evalweb: Adapt to changes in lib

evalweb/evalweb.py

 from flask import Blueprint, render_template, request
 from flask_wtf import FlaskForm  # type: ignore
 from wtforms import RadioField   # type: ignore
-from lib.parsing import ParsingError
+from lib.parser import ParsingError
 from evalweb.web_checker import WebChecker, Language, CompositeException
 from evalweb.examples import examples, convert_examples
 from typing import Optional

evalweb/examples.py

 from typing import Dict, Tuple
-from lib.parsing import Parser
+from lib import parser
 
-parser = Parser()
 examples: Dict[Tuple[str, str], Tuple[str, str]] = {}
 convert_examples: Dict[str, str] = {}
 
@@ -18,16 +17,16 @@ teacher_forms = [('DFA', teacher_dfa),
                  ('REG', student_reg)]
 
 student_forms = [('DFA', student_dfa),
-                 ('TOT', parser.dfa_to_str(parser.str_to_dfa(student_dfa)
+                 ('TOT', parser.dfa_to_str(parser.dfa(student_dfa)
                                            .total())),
-                 ('MIN', parser.dfa_to_str(parser.str_to_dfa(student_dfa)
+                 ('MIN', parser.dfa_to_str(parser.dfa(student_dfa)
                                            .minimize())),
-                 ('CAN', parser.dfa_to_str(parser.str_to_dfa(student_dfa)
+                 ('CAN', parser.dfa_to_str(parser.dfa(student_dfa)
                                            .total().canonize())),
-                 ('MIC', parser.dfa_to_str(parser.str_to_dfa(student_dfa)
+                 ('MIC', parser.dfa_to_str(parser.dfa(student_dfa)
                                            .minimize().canonize())),
                  ('EFA', student_efa),
-                 ('NFA', parser.nfa_to_str(parser.str_to_nfa(student_efa)
+                 ('NFA', parser.nfa_to_str(parser.nfa(student_efa)
                                            .eliminate_epsilon())),
                  ('GRA', student_gra),
                  ('REG', student_reg)]

evalweb/web_checker.py

-import lib.reg as reg
-from lib.parsing import Parser, ParsingError
+from lib import reg, parser
+from lib.parser import ParsingError
 from lib.checker import transform, dfa_transform, nfa_transform, check_task, \
                         check_alphabets
 from typing import List, Optional
@@ -19,7 +19,6 @@ class Language:  # contains information about formalism and its language
         self.string = string
         self.task = task
 
-        parser = Parser()
         dfa = dfa_transform(self.string, self.task)
         self.minimal = parser.dfa_to_str(dfa.minimize().canonize())
 
@@ -45,7 +44,6 @@ class Language:  # contains information about formalism and its language
 
     def gen_is_task(self, task: str) -> str:
         teacher = "NFA" if self.task == "EFA" else self.task
-        parser = Parser()
         assert self.dfa is not None
         dfa = parser.dfa_to_str(self.dfa.canonize())
         return f"{teacher}-{task}:{dfa}"
@@ -127,7 +125,6 @@ class WebChecker:
                              student_string=self.student_string)
 
     def convert(self, student_type: str) -> str:
-        parser = Parser()
         if self.task in {"DFA", "TOT", "MIN", "CAN", "MIC"}:
             dfa = dfa_transform(self.student_string, student_type)
             # avoid confusion by making the automaton total if the input
@@ -220,7 +217,6 @@ class WebChecker:
         return picture  # name of static image file to show in feedback
 
     def language(self, dfa: reg.DFA) -> Language:
-        parser = Parser()
         return Language(parser.dfa_to_str(dfa))
 
     def DFA_lines(self, str_: str) -> None: