✨ New features

 - Better error messages
 - Changable parser

Ready for release!

lark_shell.py

@@ -21,56 +21,98 @@
 import warnings
 
 __version__ = "0.1.3"
+
+# Constants
+STATE_MAP = {"Earley": "earley", "LALR(1)": "lalr", "CYK": "cyk"}
+# REVERSE_MAP = list(STATE_MAP.items())[::-1]
 output = urwid.SelectableIcon(("wait", "Output waiting..."))  # Initially wait for input
-meta = urwid.SelectableIcon(
-    ("success", f"Lark version: {lark.__version__}\nLark_shell version: {__version__}")
-)
+meta = urwid.SelectableIcon(("success", f"Lark version: {lark.__version__}"))
 
 
-def _update_grammar(_, new_text: str) -> None:
-    """Update the UI when the grammar changes."""
-    _parse(new_text, grammar_input.get_edit_text(), output)
+def set_state(_, state):
+    if not state:
+        return
+    assert state
+    global current_selected_parser  # pylint: disable=W0603
+    current_selected_parser = STATE_MAP[_.label]
+
+    _parse(
+        grammar=lark_grammar.get_edit_text(),
+        parse_input=grammar_input.get_edit_text(),
+        output_obj=output,
+        chosen_parser=current_selected_parser,
+    )
+
+
+parser_list = []
+earley = urwid.RadioButton(parser_list, "Earley", on_state_change=set_state)
+lalr_1 = urwid.RadioButton(parser_list, "LALR(1)", on_state_change=set_state)
+cyk = urwid.RadioButton(parser_list, "CYK", on_state_change=set_state)
+
+assert len(parser_list) == 3
+
+# Set default values
+earley.set_state(True)
+current_selected_parser = "earley"
+
+assert earley.get_state()
+assert (earley.get_state(), lalr_1.get_state(), cyk.get_state()) == (True, False, False)
 
 
-def _parse(grammar: str, parse_input: str, output_obj: urwid.Text) -> None:
+def _parse(
+    grammar: str, parse_input: str, output_obj: urwid.Text, chosen_parser: str
+) -> None:
     """Update the UI with the given grammar and input."""
     try:
-        # Create a parser with "earley"
-        parser = lark.Lark(grammar, parser="earley", lexer="auto")
+        # Create a parser with `chosen_parser`
+        parser = lark.Lark(grammar, parser=chosen_parser, lexer="auto")
+
         # Generate a tree
         tree = parser.parse(parse_input)
 
+    # Parsing errors
     except (lark.exceptions.GrammarError, TypeError):
         output_obj.set_text(("error", "Incomplete grammar!"))
-
-    except lark.exceptions.UnexpectedEOF as e:
+    except lark.exceptions.ParseError as e:
         output_obj.set_text(("error", str(e)))
-
     except lark.exceptions.UnexpectedInput as e:
         output_obj.set_text(("error", str(e.get_context(parse_input))))
 
+    # Importing errors
     except FileNotFoundError:  # The relative imported file was not found
-        output_obj.set_text(("error", "File not found"))
-
-    except lark.exceptions.LarkError as e:
+        output_obj.set_text(("error", "File not found, did you spell it correctly?"))
+    except KeyError as e:
+        _ = e.args[0]  # The token
+        # pylint: disable=E1101
+        output_obj.set_text(("error", f"Could not import {_.type.lower()} '{_.value}'"))
+    except lark.exceptions.LarkError as e:  # Everything else
         output_obj.set_text(("error", repr(e)))
 
     else:  # Parsing succeeded
         output_obj.set_text(("success", str(tree.pretty())))
 
 
+def _update_grammar(_, new_text: str) -> None:
+    """Update the UI when the grammar changes."""
+    _parse(new_text, grammar_input.get_edit_text(), output, current_selected_parser)
+
+
 def _update_input(_, new_input: str) -> None:
     """Update the UI when the input changes."""
-    _parse(lark_grammar.get_edit_text(), new_input, output)
+    _parse(lark_grammar.get_edit_text(), new_input, output, current_selected_parser)
 
 
 lark_grammar = urwid.Edit(("bold", "Grammar\n"), multiline=True, allow_tab=True)
 grammar_input = urwid.Edit(("bold", "Grammar input\n"), multiline=True, allow_tab=True)
 
+# When the grammar is updated
 urwid.connect_signal(lark_grammar, "change", _update_grammar)
+# When the input is updated
 urwid.connect_signal(grammar_input, "change", _update_input)
 
+
 UI = [
+    urwid.Columns(parser_list),
     urwid.LineBox(lark_grammar),
     urwid.LineBox(grammar_input),
     urwid.Divider(div_char="-"),
@@ -85,10 +127,10 @@ def _update_input(_, new_input: str) -> None:
     ("success", "light green", ""),
 ]
 
-loop = urwid.MainLoop(urwid.Filler(urwid.Pile(UI)), palette=PALLETE)
 # We use urwid.Filler because it needs to be centered. If we left out urwid.Filler
 # then urwid would scream at me. I want to replace urwid.Filler, though.
 # - ThatXliner
+loop = urwid.MainLoop(urwid.Filler(urwid.Pile(UI, focus_item=1)), palette=PALLETE)
 
 
 def main() -> None: