refactor and cleanup [skip ci]

submodules/Postbox/Sources/OrderedItemListIndexTable.swift

@@ -0,0 +1,45 @@
+import Foundation
+
+final class OrderedItemListIndexTable: Table {
+    static func tableSpec(_ id: Int32) -> ValueBoxTable {
+        return ValueBoxTable(id: id, keyType: .binary, compactValuesOnCreation: false)
+    }
+    
+    private func key(collectionId: Int32, id: MemoryBuffer) -> ValueBoxKey {
+        let key = ValueBoxKey(length: 4 + id.length)
+        key.setInt32(0, value: collectionId)
+        memcpy(key.memory.advanced(by: 4), id.memory, id.length)
+        return key
+    }
+    
+    func get(collectionId: Int32, id: MemoryBuffer) -> PostboxCoding? {
+        if let value = self.valueBox.get(self.table, key: self.key(collectionId: collectionId, id: id)), let content = PostboxDecoder(buffer: value).decodeRootObject() {
+            return content
+        } else {
+            return nil
+        }
+    }
+    
+    func remove(collectionId: Int32, id: MemoryBuffer) {
+        self.valueBox.remove(self.table, key: self.key(collectionId: collectionId, id: id), secure: false)
+    }
+    
+    func set(collectionId: Int32, id: MemoryBuffer, content: PostboxCoding) {
+        let encoder = PostboxEncoder()
+        encoder.encodeRootObject(content)
+        withExtendedLifetime(encoder, {
+            self.valueBox.set(self.table, key: self.key(collectionId: collectionId, id: id), value: encoder.readBufferNoCopy())
+        })
+    }
+    
+    func getAllItemIds(collectionId: Int32) -> [MemoryBuffer] {
+        var result: [MemoryBuffer] = []
+        self.valueBox.range(self.table, start: self.key(collectionId: collectionId, id: MemoryBuffer()), end: self.key(collectionId: collectionId + 1, id: MemoryBuffer()), keys: { key in
+            let id = MemoryBuffer(memory: malloc(key.length - 4)!, capacity: key.length - 4, length: key.length - 4, freeWhenDone: true)
+            memcpy(id.memory, key.memory.advanced(by: 4), key.length - 4)
+            result.append(id)
+            return true
+        }, limit: 0)
+        return result
+    }
+}