Add URITemplate freestanding expression macro

.spi.yml

@@ -1,4 +1,4 @@
 version: 1
 builder:
   configs:
-    - documentation_targets: [ScreamURITemplate]
+    - documentation_targets: [ScreamURITemplate, ScreamURITemplateMacros]

Package.swift

@@ -1,25 +1,44 @@
 // swift-tools-version: 6.0
 
+import CompilerPluginSupport
 import PackageDescription
 
 let package = Package(
     name: "ScreamURITemplate",
+    platforms: [.macOS(.v13)],
     products: [
         .library(
             name: "ScreamURITemplate",
             targets: ["ScreamURITemplate"]),
+        .library(
+            name: "ScreamURITemplateMacros",
+            targets: ["ScreamURITemplateMacros"]),
     ],
     dependencies: [
         .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.0.0"),
+        .package(url: "https://github.com/apple/swift-syntax", from: "600.0.1"),
     ],
     targets: [
         .target(
             name: "ScreamURITemplate",
-            dependencies: [],
             resources: [.process("PrivacyInfo.xcprivacy")]),
+        .target(
+            name: "ScreamURITemplateMacros",
+            dependencies: ["ScreamURITemplate", "ScreamURITemplateCompilerPlugin"]),
+        .macro(
+            name: "ScreamURITemplateCompilerPlugin",
+            dependencies: [
+                .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
+                .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
+                "ScreamURITemplate",
+            ]),
         .testTarget(
             name: "ScreamURITemplateTests",
-            dependencies: ["ScreamURITemplate"],
+            dependencies: [
+                .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
+                .product(name: "SwiftSyntaxMacrosTestSupport", package: "swift-syntax"),
+                "ScreamURITemplate",
+                "ScreamURITemplateMacros"],
             exclude: [
                 "data/uritemplate-test/json2xml.xslt",
                 "data/uritemplate-test/LICENSE",
@@ -35,6 +54,6 @@ let package = Package(
             ]),
         .executableTarget(
             name: "ScreamURITemplateExample",
-            dependencies: ["ScreamURITemplate"]),
+            dependencies: ["ScreamURITemplate", "ScreamURITemplateMacros"]),
     ],
     swiftLanguageModes: [.v6])

Sources/ScreamURITemplateCompilerPlugin/URITemplateCompilerPlugin.swift

@@ -0,0 +1,21 @@
+//   Copyright 2018-2024 Alex Deem
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+
+import SwiftCompilerPlugin
+import SwiftSyntaxMacros
+
+@main
+struct URITemplateCompilerPlugin: CompilerPlugin {
+    var providingMacros: [Macro.Type] = [URITemplateMacro.self]
+}

Sources/ScreamURITemplateCompilerPlugin/URITemplateMacro.swift

@@ -0,0 +1,49 @@
+//   Copyright 2018-2024 Alex Deem
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+
+import SwiftCompilerPlugin
+import SwiftDiagnostics
+import SwiftSyntax
+import SwiftSyntaxMacros
+
+import ScreamURITemplate
+
+public struct URITemplateMacro: ExpressionMacro {
+    public static func expansion(
+        of node: some FreestandingMacroExpansionSyntax,
+        in _: some MacroExpansionContext) throws -> ExprSyntax {
+        guard let argument = node.arguments.first?.expression,
+              let segments = argument.as(StringLiteralExprSyntax.self)?.segments,
+              segments.count == 1,
+              case let .stringSegment(literalSegment)? = segments.first
+        else {
+            throw DiagnosticsError(diagnostics: [
+                Diagnostic(node: node,
+                           message: MacroExpansionErrorMessage("#URITemplate requires a static string literal")),
+            ])
+        }
+
+        let uriTemplateString = literalSegment.content.text
+        do {
+            _ = try URITemplate(string: uriTemplateString)
+        } catch {
+            throw DiagnosticsError(diagnostics: [
+                Diagnostic(node: literalSegment,
+                           message: MacroExpansionErrorMessage("Invalid URI template: \(error.reason) at \"\(uriTemplateString.suffix(from: error.position).prefix(50))\"")),
+            ])
+        }
+
+        return "try! URITemplate(string: \(argument))"
+    }
+}

Sources/ScreamURITemplateExample/main.swift

@@ -14,6 +14,7 @@
 
 import Foundation
 import ScreamURITemplate
+import ScreamURITemplateMacros
 
 let template = try URITemplate(string: "https://api.github.com/repos/{owner}/{repo}/collaborators/{username}")
 let variables = [
@@ -27,3 +28,6 @@ let urlString = try template.process(variables: variables)
 let url = URL(string: urlString)!
 print("Expanding \(template)\n     with \(variables):\n")
 print(url.absoluteString)
+
+let macroExpansion = #URITemplate("https://api.github.com/repos/{owner}/{repo}/collaborators/{username}")
+print(macroExpansion)

Sources/ScreamURITemplateMacros/Macros.swift

@@ -0,0 +1,26 @@
+//   Copyright 2018-2024 Alex Deem
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+
+import ScreamURITemplate
+
+/// Macro providing compile-time validation of a URITemplate represented by a string literal
+/// Example:
+/// ```swift
+/// let template = #URITemplate("https://api.github.com/repos/{owner}")
+/// ```
+/// - Parameters:
+///   - : A string literal representing the URI Template
+/// - Returns: A `URITemplate` constructed from the string literal
+@freestanding(expression)
+public macro URITemplate(_ stringLiteral: StaticString) -> URITemplate = #externalMacro(module: "ScreamURITemplateCompilerPlugin", type: "URITemplateMacro")

Tests/ScreamURITemplateTests/MacroTests.swift

@@ -0,0 +1,71 @@
+//   Copyright 2018-2024 Alex Deem
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+
+import ScreamURITemplateCompilerPlugin
+import SwiftSyntaxMacros
+import SwiftSyntaxMacrosTestSupport
+
+import XCTest
+
+class MacroTests: XCTestCase {
+    let testMacros: [String: Macro.Type] = [
+        "URITemplate": URITemplateMacro.self
+    ]
+
+    func testValidURITemplateMacro() throws {
+        assertMacroExpansion(
+            #"""
+            #URITemplate("https://api.github.com/repos/{owner}")
+            """#,
+            expandedSource:
+            #"""
+            try! URITemplate(string: "https://api.github.com/repos/{owner}")
+            """#,
+            diagnostics: [],
+            macros: testMacros)
+    }
+
+    func testInvalidURITemplateMacro() throws {
+        assertMacroExpansion(
+            #"""
+            #URITemplate("https://api.github.com/repos/{}/{repo}")
+            """#,
+            expandedSource:
+            #"""
+            #URITemplate("https://api.github.com/repos/{}/{repo}")
+            """#,
+            diagnostics: [
+                DiagnosticSpec(message: "Invalid URI template: Empty Variable Name at \"}/{repo}\"", line: 1, column: 15)
+            ],
+            macros: testMacros)
+    }
+
+    func testMisusedURITemplateMacro() throws {
+        assertMacroExpansion(
+            #"""
+            let s: StaticString = "https://api.github.com/repos/{owner}"
+            #URITemplate(s)
+            """#,
+            expandedSource:
+            #"""
+            let s: StaticString = "https://api.github.com/repos/{owner}"
+            #URITemplate(s)
+            """#,
+            diagnostics: [
+                DiagnosticSpec(message: "#URITemplate requires a static string literal", line: 2, column: 1)
+            ],
+            macros: testMacros)
+    }
+
+}