Each one should provide a message that will show up within LÖVE. Stop
relying on nearby prints to the terminal.
I also found some unnecessary ones.
There is some potential here for performance regressions: the format()
calls will trigger whether or not the assertion fails, and cause
allocations. So far Lua's GC seems good enough to manage the load even
with Moby Dick, even in some situations that caused issues in the past
like undo.
Not quite ideal: the scrollbar computation only considers
screen_bottom1.line and not screen_bottom1.pos, and so it always assumes
the final line is at the bottom of the screen.
I'm making a deeper change here that I might come to regret. I want to
avoid creating new book-keeping for editor mutations, so I'm putting the
work of computing scrollbar data into clear_screen_line_cache. But that
implies the editor should never clear before updating data, and I caught
one place that wasn't true before. A better name helps avoid this in
future. Let's see how much toil this causes in resolving conflicts.
Matt Wynne pointed out that snap.love would crash when a node went off
screen. While debugging it I noticed that selection1 was being set when
it shouldn't be.
Turns out I introduced a bug when I fixed the inscript bug back in June
(commit 9656e13774). One invariant I want to preserve is: selection1
should be unset after a mouse click (press and release without
intervening drag). This invariant was violated in my bugfix back in
June. I was concerned only with selection back then, and I didn't
realize I was breaking the mouse click case (in a fairly subtle way; you
can have selection set, and when it's set identically to the cursor
everything looks the same).
I think there might still be an issue in snap.love after this fix. I
noticed screen_bottom1.pos was nil, and as far as I recall that should
never happen.
All the Text functions assume the cursor is always on a text line. I was
violating that invariant.
* When scrolling up, I start the cursor at the top-most line below the
screen top.
* When scrolling down, I start the cursor at the top-most line below the
screen bottom.
I think it would feel slightly more natural for it to be the
bottom-most line above the screen bottom.
However, the Text functions maintain an invariant that the bottom-most
line in a buffer will be text. There's no such invariant for the
top-most line.
To fix this I have to first stop incrementally updating screen_bottom1
in the middle of a frame. Now it always has a good value from the end of
a frame.
I'm also running into some limitations in the test I'd ideally like to
write (that are documented in a comment), but I still get some sort of
automated test for this bugfix.
It's a hack:
- if you start selecting from below final line the start of the
selection is the most recent click even if it was forever ago
- (the crash we're currently fixing) if you start up and immediately
select all then click below final line => crash. recent_mouse was
never set.
- getting rid of it breaks no tests (except the crash we're currently
fixing)
Text.mouse_pos can sometimes set recent_mouse.time but not
recent_mouse.x/y. I'd assumed x/y is never nil in those situations, but
that's violated. It's most easily seen when typing C-a and then
clicking.
The bug has been spotted twice:
1. In snap.love, I selected text in one node, then another, and hit:
Error: text.lua:789: attempt to compare nil with number
stack traceback:
text.lua:789: in function 'lt1'
select.lua:19: in function 'clip_selection'
text.lua:32: in function 'draw'
edit.lua:117: in function 'draw'
[string "REPL"]:21: in function 'draw'
main.lua:152: in function 'draw'
app.lua:102: in function <app.lua:84>
[C]: in function 'xpcall'
app.lua:112: in function <app.lua:111>
[C]: in function 'xpcall'
Couldn't reproduce.
2. In text.love, inscript selected all text in a small buffer and then
clicked outside the text. And got:
Error: text.lua:784: attempt to compare nil with number
Traceback
[love "callbacks.lua"]:228: in function 'handler'
text.lua:784: in function 'lt1'
select.lua:19: in function 'clip_selection'
text.lua:27: in function 'draw'
edit.lua:117: in function 'draw'
run.lua:136: in function 'draw'
main.lua:148: in function 'draw'
app.lua:42: in function <app.lua:22>
[C]: in function 'xpcall'
This is reproducible, and also across forks.