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The core change here is the following: ```rust fn write_to_pty(&self, input: impl Into<Vec<u8>>); // into fn write_to_pty(&self, input: impl Into<Cow<'static, [u8]>>); ``` This matches the trait bounds that's used by the Alacritty crate. We are now allowed to effectively pass `&'static str` instead of always needing a `String`. The main benefit comes from making the `to_esc_str` function return a `Cow<'static, str>` instead of `String`. We save an allocation in the following instances: - When the user presses any special key that isn't alphanumerical (in the terminal) - When the uses presses any key while a modifier is active (in the terminal) - When focusing/un-focusing the terminal - When completing or undoing a terminal transaction - When starting a terminal assist This basically saves us an allocation on **every key** press in the terminal. NOTE: This same optimization can be done for **nearly all** keypresses in the entirety of Zed by changing the signature of the `Keystroke` struct in gpui. If the Zed team is interested in a PR for it, let me know. Release Notes: - N/A |
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Design notes:
This crate is split into two conceptual halves:
- The terminal.rs file and the src/mappings/ folder, these contain the code for interacting with Alacritty and maintaining the pty event loop. Some behavior in this file is constrained by terminal protocols and standards. The Zed init function is also placed here.
- Everything else. These other files integrate the
Terminalstruct created in terminal.rs into the rest of GPUI. The main entry point for GPUI is the terminal_view.rs file and the modal.rs file.
ttys are created externally, and so can fail in unexpected ways. However, GPUI currently does not have an API for models than can fail to instantiate. TerminalBuilder solves this by using Rust's type system to split tty instantiation into a 2 step process: first attempt to create the file handles with TerminalBuilder::new(), check the result, then call TerminalBuilder::subscribe(cx) from within a model context.
The TerminalView struct abstracts over failed and successful terminals, passing focus through to the associated view and allowing clients to build a terminal without worrying about errors.
#Input
There are currently many distinct paths for getting keystrokes to the terminal:
-
Terminal specific characters and bindings. Things like ctrl-a mapping to ASCII control character 1, ANSI escape codes associated with the function keys, etc. These are caught with a raw key-down handler in the element and are processed immediately. This is done with the
try_keystroke()method on Terminal -
GPU Action handlers. GPUI clobbers a few vital keys by adding bindings to them in the global context. These keys are synthesized and then dispatched through the same
try_keystroke()API as the above mappings -
IME text. When the special character mappings fail, we pass the keystroke back to GPUI to hand it to the IME system. This comes back to us in the
View::replace_text_in_range()method, and we then send that to the terminal directly, bypassingtry_keystroke(). -
Pasted text has a separate pathway.
Generally, there's a distinction between 'keystrokes that need to be mapped' and 'strings which need to be written'. I've attempted to unify these under the '.try_keystroke()' API and the .input() API (which try_keystroke uses) so we have consistent input handling across the terminal