parse event logs

Example/web3swiftExample/web3swiftExample/ViewController.swift

@@ -49,7 +49,13 @@ class ViewController: UIViewController {
                 let result = try await((intermediate?.call(options: options))!)
                 print("BKX token name = " + (result!["0"] as! String))
 
-
+                let erc20receipt = try await(web3Main.eth.getTransactionReceipt("0x76bb19c0b7e2590f724871960599d28db99cd587506fdfea94062f9c8d61eb30"))
+                for l in (erc20receipt?.logs)! {
+                    guard let result = contract?.parseEvent(l), let name = result.eventName, let data = result.eventData else {continue}
+                    print("Parsed event " + name)
+                    print("Parsed content")
+                    print(data)
+                }
                 // Block number on Main
 
                 let blockNumber = try await(web3Main.eth.getBlockNumber())

README.md

@@ -10,7 +10,7 @@
 - Serialize and deserialize transactions and results to native Swift types
 - Convenience functions for chain state: block number, gas price
 - Check transaction results and get receipt
-- WIP: Parse event logs for transaction
+- Parse event logs for transaction
 
 ## Example
 
@@ -40,4 +40,4 @@ Petr Korolev, @skywinder, [email protected]
 
 ## License
 
-web3swift is available under the MIT license. See the LICENSE file for more info.
+web3swift is available under the MIT license. See the LICENSE file for more info.

web3swift.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
 s.name             = "web3swift"
-s.version          = "0.1.0"
+s.version          = "0.1.1"
 s.summary          = "Web3 implementation in vanilla Swift"
 
 s.description      = <<-DESC

web3swift/ABI/Classes/ABIDecoder.swift

@@ -193,3 +193,78 @@ extension ABIElement {
         }
     }
 }
+
+extension ABIElement {
+    func decodeReturnedLogs(_ eventLog: EventLog) -> [String:Any]? {
+        switch self {
+        case .constructor(_):
+            return nil
+        case .event(let event):
+            if event.anonymous {return nil}
+            if eventLog.topics[0] != event.topic {
+                return nil
+            }
+            var eventContent = [String: Any]()
+            eventContent["name"]=event.name
+            let logs = eventLog.topics
+            var j = 1
+            for i in 0 ..< event.inputs.count {
+                let el = event.inputs[i]
+                if el.indexed {
+                    let elementData = logs[j]
+                    j = j + 1
+                    let expectedType = el.type
+                    switch expectedType {
+                    case .staticType(let type):
+                        let decoded = type.decode(expectedType: type, data: elementData, tailPointer: BigUInt(0))
+                        guard let value = decoded.value, let _ = decoded.bytesConsumed else {break}
+                        let name = "\(i)"
+                        eventContent[name] = value
+                        if el.name != "" {
+                            eventContent[el.name] = value
+                        }
+                    case .dynamicType(let type):
+                        let decoded = type.decode(expectedType: type, data: elementData, tailPointer: BigUInt(0))
+                        guard let value = decoded.value, let _ = decoded.bytesConsumed else {break}
+                        let name = "\(i)"
+                        eventContent[name] = value
+                        if el.name != "" {
+                            eventContent[el.name] = value
+                        }
+                    }
+                } else {
+                    var dataForProcessing = eventLog.data
+                    var tailPointer = BigUInt(0)
+                    let expectedType = el.type
+                    switch expectedType {
+                    case .staticType(let type):
+                        let decoded = type.decode(expectedType: type, data: dataForProcessing, tailPointer: BigUInt(0))
+                        guard let value = decoded.value, let consumed = decoded.bytesConsumed else {break}
+                        let name = "\(i)"
+                        eventContent[name] = value
+                        if el.name != "" {
+                            eventContent[el.name] = value
+                        }
+                        dataForProcessing = Data(dataForProcessing[consumed...])
+                        tailPointer = tailPointer + BigUInt(consumed)
+                    case .dynamicType(let type):
+                        let decoded = type.decode(expectedType: type, data: dataForProcessing, tailPointer: tailPointer)
+                        guard let value = decoded.value, let consumed = decoded.bytesConsumed else {break}
+                        let name = "\(i)"
+                        eventContent[name] = value
+                        if el.name != "" {
+                            eventContent[el.name] = value
+                        }
+                        dataForProcessing = Data(dataForProcessing[consumed...])
+                        tailPointer = tailPointer + BigUInt(consumed)
+                    }
+                }
+            }
+            return eventContent
+        case .fallback(_):
+            return nil
+        case .function(_):
+            return nil
+        }
+    }
+}

web3swift/ABI/Classes/ABITypes.swift

@@ -31,6 +31,9 @@ public struct ABIRecord: Decodable {
     var anonymous: Bool?
 }
 
