#==============================================================================#
# DocumentCollection #
#==============================================================================#
#' DocumentCollection
#'
#' \strong{Document Family of Classes Overview:}
#'
#' The Document family of classes is an implementation of the composite
#' pattern documented in the book "Design Patterns: Elements of Reusable
#' Object-Oriented Software" by Erich Gamma, Richard Helm, Ralph Johnson
#' and John Vlissides (hence Gang of Four). This pattern allows composite
#' and individual objects to be treated uniformly.
#'
#' The following sections include:
#' \itemize{
#' \item Class Participants: Classes the comprise this composite pattern.
#' \item Class Collaborators: Classes which interact with the Document0 class.
#' \item Class Methods: Methods included in the interface.
#' }
#'
#' \strong{Document Family of Classes Participants:}
#' The participants of the Document0 class are:
#' \itemize{
#' \item Document0: This component class specifies an abstract interface
#' for all leaf and composite document classes.
#' \item DocumentCollection: The composite class that maintains the
#' hierarchical structure of document collections (composites) and individual
#' documents (leafs).
#' \item Document: An "abstract leaf" class defines the interface for
#' DocumentText, DocumentRdata, DocumentCsv, and DocumentXlsx sub-classes.
#' \item DocumentText: This "concrete leaf" class for text documents.
#' \item DocumentCsv: This "concrete leaf" class for csv documents.
#' \item DocumentRdata: This "concrete leaf" class for RData documents.
#' \item DocumentXlsx: This "concrete leaf" class for excel documents.
#' }
#'
#' \strong{DocumentCollection Collaborators:}
#' The collaborators of the Document family are:
#' \itemize{
#' \item Lab: This class maintains a one-to-many "has a" association
#' relationship with the Document Class Family.
#' \item State: Class responsible for saving current and restoring prior states of objects.
#' \item Historian: Class responsible for maintaining the history of events on objects.
#' \item Reader: Class responsible for initiating the document read operation.
#' \item Writer: Class responsible for initiating the document write operation.
#' \item Validator: Class responsible for validating method parameters.
#' }
#'
#' \strong{DocumentCollection Methods:}
#' There are six types of methods within the DocumentCollection class and they are:
#' \itemize{
#' \item{Core Methods: Core methods shared by both Document and
#' DocumentCollection objects.}
#' \item{Getter/Setter Methods: Active binding methods for getting and setting
#' selected private members.}
#' \item{Composite Methods: Methods implemented by the DocumentCollection
#' class to maintain the document heirarchy.}
#' \item{State Methods: Methods for saving current and restoring prior object states.}
#' \item{Visitor Methods: Methods for implementation of and messaging
#' with objects of the visitor classes.}
#' }
#'
#' \strong{DocumentCollection Core Methods:}
#' \itemize{
#' \item{\code{new(name, desc)}}{Method for instantiating a document collection.}
#' \item{\code{getName()}}{Method returns the name of the DocumentCollection object.}
#' \item{\code{exposeObject(requester)}}{Method that returns the elements of the current DocumentCollection object, if invoked by an authorized method.}
#' \item{\code{restore(requester, prior)}}{Method for restoring a document collection to a prior state, as per the object parameter.}
#' }
#'
#' \strong{DocumentCollection Field Getter/Setter Active Binding Methods:}
#' \itemize{
#' \item{\code{desc()}}{Method used to get / set the description variable.
#' Implemented as an active binding and so the field may be updated
#' by assignment. This method is inherited from the Document0 class.}
#' }
#'
#' \strong{DocumentCollection Composite Methods:}
#' \itemize{
#' \item{\code{addChild(document)}}{Method adds a Document or DocumentCollection object
#' as a child object.}
#' \item{\code{getChildren()}}{Method retrieves the child documents of the object.}
#' \item{\code{removeChild(document)}}{Method removes a Document or DocumentCollection
#' object from its list of child documents.}
#' \item{\code{parent(value)}}{Getter/setter method for the parent field, implemented as an active binding on the private member.}
#' }
#'
#' #' \strong{DocumentCollection State Methods:}
#' \itemize{
#' \item{\code{saveState()}}{Method for saving current state of an object.}
#' \item{\code{restoreState()}}{Methods for restoring an object to a prior state.}
#' }
#'
#'
#' \strong{DocumentCollection Visitor Methods:}
#' \itemize{
#' \item{\code{accept(visitor)}}{Method for accepting the objects of a visitor class.}
#' }
#'
#'
#' @param name Character string indicating the name of the document or file. Required for all objects.
