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Pol Piella Abadia - 04/07/2022
Code generation using Swift
Package Plugins
π NSManchester π
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Letβs get started! π
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Letβs get started! π - Context
β’ A new package exposes a protocol - very similar to decodable.
β’ Many features implement types which conform to it. New package decodes these types
from data.
β’ A fallback json
fi
le is shipped with the app. It must always work with all models.
β’ Decoding errors are all runtime and would cause issues when certain screens are accessed.
β’ We gained con
fi
dence by testing, but doing this manually is not very scalableβ¦
β’ Very di
ff
i
cult to automate at the time as we have a mix of Swift Packages and Xcode projects.
β’ Xcode 14 will allow us to use plugins for Xcode projects too! π
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Letβs get started! π - Specifics
β’ A build tool Swift Package Plugin.
β’ Uses SourceKitten (SourceKit under the hood) to
fi
nd all types conforming to
a speci
fi
c protocol.
β’ Automatically generates tests for each type which conforms to such protocol.
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swift package init π»
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: ["CodeGenSample"]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π Tests
π CodeGenSampleTests
Empty.swift
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The executable π
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The executable π
Scan target for Swift Files
π
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The executable π
Extract types conforming to the
protocol
π
Scan target for Swift Files
π
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The executable π
Extract types conforming to the
protocol
π
Generate a XCTestCase
π¨
Scan target for Swift Files
π
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: ["CodeGenSample"]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
.package(url: "https://github.com/jpsim/SourceKitten.git", exact: "0.32.0"),
.package(url: "https://github.com/apple/swift-argument-parser", from: "1.0.0")
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: ["CodeGenSample"]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
.package(url: "https://github.com/jpsim/SourceKitten.git", exact: "0.32.0"),
.package(url: "https://github.com/apple/swift-argument-parser", from: "1.0.0")
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: ["CodeGenSample"]
),
.executableTarget(
name: "PluginExecutable",
dependencies: [
.product(name: "SourceKittenFramework", package: "SourceKitten"),
.product(name: "ArgumentParser", package: "swift-argument-parser")
]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
func run() throws {
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
func run() throws {
let files = try deepSearch(URL(fileURLWithPath: input, isDirectory: true))
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
func run() throws {
let files = try deepSearch(URL(fileURLWithPath: input, isDirectory: true))
let structures = try files.map { try Structure(file: File(path: $0.path)!) }
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
func run() throws {
let files = try deepSearch(URL(fileURLWithPath: input, isDirectory: true))
let structures = try files.map { try Structure(file: File(path: $0.path)!) }
var matchedTypes = [String]()
structures.forEach { walkTree(dictionary: $0.dictionary, acc: &matchedTypes) }
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
func run() throws {
let files = try deepSearch(URL(fileURLWithPath: input, isDirectory: true))
let structures = try files.map { try Structure(file: File(path: $0.path)!) }
var matchedTypes = [String]()
structures.forEach { walkTree(dictionary: $0.dictionary, acc: &matchedTypes) }
try createOutputFile(withContent: matchedTypes)
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π PluginExecutable.swift
import SourceKittenFramework
import ArgumentParser
import Foundation
@main
struct PluginExecutable: ParsableCommand {
@Argument(help: "The protocol name to match")
var protocolName: String
@Argument(help: "The module's name")
var moduleName: String
@Option(help: "Directory containing the swift files")
var input: String
@Option(help: "The path where the generated files will be created")
var output: String
func run() throws {
// Needed to ensure that sourcekit runs in a single process
setenv("IN_PROCESS_SOURCEKIT", "YES", 1)
let files = try deepSearch(URL(fileURLWithPath: input, isDirectory: true))
let structures = try files.map { try Structure(file: File(path: $0.path)!) }
var matchedTypes = [String]()
structures.forEach { walkTree(dictionary: $0.dictionary, acc: &matchedTypes) }
try createOutputFile(withContent: matchedTypes)
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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More contextβ¦
β Thanks to @jozasvalancius, which did all the work for this.
