Semantic message types for the Model-View-Update architecture.

Raw events from the terminal are converted to semantic Msg types. This decouples the Update function from the event system, making it easier to test and reason about.

Example

msg = Msg::Input.new(event: key_event)
msg = Msg::Quit.new

Source Code

# frozen_string_literal: true

#--
# SPDX-FileCopyrightText: 2026 Kerrick Long <me@kerricklong.com>
# SPDX-License-Identifier: AGPL-3.0-or-later
#++

# Semantic message types for the Model-View-Update architecture.
#
# Raw events from the terminal are converted to semantic Msg types. This
# decouples the Update function from the event system, making it easier
# to test and reason about.
#
# === Example
#
#   msg = Msg::Input.new(event: key_event)
#   msg = Msg::Quit.new
module Msg
  # A keyboard, mouse, or paste event to record.
  Input = Data.define(:event)

  # A terminal resize event.
  #
  # [width] Integer new terminal width
  # [height] Integer new terminal height
  # [previous_size] Array [width, height] before resize
  Resize = Data.define(:width, :height, :previous_size)

  # A focus change event.
  #
  # [gained] Boolean true if focus was gained, false if lost
  Focus = Data.define(:gained)

  # A none/timeout event (no input received).
  NoneEvent = Data.define

  # A quit signal.
  Quit = Data.define
end