tests working, nice error messages

src/ytdl_sub/script/parser.py

@@ -15,6 +15,8 @@ from ytdl_sub.script.types.syntax_tree import SyntaxTree
 from ytdl_sub.script.types.variable import FunctionArgument
 from ytdl_sub.script.types.variable import Variable
 from ytdl_sub.script.utils.exceptions import InvalidSyntaxException
+from ytdl_sub.script.utils.exceptions import NonFormattedInvalidSyntaxException
+from ytdl_sub.script.utils.parser_exception_formatter import ParserExceptionFormatter
 from ytdl_sub.utils.exceptions import StringFormattingException
 from ytdl_sub.validators.string_formatter_validators import is_valid_source_variable_name
 
@@ -43,18 +45,10 @@ class _Parser:
         parked_pos = self._pos
         try:
             yield
-        except InvalidSyntaxException as exc:
-            border = 4
-            text_left = max(0, parked_pos - border)
-            text_right = min(len(self._text), self._pos + border)
-            text_len = text_right - text_left
-
-            raise InvalidSyntaxException(
-                "Invalid syntax:\n"
-                f"  {self._text[text_left:text_right]}\n"
-                f"  {' ' * border}{'^' * text_len}\n\n"
-                f"{str(exc)}"
-            ) from exc
+        except NonFormattedInvalidSyntaxException as exc:
+            raise ParserExceptionFormatter(
+                self._text, parked_pos, self._pos, exc
+            ).highlight() from exc
 
     def _read(self, increment_pos: bool = True, length: int = 1) -> Optional[str]:
         try:
@@ -250,7 +244,7 @@ class _Parser:
             while ch := self._read(increment_pos=False):
                 if ch == "}":
                     if key is not None:
-                        raise InvalidSyntaxException("Map has a key with no value")
+                        raise NonFormattedInvalidSyntaxException("Map has a key with no value")
 
                     self._pos += 1
                     return UnresolvedMap(value=output)
@@ -264,19 +258,21 @@ class _Parser:
                     in_comma = True
                     self._pos += 1
                 elif key is None:
-                    in_comma = False
-                    key_args = self._parse_args(breaking_chars=":")
-                    if len(key_args) != 1:
-                        raise StringFormattingException("Lazy parsing but got mlutiple args")
-                    key = key_args[0]
+                    with self._error_formatting():
+                        in_comma = False
+                        key_args = self._parse_args(breaking_chars=":")
+                        if len(key_args) != 1:
+                            raise StringFormattingException("Lazy parsing but got mlutiple args")
+                        key = key_args[0]
                 elif key is not None and ch == ":":
-                    self._pos += 1
-                    value_args = self._parse_args(breaking_chars=",}")
-                    if len(value_args) != 1:
-                        raise InvalidSyntaxException("Map has a key with no value")
+                    with self._error_formatting():
+                        self._pos += 1
+                        value_args = self._parse_args(breaking_chars=",}")
+                        if len(value_args) != 1:
+                            raise NonFormattedInvalidSyntaxException("Map has a key with no value")
 
-                    output[key] = value_args[0]
-                    key = None
+                        output[key] = value_args[0]
+                        key = None
                 else:
                     raise StringFormattingException("Invalid map")
 

src/ytdl_sub/script/types/function.py

@@ -197,8 +197,8 @@ class CustomFunction(Function):
                 resolved_variables=resolved_variables_with_args,
                 custom_functions=custom_functions,
             )
-        else:
-            raise StringFormattingException(f"Custom function {self.name} does not exist")
+
+        raise StringFormattingException(f"Custom function {self.name} does not exist")
 
 
 class BuiltInFunction(Function):

src/ytdl_sub/script/utils/exceptions.py

@@ -3,3 +3,9 @@ from ytdl_sub.utils.exceptions import ValidationException
 
 class InvalidSyntaxException(ValidationException):
     """Syntax is incorrect"""
+
+
+class NonFormattedInvalidSyntaxException(InvalidSyntaxException):
+    """
+    Syntax is incorrect, and the exception itself has not been formatted yet to be user-facing
+    """

src/ytdl_sub/script/utils/parser_exception_formatter.py

@@ -0,0 +1,77 @@
+import sys
+from typing import List
+
+from ytdl_sub.script.utils.exceptions import InvalidSyntaxException
+from ytdl_sub.script.utils.exceptions import NonFormattedInvalidSyntaxException
+
+
+class ParserExceptionFormatter:
+    def __init__(
+        self, text: str, start: int, end: int, exception: NonFormattedInvalidSyntaxException
+    ):
+        self._text = text
+        self._start = start
+        self._end = end
+        self._exception = exception
+
+    def exception_text(self, border: int):
+        text_left = max(0, self._start - border)
+        text_right = min(len(self._text), self._start + border)
+        relative_start = self._start - text_left
+
+        exception_text: str = ""
+        if text_left > 3:
+            exception_text = "… "
+            relative_start += len(exception_text)
+
+        exception_text += self._text[text_left:text_right]
+
+        if text_right < len(self._text) - 3:
+            exception_text += " …"
+
+        exception_text += "\n"
+        exception_text += f"{' ' * relative_start}^"
+
+        return "\n" + exception_text
+
+    @property
+    def is_multi_line(self) -> bool:
+        return "\n" in self._text
+
+    def exception_text_lines(self, border_lines: int = 0) -> str:
+        split_text = self._text.split("\n")
+
+        start_line: int = sys.maxsize
+        end_line: int = -1
+        pos: int = 0
+        for idx, line in enumerate(split_text):
+            if self._start <= pos < self._end:
+                start_line = min(start_line, idx)
+                end_line = max(end_line, idx + 1)
+            pos += len(line)
+
+        true_start_line = start_line
+        start_line = max(0, start_line - border_lines)
+        end_line = min(len(split_text), end_line + border_lines)
+
+        # Get min leading spaces between all lines to return
+        min_leading_spaces = sys.maxsize
+        for line in split_text[start_line:end_line]:
+            min_leading_spaces = min(min_leading_spaces, len(line) - len(line.lstrip()))
+
+        to_return: List[str] = []
+        for idx in range(start_line, end_line):
+            if idx == true_start_line:
+                to_return.append(f">>> {split_text[idx][min_leading_spaces:]}")
+            else:
+                to_return.append(f"    {split_text[idx][min_leading_spaces:]}")
+
+        return "\n" + "\n".join(to_return)
+
+    def highlight(self) -> InvalidSyntaxException:
+        if self.is_multi_line:
+            invalid_syntax = self.exception_text_lines(border_lines=3)
+        else:
+            invalid_syntax = self.exception_text(border=20)
+
+        return InvalidSyntaxException(f"{invalid_syntax}\n{str(self._exception)}")

tests/unit/script/types/test_map.py

@@ -72,5 +72,5 @@ class TestMap:
         ],
     )
     def test_key_has_no_value(self, value: str):
-        # with pytest.raises(InvalidSyntaxException, match=re.escape("Map has a key with no value")):
-        Script({"map": value}).resolve()
+        with pytest.raises(InvalidSyntaxException, match=re.escape("Map has a key with no value")):
+            Script({"map": value}).resolve()