callcc Dream Baby

continuation.rb

require 'continuation'
require 'pry'
require 'pry-rescue'
require 'byebug'
require 'pry-stack_explorer'
require 'singleton'

module ContinuationStack
  extend self

  module Continuable
    attr_accessor :name, :my_binding

    def initialize(name, my_binding)
      self.name = name
      self.my_binding = my_binding
      Byebug.run_init_script(StringIO.new)
    end

    def continue
      @continuing = true
      @continuation.call
    end

    def remember
      callcc { |cc| @continuation = cc }
      if @continuing
        Byebug.start
        Byebug.current_context.step_out(1)
        Pry.start_with_pry_byebug(my_binding)
      end
    ensure
      @continuing = false
    end
  end

  def methods
    @methods ||= Array(Method.new("(top)", TOPLEVEL_BINDING))
  end

  def method
    methods.last
  end

  def line
    methods.last.lines.last
  end

  def set!
    last.remember
  end

  def last
    if method.begun?
      method.line
    else
      method
    end
  end

  class Method
    include Continuable

    def continue
      # this should be the line that called my method
      super
    end

    def lines
      @lines ||= []
    end
        def line
      lines.last
    end

    def begun?
      lines.size > 0
    end
  end

  class Line
    include Continuable

    attr_reader :path

    def initialize(lineno, path, binding)
      super(lineno, binding)
      @path = path
    end

    def continue
      super
    end
  end
end

$continuation_stack = {}
disable_trace = false
$trace = TracePoint.new(:call, :line, :return) do |tp|

  if tp.event == :call && tp.method_id == :pry
    disable_trace = true
  elsif tp.event == :return && tp.method_id == :pry
    disable_trace = false
    next
  end

  next if disable_trace

  case tp.event
  when :call
    ContinuationStack.methods << ContinuationStack::Method.new(tp.method_id, tp.binding.freeze)
    ContinuationStack.set!
  when :line
    ContinuationStack.method.lines << ContinuationStack::Line.new(tp.lineno, tp.path, tp.binding.freeze)
    ContinuationStack.set!
  when :return
    ContinuationStack.methods.pop
    ContinuationStack.set!
  end
end

$trace.enable

class Thing
  def foo
    a ||= 1
    puts a += 1
    puts a += 1
    puts a += 1
    binding.pry
  end
end

Thing.new.foo