craft-keymap holds the data and logic for keyboard bindings in the Craft apps: chords and their text forms, bindings from chords to commands, scopes, conflicts, user overrides, and an import pipeline for other applications' shortcut sets. Each application supplies its command catalog, its file-format readers and its UI.

Boundaries

Data and logic only. The apps keep the command catalog (ids, labels, menu paths, defaults), the readers for other applications' files, the shortcut editor UI and running the commands.
Never crashes: no panics, no unsafe. Loading settings never fails; what cannot be used is kept or reported (Keymap::problems, the import report).
Hostile input is capped: commands, bindings per command, text lengths, import entries, keys, path segments and fuzzy suggestions (the MAX_* constants). What is cut is counted.
Reserved chords are opt-in. A keymap reserves no chord unless the app passes a list to Keymap::with_reserved, e.g. reserved::system(platform) for the operating system's window switching and closing chords. A reserved chord cannot be assigned or bound.
Dependencies: serde and serde_json; egui with the egui feature.

A catalog and dispatch

A command with parameters has the key window.panel {"panel":"layers"} in settings and reports. Tools of one group share a key and cycle. A binding can name a scope other than the command's home scope.

use craft_keymap::{Active, Bindable, Binding, Chord, CommandRef, Keymap, Kind, Lookup, Platform, Scope, Scopes};
use serde_json::json;

let key = |text: &str| Binding::parse(text).unwrap();
let layers = CommandRef::with_params("window.panel", json!({"panel": "layers"}));
let select = Kind::Tool { group: Some("select".into()) };
let catalog = vec![
    Bindable::new("file.save", "Save", Scope::app()).with_path(vec!["File".into(), "Save".into()]).with_default(key("Cmd+S")),
    Bindable::new(layers.clone(), "Layers", Scope::app()).with_path(vec!["Window".into(), "Layers".into()]).with_default(key("F7")),
    Bindable::new("tool.marquee", "Marquee Tool", Scope::app()).with_kind(select.clone()).with_default(key("M")),
    Bindable::new("tool.ellipse", "Elliptical Marquee Tool", Scope::app()).with_kind(select).with_default(key("M")),
    // Home scope: the Timeline panel, where it wins over the app's L.
    Bindable::new("timeline.loop", "Loop", Scope::new("Timeline").unwrap()).with_default(key("L")),
    Bindable::new("layer.lock", "Lock Layer", Scope::app()).with_default(key("L")),
    // An app command whose binding works only in the Text context.
    Bindable::new("type.bold", "Bold", Scope::app()).with_default(key("Text: Cmd+B")),
];
let keymap = Keymap::new(catalog, Scopes::new().with_panel("Timeline").with_context("Text"), Platform::Mac);

// Dispatch: the chord pressed, whether it is a double press, and what has the keyboard.
let press = |text: &str, active: &Active| keymap.lookup(&Chord::parse(text).unwrap(), false, active);
assert_eq!(press("F7", &Active::NONE), Lookup::Run(layers));
assert_eq!(press("L", &Active::panel("Timeline")), Lookup::Run("timeline.loop".into()));
assert_eq!(press("L", &Active::NONE), Lookup::Run("layer.lock".into()));
assert_eq!(press("M", &Active::NONE), Lookup::Cycle(vec!["tool.marquee".into(), "tool.ellipse".into()]));
let editing = Active { contexts: &["Text"], typing: true, ..Active::NONE };
assert_eq!(press("Cmd+B", &editing), Lookup::Run("type.bold".into()));
assert_eq!(press("M", &editing), Lookup::None, "plain keys go to the text field");

While a text field has the keyboard (Active::typing), the keymap's TypingRule decides which app and panel bindings wait: plain keys (the default), everything without the command modifier, or everything. Under every rule, the platform's text-editing chords (text_editing_chords) go to the field too: undo and redo, select all, and moving and deleting by word, line and text (Cmd+Z, Alt+Left and Cmd+Backspace on macOS; Ctrl+Z, Ctrl+Y, Ctrl+Left and Ctrl+Home elsewhere). Other command chords, such as Cmd+S, still fire. Bindings in an active context always fire, so Text: Cmd+B works while typing, and a Text: Cmd+Z binding takes undo from the field.

