Build Text instances in a declarative manner, similar to regular views, from Text and Image. This ensures the font’s kerning, ligatures, and other properties are preserved across the entire text.

TextBuilder.swift

//
//  TextBuilder.swift
//  SemanticalKit
//
//  Created by Valentin Walter on 14.02.23.
//

import SwiftUI

/// Build Text instances in a declarative manner, similar to regular views, from
/// Text and Image. This ensures the font’s kerning, ligatures, and other
/// properties are preserved across the entire text.
///
/// Example
///
/// ```swift
/// Text {
///     for index in 0..<10 {
///         Image(systemName: "\(index).circle")
///             .foregroundStyle(.secondary)
///     }
///
///     if showLabel {
///         Text(label)
///             .font(.headline)
///     }
/// }
/// ```
///
@resultBuilder
public struct TextBuilder {
    public typealias Component = [Text]
    
    @inlinable
    public static func buildPartialBlock(first: Component) -> Component {
        first
    }
    
    @inlinable
    public static func buildPartialBlock(accumulated: Component, next: Component) -> Component {
        accumulated + next
    }
    
    @inlinable
    public static func buildArray(_ components: [Component]) -> Component {
        components.flatMap(\.self)
    }
    
    @inlinable
    public static func buildEither(first component: Component) -> Component {
        component
    }
    
    @inlinable
    public static func buildEither(second component: Component) -> Component {
        component
    }
    
    @inlinable
    public static func buildOptional(_ component: Component?) -> Component {
        component ?? []
    }
    
    @inlinable
    public static func buildExpression(_ image: Image) -> Component {
        [Text("\(image)")]
    }
    
    @inlinable
    public static func buildExpression(_ text: Text) -> Component {
        [text]
    }
    
    @inlinable
    public static func buildFinalResult(_ component: Component) -> Component {
        component
    }
    
    @inlinable
    public static func buildFinalResult(_ component: Component) -> Text {
        component.dropFirst().reduce(component.first ?? Text(""), +)
    }
}

// MARK: - Text+

extension Text {
    /// Build `Text` instances in a declarative manner, similar to regular
    /// views, from `Text` and `Image`. This ensures the font's kerning,
    /// ligatures, and other properties are preserved across the entire text.
    ///
    /// Example
    ///
    /// ```swift
    /// Text {
    ///     for index in 0..<10 {
    ///         Image(systemName: "\(index).circle")
    ///             .foregroundStyle(.secondary)
    ///     }
    ///
    ///     if showLabel {
    ///         Text(label)
    ///             .font(.headline)
    ///     }
    /// }
    /// ```
    ///
    public init(separator: String = "", @TextBuilder content: () -> [Text]) {
        let texts = content()
        self = texts.dropFirst().reduce(texts.first) {
            if let partialResult = $0 {
                partialResult + Text(separator) + $1
            } else {
                nil
            }
        } ?? Text("")
    }
    
    public init(
        @TextBuilder content: () -> [Text],
        @TextBuilder separator: () -> Text,
    ) {
        let texts = content()
        self = texts.dropFirst().reduce(texts.first) {
            if let partialResult = $0 {
                partialResult + separator() + $1
            } else {
                nil
            }
        } ?? Text("")
    }
}

// MARK: - Image+

extension Image {
    @inlinable
    public func foregroundStyle(_ style: some ShapeStyle) -> Text {
        Text("\(self)").foregroundStyle(style)
    }
    
    @inlinable
    public func font(_ font: Font) -> Text {
        Text("\(self)").font(font)
    }
}

// MARK: - Previews

#Preview {
    let showLabel = true
    return Text {
        for index in 0..<4 {
            Image(systemName: "\(index).circle")
                .foregroundStyle(.secondary)
        }
        
        Text(" ")
        
        if showLabel {
            Text("Label")
                .font(.headline)
        }
    }
}