adwaita-swift/Sources/Adwaita/Model/ArrayBuilder.swift
2023-09-12 08:17:52 +02:00

116 lines
3.6 KiB
Swift

//
// ArrayBuilder.swift
// Adwaita
//
// Created by david-swift on 05.08.23.
//
// Thanks to Jaden Geller for the GitHub Gist:
// "ArrayBuilder.swift"
// https://gist.github.com/JadenGeller/c375fc15ad5900a0ddac4ed8ba8307a9
//
import Foundation
/// The ``ArrayBuilder`` is a simple result builder that outputs an array of any type.
///
/// You can define any array using Swift's DSL:
/// ```swift
/// @ArrayBuilder<String> var string: [String] {
/// "Hello, "
/// if bool {
/// "world!"
/// } else {
/// "colibri!"
/// }
/// for x in 0...10 {
/// "\nIteration Number \(x)"
/// }
/// }
/// ```
@resultBuilder
public enum ArrayBuilder<Element> {
/// A component used in the ``ArrayBuilder``.
public enum Component {
/// An element as a component.
case element(_: Element)
/// An array of components as a component.
case components(_: [Self])
}
/// Build combined results from statement blocks.
/// - Parameter components: The components.
/// - Returns: The components in a component.
public static func buildBlock(_ elements: Component...) -> Component {
.components(elements)
}
/// Translate an element into an ``ArrayBuilder.Component``.
/// - Parameter element: The element to translate.
/// - Returns: A component created from the element.
public static func buildExpression(_ element: Element) -> Component {
.element(element)
}
/// Translate an array of elements into an ``ArrayBuilder.Component``.
/// - Parameter elements: The elements to translate.
/// - Returns: A component created from the element.
public static func buildExpression(_ elements: [Element]) -> Component {
var components: [Component] = []
for element in elements {
components.append(.element(element))
}
return .components(components)
}
/// Fetch a component.
/// - Parameter component: A component.
/// - Returns: The component.
public static func buildExpression(_ component: Component) -> Component {
component
}
/// Enables support for `if` statements without an `else`.
/// - Parameter component: An optional component.
/// - Returns: A nonoptional component.
public static func buildOptional(_ component: Component?) -> Component {
component ?? .components([])
}
/// Enables support for `if`-`else` and `switch` statements.
/// - Parameter component: A component.
/// - Returns: The component.
public static func buildEither(first component: Component) -> Component {
component
}
/// Enables support for `if`-`else` and `switch` statements.
/// - Parameter component: A component.
/// - Returns: The component.
public static func buildEither(second component: Component) -> Component {
component
}
/// Enables support for `for..in` loops.
/// - Parameter components: The components as a two dimensional array.
/// - Returns: The components as a one dimensional array.
public static func buildArray(_ components: [Component]) -> Component {
.components(components)
}
/// Convert a component to an array of elements.
/// - Parameter component: The component to convert.
/// - Returns: The generated array of elements.
public static func buildFinalResult(_ component: Component) -> [Element] {
switch component {
case let .element(element):
return [element]
case let .components(components):
return components.flatMap { buildFinalResult($0) }
}
}
}