Module: Clack::Core::KeyReader

Defined in:
lib/clack/core/key_reader.rb

Overview

Reads single keystrokes from the terminal in raw mode. Handles escape sequences for arrow keys and other special keys.

Constant Summary collapse

ESCAPE_TIMEOUT =

Timeout for detecting if Escape is part of a sequence (50ms). If no follow-up character arrives, treat Escape as a standalone key.

0.05
SEQUENCE_TIMEOUT =

Timeout for reading additional characters in a CSI sequence (10ms). Short because subsequent bytes in a sequence arrive almost instantly.

0.01

Class Method Summary collapse

Class Method Details

.read(input = nil) ⇒ String?

Read a single keystroke in raw mode. When input is an IO backed by a console, uses raw mode. When input is a StringIO or test double, reads directly.

Parameters:

  • input (IO, nil) (defaults to: nil) —

    input stream (defaults to IO.console)

Returns:

  • (String, nil) —

    the key code, or nil on EOF



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# File 'lib/clack/core/key_reader.rb', line 25

def read(input = nil)
  io = input || IO.console
  raise IOError, "No console available (not a TTY?)" unless io

  # StringIO / test doubles don't support raw mode
  return read_from(io) unless io.respond_to?(:raw)

  io.raw { |raw_io| read_from(raw_io) }
rescue Errno::EIO, Errno::EBADF, IOError
  # Terminal disconnected or closed - treat as cancel
  "\u0003" # Ctrl+C
end