π This is also a
fi
x for getting SwiftLint to work with SPM plugins
π Link to the PR: https://github.com/jpsim/SourceKitten/pull/728
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The plugin π
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
.package(url: "https://github.com/jpsim/SourceKitten.git", exact: "0.32.0"),
.package(url: "https://github.com/apple/swift-argument-parser", from: "1.0.0")
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: ["CodeGenSample"]
),
.executableTarget(
name: "PluginExecutable",
dependencies: [
.product(name: "SourceKittenFramework", package: "SourceKitten"),
.product(name: "ArgumentParser", package: "swift-argument-parser")
]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
.package(url: "https://github.com/jpsim/SourceKitten.git", exact: "0.32.0"),
.package(url: "https://github.com/apple/swift-argument-parser", from: "1.0.0")
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: ["CodeGenSample"]
),
.executableTarget(
name: "PluginExecutable",
dependencies: [
.product(name: "SourceKittenFramework", package: "SourceKitten"),
.product(name: "ArgumentParser", package: "swift-argument-parser")
]
),
.plugin(
name: "SourceKitPlugin",
capability: .buildTool(),
dependencies: [.target(name: "PluginExecutable")]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π Package.swift
// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "CodeGenSample",
platforms: [.macOS(.v10_11)],
products: [
.library(
name: "CodeGenSample",
targets: ["CodeGenSample"]),
],
dependencies: [
.package(url: "https://github.com/jpsim/SourceKitten.git", exact: "0.32.0"),
.package(url: "https://github.com/apple/swift-argument-parser", from: "1.0.0")
],
targets: [
.target(
name: "CodeGenSample",
dependencies: []
),
.testTarget(
name: "CodeGenSampleTests",
dependencies: [βCodeGenSample"],
plugins: [βSourceKitPluginβ],
),
.executableTarget(
name: "PluginExecutable",
dependencies: [
.product(name: "SourceKittenFramework", package: "SourceKitten"),
.product(name: "ArgumentParser", package: "swift-argument-parser")
]
),
.plugin(
name: "SourceKitPlugin",
capability: .buildTool(),
dependencies: [.target(name: "PluginExecutable")]
)
]
)
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
π€·,
"--input",
π€·,
"--output",
π€·
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [π€·]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
let outputPath = context.pluginWorkDirectory.appending(βGeneratedTests.swiftβ)
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
π€·,
"--input",
π€·,
"--output",
outputPath
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [outputPath]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
let outputPath = context.pluginWorkDirectory.appending(βGeneratedTests.swiftβ)
let dependencyTarget = target
.dependencies
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
π€·,
"--input",
π€·,
"--output",
outputPath
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [outputPath]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
let outputPath = context.pluginWorkDirectory.appending(βGeneratedTests.swiftβ)
let dependencyTarget = target
.dependencies
.compactMap { dependency -> Target? in
switch dependency {
case .target(let target): return target
default: return nil
}
}
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
π€·,
"--input",
π€·,
"--output",
outputPath
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [outputPath]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
let outputPath = context.pluginWorkDirectory.appending(βGeneratedTests.swiftβ)
let dependencyTarget = target
.dependencies
.compactMap { dependency -> Target? in
switch dependency {
case .target(let target): return target
default: return nil
}
}
.filter { "\($0.name)Tests" == target.name }
.first
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
π€·,
"--input",
π€·,
"--output",
outputPath
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [outputPath]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
let outputPath = context.pluginWorkDirectory.appending(βGeneratedTests.swiftβ)
guard let dependencyTarget = target
.dependencies
.compactMap { dependency -> Target? in
switch dependency {
case .target(let target): return target
default: return nil
}
}
.filter { "\($0.name)Tests" == target.name }
.first else {
Diagnostics.error("Could not get a dependency to scan!β)
return []
}
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
π€·,
"--input",
π€·,
"--output",
outputPath
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [outputPath]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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π SourceKitPlugin.swift
import PackagePlugin
@main
struct SourceKitPlugin: BuildToolPlugin {
func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
let outputPath = context.pluginWorkDirectory.appending(βGeneratedTests.swiftβ)
guard let dependencyTarget = target
.dependencies
.compactMap { dependency -> Target? in
switch dependency {
case .target(let target): return target
default: return nil
}
}
.filter { "\($0.name)Tests" == target.name }
.first else {
Diagnostics.error("Could not get a dependency to scan!β)
return []
}
return [
.buildCommand(
displayName: "Protocol Extraction!",
executable: try context.tool(named: "PluginExecutable").path,
arguments: [
"FindThis",
dependencyTarget.name,
"--input",
dependencyTarget.directory,
"--output",
outputPath
],
environment: ["IN_PROCESS_SOURCEKIT": "YES"],
outputFiles: [outputPath]
)
]
}
}
Package.swift
π Sources
π CodeGenSample
CodeGenSample.swift
π PluginExecutable
PluginExecutable.swift
π Tests
π CodeGenSampleTests
Empty.swift
π Plugins
π SourceKitPlugin
SourceKitPlugin.swift
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Letβs see it
running!