Fully implement splittext and add test

Content.Tests/DMProject/Tests/Text/Splittext.dm

@@ -0,0 +1,34 @@
+/proc/RunTest()
+	var/test_text = "The average of 1, 2, 3, 4, 5 is: 3"
+	var/list/test1 = splittext(test_text, " ")
+	var/list/test1_expected = list("The","average","of","1,","2,","3,","4,","5","is:","3")
+	ASSERT(test1 ~= test1_expected)
+
+	var/list/test2 = splittext(test_text, " ", 5)
+	var/test2_expected = list("average","of","1,","2,","3,","4,","5","is:","3")
+	ASSERT(test2 ~= test2_expected)
+
+	var/list/test3 = splittext(test_text, " ", 5, 10)
+	var/test3_expected = list("avera")
+	ASSERT(test3 ~= test3_expected)
+
+	var/list/test4 = splittext(test_text, " ", 10, 20)
+	var/test4_expected = list("ge","of","1,","2")
+	ASSERT(test4 ~= test4_expected)
+
+	var/list/test5 = splittext(test_text, " ", 10, 20, 1)
+	var/test5_expected = list("ge"," ","of"," ","1,"," ","2")
+	ASSERT(test5 ~= test5_expected)
+
+	//it's regex time
+	var/test6 = splittext(test_text, regex(@"\d"))
+	var/test6_expected = list("The average of ",", ",", ",", ",", "," is: ","")
+	ASSERT(test6 ~= test6_expected)
+
+	var/test7 = splittext(test_text, regex(@"\d"), 5, 30)
+	var/test7_expected = list("average of ",", ",", ",", ",", "," ")
+	ASSERT(test7 ~= test7_expected)
+
+	var/test8 = splittext(test_text, regex(@"\d"), 5, 30, 1)
+	var/test8_expected = list("average of ","1",", ","2",", ","3",", ","4",", ","5"," ")
+	ASSERT(test8 ~= test8_expected)

OpenDreamRuntime/Procs/Native/DreamProcNativeRoot.cs

@@ -2361,22 +2361,65 @@ public static DreamValue NativeProc_splicetext_char(NativeProc.Bundle bundle, Dr
         [DreamProc("splittext")]
         [DreamProcParameter("Text", Type = DreamValueTypeFlag.String)]
         [DreamProcParameter("Delimiter", Type = DreamValueTypeFlag.String)]
+        [DreamProcParameter("Start", Type = DreamValueTypeFlag.Float, DefaultValue = 1)]
+        [DreamProcParameter("End", Type = DreamValueTypeFlag.Float, DefaultValue = 0)]
+        [DreamProcParameter("include_delimiters", Type = DreamValueTypeFlag.Float, DefaultValue = 0)]
         public static DreamValue NativeProc_splittext(NativeProc.Bundle bundle, DreamObject? src, DreamObject? usr) {
             if (!bundle.GetArgument(0, "Text").TryGetValueAsString(out var text)) {
                 return new DreamValue(bundle.ObjectTree.CreateList());
             }
 
-            var arg2 = bundle.GetArgument(1, "Delimiter");
-            if (!arg2.TryGetValueAsString(out var delimiter)) {
-                if (!arg2.Equals(DreamValue.Null)) {
-                    return new DreamValue(bundle.ObjectTree.CreateList());
+            int start = 0;
+            int end = 0;
+            if(bundle.GetArgument(2, "Start").TryGetValueAsInteger(out start))
+                start -= 1; //1-indexed
+            if(bundle.GetArgument(3, "End").TryGetValueAsInteger(out end))
+                if(end == 0)
+                    end = text.Length;
+                else
+                    end -= 1; //1-indexed
+            bool includeDelimiters = false;
+            if(bundle.GetArgument(4, "include_delimiters").TryGetValueAsInteger(out var includeDelimitersInt))
+                includeDelimiters = includeDelimitersInt != 0; //idk why BYOND doesn't just use truthiness, but it doesn't, so...
+
+            if(start > 0 || end < text.Length)
+                text = text[Math.Max(start,0)..Math.Min(end, text.Length)];
+
+            var delim = bundle.GetArgument(1, "Delimiter"); //can either be a regex or string
+
+            if (delim.TryGetValueAsDreamObject<DreamObjectRegex>(out var regexObject)) {
+                if(includeDelimiters) {
+                    var values = new List<string>();
+                    int pos = 0;
+                    foreach (Match m in regexObject.Regex.Matches(text)) {
+                        values.Add(text.Substring(pos, m.Index - pos));
+                        values.Add(m.Value);
+                        pos = m.Index + m.Length;
+                    }
+                    values.Add(text.Substring(pos));
+                    return new DreamValue(bundle.ObjectTree.CreateList(values.ToArray()));
+                } else {
+                    return new DreamValue(bundle.ObjectTree.CreateList(regexObject.Regex.Split(text)));
+                }
+            } else if (delim.TryGetValueAsString(out var delimiter)) {
+                string[] splitText;
+                if(includeDelimiters) {
+                    //basically split on delimeter, and then add the delimiter back in after each split (except the last one)
+                    splitText= text.Split(delimiter);
+                    string[] longerSplitText = new string[splitText.Length * 2 - 1];
+                    for(int i = 0; i < splitText.Length; i++) {
+                        longerSplitText[i * 2] = splitText[i];
+                        if(i < splitText.Length - 1)
+                            longerSplitText[i * 2 + 1] = delimiter;
+                    }
+                    splitText = longerSplitText;
+                } else {
+                    splitText = text.Split(delimiter);
                 }
+                return new DreamValue(bundle.ObjectTree.CreateList(splitText));
+            } else {
+                return new DreamValue(bundle.ObjectTree.CreateList());
             }
-
-            string[] splitText = text.Split(delimiter);
-            DreamList list = bundle.ObjectTree.CreateList(splitText);
-
-            return new DreamValue(list);
         }
 
         private static void OutputToStatPanel(DreamManager dreamManager, DreamConnection connection, DreamValue name, DreamValue value) {