std/keybindings

Key bindings, as editors have them: keys as text, chords of several strokes, conditions on when a binding applies, defaults for each platform, and the user's bindings over them.

import "std/keybindings"

KeyMap keys = key_map([
    KeyBinding("mod+s", "file.save"),
    KeyBinding("ctrl+k ctrl+c", "editor.comment", condition: "textFocus && !readOnly"),
], user_bindings)?
map[str, Json] context = {"textFocus": Json.BOOL(true)}
KeyOutcome o = keys.press(key_stroke("k", ctrl: true), context)   // pending
o = keys.press(key_stroke("c", ctrl: true), context)               // editor.comment

Keys are written as strokes separated by spaces, each its modifiers and key joined by +: ctrl, alt (or option), shift, meta (or cmd, win, super), and mod, which is Cmd on macOS and Ctrl elsewhere; keys are characters or enter, escape, tab, space, backspace, delete, the arrows up, down, left, and right, home, end, page_up, page_down, insert, and f1 to f24.

Function or method
`parse_keys(text, platform)`	the `KeyStroke`s of keys as text: `key`, `ctrl`, `alt`, `shift`, `meta`
`format_keys(strokes, platform)`	as people read them: `Ctrl+K Ctrl+S`, or `⌘S` on macOS
`key_stroke(key, ctrl, alt, shift, meta)`	a stroke, as a key event gives it
`when_holds(condition, context)`	whether a condition holds: names of values in `context`, `!`, `&&`, `
`key_map(defaults, user, platform)`	a `KeyMap`; a user binding whose command starts with `-` takes away that command's bindings, of its keys when it gives some
`keys.press(stroke, context)`	a `KeyOutcome`: the `command` and `args` of the last binding added whose keys and condition match, or `pending` while a chord waits for its next stroke
`keys.cancel()`, `keys.keys_for(command, context)`	forgets a chord started; the keys a menu shows for a command
`key_bindings_from_json(value)`	bindings as an editor's keybindings.json writes them: `key`, `command`, `when`, `args`, and `mac`, `linux`, and `win` for other keys there

A KeyBinding has keys, command, condition, args, and mac, linux, and windows keys for those platforms.