90 lines
3.0 KiB
Swift
90 lines
3.0 KiB
Swift
//
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// ViewBuilder.swift
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// Meta
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//
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// Created by david-swift on 26.05.24.
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//
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import Foundation
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/// The ``ViewBuilder`` is a result builder for views.
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@resultBuilder
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public enum ViewBuilder {
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/// A component used in the ``ViewBuilder``.
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public enum Component {
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/// A view as a component.
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case element(_: AnyView)
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/// An array of components as a component.
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case components(_: [Self])
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}
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/// Build combined results from statement blocks.
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/// - Parameter elements: The components.
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/// - Returns: The components in a component.
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public static func buildBlock(_ elements: Component...) -> Component {
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.components(elements)
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}
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/// Translate an element into a ``ViewBuilder/Component``.
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/// - Parameter element: The element to translate.
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/// - Returns: A component created from the element.
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public static func buildExpression(_ element: AnyView) -> Component {
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.element(element)
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}
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/// Translate an array of elements into a ``ViewBuilder/Component``.
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/// - Parameter elements: The elements to translate.
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/// - Returns: A component created from the element.
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public static func buildExpression(_ elements: [AnyView]) -> Component {
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var components: [Component] = []
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for element in elements {
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components.append(.element(element))
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}
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return .components(components)
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}
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/// Fetch a component.
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/// - Parameter component: A component.
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/// - Returns: The component.
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public static func buildExpression(_ component: Component) -> Component {
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component
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}
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/// Enables support for `if` statements without an `else`.
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/// - Parameter component: An optional component.
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/// - Returns: A nonoptional component.
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public static func buildOptional(_ component: Component?) -> Component {
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.element(DummyEitherView(condition: component != nil, view1: buildFinalResult(component ?? .element([]))))
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}
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/// Enables support for `if`-`else` and `switch` statements.
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/// - Parameter component: A component.
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/// - Returns: The component.
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public static func buildEither(first component: Component) -> Component {
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.element(DummyEitherView(condition: true, view1: buildFinalResult(component)))
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}
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/// Enables support for `if`-`else` and `switch` statements.
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/// - Parameter component: A component.
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/// - Returns: The component.
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public static func buildEither(second component: Component) -> Component {
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.element(DummyEitherView(condition: false, view2: buildFinalResult(component)))
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}
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/// Convert a component to an array of elements.
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/// - Parameter component: The component to convert.
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/// - Returns: The generated array of elements.
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public static func buildFinalResult(_ component: Component) -> Body {
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switch component {
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case let .element(element):
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return [element]
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case let .components(components):
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return components.flatMap { buildFinalResult($0) }
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}
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}
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}
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