Espresso Cash

The solana package is a comprehensive Dart library for interacting with the Solana blockchain. It provides a complete implementation of the JSON RPC API and a subscription client.

Key capabilities include:

• Program Support: Built-in implementations for System Program, Token Program, Memo Program, Stake Program, and Associated Token Account Program.
• Key Management: Support for Hierarchical Deterministic (HD) derivation, BIP39 seed phrases, and raw private key bytes.
• Transaction Management: Encoding, signing, and building transactions (including offline support). It includes convenience methods to sign and send transactions and listen for signature status changes (e.g., waiting for confirmed or finalized states).
• NFT Support: Decoding Metaplex NFT metadata.
• Subscriptions: Full support for the JSON RPC subscription variant of the API.

To implement Borsh serialization and deserialization for Dart classes, use the borsh and borsh_annotation packages.

• borsh_annotation provides the annotations required to mark classes for serialization.
• borsh acts as the code generator that processes these annotations to produce the necessary serialization logic.

For developers building Solana DApps or wallets on mobile, the repository provides two complementary packages:

• solana_mobile_wallet: Use this if you are implementing a wallet. It serves as a reference implementation of the Solana Mobile Wallet Adapter spec and includes a Fake Wallet example.
• solana_mobile_client: Use this if you are building a DApp. It is the client-side implementation for interacting with wallets via MWA and includes a Fake DApp example.

You can extend the library by adding new programs. The convention is to create a new subdirectory under lib/src/programs/ named ${program_name}_program.

Each new program should contain at least two files:

1. ${program_name}_program.dart: Contains factory constructors that build messages with one or more instructions.
2. ${program_name}_instructions.dart: Contains factory constructors for single instructions.

Additional files may be added to separate code from definitions if necessary.

Espresso Cash uses a BLoC-inspired architecture designed with Functional Programming principles in mind.

Key architectural characteristics:

• BLoCs: Act as pure business-logic components.
• Immutability: All states and events are implemented as immutable freezed classes.
• Module Hierarchy:
  • core: Contains core feature modules that other modules can depend on.
  • features: Contains feature-specific modules. Features can depend on core, but should avoid depending on other features to maintain decoupling.
  • l10n: Handles localization and internationalization.
  • app: Contains the main app screens and serves as the minimal entrypoint to the various features.

To add a missing RPC method or update an outdated one, you must modify the abstract class in lib/src/rpc/client.dart.

Steps for adding a method:

1. Add the method definition to the abstract class in lib/src/rpc/client.dart using standard Dart syntax.
2. If the method requires new parameter or response types, define those classes in the lib/src/rpc/dto/ directory.
3. Rebuild the package; the implementation for the new method will be automatically generated.

For deletions, simply remove the method from the abstract class.

Add solana_mobile_client to your pubspec.yaml dependencies to integrate Solana Mobile features into your Flutter app.

dependencies:
  solana_mobile_client: ^<latest_version>