lib/pry/method/weird_method_locator.rb
# frozen_string_literal: true
class Pry
class Method
# This class is responsible for locating the *real* `Pry::Method`
# object captured by a binding.
#
# Given a `Binding` from inside a method and a 'seed' Pry::Method object,
# there are primarily two situations where the seed method doesn't match
# the Binding:
# 1. The Pry::Method is from a subclass
# 2. The Pry::Method represents a method of the same name while the original
# was renamed to something else. For 1. we search vertically up the
# inheritance chain, and for 2. we search laterally along the object's
# method table.
#
# When we locate the method that matches the Binding we wrap it in
# Pry::Method and return it, or return nil if we fail.
class WeirdMethodLocator
class << self
# Whether the given method object matches the associated binding.
# If the method object does not match the binding, then it's
# most likely not the method captured by the binding, and we
# must commence a search.
#
# @param [Pry::Method] method
# @param [Binding] binding
# @return [Boolean]
def normal_method?(method, binding)
if method && method.source_file && method.source_range
if binding.respond_to?(:source_location)
binding_file, binding_line = binding.source_location
else
binding_file = binding.eval('__FILE__')
binding_line = binding.eval('__LINE__')
end
(File.expand_path(method.source_file) == File.expand_path(binding_file)) &&
method.source_range.include?(binding_line)
end
rescue StandardError
false
end
def weird_method?(method, binding)
!normal_method?(method, binding)
end
end
attr_accessor :method
attr_accessor :target
# @param [Pry::Method] method The seed method.
# @param [Binding] target The Binding that captures the method
# we want to locate.
def initialize(method, target)
@method = method
@target = target
end
# @return [Pry::Method, nil] The Pry::Method that matches the
# given binding.
def find_method
find_method_in_superclass || find_renamed_method
end
# @return [Boolean] Whether the Pry::Method is unrecoverable
# This usually happens when the method captured by the Binding
# has been subsequently deleted.
def lost_method?
!!(find_method.nil? && renamed_method_source_location)
end
private
def skip_superclass_search?
target_mod = @target.eval('self').class
target_mod.ancestors.take_while { |mod| mod != target_mod }.any?
end
def normal_method?(method)
self.class.normal_method?(method, target)
end
def target_self
target.eval('self')
end
def target_file
file =
if target.respond_to?(:source_location)
target.source_location.first
else
target.eval('__FILE__')
end
pry_file? ? file : File.expand_path(file)
end
def target_line
if target.respond_to?(:source_location)
target.source_location.last
else
target.eval('__LINE__')
end
end
def pry_file?
file =
if target.respond_to?(:source_location)
target.source_location.first
else
target.eval('__FILE__')
end
Pry.eval_path == file
end
# it's possible in some cases that the method we find by this approach is
# a sub-method of the one we're currently in, consider:
#
# class A; def b; binding.pry; end; end
# class B < A; def b; super; end; end
#
# Given that we can normally find the source_range of methods, and that we
# know which __FILE__ and __LINE__ the binding is at, we can hope to
# disambiguate these cases.
#
# This obviously won't work if the source is unavailable for some reason,
# or if both methods have the same __FILE__ and __LINE__.
#
# @return [Pry::Method, nil] The Pry::Method representing the
# superclass method.
def find_method_in_superclass
guess = method
return guess if skip_superclass_search?
while guess
# needs rescue if this is a Disowned method or a C method or something...
# TODO: Fix up the exception handling so we don't need a bare rescue
return guess if normal_method?(guess)
break if guess == guess.super
guess = guess.super
end
# Uhoh... none of the methods in the chain had the right `__FILE__` and
# `__LINE__` due to unknown circumstances.
# TODO: we should warn the user when this happens.
nil
end
# This is the case where the name of a method has changed
# (via alias_method) so we locate the Method object for the
# renamed method.
#
# @return [Pry::Method, nil] The Pry::Method representing the
# renamed method
def find_renamed_method
return unless valid_file?(target_file)
alias_name = all_methods_for(target_self).find do |v|
location = target_self.method(v).source_location
location && expanded_source_location(location) == renamed_method_source_location
end
alias_name && Pry::Method(target_self.method(alias_name))
end
def expanded_source_location(source_location)
return unless source_location
if pry_file?
source_location
else
[File.expand_path(source_location.first), source_location.last]
end
end
# Use static analysis to locate the start of the method definition.
# We have the `__FILE__` and `__LINE__` from the binding and the
# original name of the method so we search up until we find a
# def/define_method, etc defining a method of the appropriate name.
#
# @return [Array<String, Fixnum>] The `source_location` of the
# renamed method
def renamed_method_source_location
if defined?(@original_method_source_location)
return @original_method_source_location
end
source_index = lines_for_file(target_file)[0..(target_line - 1)].rindex do |v|
Pry::Method.method_definition?(method.name, v)
end
@original_method_source_location =
source_index && [target_file, index_to_line_number(source_index)]
end
def index_to_line_number(index)
# Pry.line_buffer is 0-indexed
pry_file? ? index : index + 1
end
def valid_file?(file)
(File.exist?(file) && !File.directory?(file)) || Pry.eval_path == file
end
def lines_for_file(file)
@lines_for_file ||= {}
@lines_for_file[file] ||= if Pry.eval_path == file
Pry.line_buffer
else
File.readlines(file)
end
end
def all_methods_for(obj)
obj.public_methods(false) +
obj.private_methods(false) +
obj.protected_methods(false)
end
end
end
end