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CDDL to Swift

Generate Swift type definitions from CDDL as structs, typealiases and enums.

cddl2swift converts a parsed CDDL schema into Swift source code. Groups become structs, named assignments become typealiases, and choices become enums.

Install

Use the CLI:

npm install cddl2swift

Use the programmatic API:

npm install cddl cddl2swift

What It Generates

cddl2swift maps common CDDL constructs into idiomatic Swift, including:

  • named CDDL assignments to typealias declarations
  • groups to struct declarations
  • optional group fields to Swift optionals (T?)
  • arrays to [T]
  • record groups (*text => T) to [String: T]
  • string-literal choices to raw-value backed enums (enum X: String, Codable)
  • choices of named types to enums with associated values

It also normalizes names for Swift code by turning type names into PascalCase and field names into camelCase, escaping Swift keywords with backticks.

Because Swift has no structural union or intersection types, inline unions of more than one concrete type fall back to Any, and group mixins (unnamed group references) are flattened by inlining the referenced group's fields.

CLI

The CLI reads a CDDL file and writes generated Swift code to stdout, so the normal workflow is to redirect the output into a .swift file.

npx cddl2swift ./path/to/schema.cddl > ./Types.swift

Show help:

npx cddl2swift --help

Programmatic API

The package exports a single transform() function. It accepts the parsed CDDL AST and returns the generated Swift source as a string.

import { parse } from 'cddl'
import { transform } from 'cddl2swift'

const ast = parse('./schema.cddl')
const swift = transform(ast)

console.log(swift)

Example

Input CDDL:

person = {
  name: tstr,
  age: uint,
  ?nickname: tstr,
}

Generated Swift:

public struct Person {
    public var name: String
    public var age: Int
    public var nickname: String?
}

Notes

  • Generated files include a header comment with the cddl2swift version used.
  • The CLI validates that the input file exists before attempting to parse it.

If you want to contribute fixes or improvements, see the repository contributing guide.