Add a SourceKit plugin to handle code completion requests

This adds a sourcekitd plugin that drives the code completion requests. It also includes a `CompletionScoring` module that’s used to rank code completion results based on their contextual match, allowing us to show more relevant code completion results at the top.

Package.swift

@@ -13,6 +13,8 @@ var products: [Product] = [
   .executable(name: "sourcekit-lsp", targets: ["sourcekit-lsp"]),
   .library(name: "_SourceKitLSP", targets: ["SourceKitLSP"]),
   .library(name: "LSPBindings", targets: ["LanguageServerProtocol", "LanguageServerProtocolJSONRPC"]),
+  .library(name: "SwiftSourceKitPlugin", type: .dynamic, targets: ["SwiftSourceKitPlugin"]),
+  .library(name: "SwiftSourceKitClientPlugin", type: .dynamic, targets: ["SwiftSourceKitClientPlugin"]),
 ]
 
 var targets: [Target] = [
@@ -109,6 +111,40 @@ var targets: [Target] = [
     dependencies: []
   ),
 
+  // MARK: CompletionScoring
+
+  .target(
+    name: "CompletionScoring",
+    dependencies: [],
+    swiftSettings: globalSwiftSettings
+  ),
+
+  .target(
+    name: "CompletionScoringForPlugin",
+    dependencies: [],
+    swiftSettings: globalSwiftSettings
+  ),
+
+  .testTarget(
+    name: "CompletionScoringTests",
+    dependencies: ["CompletionScoring", "CompletionScoringTestSupport", "SwiftExtensions"],
+    swiftSettings: globalSwiftSettings
+  ),
+
+  .testTarget(
+    name: "CompletionScoringPerfTests",
+    dependencies: ["CompletionScoring", "CompletionScoringTestSupport", "SwiftExtensions"],
+    swiftSettings: globalSwiftSettings
+  ),
+
+  // MARK: CompletionScoringTestSupport
+
+  .target(
+    name: "CompletionScoringTestSupport",
+    dependencies: ["CompletionScoring", "SwiftExtensions"],
+    swiftSettings: globalSwiftSettings
+  ),
+
   // MARK: CSKTestSupport
 
   .target(
@@ -273,6 +309,21 @@ var targets: [Target] = [
     swiftSettings: globalSwiftSettings + lspLoggingSwiftSettings
   ),
 
+  .target(
+    name: "SKLoggingForPlugin",
+    dependencies: [
+      "SwiftExtensionsForPlugin"
+    ],
+    exclude: ["CMakeLists.txt"],
+    swiftSettings: globalSwiftSettings + lspLoggingSwiftSettings + [
+      // We can't depend on swift-crypto in the plugin because we can't module-alias it due to https://github.com/swiftlang/swift-package-manager/issues/8119
+      .define("NO_CRYPTO_DEPENDENCY"),
+      .unsafeFlags([
+        "-module-alias", "SwiftExtensions=SwiftExtensionsForPlugin",
+      ]),
+    ]
+  ),
+
   .testTarget(
     name: "SKLoggingTests",
     dependencies: [
@@ -308,6 +359,21 @@ var targets: [Target] = [
     swiftSettings: globalSwiftSettings
   ),
 
+  .target(
+    name: "SKUtilitiesForPlugin",
+    dependencies: [
+      "SKLoggingForPlugin",
+      "SwiftExtensionsForPlugin",
+    ],
+    exclude: ["CMakeLists.txt"],
+    swiftSettings: globalSwiftSettings + [
+      .unsafeFlags([
+        "-module-alias", "SKLogging=SKLoggingForPlugin",
+        "-module-alias", "SwiftExtensions=SwiftExtensionsForPlugin",
+      ])
+    ]
+  ),
+
   .testTarget(
     name: "SKUtilitiesTests",
     dependencies: [
@@ -354,6 +420,22 @@ var targets: [Target] = [
     swiftSettings: globalSwiftSettings
   ),
 
