ask for user confirmation before expanding huge squeezed outputs

python · taleinat · Sep 25, 2018 · Jun 11, 2018 · Aug 12, 2018 · Aug 12, 2018
commit 45fb1a69581ffddb250a798d7b63e303567004e5
diff --git a/Lib/idlelib/idle_test/test_squeezer.py b/Lib/idlelib/idle_test/test_squeezer.py
@@ -490,7 +490,7 @@ def test_expand(self):
         retval = expandingbutton.expand(event=Mock())
         self.assertEqual(retval, None)
 
-        # check that the text was inserting into the text widget
+        # check that the text was inserted into the text widget
         self.assertEqual(text_widget.get('1.0', 'end'), 'TEXT\n')
 
         # check that the 'TAGS' tag was set on the inserted text
@@ -503,6 +503,47 @@ def test_expand(self):
         self.assertEqual(squeezer.expandingbuttons.remove.call_count, 1)
         squeezer.expandingbuttons.remove.assert_called_with(expandingbutton)
 
+    def test_expand_dangerous_oupput(self):
+        """attempting to expand very long output asks user for confirmation"""
+        squeezer = self.make_mock_squeezer()
+        text = 'a' * 10**5
+        expandingbutton = ExpandingButton(text, 'TAGS', 30, squeezer)
+        expandingbutton.set_is_dangerous()
+        self.assertTrue(expandingbutton.is_dangerous)
+
+        # insert the button into the text widget
+        # (this is normally done by the Squeezer class)
+        text_widget = expandingbutton.text
+        text_widget.window_create("1.0", window=expandingbutton)
+
+        # set base_text to the text widget, so that changes are actually made
+        # to it (by ExpandingButton) and we can inspect these changes afterwards
+        expandingbutton.base_text = expandingbutton.text
+
+        # patch the message box module to always return False
+        with patch('idlelib.squeezer.tkMessageBox') as mock_msgbox:
+            mock_msgbox.askokcancel.return_value = False
+            mock_msgbox.askyesno.return_value = False
+
+            # trigger the expand event
+            retval = expandingbutton.expand(event=Mock())
+
+        # check that the event chain was broken and no text was inserted
+        self.assertEqual(retval, 'break')
+        self.assertEqual(expandingbutton.text.get('1.0', 'end-1c'), '')
+
+        # patch the message box module to always return True
+        with patch('idlelib.squeezer.tkMessageBox') as mock_msgbox:
+            mock_msgbox.askokcancel.return_value = True
+            mock_msgbox.askyesno.return_value = True
+
+            # trigger the expand event
+            retval = expandingbutton.expand(event=Mock())
+
+        # check that the event chain wasn't broken and the text was inserted
+        self.assertEqual(retval, None)
+        self.assertEqual(expandingbutton.text.get('1.0', 'end-1c'), text)
+
     def test_copy(self):
         """test the copy event"""
         # testing with the actual clipboard proved problematic, so this test

diff --git a/Lib/idlelib/squeezer.py b/Lib/idlelib/squeezer.py
@@ -18,6 +18,7 @@
 
 import tkinter as tk
 from tkinter.font import Font
+import tkinter.messagebox as tkMessageBox
 
 from idlelib.config import idleConf
 from idlelib.textview import view_text
@@ -106,6 +107,7 @@ class ExpandingButton(tk.Button):
     def __init__(self, s, tags, numoflines, squeezer):
         self.s = s
         self.tags = tags
+        self.numoflines = numoflines
         self.squeezer = squeezer
         self.editwin = editwin = squeezer.editwin
         self.text = text = editwin.text
@@ -114,7 +116,7 @@ def __init__(self, s, tags, numoflines, squeezer):
         # before the iomark
         self.base_text = editwin.per.bottom
 
-        button_text = "Squeezed text (%d lines)." % numoflines
+        button_text = "Squeezed text (%d lines)." % self.numoflines
         tk.Button.__init__(self, text, text=button_text,
                            background="#FFFFC0", activebackground="#FFFFE0")
 
@@ -132,12 +134,45 @@ def __init__(self, s, tags, numoflines, squeezer):
         self.selection_handle(
             lambda offset, length: s[int(offset):int(offset) + int(length)])
 
+        self.is_dangerous = None
+        self.after_idle(self.set_is_dangerous)
+
+    def set_is_dangerous(self):
+        dangerous_line_len = 50 * self.text.winfo_width()
+        self.is_dangerous = (
+            self.numoflines > 1000 or
+            len(self.s) > 50000 or
+            any(
+                len(line_match.group(0)) >= dangerous_line_len
+                for line_match in re.finditer(r'[^\n]+', self.s)
+            )
+        )
+
     def expand(self, event):
         """expand event handler
 
         This inserts the original text in place of the button in the Text
         widget, removes the button and updates the Squeezer instance.
+
+        If the original text is dangerously long, i.e. expanding it could
+        cause a performance degradation, ask the user for confirmation.
         """
+        if self.is_dangerous is None:
+            self.set_is_dangerous()
+        if self.is_dangerous:
+            confirm = tkMessageBox.askokcancel(
+                title="Expand huge output?",
+                message="\n\n".join([
+                    "The squeezed output is very long: %d lines, %d chars.",
+                    "Expanding it could make IDLE slow or unresponsive.",
+                    "It is recommended to preview or copy the output instead.",
+                    "Really expand?"
+                ]) % (self.numoflines, len(self.s)),
+                default=tkMessageBox.CANCEL,
+                parent=self.text)
+            if not confirm:
+                return "break"
+
         self.base_text.insert(self.text.index(self), self.s, self.tags)
         self.base_text.delete(self)
         self.squeezer.expandingbuttons.remove(self)