With the egui feature, egui::Dispatcher does this for a frame's key events (see Features).

Chords

A Chord is a key plus the modifiers cmd, ctrl, alt and shift. cmd is the command modifier: ⌘ on macOS, Ctrl on Windows and Linux. ctrl is the Mac Control key; off macOS it folds into cmd (Chord::effective).

Canonical text, as stored and sent: Cmd+Ctrl+Alt+Shift+K, Cmd++ for Plus, A A for a double press.
Chord::parse also reads common aliases (⇧⌘Z, opt+left, Ctrl+Cmd+M).
Chord::display(Platform) gives ⇧⌘Z on macOS and Ctrl+Shift+Z elsewhere.
chord::foreign::read_foreign reads key text written by other applications (Windows or Mac modifier names, numeric keypad keys).

Keyboard layouts

layout decides which chord a key press means, the same way for matching (Layout::candidates), the shortcut recorder (Layout::resolve) and labels (Chord::display_for):

Letters A–Z: the layout's Latin letter for the key. On a layout that is not Latin (Russian, Arabic, Hebrew, Greek, Thai), the suite's egui reports the Latin layout's character for each key: Ctrl+С on Dvorak + Russian is Dvorak's Ctrl+J, and Ctrl+Й, ' on Dvorak, runs no letter binding. Without that report, the letter the toolkit reports for shortcuts, else the key's position. On a Latin layout (Dvorak, AZERTY), the letter typed. Arabic Ctrl+Shift+D is Ctrl+Shift+D, not the ] it types.
Digits: the digit typed, else the key's position (AZERTY's &é" row). A digit-row key that types punctuation also matches its digit when the punctuation has no binding.
Punctuation: the character typed, without Shift when the layout needs Shift for it: German / is ⇧7, so ⇧⌘7 runs ⌘/.
Whether a layout is Latin is decided for the layout, not per key.
With Shift held on a Latin layout, a press that egui reports as the letter at its own position, because the character typed has no key (Dvorak's ⇧, types <), runs nothing when that position has been seen typing something other than its letter: once a , has been typed, Ctrl+Shift+, never runs Ctrl+Shift+W. A change in the reported Latin status clears what the positions typed; an app that learns of a layout switch itself calls Layout::forget_letters.
Labels show letters and digits by name, and a punctuation key as the character the layout types at its position when that character has no key of its own (Ctrl+Ü for Ctrl+[ on German).

A KeyInput holds what the toolkit reports for one press: modifiers, the key typed, the physical key, and, when the platform reports them, the layout's Latin letter (Windows virtual-key code, macOS ⌘ table, Linux Latin layout group) and whether Shift was needed. A Layout holds whether the layout is Latin, as the platform reports it or as plain typing shows it (Layout::observe), and the characters it types at punctuation positions.

Storing overrides

Overrides is a field of the app's settings type. It is stored as a map of one text per command ({ "file.save": "Cmd+Alt+S", "edit.copy": "" }, "" for no shortcut) while no command has more than one binding, so apps that stored that map before keep reading it in older builds. Once a command has several bindings it is stored as an array of { command, keys } tables ([{ command = "file.save", keys = ["Cmd+Alt+S", "F12"] }]). Both forms load, and in the map form a list of texts loads too.

In a craft-settings type, put #[serde(with = "craft_keymap::keymap::overrides_list")] on the field, which always writes the array: craft-settings merges tables key by key with what the file holds but replaces an array whole, so only the array lets a reset command (an entry removed) stay removed after saving. Hand-written [[shortcuts]] blocks load as the array.

