nostrdb: add initial swift integration

nostrdb/NdbTagIterator.swift

@@ -0,0 +1,47 @@
+//
+//  NdbTagIterators.swift
+//  damus
+//
+//  Created by William Casarin on 2023-07-21.
+//
+
+import Foundation
+
+struct TagSequence: Sequence {
+    let note: UnsafeMutablePointer<ndb_note>
+    let tag: UnsafeMutablePointer<ndb_tag>
+
+    func makeIterator() -> TagIterator {
+        return TagIterator(note: note, tag: tag)
+    }
+}
+
+struct TagIterator: IteratorProtocol {
+    typealias Element = NdbTagElem
+
+    mutating func next() -> NdbTagElem? {
+        guard index < tag.pointee.count else { return nil }
+        let el = NdbTagElem(note: note, tag: tag, index: index)
+
+        index += 1
+
+        return el
+    }
+
+    var index: Int32
+    let note: UnsafeMutablePointer<ndb_note>
+    var tag: UnsafeMutablePointer<ndb_tag>
+
+    init(note: UnsafeMutablePointer<ndb_note>, tag: UnsafeMutablePointer<ndb_tag>) {
+        self.note = note
+        self.tag = tag
+        self.index = 0
+    }
+}
+
+
+func ndb_maybe_pointee<T>(_ p: UnsafeMutablePointer<T>!) -> T? {
+    guard p != nil else { return nil }
+    return p.pointee
+}
+