[FEATURE] Support newlines and tabs in scripting strings (#1105)

Allows the usage of `\n` and `\t` in scripting strings

src/ytdl_sub/script/parser.py

@@ -301,8 +301,16 @@ class _Parser:
                 self._pos += len(str_open_token)
                 return String(value=string_value)
 
-            self._pos += 1
-            string_value += ch
+            # Read literal "\n" as newlines
+            if self._read(increment_pos=False, length=2) == "\\n":
+                string_value += "\n"
+                self._pos += 2
+            elif self._read(increment_pos=False, length=2) == "\\t":
+                string_value += "\t"
+                self._pos += 2
+            else:
+                self._pos += 1
+                string_value += ch
 
         raise STRINGS_NOT_CLOSED
 

tests/unit/script/functions/test_string_functions.py

@@ -132,6 +132,7 @@ class TestNumericFunctions:
             ("no splits", " | ", None, ["no splits"]),
             ("one | split", " | ", None, ["one", "split"]),
             ("max | split | one", " | ", 1, ["max", "split | one"]),
+            ("multiline\ndescription", "\\n", None, ["multiline", "description"]),
         ],
     )
     def test_split(

tests/unit/script/types/test_string.py

@@ -1,6 +1,7 @@
 import re
 
 import pytest
+from unit.script.conftest import single_variable_output
 
 from ytdl_sub.script.parser import STRINGS_NOT_CLOSED
 from ytdl_sub.script.parser import STRINGS_ONLY_ARGS
@@ -45,10 +46,13 @@ class TestString:
             ("{%string('backslash \\\\')}", "backslash \\\\"),
             ("{%string('''triple quote with \" ' \\''')}", "triple quote with \" ' \\"),
             ('{%string("""triple quote with " \' \\""")}', "triple quote with \" ' \\"),
+            ("{%string('literal \\n newlines')}", "literal \n newlines"),
+            ("{%string('supports \t tabs')}", "supports \t tabs"),
+            ("{%string('literal \\t tabs')}", "literal \t tabs"),
         ],
     )
     def test_string(self, string: str, expected_string: str):
-        assert Script({"out": string}).resolve() == ScriptOutput({"out": String(expected_string)})
+        assert single_variable_output(string) == expected_string
 
     def test_null_is_empty_string(self):
         assert Script({"out": "{%string(null)}"}).resolve() == ScriptOutput({"out": String("")})