GitRef: a Reference type for tracking pending changes to another target object.

gitref.gd

# GitRef
# Author: willnationsdev
# Enables users to pass around a reference to pending changes for another target object.
# The changes can be applied to the target or reset with the apply() and reset() functions.
# To create layers of pending changes, call branch() and receive a new GitRef with the 
#     calling GitRef as its upstream reference.
# In a chained GitRef, apply() and reset() still modify the target as before, but now 
#     revert() can be called to reset the target to the state of the upstream GitRef.
extends Reference

var __is_base__= true
var __backup__ = null setget , get_backup
var __upstream__ = null setget , get_upstream
var __data__ = null setget , get_data

func _init(p_node):
	__upstream__ = p_node
	if p_node and p_node is get_script():
		__backup__ = p_node.get_backup()
	else:
		__backup__ = {}

func _get(p_name):
	for a_prop in get_property_list():
		if a_prop.name == p_name:
			return get(p_name)
	return __data__[p_name]

func _set(p_name, p_value):
	for a_prop in get_property_list():
		if a_prop.name == p_name:
			return set(p_name, p_value)
	__backup__[p_name] = get_base().get(p_name)
	__data__[p_name] = p_value

func get_data():
	return __data__

func get_upstream():
	return __upstream__

func get_backup():
	return __backup__

func branch():
	return get_script().new(self)

func apply():
	__is_base__ = false
	var node = get_base()
	for a_prop in __data__:
		node.set(a_prop, __data__[a_prop])

func revert():
	var is_base_val = true
	var node = get_base()
	for a_prop in __data__:
		var val = null
		if __upstream__.get_data().has(a_prop):
			val = __upstream__.get(a_prop)
		else:
			val = __backup__[a_prop]
			__backup__.erase(a_prop)
		node.set(a_prop, val)
	for a_prop in __data__:
		if __backup__[a_prop] != __data__[a_prop]:
			is_base_val = false
			break
	if is_base_val:
		__is_base__ = true

func reset():
	__is_base__ = true
	var node = get_base()
	for a_prop in __data__:
		node.set(a_prop, __backup__[a_prop])

func get_base():
	var node = __upstream__
	while node is get_script():
		node = node.get_upstream()
	return node

func is_base():
	return __is_base__