Class: Ladybug::Debugger

Inherits:
Object
  • Object
show all
Extended by:
Memoist
Defined in:
lib/ladybug/debugger.rb

Defined Under Namespace

Classes: InvalidBreakpointLocationError, InvalidExpressionError

Instance Method Summary collapse

Constructor Details

#initialize(preload_paths: []) ⇒ Debugger

preload_paths (optional):

paths to pre-parse into Ruby code so that
later we can quickly respond to requests for breakpoint locations



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# File 'lib/ladybug/debugger.rb', line 17

def initialize(preload_paths: [])
  @breakpoints = []

  @to_main_thread = Queue.new
  @from_main_thread = Queue.new

  @on_pause = -> {}
  @on_resume = -> {}

  @parsed_files = {}

  @break = nil

  # Todo: consider thread safety of mutating this hash
  Thread.new do
    preload_paths.each do |preload_path|
      parse(preload_path)
    end
  end
end

Instance Method Details

#debug ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 46

def debug
  RubyVM::InstructionSequence.compile_option = {
    trace_instruction: true
  }
  Thread.current.set_trace_func trace_func

  yield
ensure
  RubyVM::InstructionSequence.compile_option = {
    trace_instruction: false
  }
  Thread.current.set_trace_func nil
end

#evaluate(expression) ⇒ Object

Raises:



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# File 'lib/ladybug/debugger.rb', line 84

def evaluate(expression)
  raise InvalidExpressionError if !parseable?(expression)

  @to_main_thread.push({
    command: 'eval',
    arguments: {
      expression: expression
    }
  })

  # Block on eval, returns result
  @from_main_thread.pop
end

#get_possible_breakpoints(path:, start_num:, end_num:) ⇒ Object

Given a filename line number range of a requested breakpoint, give the line numbers of possible breakpoints.

In practice, start and end number tend to be the same when Chrome devtools is the client.

A breakpoint can be set at the beginning of any Ruby statement. (more details in #line_numbers_with_code)



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# File 'lib/ladybug/debugger.rb', line 143

def get_possible_breakpoints(path:, start_num:, end_num:)
  (start_num..end_num).to_a & line_numbers_with_code(path)
end

#on_pause(&block) ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 60

def on_pause(&block)
  @on_pause = block
end

#on_resume(&block) ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 64

def on_resume(&block)
  @on_resume = block
end

#remove_breakpoint(breakpoint_id) ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 128

def remove_breakpoint(breakpoint_id)
  filename, line_number = breakpoint_id.split(":")
  line_number = line_number.to_i

  @breakpoints.delete_if { |bp| bp[:id] == breakpoint_id }
end

#resume ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 68

def resume
  @to_main_thread.push({ command: 'continue' })
end

#set_breakpoint(filename:, line_number:) ⇒ Object

Sets a breakpoint and returns a breakpoint object.



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# File 'lib/ladybug/debugger.rb', line 99

def set_breakpoint(filename:, line_number:)
  possible_lines = line_numbers_with_code(filename)

  # It's acceptable for a caller to request setting a breakpoint
  # on a location where it's not possible to set a breakpoint.
  # In this case, we set a breakpoint on the next possible location.
  if !possible_lines.include?(line_number)
    line_number = possible_lines.sort.find { |ln| ln > line_number }
  end

  # Sometimes the above check will fail and there's no possible breakpoint.
  if line_number.nil?
    raise InvalidBreakpointLocationError,
          "invalid breakpoint line: #{filename}:#{line_number}"
  end

  breakpoint = {
    # We need to use the absolute path here
    # because set_trace_func ends up checking against that
    filename: File.absolute_path(filename),
    line_number: line_number,
    id: "#{filename}:#{line_number}"
  }

  @breakpoints.push(breakpoint)

  breakpoint
end

#start ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 38

def start
  RubyVM::InstructionSequence.compile_option = {
    trace_instruction: true
  }

  set_trace_func trace_func
end

#step_into ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 76

def step_into
  @to_main_thread.push({ command: 'step_into' })
end

#step_out ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 80

def step_out
  @to_main_thread.push({ command: 'step_out' })
end

#step_over ⇒ Object 



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# File 'lib/ladybug/debugger.rb', line 72

def step_over
  @to_main_thread.push({ command: 'step_over' })
end