Resolve "Use the code module for the interactive session"

Closes #241 (closed)

src/virtmat/language/interpreter/session_manager.py

 """manage sessions for dynamic model processing / incremental development"""
 import os
+import sys
+import readline  # noqa  # pylint: disable=unused-import
+from code import InteractiveConsole
 from functools import cached_property
 from textx import metamodel_from_file, textx_isinstance
 from virtmat.language.metamodel.processors import table_processor, null_processor, number_processor
@@ -94,10 +97,11 @@ def expand_query_prefix(query):
     return {k: _recursive_q(v, p_map[k]) for k, v in query.items()}
 
 
-class SessionManager():
+class SessionManager(InteractiveConsole):
     """session manager for basic interactive work using a text terminal"""
 
     def __init__(self, lpad, **kwargs):
+        super().__init__()
         self.lpad = lpad
         self.kwargs = dict(kwargs)
         del self.kwargs['uuid']
@@ -115,29 +119,38 @@ class SessionManager():
                           'Table': table_processor}
         self.metamodel.register_obj_processors(obj_processors)
 
+    def main_loop(self):
+        """this is the main loop of the interactive session"""
+        if not sys.stdin.isatty():
+            msg = 'Session running in a shell not connected to a terminal'
+            get_logger(__name__).warning(msg)
+            warnings.warn(msg, TextSUserWarning)
+        ps1_save = getattr(sys, 'ps1', None)
+        ps2_save = getattr(sys, 'ps2', None)
+        try:
+            sys.ps1 = 'Input > '
+            sys.ps2 = '      > '
+            self.interact(banner='', exitmsg='')
+        finally:
+            print('Exiting')
+            self.session.stop_runner()
+            sys.ps1 = ps1_save
+            sys.ps2 = ps2_save
+
+    def runsource(self, source, filename=None, symbol=None):
+        """this is used by the superclass to realize a REPL"""
+        if source.strip():
+            try:
+                self.process_input(source)
+            finally:
+                self.check_session()
+        return False
+
     @error_handler
     def get_model_value(self, *args, **kwargs):
         """wrapped and evaluated version of get_model() of the Session class"""
         return getattr(self.session.get_model(*args, uuid=self.uuid, **kwargs), 'value', '')
 
-    def main_loop(self):
-        """this is the main loop of the interactive session"""
-        while True:
-            try:
-                input_str = input('Input > ')
-            except EOFError:
-                print('\nExiting')
-                self.session.stop_runner()
-                break
-            except KeyboardInterrupt:
-                print('\nType %exit or %close or Ctrl+D to close session')
-                continue
-            if not input_str.strip():
-                continue
-            if self.process_input(input_str):
-                break
-            self.check_session()
-
     def check_session(self):
         """check session consistency"""
         if (len(self.session.models) != len(self.session.uuids) or
@@ -154,9 +167,7 @@ class SessionManager():
         get_logger(__name__).debug('process_input: session model: %s', model)
         if textx_isinstance(model, self.metamodel['Magic']):
             if model.com in ('exit', 'bye', 'close', 'quit'):
-                print('Exiting')
-                self.session.stop_runner()
-                return True
+                raise SystemExit()
             self.process_magic(model)
             return False
         if textx_isinstance(model, self.metamodel['Expression']):