreach loop
 foreach (var line in main_language_lines)
 {
     string[] line_content = line.Split('|');
 
     string key = line_content[0];
     string value = line_content[1].Replace("\\n", "\n");
     var match = Regex.Match(value, pattern);
     if (match.Success)
     {
         value = Regex.Replace(value, pattern, main[match.Groups[1].Value]);
     }
     main.Add(key, value);
 }

Please note, that this is solution for single replacement. If you had the following line:

 {GAME_NAME}, version {VERSION}

then you need to modify the sample code.

Replace with a value from hashtable

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