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//
// QuerySet.swift
// QueryKit
//
// Created by Kyle Fuller on 06/07/2014.
//
//
import Foundation
import CoreData
class QuerySet<T : NSManagedObject> : Sequence, Equatable {
let context:NSManagedObjectContext
let entityName:String
let sortDescriptors = [NSSortDescriptor]()
let predicate:NSPredicate?
let range:Range<Int>?
// Initialization
init(_ context:NSManagedObjectContext, _ entityName:String) {
self.context = context
self.entityName = entityName
}
init(queryset:QuerySet<T>, sortDescriptors:[NSSortDescriptor]?, predicate:NSPredicate?, range:Range<Int>?) {
self.context = queryset.context
self.entityName = queryset.entityName
if let sortDescriptors = sortDescriptors {
self.sortDescriptors = sortDescriptors
}
self.predicate = predicate
self.range = range
}
// Sorting
func orderBy(sortDescriptor:NSSortDescriptor) -> QuerySet<T> {
return orderBy([sortDescriptor])
}
func orderBy(sortDescriptors:[NSSortDescriptor]) -> QuerySet<T> {
return QuerySet(queryset:self, sortDescriptors:sortDescriptors, predicate:predicate, range:range)
}
// Filtering
func filter(predicate:NSPredicate) -> QuerySet<T> {
var futurePredicate = predicate
if let existingPredicate = self.predicate {
futurePredicate = NSCompoundPredicate(type: NSCompoundPredicateType.AndPredicateType, subpredicates: [existingPredicate, predicate])
}
return QuerySet(queryset:self, sortDescriptors:sortDescriptors, predicate:futurePredicate, range:range)
}
func filter(predicates:[NSPredicate]) -> QuerySet<T> {
let newPredicate = NSCompoundPredicate(type: NSCompoundPredicateType.AndPredicateType, subpredicates: predicates)
return filter(newPredicate)
}
func exclude(predicate:NSPredicate) -> QuerySet<T> {
let excludePredicate = NSCompoundPredicate(type: NSCompoundPredicateType.NotPredicateType, subpredicates: [predicate])
return filter(excludePredicate)
}
func exclude(predicates:[NSPredicate]) -> QuerySet<T> {
let excludePredicate = NSCompoundPredicate(type: NSCompoundPredicateType.AndPredicateType, subpredicates: predicates)
return exclude(excludePredicate)
}
// Subscripting
subscript(index: Int) -> (object:T?, error:NSError?) {
get {
var request = fetchRequest
request.fetchOffset = index
request.fetchLimit = 1
var error:NSError?
let items = context.executeFetchRequest(request, error:&error)
return (object:items[0] as? T, error:error)
}
}
subscript(index: Int) -> T? {
get {
return self[index].object
}
}
subscript(range:Range<Int>) -> QuerySet<T> {
get {
var fullRange = range
if let currentRange = self.range {
fullRange = Range<Int>(start: currentRange.startIndex + range.startIndex, end: range.endIndex)
}
return QuerySet(queryset:self, sortDescriptors:sortDescriptors, predicate:predicate, range:fullRange)
}
}
// Conversion
var fetchRequest:NSFetchRequest {
var request = NSFetchRequest(entityName:entityName)
request.predicate = predicate
request.sortDescriptors = sortDescriptors
if let range = range {
request.fetchOffset = range.startIndex
request.fetchLimit = range.endIndex - range.startIndex
}
return request
}
func array() -> (objects:([T]?), error:NSError?) {
var error:NSError?
var objects = context.executeFetchRequest(fetchRequest, error:&error) as? [T]
return (objects:objects, error:error)
}
func array() -> [T]? {
return array().objects
}
// Count
func count() -> (count:Int?, error:NSError?) {
var error:NSError?
var count:Int? = context.countForFetchRequest(fetchRequest, error: &error)
if count! == NSNotFound {
count = nil
}
return (count:count, error:error)
}
func count() -> Int? {
return count().count
}
// Deletion
func delete() -> (count:Int, error:NSError?) {
var result = array() as (objects:([T]?), error:NSError?)
var deletedCount = 0
if let objects = result.objects {
for object in objects {
context.deleteObject(object)
}
deletedCount = objects.count
}
return (count:deletedCount, error:result.error)
}
// Sequence
func generate() -> IndexingGenerator<Array<T>> {
var result = self.array() as (objects:([T]?), error:NSError?)
if let objects = result.objects {
return objects.generate()
}
return [].generate()
}
}
func == <T : NSManagedObject>(lhs: QuerySet<T>, rhs: QuerySet<T>) -> Bool {
let context = lhs.context == rhs.context
let entityName = lhs.entityName == rhs.entityName
let sortDescriptors = lhs.sortDescriptors == rhs.sortDescriptors
let predicate = lhs.predicate == rhs.predicate
let startIndex = lhs.range?.startIndex == rhs.range?.startIndex
let endIndex = lhs.range?.endIndex == rhs.range?.endIndex
return context && entityName && sortDescriptors && predicate && startIndex && endIndex
}