Add separate Builder class, use WasmTransformer (#131)

Resolves #127.

* Add separate Builder class, use WasmTransformer

* Don't apply the transformer in non-browser environments

* Fix macOS Swift 5.2 build failure

* Fix Package.swift errors

* Fix cyclic dependency in `Package.swift`

* Bump WasmTransformer requirement to 0.0.1

* Rename `case wasmer` to `case other`

.vscode/tasks.json

@@ -33,6 +33,11 @@
       "type": "shell",
       "command": "swift build && cd TestApp && ../.build/debug/carton dev"
     },
+    {
+      "label": "build release and run dev",
+      "type": "shell",
+      "command": "swift build -c release && cd TestApp && ../.build/release/carton dev"
+    },
     {
       "label": "build and run dev on 9090 port",
       "type": "shell",

Package.resolved

@@ -163,6 +163,15 @@
           "version": "4.32.0"
         }
       },
+      {
+        "package": "WasmTransformer",
+        "repositoryURL": "https://github.com/swiftwasm/WasmTransformer",
+        "state": {
+          "branch": null,
+          "revision": "c7cb17309372e57c9f75f7abd5c7323d667eaddc",
+          "version": "0.0.1"
+        }
+      },
       {
         "package": "websocket-kit",
         "repositoryURL": "https://github.com/vapor/websocket-kit.git",

Package.swift

@@ -26,6 +26,7 @@ let package = Package(
     .package(url: "https://github.com/vapor/vapor.git", from: "4.29.3"),
     .package(url: "https://github.com/apple/swift-crypto.git", from: "1.1.0"),
     .package(url: "https://github.com/JohnSundell/Splash.git", from: "0.14.0"),
+    .package(url: "https://github.com/swiftwasm/WasmTransformer", .upToNextMinor(from: "0.0.1")),
   ],
   targets: [
     // Targets are the basic building blocks of a package. A target can define a module
@@ -51,6 +52,7 @@ let package = Package(
         .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
         "CartonHelpers",
         openCombineProduct,
+        "WasmTransformer",
       ]
     ),
     .target(

Package@swift-5.2.swift

@@ -20,6 +20,7 @@ let package = Package(
     .package(url: "https://github.com/vapor/vapor.git", from: "4.29.3"),
     .package(url: "https://github.com/apple/swift-crypto.git", from: "1.1.0"),
     .package(url: "https://github.com/JohnSundell/Splash.git", from: "0.14.0"),
+    .package(url: "https://github.com/swiftwasm/WasmTransformer", .upToNextMinor(from: "0.0.1")),
   ],
   targets: [
     // Targets are the basic building blocks of a package. A target can define a module
@@ -45,6 +46,7 @@ let package = Package(
         .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
         "CartonHelpers",
         "OpenCombine",
+        "WasmTransformer",
       ]
     ),
     .target(

Sources/CartonHelpers/ProcessRunner.swift

@@ -21,7 +21,7 @@ import OpenCombine
 #endif
 import TSCBasic
 
-extension Subscribers.Completion {
+public extension Subscribers.Completion {
   var result: Result<(), Failure> {
     switch self {
     case let .failure(error):

Sources/SwiftToolchain/Builder.swift

@@ -0,0 +1,100 @@
+// Copyright 2020 Carton contributors
+//
+// 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 CartonHelpers
+#if canImport(Combine)
+import Combine
+#else
+import OpenCombine
+#endif
+import Foundation
+import TSCBasic
+import WasmTransformer
+
+public final class Builder {
+  public enum Environment {
+    case other
+    case browser
+  }
+
+  public let mainWasmPath: AbsolutePath
+
+  private var currentProcess: ProcessRunner?
+  private let arguments: [String]
+  private let environment: Environment
+  private let terminal: InteractiveWriter
+  private let fileSystem: FileSystem
+  private var subscription: AnyCancellable?
+
+  public init(
+    arguments: [String],
+    mainWasmPath: AbsolutePath,
+    environment: Environment = .browser,
+    _ fileSystem: FileSystem,
+    _ terminal: InteractiveWriter
+  ) {
+    self.arguments = arguments
+    self.mainWasmPath = mainWasmPath
+    self.environment = environment
+    self.terminal = terminal
+    self.fileSystem = fileSystem
+  }
+
+  public func run() -> AnyPublisher<String, Error> {
+    let buildStarted = Date()
+    let process = ProcessRunner(arguments, loadingMessage: "Compiling...", terminal)
+    currentProcess = process
+
+    return process
+      .publisher
+      .handleEvents(receiveCompletion: { [weak self] in
+        guard case .finished = $0, let self = self else { return }
+
+        self.terminal.logLookup(
+          "`swift build` completed in ",
+          String(format: "%.2f seconds", abs(buildStarted.timeIntervalSinceNow))
+        )
+
+        guard self.environment == .browser else { return }
+
+        // FIXME: errors from these `try` expressions should be recoverable, not sure how to
+        // do that in `handleEvents`, and `flatMap` doesnt' fit here as we need to track
+        // publisher completion.
+        // swiftlint:disable force_try
+        let binary = try! self.fileSystem.readFileContents(self.mainWasmPath)
+
+        let loweringStarted = Date()
+        let loweredBinary = try! lowerI64Imports(binary.contents)
+
+        self.terminal.logLookup(
+          "Binary transformation for Safari compatibility completed in ",
+          String(format: "%.2f seconds", abs(loweringStarted.timeIntervalSinceNow))
+        )
+
+        try! self.fileSystem.writeFileContents(self.mainWasmPath, bytes: .init(loweredBinary))
+        // swiftlint:enable force_try
+      })
+      .eraseToAnyPublisher()
+  }
+
+  public func runAndWaitUntilFinished() throws {
+    try await { completion in
+      subscription = run()
+        .sink(
+          receiveCompletion: { completion($0.result) },
+          receiveValue: { _ in }
+        )
+    }
+  }
+}

