Re-implement @TextBuilder as macro

.github/workflows/ci.yml

@@ -23,8 +23,10 @@ jobs:
       matrix:
         platform:
           - iOS
+          - mac-catalyst
           - macOS
           - tvOS
+          - visionOS
           - watchOS
         swift:
           - "6.0"
@@ -39,14 +41,20 @@ jobs:
         with:
           swift: ~${{ matrix.swift }}
           action: none
+          verbosity: xcbeautify
 
-      - if: matrix.platform != 'macOS'
+      - if: matrix.platform != 'mac-catalyst' && matrix.platform != 'macOS'
         name: Download Required Runtime
         run: xcodebuild -downloadPlatform ${{ matrix.platform }}
 
-      - uses: mxcl/xcodebuild@v3
+      - if: matrix.platform != 'mac-catalyst' && matrix.platform != 'macOS'
+        name: List Available Simulators
+        run: xcrun simctl list devices
+
+      - name: Run Tests
+        uses: mxcl/xcodebuild@v3
         with:
           swift: ~${{ matrix.swift }}
           platform: ${{ matrix.platform }}
-          scheme: TextBuilder
           action: test
+          verbosity: xcbeautify

.gitignore

@@ -5,3 +5,4 @@
 /*.xcodeproj
 xcuserdata/
 DerivedData/
+*.xcresult

Package.swift

@@ -1,5 +1,6 @@
-// swift-tools-version:6.0
+// swift-tools-version: 6.0
 
+import CompilerPluginSupport
 import PackageDescription
 
 let package = Package(
@@ -16,12 +17,23 @@ let package = Package(
 	targets: [
 		.target(name: "TextBuilder", dependencies: [
 			.product(name: "Builders", package: "swift-builders"),
+			"TextBuilderMacro",
 		]),
 		.testTarget(name: "TextBuilderTests", dependencies: [
 			.product(name: "CustomDump", package: "swift-custom-dump"),
 			.target(name: "TextBuilder"),
 		]),
 
+		.macro(name: "TextBuilderMacro", dependencies: [
+			.product(name: "SwiftSyntax", package: "swift-syntax"),
+			.product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
+			.product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
+		]),
+		.testTarget(name: "TextBuilderMacroTests", dependencies: [
+			"TextBuilderMacro",
+			.product(name: "MacroTesting", package: "swift-macro-testing"),
+		]),
+
 		.executableTarget(name: "Benchmarks", dependencies: [
 			.product(name: "Benchmark", package: "swift-benchmark"),
 			.target(name: "TextBuilder"),
@@ -33,4 +45,15 @@ package.dependencies = [
 	.package(url: "https://github.com/google/swift-benchmark", from: "0.1.2"),
 	.package(url: "https://github.com/davdroman/swift-builders", from: "0.10.0"),
 	.package(url: "https://github.com/pointfreeco/swift-custom-dump", from: "1.0.0"),
+
+	.package(url: "https://github.com/pointfreeco/swift-macro-testing", from: "0.6.0"),
+	.package(url: "https://github.com/swiftlang/swift-syntax", "600.0.0"..<"603.0.0"),
 ]
+
+for target in package.targets {
+	target.swiftSettings = target.swiftSettings ?? []
+	target.swiftSettings? += [
+		.enableUpcomingFeature("ExistentialAny"),
+		.enableUpcomingFeature("InternalImportsByDefault"),
+	]
+}

Sources/Benchmarks/main.swift

@@ -3,7 +3,7 @@ import SwiftUI
 import TextBuilder
 
 benchmark("Result Builder") {
-	@TextBuilderWithSpaces
+	@TextBuilder(separator: " ")
 	func complexTextBuilderText() -> Text {
 		"Lorem".text.underline().foregroundColor(.blue)
 		if false {

