Refactor sections as enum types

2026-04-20 00:24:43 +02:00 · 2022-04-04 09:24:22 +01:00
parent 6cde2f4461
commit 3f34fd655a
10 changed files with 454 additions and 296 deletions
@@ -0,0 +1,78 @@
+// 
+// Copyright 2022 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+/**
+ Data structure representing the current arrangement of sections in a given data source,
+ where a numerical session index (used for table views) is associated with its semantic
+ value (e.g. "favorites" = 2).
+ */
+@objc class RecentsDataSourceSections: NSObject {
+    typealias SectionIndex = Int
+    static let MissingSectionIndex = -1
+    
+    @objc var count: Int {
+        sections.count
+    }
+    
+    @objc var sectionTypes: [NSNumber] {
+        sections
+            .sorted { $0.value < $1.value }
+            .map { NSNumber(value: $0.key.rawValue) }
+    }
+
+    private var sections: [RecentsDataSourceSectionType: SectionIndex] = [:]
+    
+    init(sectionTypes: [RecentsDataSourceSectionType]) {
+        sections = sectionTypes
+            .enumerated()
+            .reduce(into: [RecentsDataSourceSectionType: SectionIndex]()) { dict, item in
+                dict[item.element] = item.offset
+            }
+    }
+    
+    // Objective-C cannot represent int-enums as an array, so a convenience function
+    // allows passing them as a list of NSNumbers, that are internally extracted
+    @objc convenience init(sectionTypes: [NSNumber]) {
+        let types = sectionTypes.compactMap {
+            RecentsDataSourceSectionType(rawValue: $0.intValue)
+        }
+        self.init(sectionTypes: types)
+    }
+    
+    @objc func contains(_ sectionType: RecentsDataSourceSectionType) -> Bool {
+        return sections.contains {
+            $0.key == sectionType
+        }
+    }
+    
+    @objc func sectionIndex(forSectionType sectionType: RecentsDataSourceSectionType) -> SectionIndex {
+        guard let index = sections[sectionType] else {
+            // Objective-c code does not allow returning optional Int, so must use -1
+            return Self.MissingSectionIndex
+        }
+        return index
+    }
+    
+    @objc func sectionType(forSectionIndex sectionIndex: SectionIndex) -> RecentsDataSourceSectionType {
+        guard let item = sections.first(where: { $0.value == sectionIndex }) else {
+            // Objective-c code does not allow returning optional Int, so must use .unknown
+            return .unknown
+        }
+        return item.key
+    }
+}