+  .target(
+    name: "SourceKitDForPlugin",
+    dependencies: [
+      "Csourcekitd",
+      "SKLoggingForPlugin",
+      "SwiftExtensionsForPlugin",
+    ],
+    exclude: ["CMakeLists.txt", "sourcekitd_uids.swift.gyb"],
+    swiftSettings: globalSwiftSettings + [
+      .unsafeFlags([
+        "-module-alias", "SKLogging=SKLoggingForPlugin",
+        "-module-alias", "SwiftExtensions=SwiftExtensionsForPlugin",
+      ])
+    ]
+  ),
+
   .testTarget(
     name: "SourceKitDTests",
     dependencies: [
@@ -429,6 +511,13 @@ var targets: [Target] = [
     swiftSettings: globalSwiftSettings
   ),
 
+  .target(
+    name: "SwiftExtensionsForPlugin",
+    dependencies: ["CAtomics"],
+    exclude: ["CMakeLists.txt"],
+    swiftSettings: globalSwiftSettings
+  ),
+
   .testTarget(
     name: "SwiftExtensionsTests",
     dependencies: [
@@ -439,6 +528,80 @@ var targets: [Target] = [
     swiftSettings: globalSwiftSettings
   ),
 
+  // MARK: SwiftSourceKitClientPlugin
+
+  .target(
+    name: "SwiftSourceKitClientPlugin",
+    dependencies: [
+      "Csourcekitd",
+      "SourceKitDForPlugin",
+      "SwiftSourceKitPluginCommon",
+    ],
+    swiftSettings: globalSwiftSettings + [
+      .unsafeFlags([
+        "-module-alias", "SourceKitD=SourceKitDForPlugin",
+      ])
+    ]
+  ),
+
+  // MARK: SwiftSourceKitPluginCommon
+
+  .target(
+    name: "SwiftSourceKitPluginCommon",
+    dependencies: [
+      "Csourcekitd",
+      "SourceKitDForPlugin",
+      "SwiftExtensionsForPlugin",
+      "SKLoggingForPlugin",
+    ],
+    swiftSettings: globalSwiftSettings + [
+      .unsafeFlags([
+        "-module-alias", "SourceKitD=SourceKitDForPlugin",
+        "-module-alias", "SwiftExtensions=SwiftExtensionsForPlugin",
+        "-module-alias", "SKLogging=SKLoggingForPlugin",
+      ])
+    ]
+  ),
+
+  // MARK: SwiftSourceKitPlugin
+
+  .target(
+    name: "SwiftSourceKitPlugin",
+    dependencies: [
+      "Csourcekitd",
+      "CompletionScoringForPlugin",
+      "SKUtilitiesForPlugin",
+      "SKLoggingForPlugin",
+      "SourceKitDForPlugin",
+      "SwiftSourceKitPluginCommon",
+      "SwiftExtensionsForPlugin",
+    ],
+    swiftSettings: globalSwiftSettings + [
+      .unsafeFlags([
+        "-module-alias", "CompletionScoring=CompletionScoringForPlugin",
+        "-module-alias", "SKUtilities=SKUtilitiesForPlugin",
+        "-module-alias", "SourceKitD=SourceKitDForPlugin",
+        "-module-alias", "SKLogging=SKLoggingForPlugin",
+        "-module-alias", "SwiftExtensions=SwiftExtensionsForPlugin",
+      ])
+    ]
+  ),
+
+  .testTarget(
+    name: "SwiftSourceKitPluginTests",
+    dependencies: [
+      "BuildSystemIntegration",
+      "CompletionScoring",
+      "Csourcekitd",
+      "LanguageServerProtocol",
+      "SKTestSupport",
+      "SourceKitD",
+      "SwiftExtensions",
+      "ToolchainRegistry",
+    ],
+    swiftSettings: globalSwiftSettings
+  ),
+
   // MARK: ToolchainRegistry
 