Texts the keymap cannot use (a key name from a newer version, an unknown scope, a reserved chord) stay in the entry when the command is edited, unless the edit leaves it without bindings. Keymap::problems lists them.

use craft_keymap::{Binding, Keymap, Overrides, Platform, Policy, Scopes};
use craft_settings::{Location, Settings, SettingsStore};
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize, Default, Clone, PartialEq)]
#[serde(default)]
struct Prefs {
    #[serde(with = "craft_keymap::keymap::overrides_list")]
    shortcuts: Overrides,
}

impl Settings for Prefs {
    const APP_ID: &'static str = "acmecraft";
    const SCHEMA_VERSION: u32 = 1;
}

// `catalog` is the app's Vec<Bindable>.
let (mut store, _report) = SettingsStore::<Prefs>::open(Location::Auto);
let mut keymap = Keymap::new(catalog, Scopes::new(), Platform::current()).with_overrides(store.get().shortcuts.clone());
// Entries for unknown commands and texts that do not parse are kept and listed here.
let _problems = keymap.problems();

// After each change in the shortcut editor:
keymap.set_bindings(&"file.save".into(), vec![Binding::parse("Cmd+Alt+S").unwrap()], Policy::Steal).ok();
store.update(|p| p.shortcuts = keymap.overrides().clone());

Editing

set_bindings(&command, bindings, policy) replaces a command's bindings. An editor with one shortcut per command calls it with the one binding (vec![binding]); assign adds a binding to those the command has.
remove takes one binding away, clear leaves the command without shortcuts, reset gives it its defaults back and reset_all does so for every command.
Policy says what happens to other commands holding the chord: Steal takes it from them, Keep lets both keep it and reports the clash, Refuse changes nothing and returns AssignError::Taken.
conflicts() lists every pair of commands on one chord; conflicts_with(&command) lists the commands that share one command's chords, with that command as a.

Importing a shortcut set

The app's reader turns a file (an InDesign Show Set, an Illustrator .kys) into an import::ForeignSet: entries with a menu, a path and keys read by ForeignKey::read. import::plan matches each entry to one command and changes nothing; ImportPlan::apply applies the plan and returns an ImportReport (serde, camelCase). Report rows carry the entry's item (its path) and line.

use craft_keymap::{Bindable, Binding, ContextRule, Flavor, ForeignEntry, ForeignKey, ForeignSet, ImportOptions, Keymap, Platform};
use craft_keymap::{Scope, Scopes, plan};

let save = Bindable::new("file.save", "Save", Scope::app())
    .with_path(vec!["File".into(), "Save".into()])
    .with_default(Binding::parse("Cmd+S").unwrap());
let mut keymap = Keymap::new(vec![save], Scopes::new(), Platform::Windows);

let read = |text: &str| ForeignKey::read(Some("Default"), text, Flavor::Windows);
let set = ForeignSet {
    name: Some("My Set".into()),
    entries: vec![
        ForeignEntry::new(Some("File"), ["Save"]).with_key(read("Ctrl+Alt+S")).at_line(12),
        ForeignEntry::new(Some("File"), ["Frobnicate"]).with_key(read("Ctrl+F")).at_line(13),
    ],
};
let options = ImportOptions { contexts: vec![("Default".into(), ContextRule::Home)], ..ImportOptions::default() };
let planned = plan(&set, &keymap, &options);
// A review UI can show planned.commands and planned.report here.
let report = planned.apply(&mut keymap);
assert_eq!(report.changed[0].to, ["Cmd+Alt+S"]);
assert_eq!((report.unmatched[0].item.as_str(), report.unmatched[0].line), ("File > Frobnicate", Some(13)));

