fix #194: correctly display edit prompt when interrupting a syntax error trap with ctrl+break

robhagemans · robhagemans · commit eb495cde4ed9 · 2022-07-11T20:56:41.000+01:00
diff --git a/pcbasic/basic/base/error.py b/pcbasic/basic/base/error.py
@@ -103,10 +103,13 @@ class Break(Interrupt):
 
     message = b'Break'
 
-    def __init__(self, stop=False):
+    def __init__(self, stop=False, pos=None):
         """Initialise break."""
         Interrupt.__init__(self)
         self.stop = stop
+        self.pos = pos
+        self.trapped_error_num = None
+        self.trapped_error_pos = None
 
 
 class BASICError(Interrupt):
diff --git a/pcbasic/basic/implementation.py b/pcbasic/basic/implementation.py
@@ -400,12 +400,20 @@ def _handle_exceptions(self):
         """Context guard to handle BASIC exceptions."""
         try:
             yield
-        except error.Break:
+        except error.Break as e:
+            # ctrl-break stops foreground and background sound
             self.sound.stop_all_sound()
-            self._prompt = False
+            if not self.interpreter.run_mode and not e.stop:
+                self._prompt = False
+            else:
+                self.interpreter.set_pointer(False)
+                # call _handle_error to write a message, etc.
+                self._handle_error(e)
+                # override position of syntax error
+                if e.trapped_error_num == error.STX:
+                    self._syntax_error_edit_prompt(e.trapped_error_pos)
         except error.BASICError as e:
             self._handle_error(e)
-            self._prompt = True
         except error.Exit:
             raise
 
@@ -416,13 +424,18 @@ def _handle_error(self, e):
         self.console.write(e.get_message(self.program.get_line_number(e.pos)))
         self.interpreter.set_parse_mode(False)
         self.interpreter.input_mode = False
+        self._prompt = True
         # special case: syntax error
         if e.err == error.STX:
-            # for some reason, err is reset to zero by GW-BASIC in this case.
-            self.interpreter.error_num = 0
-            if e.pos is not None and e.pos != -1:
-                # line edit gadget appears
-                self._edit_prompt = (self.program.get_line_number(e.pos), e.pos+1)
+            self._syntax_error_edit_prompt(e.pos)
+
+    def _syntax_error_edit_prompt(self, pos):
+        """Show an EDIT prompt at the location of a syntax error."""
+        # for some reason, err is reset to zero by GW-BASIC in this case.
+        self.interpreter.error_num = 0
+        if pos is not None and pos != -1:
+            # line edit gadget appears
+            self._edit_prompt = (self.program.get_line_number(pos), pos+1)
 
     ###########################################################################
     # callbacks
diff --git a/pcbasic/basic/interpreter.py b/pcbasic/basic/interpreter.py
@@ -123,7 +123,6 @@ def loop(self):
             # parse until break or end
             self.parse()
         except error.Break as e:
-            # ctrl-break stops foreground and background sound
             self._sound.stop_all_sound()
             self._handle_break(e)
         # move pointer to the start of direct line (for both on and off!)
@@ -150,11 +149,15 @@ def _handle_break(self, e):
             else:
                 self._program.bytecode.skip_to(tk.END_STATEMENT)
                 self.stop = self._program.bytecode.tell()
-        self._console.start_line()
-        self._console.write(e.get_message(self._program.get_line_number(pos)))
-        self.set_parse_mode(False)
-        self.input_mode = False
         self.parser.redo_on_break = False
+        if self.error_handle_mode:
+            e.trapped_error_num = self.error_num
+            e.trapped_error_pos = self.error_pos
+            #self.error_handle_mode = False
+        # ensure we can handle the break like an error
+        e.err = 0
+        e.pos = pos
+        raise e
 
     ###########################################################################
     # clear state
