BuildTool Plugin

Author: wickwirew

Package.swift

@@ -17,6 +17,7 @@ let package = Package(
         .library(name: "Otter", targets: ["Otter"]),
         .library(name: "Compiler", targets: ["Compiler"]),
         .executable(name: "OtterCLI", targets: ["OtterCLI"]),
+        .plugin(name: "OtterPlugin", targets: ["OtterPlugin"])
     ],
     dependencies: [
         .package(url: "https://github.com/swiftlang/swift-syntax", from: "600.0.0-latest"),
@@ -48,6 +49,7 @@ let package = Package(
                 .product(name: "OrderedCollections", package: "swift-collections"),
                 .product(name: "SwiftSyntax", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
+                "Yams",
             ]
         ),
 
@@ -56,9 +58,22 @@ let package = Package(
             dependencies: [
                 "Compiler",
                 .product(name: "ArgumentParser", package: "swift-argument-parser"),
-                "Yams",
             ]
         ),
+        
+        .plugin(
+            name: "OtterPlugin",
+            capability: .buildTool(),
+//            capability: .command(
+//                intent: .custom(
+//                    verb: "otter", description: "Generates the database queries"
+//                ),
+//                permissions: [
+//                    .writeToPackageDirectory(reason: "Writes the queries out to a swift file."),
+//                ]
+//            ),
+            dependencies: ["OtterCLI"]
+        ),
 
         .testTarget(
             name: "OtterTests",

PluginTests/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

PluginTests/Package.resolved

@@ -0,0 +1,18 @@
+// swift-tools-version: 6.1
+
+import PackageDescription
+
+let package = Package(
+    name: "PluginTests",
+    platforms: [.macOS(.v10_15)],
+    dependencies: [
+        .package(path: "../"),
+    ],
+    targets: [
+        .executableTarget(
+            name: "PluginTests",
+            dependencies: ["Otter"],
+            plugins: [.plugin(name: "OtterPlugin", package: "Otter")]
+        ),
+    ]
+)

PluginTests/Package.swift

@@ -0,0 +1 @@
+CREATE TABLE foo (bar INTEGER PRIMARY KEY AUTOINCREMENT);

PluginTests/Sources/Migrations/0.sql

@@ -0,0 +1,5 @@
+selectFoos:
+SELECT * FROM foo;
+
+insertFoo:
+INSERT INTO foo DEFAULT VALUES;

PluginTests/Sources/Queries/Foo.sql

@@ -0,0 +1,13 @@
+import Otter
+
+let db = try DB.inMemory()
+
+try await db.fooQueries.insertFoo.execute()
+try await db.fooQueries.insertFoo.execute()
+try await db.fooQueries.insertFoo.execute()
+
+let foos = try await db.fooQueries.selectFoos.execute()
+
+for foo in foos {
+    print(foo.bar)
+}

PluginTests/Sources/main.swift

@@ -0,0 +1,3 @@
+databaseName: DB
+migrations: Sources/Migrations
+queries: Sources/Queries

PluginTests/otter.yaml

@@ -0,0 +1,44 @@
+//
+//  OtterPlugin.swift
+//  Otter
+//
+//  Created by Wes Wickwire on 8/11/25.
+//
+
+import PackagePlugin
+
+@main
+struct OtterPlugin: BuildToolPlugin {
+    func createBuildCommands(
+        context: PluginContext,
+        target: Target
+    ) throws -> [Command] {
+        guard target is SourceModuleTarget else { return [] }
+        
+        let sourceRoot = context.package.directoryURL.absoluteString
+        
+        let queries = context.pluginWorkDirectoryURL
+            .appending(component: "Queries.swift")
+        
+        let inputFiles = target.sourceModule?.sourceFiles
+            .filter { $0.url.pathExtension == "sql" }
+            .map(\.url)
+        
+        return [
+            .buildCommand(
+                displayName: "Running otter generate",
+                executable: try context.tool(named: "OtterCLI").url,
+                arguments: [
+                    "generate",
+                    "--path",
+                    sourceRoot,
+                    "--override-output",
+                    queries.absoluteString,
+                    "--skip-directory-create"
+                ],
+                inputFiles: inputFiles ?? [],
+                outputFiles: [queries]
+            )
+        ]
+    }
+}

Plugins/OtterPlugin/OtterPlugin.swift

@@ -0,0 +1,48 @@
+//
+//  Config.swift
+//  Otter
+//
+//  Created by Wes Wickwire on 8/5/25.
+//
+
+import Foundation
+import Yams
+
+public struct Config: Codable {
+    public let queries: String
+    public let migrations: String
+    public let output: String?
+    public let databaseName: String?
+    public let additionalImports: [String]?
+    
+    struct NotFoundError: Error, CustomStringConvertible {
+        var description: String { "Config does not exist" }
+    }
+    
+    public init(at path: String) throws {
+        var url = URL(fileURLWithPath: path)
+        
+        if url.lastPathComponent != "otter.yaml" {
+            url.appendPathComponent("otter.yaml")
+        }
+        
+        guard FileManager.default.fileExists(atPath: url.path) else {
+            throw NotFoundError()
+        }
+        
+        let data = try Data(contentsOf: url)
+        
+        let decoder = YAMLDecoder()
+        self = try decoder.decode(Config.self, from: data)
+    }
+    
+    public func project(at path: String) -> Project {
+        let url = URL(fileURLWithPath: path)
+        
+        return Project(
+            generatedOutputFile: url.appendingPathComponent(output ?? "Queries.swift"),
+            migrationsDirectory: url.appendingPathComponent(migrations),
+            queriesDirectory: url.appendingPathComponent(queries)
+        )
+    }
+}