Module: Interactive::Rewindable

Includes:
Interactive
Defined in:
lib/interact/rewindable.rb

Overview

Copyright © 2012 Alex Suraci

Defined Under Namespace

Classes: JumpToPrompt

Constant Summary collapse

HAS_CALLCC =

:nodoc:

true

Constants included from Interactive

ESCAPES, EVENTS

Instance Method Summary collapse

Methods included from Interactive

#read_char, #read_event, #read_line

Instance Method Details

#ask(question, options = {}) ⇒ Object

Ask a question and get an answer. Rewind-aware; call disable_rewind on your class to disable.

See Interact#ask for the other possible values in options.

question

The prompt, without “: ” at the end.

options

An optional hash containing the following options.

forget

Set to true to prevent rewinding from remembering the user’s answer.



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# File 'lib/interact/rewindable.rb', line 39

def ask(question, options = {})
  rewind = HAS_CALLCC

  if rewind
    prompt, answer = callcc { |cc| [cc, nil] }
  else
    prompt, answer = nil, nil
  end

  if answer
    options[:default] = answer
  end

  prompts = (@__prompts ||= [])

  options[:prompts] = prompts

  ans = super

  if rewind
    prompts << [prompt, options[:forget] ? nil : ans]
  end

  ans
end

#finalize ⇒ Object

Clear prompts.

Questions asked after this are rewindable, but questions asked beforehand are no longer reachable.

Use this after you’ve performed some mutation based on the user’s input.



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# File 'lib/interact/rewindable.rb', line 71

def finalize
  @__prompts = []
end

#handler(which, state) ⇒ Object 



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# File 'lib/interact/rewindable.rb', line 75

def handler(which, state)
  prompts = state.options[:prompts] || []

  case which
  when :up
    if back = prompts.pop
      raise JumpToPrompt, back
    end
  end

  super
end

#with_char_io(input) ⇒ Object 



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# File 'lib/interact/rewindable.rb', line 88

def with_char_io(input)
  before = set_input_state(input)
  yield
rescue JumpToPrompt => e
  restore_input_state(input, before)
  e.jump
ensure
  restore_input_state(input, before)
end