web3_universal_abi 0.1.1

Ethereum Contract ABI encoding and decoding for Web3 Universal SDK.

dart_web3_abi

A type-safe ABI codec for Ethereum contract interaction. Encodes and decodes Solidity types with precision and full compliance with the Ethereum ABI specification.

🚀 Features

• Full Type Support: Handles uint8-256, int8-256, address, bool, bytes1-32, and string.
• Dynamic Arrays: Support for variable length types and complex nested arrays.
• ABI v2 (Tuples): Full recursive support for structs and nested tuple objects.
• Event Logs: Specialized decoders for indexing and parsing block log topics.

Usage Flow

graph TD
    A[ABI JSON] --> B[Parser]
    B --> C[Encoder/Decoder]
    C --> D[Bytecode]

Encoding Flow

sequenceDiagram
    participant D as Developer
    participant E as Encoder
    participant B as Bytes
    D->>E: encode(types, values)
    E->>E: padding & alignment
    E->>B: generate
    B-->>D: payload

🏗️ Architecture

graph TD
    JSON[JSON ABI String] --> Parser[AbiParser]
    Parser --> Model[AbiDefinition]
    
    subgraph Execution [Codec Engine]
        Encoder[Encoder]
        Decoder[Decoder]
    end
    
    Model --> Encoder
    Model --> Decoder
    Encoder --> Bytes[Contract Data]
    Bytes --> Decoder

📚 Technical Reference

Core Classes

Class	Responsibility
AbiFunction	Logic for encoding method selector and parameters.
AbiEvent	Logic for parsing log topics and data into objects.
ContractAbi	A container for all functions and events in a smart contract.
AbiType	Abstract base for individual codec logic (UintType, AddressType, etc.).

🛡️ Security Considerations

• Overflow Validation: The encoder checks if provided values fit within the specific bit-width (e.g., uint8). Always handle the ArgumentError if your data sources are untrusted.
• Selector Collisions: Be aware that different function signatures can result in the same 4-byte selector. The SDK strictly validates against the Provided ABI.
• Malformed Inputs: The decoder uses safe-padding checks to prevent buffer overflow attacks from malicious RPC responses.

💻 Usage

Decoding Event Logs

import 'package:dart_web3_abi/dart_web3_abi.dart';

void main() {
  final transferEvent = AbiEvent(
    name: 'Transfer',
    params: [
      AbiParameter('from', 'address', indexed: true),
      AbiParameter('to', 'address', indexed: true),
      AbiParameter('value', 'uint256', indexed: false),
    ],
  );

  final decoded = transferEvent.decode(
    topics: ['0x...', '0x...', '0x...'],
    data: '0x0000000000000000000000000000000000000000000000000000000005f5e100',
  );
  
  print('Value: ${decoded['value']}');
}

📦 Installation

dependencies:
  dart_web3_abi: ^0.1.0