Sources/TextBuilder/TextBuilder.swift

@@ -1,81 +1,45 @@
-import SwiftUI
+public import SwiftUI
 
-/// A custom attribute that constructs combined text views.
+/// A body macro that lets you build a single `SwiftUI.Text` from multiple parts using a builder-style closure. Write
+/// `Text` fragments and string-like values across multiple lines, and they will be concatenated into one `Text`,
+/// optionally inserting a separator between items.
 ///
-/// You can use ``TextBuilder`` as an attribute for text-producing properties
-/// or function parameters, allowing them to provide combined text views. For example,
-/// the following `loremIpsum` property will create a single styled text view with each
-/// text separated using eggplant emoji.
+/// ## Behavior
+/// - Empty bodies produce `Text(verbatim: "")`.
+/// - You can mix `Text` values and string-like values (e.g., string literals, `String`, results of `String(i)`, etc.).
+///   These string values are treated as verbatim text.
+/// - Control flow is supported: `if`/`else`, `if let`, and `for` loops can conditionally emit or repeat parts.
+/// - Modifiers applied to individual segments (e.g., `.bold()`, `.underline()`, `.foregroundColor(_:)`) are preserved
+///   for those segments.
+/// - When a separator is provided, it is inserted between emitted segments, not before the first or after the last one.
 ///
-///     struct EggplantSeparator: TextBuilderSeparator {
-///         static var separator: String? { " 🍆 " }
-///     }
+/// ## Example
+/// ```swift
+/// @TextBuilder(separator: " ")
+/// func message() -> Text {
+///     Text("Hello").bold()
+///     "world, the year is"
+///     String(2025)
+/// }
+/// ```
 ///
-///     @TextBuilder<EggplantSeparator>
-///     var loremIpsum: Text {
-///         Text("Lorem").underline().foregroundColor(.blue)
-///         Text("ipsum dolor")
-///         Text("sit").bold()
-///         Text("amet, consectetur")
-///     }
-///
-@resultBuilder
-public struct TextBuilderWith<Separator: TextBuilderSeparator> {
-	@inlinable
-	public static func buildPartialBlock(first: Text?) -> Text? {
-		first
-	}
-
-	@inlinable
-	public static func buildPartialBlock(accumulated: Text?, next: Text?) -> Text? {
-		guard let next else {
-			return accumulated
-		}
-		guard let accumulated else {
-			return next
-		}
-		guard let separator = Separator.separator else {
-			return accumulated + next
-		}
-		return accumulated + Text(separator) + next
-	}
-
-	public static func buildArray(_ components: [Text?]) -> Text? {
-		components.lazy.compactMap { $0 }.joined(separator: Separator.separator.map { Text($0) })
-	}
-
-	@inlinable
-	public static func buildEither(first component: Text?) -> Text? {
-		component
-	}
-
-	@inlinable
-	public static func buildEither(second component: Text?) -> Text? {
-		component
-	}
-
-	@inlinable
-	public static func buildExpression(_ string: some StringProtocol) -> Text? {
-		Text(string)
-	}
-
-	@inlinable
-	public static func buildExpression(_ component: Text) -> Text? {
-		component
-	}
-
-	@inlinable
-	public static func buildLimitedAvailability(_ component: Text?) -> Text? {
-		component
-	}
-
-	@inlinable
-	public static func buildOptional(_ component: Text??) -> Text? {
-		component ?? nil
-	}
+/// ## Notes
+/// - The expansion relies on the ``Text.init(separator:default:content:)-(Text?,_,_)`` builder-style API that is
+///   included as part of this package, which performs concatenation and separator insertion.
+/// - Apply `@TextBuilder` to functions that return `Text`.
+/// - Applying `@TextBuilder` to computed properties that return `Text` is currently unsupported due to limitations in
+///   Swift. See https://github.com/swiftlang/swift/issues/75715 for details.
+@attached(body)
+public macro TextBuilder(separator: Text? = nil) = #externalMacro(
+	module: "TextBuilderMacro",
+	type: "TextBuilderMacro"
+)
+
+/// Convenience overload that accepts any `StringProtocol` as the separator, which is treated as verbatim text
+/// (equivalent to `Text(verbatim: separator)`).
+@attached(body)
+public macro TextBuilder<Separator: StringProtocol>(separator: Separator) = #externalMacro(
+	module: "TextBuilderMacro",
+	type: "TextBuilderMacro"
+)
 
-	@inlinable
-	public static func buildFinalResult(_ component: Text?) -> Text {
-		component ?? .empty
-	}
-}