Sources/SwiftToolchain/Toolchain.swift

@@ -225,10 +225,10 @@ public final class Toolchain {
       "--enable-test-discovery", "--destination", destination ?? inferDestinationPath().pathString,
     ]
 
-    try ProcessRunner(builderArguments, loadingMessage: "Compiling...", terminal)
+    try Builder(arguments: builderArguments, mainWasmPath: mainWasmPath, fileSystem, terminal)
-      .waitUntilFinished()
+      .runAndWaitUntilFinished()
 
-    guard localFileSystem.exists(mainWasmPath) else {
+    guard fileSystem.exists(mainWasmPath) else {
       terminal.write(
         "Failed to build the main executable binary, fix the build errors and restart\n",
         inColor: .red
@@ -257,9 +257,16 @@ public final class Toolchain {
       "-Xswiftc", "-color-diagnostics",
     ]
 
-    try ProcessRunner(builderArguments, terminal).waitUntilFinished()
+    try Builder(
+      arguments: builderArguments,
+      mainWasmPath: testBundlePath,
+      environment: .other,
+      fileSystem,
+      terminal
+    )
+    .runAndWaitUntilFinished()
 
-    guard localFileSystem.exists(testBundlePath) else {
+    guard fileSystem.exists(testBundlePath) else {
       terminal.write(
         "Failed to build the test bundle, fix the build errors and restart\n",
         inColor: .red

Sources/carton/Commands/Dev.swift

@@ -84,9 +84,8 @@ struct Dev: ParsableCommand {
     let sources = try paths.flatMap { try localFileSystem.traverseRecursively($0) }
 
     try Server(
-      builderArguments: arguments,
+      builder: Builder(arguments: arguments, mainWasmPath: mainWasmPath, localFileSystem, terminal),
       pathsToWatch: sources,
-      mainWasmPath: mainWasmPath,
       customIndexContent: HTML.readCustomIndexPage(at: customIndexPage, on: localFileSystem),
       // swiftlint:disable:next force_try
       package: try! toolchain.package.get(),

Sources/carton/Server/Server.swift

@@ -37,15 +37,13 @@ final class Server {
   private var connections = Set<WebSocket>()
   private var subscriptions = [AnyCancellable]()
   private let watcher: Watcher
-  private var builder: ProcessRunner?
   private let app: Application
   private let localURL: String
   private let skipAutoOpen: Bool
 
   init(
-    builderArguments: [String],
+    builder: Builder,
     pathsToWatch: [AbsolutePath],
-    mainWasmPath: AbsolutePath,
     customIndexContent: String?,
     package: SwiftToolchain.Package,
     verbose: Bool,
@@ -63,7 +61,7 @@ final class Server {
     app = Application(env)
     app.configure(
       port: port,
-      mainWasmPath: mainWasmPath,
+      mainWasmPath: builder.mainWasmPath,
       customIndexContent: customIndexContent,
       package: package,
       onWebSocketOpen: { [weak self] in
@@ -85,8 +83,8 @@ final class Server {
         for change in changes.map(\.pathString) {
           terminal.write("- \(change)\n", inColor: .cyan)
         }
-        return ProcessRunner(builderArguments, terminal)
+        return builder
-          .publisher
+          .run()
           .handleEvents(receiveCompletion: { [weak self] in
             guard case .finished = $0, let self = self else { return }