+public struct EventLogJSON {
+
+}
 
 // Native parsing
 
@@ -233,6 +236,17 @@ extension ABIElement.Function {
     }
 }
 
+// MARK: - Event topic
+extension ABIElement.Event {
+    public var signature: String {
+        return "\(name)(\(inputs.map { $0.type.abiRepresentation }.joined(separator: ",")))"
+    }
+
+    public var topic: Data {
+        return signature.data(using: .ascii)!.sha3(.keccak256)
+    }
+}
+
 protocol AbiEncoding {
     var abiRepresentation: String { get }
 }
@@ -284,3 +298,4 @@ extension ABIElement.ParameterType.DynamicType: AbiEncoding {
         }
     }
 }
+

web3swift/Contract/Classes/Contract.swift

@@ -25,6 +25,20 @@ public struct Contract {
         }
         return toReturn
     }
+    var events: [String: ABIElement] {
+        var toReturn = [String: ABIElement]()
+        for m in self._abi {
+            switch m {
+            case .event(let event):
+                let name = event.name
+                toReturn[name] = m
+            default:
+                continue
+            }
+        }
+        return toReturn
+    }
+
     var options: Web3Options? = Web3Options.defaultOptions()
     var chainID: BigUInt = BigUInt(1)
 
@@ -83,4 +97,14 @@ public struct Contract {
         let transaction = EthereumTransaction(nonce: nonce, gasPrice: gasPrice, gasLimit: gas, to: to, value: value, data: encodedData, v: chainID, r: BigUInt(0), s: BigUInt(0))
         return transaction
     }
+
+    public func parseEvent(_ eventLog: EventLog) -> (eventName:String?, eventData:[String:Any]?) {
+        for (eName, ev) in self.events {
+            let parsed = ev.decodeReturnedLogs(eventLog)
+            if parsed != nil {
+                return (eName, parsed!)
+            }
+        }
+        return (nil, nil)
+    }
 }

web3swift/Contract/Classes/Web3+Contract.swift

@@ -192,5 +192,9 @@ extension web3 {
             let intermediate = transactionIntermediate(transaction: tx, web3: self.web3, contract: self.contract, method: method, options: mergedOptions)
             return intermediate
         }
+
+        public func parseEvent(_ eventLog: EventLog) -> (eventName:String?, eventData:[String:Any]?) {
+            return self.contract.parseEvent(eventLog)
+        }
     }
 }

web3swift/Contract/Classes/Web3+Structures.swift

@@ -65,7 +65,7 @@ public struct TransactionReceipt {
     public var contractAddress: EthereumAddress?
     public var cumulativeGasUsed: BigUInt
     public var gasUsed: BigUInt
-    public var logs: [Data] = [Data]()
+    public var logs: [EventLog]
     public var status: TXStatus
 
     public enum TXStatus {
@@ -81,7 +81,7 @@ public struct TransactionReceipt {
         let ca = json["contractAddress"] as? String
         guard let cgu = json["cumulativeGasUsed"] as? String else {return nil}
         guard let gu = json["gasUsed"] as? String else {return nil}
-//        guard let ls = json["logs"] as? [String] else {return nil}
+        guard let ls = json["logs"] as? Array<[String:Any]> else {return nil}
         guard let st = json["status"] as? String else {return nil}
 
         transactionHash = h
@@ -97,11 +97,11 @@ public struct TransactionReceipt {
         cumulativeGasUsed = cguUnwrapped
         guard let guUnwrapped = BigUInt(gu.stripHexPrefix(), radix: 16) else {return nil}
         gasUsed = guUnwrapped
-        var allLogs = [Data]()
-//        for l in ls {
-//            let logData = Data(Array<UInt8>(hex: l.lowercased().stripHexPrefix()))
-//            allLogs.append(logData)
-//        }
+        var allLogs = [EventLog]()
+        for l in ls {
+            guard let log = EventLog(l) else {return nil}
+            allLogs.append(log)
+        }
         logs = allLogs
         if st == "0x1" {
             status = TXStatus.ok
@@ -111,3 +111,31 @@ public struct TransactionReceipt {
     }
 }
 
+public struct EventLog {
+    public var address: EthereumAddress
+    public var data: Data
+    public var logIndex: BigUInt
+    public var removed: Bool
+    public var topics: [Data]
+
+    public init? (_ json: [String: Any]) {
+        guard let ad = json["address"] as? String else {return nil}
+        guard let d = json["data"] as? String else {return nil}
+        guard let li = json["logIndex"] as? String else {return nil}
+        guard let rm = json["removed"] as? Int else {return nil}
+        guard let tpc = json["topics"] as? [String] else {return nil}
+        address = EthereumAddress(ad)
+        data = Data(Array<UInt8>(hex: d.lowercased().stripHexPrefix()))
+
+        guard let liUnwrapped = BigUInt(li.stripHexPrefix(), radix: 16) else {return nil}
+        logIndex = liUnwrapped
+        removed = rm == 1 ? true : false
+        var tops = [Data]()
+        for t in tpc {
+            let topic = Data(Array<UInt8>(hex: t.lowercased().stripHexPrefix()))
+            tops.append(topic)
+        }
+        topics = tops
+    }
+}
+