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Create NostrDB streaming and async lookup interfaces

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This commit introduces new interfaces for working with NostrDB from
Swift, including `NostrFilter` conversion, subscription streaming via
AsyncStreams and lookup/wait functions.

No user-facing changes.

Changelog-None
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
This commit is contained in:
Daniel D’Aquino
2025-04-09 22:41:50 -07:00
parent f8185d0ca5
commit 8f32c81b6c
8 changed files with 755 additions and 31 deletions
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nostrdb/NdbFilter.swift Normal file
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//
// NdbFilter.swift
// damus
//
// Created by Daniel D'Aquino on 2025-06-02.
//
import Foundation
/// A safe Swift wrapper around `UnsafeMutablePointer<ndb_filter>` that manages memory automatically.
///
/// This class provides a safe interface to the underlying C `ndb_filter` structure, handling
/// memory allocation and deallocation automatically. It eliminates the need for manual memory
/// management when working with NostrDB filters.
///
/// ## Usage
/// ```swift
/// let nostrFilter = NostrFilter(kinds: [.text_note])
/// let ndbFilter = try NdbFilter(from: nostrFilter)
/// // Use ndbFilter.ndbFilter or ndbFilter.unsafePointer as needed
/// // Memory is automatically cleaned up when ndbFilter goes out of scope
/// ```
class NdbFilter {
private let filterPointer: UnsafeMutablePointer<ndb_filter>
/// Creates a new NdbFilter from a NostrFilter.
/// - Parameter nostrFilter: The NostrFilter to convert
/// - Throws: `NdbFilterError.conversionFailed` if the underlying conversion fails
init(from nostrFilter: NostrFilter) throws {
do {
self.filterPointer = try Self.from(nostrFilter: nostrFilter)
} catch {
throw NdbFilterError.conversionFailed(error)
}
}
/// Provides access to the underlying `ndb_filter` structure.
/// - Returns: The underlying `ndb_filter` value (not a pointer)
var ndbFilter: ndb_filter {
return filterPointer.pointee
}
/// Provides access to the underlying unsafe pointer when needed for C interop.
/// - Warning: The caller must not deallocate this pointer. It will be automatically
/// deallocated when this NdbFilter is destroyed.
/// - Returns: The unsafe mutable pointer to the underlying ndb_filter
var unsafePointer: UnsafeMutablePointer<ndb_filter> {
return filterPointer
}
/// Creates multiple NdbFilter instances from an array of NostrFilters.
/// - Parameter nostrFilters: Array of NostrFilter instances to convert
/// - Returns: Array of NdbFilter instances
/// - Throws: `NdbFilterError.conversionFailed` if any conversion fails
static func create(from nostrFilters: [NostrFilter]) throws -> [NdbFilter] {
return try nostrFilters.map { try NdbFilter(from: $0) }
}
// MARK: - Conversion to/from ndb_filter
// TODO: This function is long and repetitive, refactor it into something cleaner.
private static func from(nostrFilter: NostrFilter) throws(NdbFilterConversionError) -> UnsafeMutablePointer<ndb_filter> {
let filterPointer = UnsafeMutablePointer<ndb_filter>.allocate(capacity: 1)
guard ndb_filter_init(filterPointer) == 1 else {
filterPointer.deallocate()
throw NdbFilterConversionError.failedToInitialize
}
// Handle `ids` field
if let ids = nostrFilter.ids {
guard ndb_filter_start_field(filterPointer, NDB_FILTER_IDS) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for noteId in ids {
do {
try noteId.withUnsafePointer({ idPointer in
if ndb_filter_add_id_element(filterPointer, idPointer) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
})
}
catch {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `kinds` field
if let kinds = nostrFilter.kinds {
guard ndb_filter_start_field(filterPointer, NDB_FILTER_KINDS) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for kind in kinds {
if ndb_filter_add_int_element(filterPointer, UInt64(kind.rawValue)) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `referenced_ids` field
if let referencedIds = nostrFilter.referenced_ids {
guard ndb_filter_start_tag_field(filterPointer, CChar(UnicodeScalar("e").value)) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for refId in referencedIds {
do {