Matching, most specific first, each step needing exactly one command: the user's remembered answers, the full menu path, the joined submenu segments as a label or alias in that menu, the label in that menu, the joined segments as a label or alias anywhere, the label anywhere. An entry with no menu and several segments matches only by its full path, unless the reader marks it in_panel_menu(). Tool entries match only tools.
Names are compared after import::normalize_label: case, …, ..., &, colons and extra spaces aside, so the alias Preferences: General… matches Edit > Preferences > General.... Aliases (Bindable::with_alias) count wherever labels do.
Panel menus: sources list panel-menu items with the panel's name in front (InDesign's Panel Menus area writes Character: All Caps; Illustrator and Photoshop sets have similar areas). The reader splits the name into segments and marks the entry ForeignEntry::in_panel_menu(). Such an entry also matches a catalog path that ends with its segments (with the command's label or the path's last segment last), and its last segment alone as a label. The last segment alone counts only when the first segment, the panel, is a segment of some catalog path, so History: New Document matches nothing in an app without a History panel. An entry without keys that matched only these ways leaves the command's shortcuts alone and is listed in matched_without_change (reason PanelMenu).
Show/Hide: a source often lists one toggle as two items, Show Rulers and Hide Rulers. Names are matched as written first. When no step finds a command, the steps run again on commands marked Bindable::toggle(), with a leading Show , Hide or Show/Hide dropped from the entry's label and from the command's label, aliases and path labels. A command not marked as a toggle never matches through a dropped prefix, so Hide Conveyor does not match Conveyor.
ImportOptions.contexts says what each source context becomes (home scope, another scope, the home scope only without a home entry, or skipped).
The set wins: a chord it gives to a command is taken from commands outside it (except twins sharing it as a default), a later entry takes a chord from an earlier one (as when the entries are applied in file order; the earlier key is listed in skipped), and an entry without keys can clear its command. It clears it only when no entry matched to the same command has keys, whatever the order of the entries.
Keys read approximately (a numeric keypad key bound as the main key) are listed in approximated.
With ImportOptions.suggest, unmatched entries get fuzzy candidates (import::namematch); they are reported, never applied. Only the first 200 unmatched entries with keys get them, and only the first 200 characters of a name are compared. Keys in ContextRule::Skip contexts do not count: an unmatched entry with only such keys counts in unmatched_without_shortcut.

Features

egui: conversions to and from egui keys and modifiers; KeyInput::from_egui; egui::matches, which accepts the shifted key egui reports for a Shift binding (Shift+; matches :); and egui::Dispatcher, which runs a frame's key presses against the keymap, reading them by the layout it learns from typing or is given (with_layout, layout()):
```
let hits = ctx.input_mut(|i| dispatcher.dispatch(i, &keymap, &active));
for hit in hits {
    app.run(&hit.command);
}
```
A press that runs a command is removed from egui's events, with the text it typed, so widgets do not see it too. Each Hit carries the trigger that matched and exact, which is false when the press matched through a stand-in (: for Shift+;, + for =). dispatch_filtered takes a predicate that can decline a hit, for example a chord the native menu has already handled: the press and its text then stay in egui's events, in their place. While a text field has the keyboard, plain clipboard key presses and presses that typed text in the same frame stay with it. That covers AltGr, which a browser on Windows reports as Ctrl+Alt followed by the text; a Ctrl+Alt press that types nothing is a command chord. Dispatcher::new().with_repeat(true) also runs commands on key repeats (held arrows).

On the desktop, egui-winit sends egui's Copy, Cut and Paste events in place of the key press for any chord of Cmd with C, X or V (Ctrl off macOS); the web build sends the press and then the event. For the plain chords Cmd+C, Cmd+X and Cmd+V (and Cmd+Insert, Shift+Delete, Shift+Insert), the events stay with the app by default, so a binding on those chords runs only with with_clipboard_events(true). Then the events count as their chords outside text fields, and a Paste event's text moves to Hit::pasted. On the web, the press runs the command and takes the event, with its text, along. An app whose paste command asks egui for a paste gets a Paste event back, which runs that command again; such an app keeps the default. A clipboard event with more modifiers held (Cmd+Shift+V, Cmd+Alt+C) always counts as its chord, also while typing, and stays when that chord has no binding. egui-winit sends no Paste event when the clipboard is empty or holds an image, so a binding on a Cmd+V chord cannot run then on the desktop.

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