nushell/crates/nu-std/std/input.nu
Artemiy 2bb0c1c618
Command to get individual keys (#9453)
# Description
Add a `keybindings get` command to listen and get individual "keyboard"
events. This includes different keyboard keys (see example of use) on
seemingly all terminals and mouse, resize, focus and paste events on
some special once. The record returned by this command is similar to
crossterm event structure and is documented in help message. For ease of
use, option `--types` can get a list of event types to filter only
desired events automatically. Additionally `--raw` options displays raw
code of char keys and numeric format of modifier flags.

Example of use, moving a character around a grid with arrow keys:
```nu
def test [] {
  mut x = 0
  mut y = 0
  loop {
    clear
    $x = ([([$x 4] | math min) 0] | math max)
    $y = ([([$y 4] | math min) 0] | math max)

    for i in 0..4 {
      for j in 0..4 {
        if $j == $x and $i == $y {
          print -n "*"
        } else {
          print -n "."
        }
      }
      print ""
    }
    
    let inp = (input listen-t [ key ])
    match $inp.key {
      {type: other key: enter} => (break)
      {type: other key: up} => ($y = $y - 1)
      {type: other key: down} => ($y = $y + 1)
      {type: other key: left} => ($x = $x - 1)
      {type: other key: right} => ($x = $x + 1)
      _ => ()
    }
  }
}

```

# User-Facing Changes
- New `keybindngs get` command
- `keybindings listen` is left as is
- New `input display` command in std, mirroring functionality of
`keybindings listen`

# Tests + Formatting
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2023-07-03 10:23:44 -05:00

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def format-event [ ] {
let record = $in
# Replace numeric value of raw_code with hex string
let record = match $record {
{raw_code: $code} => {
$record | update raw_code {|| $in | fmt | get upperhex}
}
_ => $record
}
# Replace numeric value of raw_modifiers with binary string
let record = match $record {
{raw_modifiers: $flags} => {
$record | update raw_modifiers {|| $in | fmt | get binary}
}
_ => $record
}
# Format into oneliner with `to nuon` and remove wrapping bracket pair
$record | to nuon | str substring 1..-1
}
# Display user interface events
#
# Press escape to stop
#
# To get individual events as records use "input listen"
export def display [
--types(-t): list<string> # Listen for event of specified types only (can be one of: focus, key, mouse, paste, resize)
--raw(-r) # Add raw_code field with numeric value of keycode and raw_flags with bit mask flags
] {
let arg_types = if $types == null {
[ key focus mouse paste resize ]
} else if 'key' not-in $types {
$types | append 'key'
} else {
$types
}
# To get exit key 'escape' we need to read key
# type events, however user may filter them out
# using --types and they should not be displayed
let filter_keys = ($types != null and 'key' not-in $types)
loop {
let next_key = if $raw {
input listen -t $arg_types -r
} else {
input listen -t $arg_types
}
match $next_key {
{type: key key_type: other code: esc modifiers: []} => {
return
}
_ => {
if (not $filter_keys) or $next_key.type != 'key' {
$next_key | format-event | print
}
}
}
}
}