Internal method for object merge, adopted form obj.merge from Sugar.js

gistfile1.coffee

###
Internal method for object merge, adopted form obj.merge from Sugar.js
###
_merge: (target, source, deep, resolve) ->
	
	###
	Some checking at start, we are dont need merge void objects at all
	###
	unless target? and source?
		throw new Error """
										null object given to _merge
											target |#{target}|
											source |#{source}|
										"""
	###
	Strings cannot be reliably merged thanks to their properties not being enumerable in < IE8
	###
	throw new Error "cant merge with String type source |#{source}|" if _.isString source
	
	for own key, val of source
		
		# Conflict!
		unless target[key]
			continue if resolve is false # Do not merge.
			# Use the result of the callback as the result
			if _.isFunction resolve
				val = resolve.call source, key, target[key], source[key]
		
		if deep is true and _.isObject val
			unless target[key] 
				target[key] = if _.isArray val then [] else {}
			
			@_merge target[key], source[key], deep
			continue
		
		target[key] = val

  target