evalweb: Avoid error 500 for automata with unreachable states, #16

evalweb/evalweb.py

@@ -116,6 +116,7 @@ def compare() -> str:
                                alphabets=checker.alphabets,
                                extra_word_ce=extra_word_ce,
                                missing_word_ce=missing_word_ce,
+                               is_task_valid=checker.is_task_valid,
                                is_task=checker.is_task,
                                img_src=checker.img_src,
                                langs=checker.languages,
@@ -175,7 +176,7 @@ def convert() -> str:
             return render_template('convert.html', error=ex, **convert_args)
 
         student = Language(string=student_string, task=student_type)
-        is_task = student.gen_is_task(task=task)
+        is_task_valid, is_task = student.gen_is_task(task=task)
 
         return render_template('result_convert.html', compare=False,
                                student_string=student_string,
@@ -184,6 +185,7 @@ def convert() -> str:
                                raw_in_type=student_type,
                                raw_out_type=task,
                                output=output,
+                               is_task_valid=is_task_valid,
                                is_task=is_task)
 
     if request.method == 'POST' and 'example_button' in request.form:

evalweb/templates/genodp.html

+{% if is_task_valid %}
 <h4>Vygenerovaný řetězec pro odpovědník</h4>
 <details>
 <summary>zobrazit/skrýt</summary>
@@ -6,3 +7,7 @@ Zkonstruujte {{student_type_string|default(task)}}…
  :e1a___
 :e1a="d:?{{is_task}}"</pre>
 </details>
+{% else %}
+<h4>Chyba při generování řetězce pro odpovědník</h4>
+{{is_task}}
+{% endif %}

evalweb/web_checker.py

@@ -2,7 +2,7 @@ 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
+from typing import List, Optional, Tuple
 from enum import Enum
 import enum
 
@@ -42,11 +42,14 @@ class Language:  # contains information about formalism and its language
         self.sizename = name[size.name]
         self.dfa = dfa
 
-    def gen_is_task(self, task: str) -> str:
+    def gen_is_task(self, task: str) -> Tuple[bool, str]:
         teacher = "NFA" if self.task == "EFA" else self.task
         assert self.dfa is not None
-        dfa = parser.dfa_to_str(self.dfa.canonize())
-        return f"{teacher}-{task}:{dfa}"
+        try:
+            dfa = parser.dfa_to_str(self.dfa.canonize())
+            return True, f"{teacher}-{task}:{dfa}"
+        except Exception as ex:
+            return False, str(ex.args[0])
 
 
 class CompositeException(Exception):
@@ -64,7 +67,8 @@ class WebChecker:
         self.eq: Optional[reg.IsEquivalentResult] = None
         self.teacher: Optional[Language] = None
         self.student: Optional[Language] = None
-        self.is_task: Optional[str] = None
+        self.is_task_valid = False
+        self.is_task: str = "No output!"
         self.img_src: Optional[str] = None
         self.languages: List[Optional[Language]] = [None, None, None, None]
 
@@ -88,7 +92,7 @@ class WebChecker:
 
         self.teacher = teacher
         self.student = student
-        self.is_task = teacher.gen_is_task(task=self.task)
+        self.is_task_valid, self.is_task = teacher.gen_is_task(task=self.task)
 
         if isinstance(student_solution, reg.DFA) \
                 or isinstance(student_solution, reg.NFA):