Jumping back and forth to the latest history entry, erases all histories entries on the next new history entry addition

[evandrocoan]

Description

This happens because when you go back on the history, the self.current_item is decremented twice as showed next:

    def jump_back(self, active_view):
        """
        Return the view and selection list to jump back to
        Jump back in history. If the current_item is -1, it also pushes the
        active view sel() into the history.
        """
        if self.current_item == 0:
            ...
            self.current_item = -1

        ...
        self.current_item -= 1

Then, once we go back on history and jump forth with jump_forward command, the self.current_item will be -1, instead of 0.

This will cause the line del self.history_list[self.current_item + 1:] to become

del self.history_list[-1 + 1:]

# which is equivalent to the following, and deletes the whole list
del self.history_list[:]

This simple patch can fix this whole history deletion bug while keeping the plugin correctly trimming old branches of history:

 history_list.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/history_list.py b/history_list.py
index 0dc2318..188c4a8 100644
--- a/history_list.py
+++ b/history_list.py
@@ -120,7 +120,8 @@ class JumpHistory():
         for i in range(-1, self.current_item):
             view, key = self.history_list[i]
             view.erase_regions(key)
-        del self.history_list[self.current_item + 1:]
+        if self.current_item < -1:
+            del self.history_list[self.current_item + 1:]
         # set current_item to the imaginary back (current caret position not yet pushed)
         self.current_item = 0

Note: self.current_item is either 0 or negative, but never positive because the history list is built backwards, i.e., from the front its to back.

Environment

• Operating system and version:
  • Windows 10 build 15063 x64
  • Resolution 1920x1080
  • dpi_scale 1.0
  • Sublime Text:
  • Build 3207
  • 64 bit

Related threads

1. jump_backandjump_forward` does not record most actions jump_back and jump_forward does not record most actions #2959
2. jump_prev jumps too far jump_prev jumps too far #1424
3. Jump to the last caret/cursor, on the current file Jump to the last caret/cursor, on the current file #1374
4. Jump forward doesn't work on Linux Jump forward doesn't work on Linux #861

[FichteFoll]

Shouldn't that be if self.current_item > -1:?

[evandrocoan]

Shouldn't that be if self.current_item > -1:?

As the note I added at the bottom, the possible values of self.current_item are from 0 up to -sys.maxsize, not +sys.maxsize:

Note: self.current_item is either 0 or negative, but never positive because the history list is built backwards, i.e., from the front its to back.

Also there is this note on the history_list.py explaining this:

        # current_item point to newest item of the queue, which is at the back of the
        # list. To make appending easier current_item is a negative index
        # current_item would be -1 to point to the newest item and -len to point to oldest
        self.current_item = 0
        self.key_counter = 0

[wbond]

This was significantly rewritten in build 4059, and does not appear to suffer from this bug any longer