   .target(

Sources/CompletionScoring/Semantics/CompletionScore.swift

@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+/// Represents a composite score formed from a semantic and textual components.
+///
+/// The textual component forms the bulk of the score typically having a value in the 10's to 100's.
+/// You can think of the semantic component as a bonus to the text score.
+/// It usually has a value between 0 and 2, and is used as a multiplier.
+package struct CompletionScore: Comparable {
+  package var semanticComponent: Double
+  package var textComponent: Double
+
+  package init(textComponent: Double, semanticComponent: Double) {
+    self.semanticComponent = semanticComponent
+    self.textComponent = textComponent
+  }
+
+  package init(textComponent: Double, semanticClassification: SemanticClassification) {
+    self.semanticComponent = semanticClassification.score
+    self.textComponent = textComponent
+  }
+
+  package var value: Double {
+    semanticComponent * textComponent
+  }
+
+  package static func < (_ lhs: Self, _ rhs: Self) -> Bool {
+    lhs.value < rhs.value
+  }
+}
+
+// MARK: - Deprecated -
+extension CompletionScore {
+  /// There is no natural order to these arguments, so they're alphabetical.
+  @available(
+    *,
+    deprecated,
+    renamed:
+      "SemanticClassification(completionKind:deprecationStatus:flair:moduleProximity:popularity:scopeProximity:structuralProximity:synchronicityCompatibility:typeCompatibility:)"
+  )
+  package static func semanticScore(
+    completionKind: CompletionKind,
+    deprecationStatus: DeprecationStatus,
+    flair: Flair,
+    moduleProximity: ModuleProximity,
+    popularity: Popularity,
+    scopeProximity: ScopeProximity,
+    structuralProximity: StructuralProximity,
+    synchronicityCompatibility: SynchronicityCompatibility,
+    typeCompatibility: TypeCompatibility
+  ) -> Double {
+    SemanticClassification(
+      availability: deprecationStatus,
+      completionKind: completionKind,
+      flair: flair,
+      moduleProximity: moduleProximity,
+      popularity: popularity,
+      scopeProximity: scopeProximity,
+      structuralProximity: structuralProximity,
+      synchronicityCompatibility: synchronicityCompatibility,
+      typeCompatibility: typeCompatibility
+    ).score
+  }
+}

Sources/CompletionScoring/Semantics/Components/Availability.swift

@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+package enum Availability: Equatable {
+  /// Example: Either not tagged, or explicit availability is compatible with current build context
+  case available
+
+  /// Example: Explicitly unavailable in current build context - ie, only for another platform.
+  case unavailable
+
+  /// Example: deprecated in the future
+  case softDeprecated
+
+  /// Example: deprecated in the present, or past
+  case deprecated
+
+  /// Completion provider doesn't know if the method is deprecated or not
+  case unknown
+
+  /// Example: keyword
+  case inapplicable
+
+  /// Example: Provider was written before this enum existed, and didn't have an opportunity to provide a value
+  case unspecified
+}
+
+extension Availability: BinaryCodable {
+  package init(_ decoder: inout BinaryDecoder) throws {
+    self = try decoder.decodeEnumByte { decoder, n in
+      switch n {
+      case 0: return .available
+      case 1: return .unavailable
+      case 2: return .softDeprecated
+      case 3: return .deprecated
+      case 4: return .unknown
+      case 5: return .inapplicable
+      case 6: return .unspecified
+      default: return nil
+      }
+    }
+  }
+
+  package func encode(_ encoder: inout BinaryEncoder) {
+    let value: UInt8
+    switch self {
+    case .available: value = 0
+    case .unavailable: value = 1
+    case .softDeprecated: value = 2
+    case .deprecated: value = 3
+    case .unknown: value = 4
+    case .inapplicable: value = 5
+    case .unspecified: value = 6
+    }
+    encoder.write(value)
+  }
+}
+
+@available(*, deprecated, renamed: "Availability")
+package typealias DeprecationStatus = Availability
+
+extension Availability {
+  @available(*, deprecated, renamed: "Availability.available")
+  package static let none = DeprecationStatus.available
+}