ndb: fix iterators, pack id tags, more tests

nostrdb/NdbTagElem.swift

@@ -7,9 +7,33 @@
 
 import Foundation
 
-struct NdbTagElem {
-    private let note: NdbNote
-    private let tag: UnsafeMutablePointer<ndb_tag>
+struct NdbStrIter: IteratorProtocol {
+    typealias Element = CChar
+
+    var ind: Int
+    let str: ndb_str
+    let tag: NdbTagElem // stored for lifetime reasons
+
+    mutating func next() -> CChar? {
+        let c = str.str[ind]
+        if (c != 0) {
+            ind += 1
+            return c
+        }
+
+        return nil
+    }
+
+    init(tag: NdbTagElem) {
+        self.str = ndb_tag_str(tag.note.note, tag.tag, tag.index)
+        self.ind = 0
+        self.tag = tag
+    }
+}
+
+struct NdbTagElem: Sequence {
+    let note: NdbNote
+    let tag: UnsafeMutablePointer<ndb_tag>
     let index: Int32
 
     init(note: NdbNote, tag: UnsafeMutablePointer<ndb_tag>, index: Int32) {
@@ -18,12 +42,44 @@ struct NdbTagElem {
         self.index = index
     }
 
+    var is_id: Bool {
+        return ndb_tag_str(note.note, tag, index).flag == NDB_PACKED_ID
+    }
+
+    var count: Int {
+        let r = ndb_tag_str(note.note, tag, index)
+        if r.flag == NDB_PACKED_ID {
+            return 32
+        } else {
+            return strlen(r.str)
+        }
+    }
+
     func matches_char(_ c: AsciiCharacter) -> Bool {
         return ndb_tag_matches_char(note.note, tag, index, c.cchar) == 1
     }
 
+    func data() -> NdbData {
+        let s = ndb_tag_str(note.note, tag, index)
+        return NdbData(note: note, str: s)
+    }
+
+    func id() -> Data? {
+        guard case .id(let id) = self.data() else { return nil }
+        return id.id
+    }
+
     func string() -> String {
-        return String(cString: ndb_tag_str(note.note, tag, index), encoding: .utf8) ?? ""
+        switch self.data() {
+        case .id(let id):
+            return hex_encode(id.id)
+        case .str(let s):
+            return String(cString: s.str, encoding: .utf8) ?? ""
+        }
+    }
+
+    func makeIterator() -> NdbStrIter {
+        return NdbStrIter(tag: self)
     }
 }