try refId.withUnsafePointer({ refPointer in
if ndb_filter_add_id_element(filterPointer, refPointer) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
})
}
catch {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `pubkeys`
if let pubkeys = nostrFilter.pubkeys {
guard ndb_filter_start_tag_field(filterPointer, CChar(UnicodeScalar("p").value)) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for pubkey in pubkeys {
do {
try pubkey.withUnsafePointer({ pubkeyPointer in
if ndb_filter_add_id_element(filterPointer, pubkeyPointer) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
})
}
catch {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `since`
if let since = nostrFilter.since {
if ndb_filter_start_field(filterPointer, NDB_FILTER_SINCE) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
if ndb_filter_add_int_element(filterPointer, UInt64(since)) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
ndb_filter_end_field(filterPointer)
}
// Handle `until`
if let until = nostrFilter.until {
if ndb_filter_start_field(filterPointer, NDB_FILTER_UNTIL) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
if ndb_filter_add_int_element(filterPointer, UInt64(until)) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
ndb_filter_end_field(filterPointer)
}
// Handle `limit`
if let limit = nostrFilter.limit {
if ndb_filter_start_field(filterPointer, NDB_FILTER_LIMIT) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
if ndb_filter_add_int_element(filterPointer, UInt64(limit)) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
ndb_filter_end_field(filterPointer)
}
// Handle `authors`
if let authors = nostrFilter.authors {
guard ndb_filter_start_field(filterPointer, NDB_FILTER_AUTHORS) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for author in authors {
do {
try author.withUnsafePointer({ authorPointer in
if ndb_filter_add_id_element(filterPointer, authorPointer) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
})
}
catch {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `hashtag`
if let hashtags = nostrFilter.hashtag {
guard ndb_filter_start_tag_field(filterPointer, CChar(UnicodeScalar("t").value)) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for tag in hashtags {
if ndb_filter_add_str_element(filterPointer, tag.cString(using: .utf8)) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `parameter`
if let parameters = nostrFilter.parameter {
guard ndb_filter_start_tag_field(filterPointer, CChar(UnicodeScalar("d").value)) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for parameter in parameters {
if ndb_filter_add_str_element(filterPointer, parameter.cString(using: .utf8)) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Handle `quotes`
if let quotes = nostrFilter.quotes {
guard ndb_filter_start_tag_field(filterPointer, CChar(UnicodeScalar("q").value)) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToStartField
}
for quote in quotes {
do {
try quote.withUnsafePointer({ quotePointer in
if ndb_filter_add_id_element(filterPointer, quotePointer) != 1 {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
})
}
catch {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToAddElement
}
}
ndb_filter_end_field(filterPointer)
}
// Finalize the filter
guard ndb_filter_end(filterPointer) == 1 else {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
throw NdbFilterConversionError.failedToFinalize
}
return filterPointer
}
enum NdbFilterConversionError: Error {
case failedToInitialize
case failedToStartField
case failedToAddElement
case failedToFinalize
}
deinit {
ndb_filter_destroy(filterPointer)
filterPointer.deallocate()
}
}
/// Errors that can occur when working with NdbFilter.
enum NdbFilterError: Error {
/// Thrown when conversion from NostrFilter to NdbFilter fails.
/// - Parameter Error: The underlying error that caused the conversion to fail
case conversionFailed(Error)
}
/// Extension to create multiple NdbFilters safely from an array of NostrFilters.
extension Array where Element == NostrFilter {
/// Converts an array of NostrFilters to NdbFilters.
/// - Returns: Array of NdbFilter instances
/// - Throws: `NdbFilterError.conversionFailed` if any conversion fails
func toNdbFilters() throws -> [NdbFilter] {
return try self.map { try NdbFilter(from: $0) }
}
}