[DEV] Escapable curly braces (#955)

docs/source/config_reference/scripting/scripting_types.rst

@@ -88,6 +88,12 @@ triple-quotes can be used to avoid *closing* the String.
           %string("""This has both " and ' in it.""")
         }
 
+If you want a plain string that contains literal curly braces, you can escape them like so:
+
+.. code-block:: yaml
+
+   string_variable: "This contains \\{ literal curly braces \\}"
+
 Integer
 ~~~~~~~
 

src/ytdl_sub/script/parser.py

@@ -73,6 +73,8 @@ CUSTOM_FUNCTION_ARGUMENTS_ONLY_ARGS = InvalidSyntaxException(
 
 FUNCTION_INVALID_CHAR = InvalidSyntaxException("Invalid value when parsing a function")
 
+BRACKET_INVALID_CHAR = InvalidSyntaxException("Invalid value within brackets")
+
 
 def _UNEXPECTED_CHAR_ARGUMENT(arg_type: ParsedArgType):
     return InvalidSyntaxException(f"Unexpected character when parsing {arg_type.value} arguments")
@@ -505,6 +507,10 @@ class _Parser:
                 raise UNREACHABLE
 
     def _parse_main_loop(self, ch: str) -> bool:
+        if ch == "\\" and self._read(increment_pos=False) in {"{", "}"}:
+            # Escape brackets are \{ and \}, only add the second char
+            self._literal_str += self._read()
+            return True
         if ch == "}":
             if self._bracket_counter == 0:
                 raise BRACKET_NOT_CLOSED
@@ -558,9 +564,9 @@ class _Parser:
         elif self._bracket_counter == 0:
             # Only accumulate literal str if not in brackets
             self._literal_str += ch
-        else:
-            # Should only be possible to get here if it's a space
-            assert ch.isspace()
+        elif not ch.isspace():
+            self._set_highlight_position(pos=self._pos - 1)
+            raise BRACKET_INVALID_CHAR
 
         return True
 

tests/unit/script/test_parser.py

@@ -5,6 +5,7 @@ from typing import Union
 import pytest
 
 from ytdl_sub.script.parser import _UNEXPECTED_CHAR_ARGUMENT
+from ytdl_sub.script.parser import BRACKET_INVALID_CHAR
 from ytdl_sub.script.parser import BRACKET_NOT_CLOSED
 from ytdl_sub.script.parser import ParsedArgType
 from ytdl_sub.script.parser import parse
@@ -192,6 +193,15 @@ class TestParser:
             ]
         )
 
+    def test_escaped_bracket(self):
+        assert parse("\\{ This is escape {%string('{}')} and here \\}") == SyntaxTree(
+            [
+                String(value="{ This is escape "),
+                BuiltInFunction(name="string", args=[String(value="{}")]),
+                String(value=" and here }"),
+            ]
+        )
+
 
 class TestParserBracketFailures:
     def test_bracket_open(self):
@@ -208,3 +218,8 @@ class TestParserBracketFailures:
             match=re.escape(str(_UNEXPECTED_CHAR_ARGUMENT(ParsedArgType.MAP_KEY))),
         ):
             parse("hello {%capitalize({as_arg)}")
+
+    @pytest.mark.parametrize("char", [")", ",", "*", "]"])
+    def test_extra_char_in_brackets(self, char: str):
+        with pytest.raises(InvalidSyntaxException, match=re.escape(str(BRACKET_INVALID_CHAR))):
+            parse(f"{{  %string('hi') {char} }}")