Swift Contract Extraction

Overview

The Swift extractor scans a package directory for .swift files and uses tree-sitter-swift to parse them. It identifies classes, structs, enums, protocols, actors, and free functions, extracting only public and open declarations.

API

from goga.contract.swift import swift_contract

contracts = swift_contract("path/to/package")
# Returns list[EntityContract | RoutineContract]

swift_contract accepts a path to a Swift package directory. Returns an empty list if no .swift files are found.

What Gets Extracted

Source Construct	Contract Type	Notes
public class X { ... }	EntityContract	Init params form signature
public struct X { ... }	EntityContract	Same handling as class
public actor X { ... }	EntityContract	Same handling as class
public enum X { ... }	EntityContract	Enum cases become properties
public protocol X { ... }	EntityContract	Protocol method requirements collected
public func x() -> T	RoutineContract	Top-level public functions

Visibility Rules

• Only public and open declarations are included
• internal (default) and private declarations are excluded
• Extensions are skipped entirely
• Non-public initializers are ignored (entity signature falls back to ())

Key Node Types

The parser walks these tree-sitter node types:

• class_declaration -- class, struct, actor, and enum declarations (distinguished by declaration_kind)
• protocol_declaration -- protocol declarations
• function_declaration -- free functions and type member functions
• property_declaration -- stored and computed properties
• init_declaration -- designated and failable initializers
• enum_entry -- enum cases

Example

Given a Swift file Server.swift:

public class Server {
    public init(host: String, port: Int) {}
    public func start() -> Bool { return true }
    public var name: String = ""
}

public func greet(name: String) -> String {
    return name
}

The extracted contracts are:

Name	Type	Signature
Server	EntityContract	(host: String, port: Int)
greet	RoutineContract	(name: String) -> String

Server has one property (name: String) and one method (start() -> Bool).

External Parameter Names

Swift's external parameter names are preserved in signatures:

public func configure(with host: String, port: Int) {}

Extracted signature: (with host: String, port: Int)