Class: Ladybug::ObjectManager

Inherits:
Object
  • Object
show all
Defined in:
lib/ladybug/object_manager.rb

Overview

This class:

  • serializes objects for display in the Chrome UI

  • maintains references to all objects for which it has given out IDs for; this ensures they don’t get GC’d and can be dereferenced later by ID.

TODO: Handle Chrome’s “release” APIs to enable releasing references

at some point and avoid too much memory growth

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ObjectManager

Returns a new instance of ObjectManager.



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# File 'lib/ladybug/object_manager.rb', line 12

def initialize
  @objects = {}
end

Instance Method Details

#find(id) ⇒ Object

Given an ID, return the object from our registry



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

def find(id)
  @objects[id]
end

#get_properties(object) ⇒ Object

Ruby objects don’t have properties like JS objects do, so we need to figure out the best properties to show for non-primitives.

We first give the object a chance to tell us its debug properties, then we fall back to handling a bunch of common cases, then finally we give up and just serialize its instance variables.



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# File 'lib/ladybug/object_manager.rb', line 96

def get_properties(object)
  if object.respond_to?(:chrome_debug_properties)
    get_properties(object.chrome_debug_properties)
  elsif object.is_a? Hash
    object.
      map do |key, value|
        {
          name: key,
          value: serialize(value)
        }
      end.
      reject { |property| property[:value].nil? }
  elsif object.is_a? Array
    object.map.with_index do |element, index|
      {
        name: index.to_s,
        value: serialize(element)
      }
    end

  # TODO: This section is too magical,
  # better to let users just define their own chrome_debug_properties
  # and then add an optional Rails plugin to the gem which
  # monkey patches rails classes.
  elsif object.respond_to?(:to_a)
    get_properties(object.to_a)
  elsif object.respond_to?(:attributes)
    get_properties(object.attributes)
  elsif object.respond_to?(:to_hash)
    get_properties(object.to_hash)
  elsif object.respond_to?(:to_h)
    get_properties(object.to_h)
  else
    ivar_hash = object.instance_variables.each_with_object({}) do |ivar, hash|
      hash[ivar] = object.instance_variable_get(ivar)
    end

    get_properties(ivar_hash)
  end
end

#register(object) ⇒ Object

Given an object, register it in our internal state and return an ID for it



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# File 'lib/ladybug/object_manager.rb', line 23

def register(object)
  object_id = SecureRandom.uuid
  @objects[object_id] = object
  object_id
end

#serialize(object) ⇒ Object

Convert a Ruby object to a hash representing a Chrome RemoteObject chromedevtools.github.io/devtools-protocol/tot/Runtime#type-RemoteObject



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# File 'lib/ladybug/object_manager.rb', line 31

def serialize(object)
  case object
  when String
    {
      type: "string",
      value: object,
      description: object
    }
  when Numeric
    {
      type: "number",
      value: object,
      description: object.to_s
    }
  when TrueClass, FalseClass
    {
      type: "boolean",
      value: object,
      description: object.to_s
    }
  when Symbol
    {
      type: "symbol",
      value: object,
      description: object.to_s
    }
  when Array
    result = {
      type: "object",
      className: object.class.to_s,
      description: "Array(#{object.length})",
      objectId: register(object),
      subtype: "array"
    }

    result.merge!(
      preview: result.merge(
        overflow: false,
        properties: get_properties(object)
      )
    )

    result
  when nil
    {
      type: "object",
      subtype: "null",
      value: nil
    }
  else
    {
      type: "object",
      className: object.class.to_s,
      description: object.to_s,
      objectId: register(object)
    }
  end
end