#' @param desc Character string containing the description of the document.
#' @param parent An object of the Lab or DocumentCollection class that represents
#' the parent object.
#' @param visitor An object from one of the visitor classes.
#' @param stateId Character string that uniquely identifies an object and its
#' state at a specific point in time.
#'
#' @docType class
#' @author John James, \email{jjames@@datasciencesalon.org}
#' @family Document classes
#' @export
DocumentCollection <- R6::R6Class(
classname = "DocumentCollection",
inherit = Document0,
private = list(
..documents = list()
),
public = list(
#-------------------------------------------------------------------------#
# Core Methods #
#-------------------------------------------------------------------------#
initialize = function(name, desc = NULL) {
# Instantiate variables
private$..name <- name
private$..desc <- ifelse(is.null(desc), paste(name, "Document Collection"), desc)
private$..stateDesc <- paste("DocumentCollection", name, "instantiated at", Sys.time())
private$..created <-Sys.time()
private$..modified <- Sys.time()
# Validate Document Collection
v <- Validator$new()
if (v$init(self) == FALSE) stop()
# Assign the name to the object in the global environment and update state
assign(name, self, envir = .GlobalEnv)
# Log Event
#historian$addEvent(className = "DocumentCollection", objectName = name,
# method = "initialize",
# event = private$..stateDesc)
invisible(self)
},
exposeObject = function(requester) {
v <- Validator()
if (v$exposeObject(object = self,
requester = requester) == FALSE) stop()
document <- list(
name = private$..name,
desc = private$..desc,
parent = private$..parent,
documents = private$..documents,
stateId = private$..stateId,
stateDesc = private$..stateDesc,
created = private$..created,
modified = private$..modified
)
return(document)
},
restore = function(requester, prior) {
v <- Validator()
if (v$restore(object = self,
requester = requester) == FALSE) stop()
private$..desc <- prior$desc
private$..parent <- prior$parent
private$..documents <- prior$documents
private$..stateDesc <- paste("DocumentCollection object", private$..name,
"restored to prior state designated by",
"state identifier:",
r$stateId,"at", Sys.time())
private$..stateId <- prior$stateId
private$..created <- prior$created
private$..modified <- Sys.time()
# Log event
# historian$addEvent(className = class(self)[1], objectName = name,
# method = "restore",
# event = private$..stateDesc)
invisible(self)
},
#-------------------------------------------------------------------------#
# Composite Methods #
#-------------------------------------------------------------------------#
getChildren = function() { private$..documents },
addChild = function(document) {
v <- Validator()
if (v$addChild(object = self, child = document) == FALSE) stop()
# Add document to list of documents for collection
d <- document$exposeObject()
private$..documents[[d$name]] <- document
# Update the parent of the document object
document$setAncestor(self)
# Update State
private$..stateDesc <- paste("Added", class(document)[1], "object",
"to the", private$..name, "DocumentCollection",
"at", Sys.time())
private$..modified <- Sys.time()
self$saveState()
# Log Event
# historian$addEvent(className = "DocumentCollection", objectName = private$..name,
# method = "addChild",
# event = private$..stateDesc)
},
removeChild = function(document) {
v <- Validator()
if (v$removeChild(object = self, child = document) == FALSE) stop()
# Save Memento
private$..stateDesc <- paste("Memento of DocumentCollection object", private$..name,
"prior to removing child document, ", document$getName(),
"at", Sys.time())
private$..modified <- Sys.time()
#self$saveState()
# Remove document from collection
private$..documents[[d$name]] <- NULL
# Update State
private$..stateDesc <- paste("Removed", class(document)[1], "object",
"from the", private$..name, "DocumentCollection",
"at", Sys.time())
private$..modified <- Sys.time()
#self$saveState()
# Log Event
# historian$addEvent(className = "DocumentCollection", objectName = private$..name,
# method = "removeChild",
# event = private$..stateDesc)
},
#-------------------------------------------------------------------#
# State Method #
#-------------------------------------------------------------------#
saveState = function() {
state <- State$new()
private$..stateId <- state$save(self)
},
restoreState = function(stateId) {
private$..stateId <- stateId
state <- State$new()
state$restore(self)
invisible(self)
},
#-------------------------------------------------------------------------#
# Visitor Methods #
#-------------------------------------------------------------------------#
accept = function(visitor) {
visitor$documentCollection(self)
}
)
)
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