Add BinaryParser

Didn't end up using this, but might be useful in the future

damus.xcodeproj/project.pbxproj

@@ -38,6 +38,7 @@
 		4C0A3F8F280F640A000448DE /* ThreadModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C0A3F8E280F640A000448DE /* ThreadModel.swift */; };
 		4C0A3F91280F6528000448DE /* ChatView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C0A3F90280F6528000448DE /* ChatView.swift */; };
 		4C0A3F93280F66F5000448DE /* ReplyMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C0A3F92280F66F5000448DE /* ReplyMap.swift */; };
+		4C198DF829F89323004C165C /* BinaryParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C198DF729F89323004C165C /* BinaryParser.swift */; };
 		4C1A9A1A29DCA17E00516EAC /* ReplyCounter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C1A9A1929DCA17E00516EAC /* ReplyCounter.swift */; };
 		4C1A9A1D29DDCF9B00516EAC /* NotificationSettingsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C1A9A1C29DDCF9B00516EAC /* NotificationSettingsView.swift */; };
 		4C1A9A1F29DDD24B00516EAC /* AppearanceSettingsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C1A9A1E29DDD24B00516EAC /* AppearanceSettingsView.swift */; };
@@ -416,6 +417,7 @@
 		4C0A3F8E280F640A000448DE /* ThreadModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ThreadModel.swift; sourceTree = "<group>"; };
 		4C0A3F90280F6528000448DE /* ChatView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ChatView.swift; sourceTree = "<group>"; };
 		4C0A3F92280F66F5000448DE /* ReplyMap.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ReplyMap.swift; sourceTree = "<group>"; };
+		4C198DF729F89323004C165C /* BinaryParser.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BinaryParser.swift; sourceTree = "<group>"; };
 		4C1A9A1929DCA17E00516EAC /* ReplyCounter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ReplyCounter.swift; sourceTree = "<group>"; };
 		4C1A9A1C29DDCF9B00516EAC /* NotificationSettingsView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NotificationSettingsView.swift; sourceTree = "<group>"; };
 		4C1A9A1E29DDD24B00516EAC /* AppearanceSettingsView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppearanceSettingsView.swift; sourceTree = "<group>"; };
@@ -855,6 +857,14 @@
 			path = Models;
 			sourceTree = "<group>";
 		};
+		4C198DF629F89317004C165C /* Parser */ = {
+			isa = PBXGroup;
+			children = (
+				4C198DF729F89323004C165C /* BinaryParser.swift */,
+			);
+			path = Parser;
+			sourceTree = "<group>";
+		};
 		4C1A9A1B29DDCF8B00516EAC /* Settings */ = {
 			isa = PBXGroup;
 			children = (
@@ -1644,6 +1654,7 @@
 				4C06670628FCB08600038D2A /* ImageCarousel.swift in Sources */,
 				F79C7FAD29D5E9620000F946 /* EditProfilePictureControl.swift in Sources */,
 				4C9F18E229AA9B6C008C55EC /* CustomizeZapView.swift in Sources */,
+				4C198DF829F89323004C165C /* BinaryParser.swift in Sources */,
 				4C75EFAF28049D350006080F /* NostrFilter.swift in Sources */,
 				4C3EA64C28FF59AC00C48A62 /* bech32_util.c in Sources */,
 				4CE1399029F0661A00AC6A0B /* RepostAction.swift in Sources */,

damus/Util/Parser/BinaryParser.swift

@@ -0,0 +1,48 @@
+//
+//  BinaryParser.swift
+//  damus
+//
+//  Created by William Casarin on 2023-04-25.
+//
+
+import Foundation
+
+class BinaryParser {
+    var pos: Int
+    var buf: [UInt8]
+    
+    init(buf: [UInt8], pos: Int = 0) {
+        self.pos = pos
+        self.buf = buf
+    }
+    
+    func read_byte() -> UInt8? {
+        guard pos < buf.count else {
+            return nil
+        }
+        
+        let v = buf[pos]
+        pos += 1
+        return v
+    }
+    
+    func read_bytes(_ n: Int) -> [UInt8]? {
+        guard pos + n < buf.count else {
+            return nil
+        }
+        
+        let v = [UInt8](self.buf[pos...pos+n])
+        return v
+    }
+    
+    func read_u16() -> UInt16? {
+        let start = self.pos
+
+        guard let b1 = read_byte(), let b2 = read_byte() else {
+            self.pos = start
+            return nil
+        }
+
+        return (UInt16(b1) << 8) | UInt16(b2)
+    }
+}