Support heredoc string literals.

Author: webbju

ServerCodeExciserTest/AngelscriptSyntaxTests.cs

@@ -60,8 +60,9 @@ public void FunctionModifier(string modifier)
         [DataRow("float64", "0.0")]
         [DataRow("doublt", "0.0")]
         [DataRow("bool", "false")]
-        [DataRow("FName", "n\"MyName\"")] // https://angelscript.hazelight.se/scripting/fname-literals/
-        [DataRow("string", "f\"Formatted String: {L:0.1f}\\u00B0\"")] // https://angelscript.hazelight.se/scripting/format-strings/
+        [DataRow("string", "\"\"\"\r\nmulti line string\r\n\"\"\"")] // heredoc: https://www.angelcode.com/angelscript/sdk/docs/manual/doc_datatypes_strings.html
+        [DataRow("FName", "n\"MyName\"")] // FName Literals: https://angelscript.hazelight.se/scripting/fname-literals/
+        [DataRow("string", "f\"Formatted String: {L:0.1f}\\u00B0\"")] // Formatted Strings: https://angelscript.hazelight.se/scripting/format-strings/
         public void DataType(string type, string value)
         {
             ParseScript($"{type} VAR = {value};");

UnrealAngelscriptParser/Grammar/UnrealAngelscriptLexer.g4

@@ -24,7 +24,11 @@ FloatingLiteral:
 // https://angelscript.hazelight.se/scripting/format-strings/
 fragment Angelscriptstringprefix: 'n' | 'f';
 
-StringLiteral: (Encodingprefix | Angelscriptstringprefix)? (Rawstring | '"' Schar* '"');
+// Angelscript Heredoc string literals
+// https://www.angelcode.com/angelscript/sdk/docs/manual/doc_datatypes_strings.html
+fragment HeredocString: '"""' .*? '"""';
+
+StringLiteral: (Encodingprefix | Angelscriptstringprefix)? (HeredocString | Rawstring | '"' Schar* '"');
 
 BooleanLiteral: False | True;