eeb3f8e963
helix-syntax mostly existed for the sake of the build task which checks and compiles the submodules. Since we won't be relying on that process anymore, it doesn't end up making much sense to have a very thin crate just for some functions that we could port to helix-core. The remaining build-related code is moved to helix-term which will be able to provide grammar builds through the --build-grammars CLI flag.
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| Crate | Description |
|---|---|
| helix-core | Core editing primitives, functional. |
| helix-lsp | Language server client |
| helix-view | UI abstractions for use in backends, imperative shell. |
| helix-term | Terminal UI |
| helix-tui | TUI primitives, forked from tui-rs, inspired by Cursive |
This document contains a high-level overview of Helix internals.
NOTE: Use
cargo doc --openfor API documentation as well as dependency documentation.
Core
The core contains basic building blocks used to construct the editor. It is heavily based on CodeMirror 6. The primitives are functional: most operations won't modify data in place but instead return a new copy.
The main data structure used for representing buffers is a Rope. We re-export
the excellent ropey library. Ropes are cheap
to clone, and allow us to easily make snapshots of a text state.
Multiple selections are a core editing primitive. Document selections are
represented by a Selection. Each Range in the selection consists of a moving
head and an immovable anchor. A single cursor in the editor is simply
a selection with a single range, with the head and the anchor in the same
position.
Ropes are modified by constructing an OT-like Transaction. It's represents
a single coherent change to the document and can be applied to the rope.
A transaction can be inverted to produce an undo. Selections and marks can be
mapped over a transaction to translate to a position in the new text state after
applying the transaction.
NOTE:
Transaction::change/Transaction::change_by_selectionis the main interface used to generate text edits.
Syntax is the interface used to interact with tree-sitter ASTs for syntax
highling and other features.
View
The view layer was supposed to be a frontend-agnostic imperative library that
would build on top of core to provide the common editor logic. Currently it's
tied to the terminal UI.
A Document ties together the Rope, Selection(s), Syntax, document
History, language server (etc.) into a comprehensive representation of an open
file.
A View represents an open split in the UI. It holds the currently open
document ID and other related state. Views encapsulate the gutter, status line,
diagnostics, and the inner area where the code is displayed.
NOTE: Multiple views are able to display the same document, so the document contains selections for each view. To retrieve,
document.selection()takes aViewId.
Info is the autoinfo box that shows hints when awaiting another key with bindings
like g and m. It is attached to the viewport as a whole.
Surface is like a buffer to which widgets draw themselves to, and the
surface is then rendered on the screen on each cycle.
Rects are areas (simply an x and y coordinate with the origin at the
screen top left and then a height and width) which are part of a
Surface. They can be used to limit the area to which a Component can
render. For example if we wrap a Markdown component in a Popup
(think the documentation popup with space+k), Markdown's render method
will get a Rect that is the exact size of the popup.
Widgets are called Components internally, and you can see most of them
in helix-term/src/ui. Some components like Popup and Overlay can take
other components as children.
Layers are how multiple components are displayed, and is simply a
Vec<Component>. Layers are managed by the Compositor. On each top
level render call, the compositor renders each component in the order
they were pushed into the stack. This makes multiple components "layer"
on top of one another. Hence we get a file picker displayed over the
editor, etc.
The Editor holds the global state: all the open documents, a tree
representation of all the view splits, the configuration, and a registry of
language servers. To open or close files, interact with the editor.
LSP
A language server protocol client.
Term
The terminal frontend.
The main function sets up a new Application that runs the event loop.
commands.rs is probably the most interesting file. It contains all commands
(actions tied to keybindings).
keymap.rs links commands to key combinations.
TUI / Term
TODO: document Component and rendering related stuff