evalweb: Fix error handling in convert

evalweb/evalweb.py

@@ -68,10 +68,11 @@ def compare() -> str:
                                    error="Nebyl zadán vstupní formalismus.")
 
         checker = WebChecker(student_string=student_string, task=student_type)
+        try:
             result = checker.compare(teacher_string=teacher_string,
                                      teacher_type=teacher_type)
-        if not isinstance(result, bool):
-            return render_template('parsing_error.html')
+        except ParsingError as ex:
+            return render_template('parsing_error.html', error=str(ex))
 
         extra_word_ce, missing_word_ce, inf = None, None, None
         if not result and checker.eq is not None:  # languages not equivalent
@@ -113,23 +114,26 @@ def compare() -> str:
 def convert() -> str:
     student_form = TypeForm(prefix='student_form')
     task_form = ConvertForm(prefix='task_form')
-    student_area = ""
+    convert_args = {"student_form": student_form,
+                    "task_form": task_form,
+                    "student_area": ""}
 
     if request.method == 'POST' and 'submit_button' in request.form:
         student_string = request.form['student_string']
         student_type = student_form.make.data
         task = task_form.make.data
-        student_area = student_string
+        convert_args["student_area"] = student_string
 
         if student_string == "":
-            return render_template('parsing_error.html',
-                                   error="Nebyl zadán vstupní formalismus.")
+            return render_template('convert.html',
+                                   error="Nebyl zadán vstupní formalismus.",
+                                   **convert_args)
 
         checker = WebChecker(student_string=student_string, task=task)
         try:
             output = checker.convert(student_type=student_type)
-        except ParsingError:
-            return render_template('parsing_error.html')
+        except ParsingError as ex:
+            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)
@@ -144,10 +148,9 @@ def convert() -> str:
     if request.method == 'POST' and 'example_button' in request.form:
         student_type = student_form.make.data
         if student_type in convert_examples:
-            student_area = convert_examples[student_type]
+            convert_args["student_area"] = convert_examples[student_type]
 
-    return render_template('convert.html', student_form=student_form,
-                           task_form=task_form, student_area=student_area)
+    return render_template('convert.html', **convert_args)
 
 
 @bp.route('/userref')

evalweb/static/style.css

@@ -168,3 +168,8 @@ code, pre {
 pre code {
     padding: 0;
 }
+
+.error {
+    background-color: #f99;
+    padding: 0.4rem;
+}

evalweb/templates/convert.html

@@ -16,6 +16,11 @@
         <div>
             <div style="width:400px; float:right;">
                 <textarea style="width:400px;" name="student_string" id="student_string">{{ student_area }}</textarea>
+                {% if error is defined %}
+                <div class="error">
+                    {{error}}
+                </div>
+                {% endif %}
             </div>
             {{ student_form.hidden_tag() }}
             <div style="float:left;">{{ student_form.make(style="list-style:none") }}</div>

evalweb/web_checker.py

@@ -67,15 +67,11 @@ class WebChecker:
     # nearly equivalent to dfa_task in fja_checker (for IS ROPOTs)
     def dfa_task(self, teacher_type: str, teacher_string: str,
                  task: str, student_string: str) -> bool:
-        try:
         teacher = Language(string=teacher_string, task=teacher_type)
         student = Language(string=student_string, task=self.task)
         # only for task checking
         student_solution = transform(student_string, task)
 
-        except ParsingError as ex:  # Parsing error, don't continue
-            return ex.args
-
         self.teacher = teacher
         self.student = student
         self.is_task = teacher.gen_is_task(task=self.task)
@@ -109,19 +105,12 @@ class WebChecker:
         return False
 
     def compare(self, teacher_string: str, teacher_type: str) -> bool:
-        # signal.alarm(50)  # from fja_checker: here would kill the web
-        try:
         return self.dfa_task(teacher_type=teacher_type,
                              teacher_string=teacher_string,
                              task=self.task,
                              student_string=self.student_string)
 
-        except ParsingError as ex:
-            return ex.args
-            # raise ParsingError(ex.args)
-
     def convert(self, student_type: str) -> str:
-        try:
         parser = Parser()
         if self.task in {"DFA", "TOT", "MIN"}:
             dfa = dfa_transform(self.student_string, student_type)
@@ -145,13 +134,6 @@ class WebChecker:
             return parser.reggrammar_to_str(nfa.nfa_to_reggrammar()
                                                .eliminate_useless())
 
-        except ParsingError as ex:
-            return ex.args  # FIXME
-            # raise ParsingError(ex.args)
-
-        except Exception as ex:
-            print("Error inside of web checker:", ex.args)
-
     def relation(self, eq: bool) -> str:
         assert self.teacher is not None
         assert self.student is not None