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Code Issues 95 Packages Projects Releases 10 Wiki Activity

Optimize ListSnapshot collection implementation

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This commit is contained in:
John Estropia
2020-10-05 23:12:17 +09:00
parent 3d82ee18c7
commit 4ec2b2e311
2 changed files with 125 additions and 12 deletions
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63
Sources/Internals.DiffableDataSourceSnapshot.swift
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@@ -78,7 +78,7 @@ extension Internals {
var numberOfItems: Int {
return self.structure.allItemIDs.count
return self.structure.allItemsCount
}
var numberOfSections: Int {
@@ -106,6 +106,59 @@ extension Internals {
return self.itemIdentifiers(inSection: identifier).count
}
func itemIdentifier(atAllItemsIndex index: Int) -> NSManagedObjectID? {
guard index >= 0 else {
return nil
}
var remainingIndex = index
for section in self.structure.sections {
let elements = section.elements
let sectionCount = elements.count
if remainingIndex < sectionCount {
return elements[remainingIndex].differenceIdentifier
}
remainingIndex -= sectionCount
}
return nil
}
func itemIdentifiers(atAllItemsBounds bounds: Range<Int>) -> [NSManagedObjectID] {
var remainingIndex = bounds.lowerBound
var itemIdentifiers: [NSManagedObjectID] = []
for section in self.structure.sections {
let elements = section.elements
let sectionCount = elements.count
if remainingIndex < sectionCount {
itemIdentifiers.append(
contentsOf: elements[remainingIndex..<min(sectionCount, bounds.count)]
.map({ $0.differenceIdentifier })
)
}
else if !itemIdentifiers.isEmpty {
itemIdentifiers.append(
contentsOf: elements.prefix(bounds.count - itemIdentifiers.count)
.map({ $0.differenceIdentifier })
)
}
if itemIdentifiers.count >= bounds.count {
return itemIdentifiers
}
remainingIndex -= sectionCount
}
return itemIdentifiers
}
func itemIdentifiers(inSection identifier: String) -> [NSManagedObjectID] {
return self.structure.items(in: identifier)
@@ -332,6 +385,14 @@ extension Internals {
return self.sections.map({ $0.differenceIdentifier })
}
var allItemsCount: Int {
return self.sections.reduce(into: 0) { (result, section) in
result += section.elements.count
}
}
var allItemIDs: [NSManagedObjectID] {
return self.sections.lazy.flatMap({ $0.elements }).map({ $0.differenceIdentifier })