Cleanup PackageGraph Module

Sources/Commands/SwiftTool.swift

@@ -123,8 +123,7 @@ private class ToolWorkspaceDelegate: WorkspaceDelegate {
 
             switch state {
             case .checkout(let checkoutState)?:
-                let requirement = checkoutState.requirement()
-                switch requirement {
+                switch checkoutState.requirement {
                 case .versionSet(.exact(let version)):
                     stdoutStream <<< "resolved to '\(version)'"
                 case .versionSet(_):

Sources/PackageGraph/BoundVersion.swift

@@ -0,0 +1,45 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See http://swift.org/LICENSE.txt for license information
+ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import struct TSCUtility.Version
+
+/// A bound version for a package within an assignment.
+public enum BoundVersion: Equatable, Hashable {
+    /// The assignment should not include the package.
+    ///
+    /// This is different from the absence of an assignment for a particular
+    /// package, which only indicates the assignment is agnostic to its
+    /// version. This value signifies the package *may not* be present.
+    case excluded
+
+    /// The version of the package to include.
+    case version(Version)
+
+    /// The package assignment is unversioned.
+    case unversioned
+
+    /// The package assignment is this revision.
+    case revision(String)
+}
+
+extension BoundVersion: CustomStringConvertible {
+    public var description: String {
+        switch self {
+        case .excluded:
+            return "excluded"
+        case .version(let version):
+            return version.description
+        case .unversioned:
+            return "unversioned"
+        case .revision(let identifier):
+            return identifier
+        }
+    }
+}

Sources/PackageGraph/CMakeLists.txt

@@ -7,18 +7,30 @@
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
 add_library(PackageGraph
+  BoundVersion.swift
   CheckoutState.swift
+  DependencyResolutionNode.swift
   DependencyResolver.swift
+  Diagnostics.swift
+  GraphLoadingNode.swift
+  LocalPackageContainer.swift
+  PackageContainer.swift
   PackageGraph.swift
-  PackageGraphLoader.swift
+  PackageGraph+Loading.swift
   PackageGraphRoot.swift
+  PackageModel+Extensions.swift
+  PackageRequirement.swift
   PinsStore.swift
-  Pubgrub.swift
-  RawPackageConstraints.swift
+  Pubgrub/Assignment.swift
+  Pubgrub/Incompatibility.swift
+  Pubgrub/PartialSolution.swift
+  Pubgrub/PubgrubDependencyResolver.swift
+  Pubgrub/Term.swift
+  RepositoryPackageContainer.swift
   ResolvedPackage.swift
   ResolvedProduct.swift
   ResolvedTarget.swift
-  RepositoryPackageContainerProvider.swift
+  Version+Extensions.swift
   VersionSetSpecifier.swift)
 target_link_libraries(PackageGraph PUBLIC
   TSCBasic

Sources/PackageGraph/CheckoutState.swift

@@ -15,7 +15,7 @@ import TSCUtility
 /// A checkout state represents the current state of a repository.
 ///
 /// A state will always has a revision. It can also have a branch or a version but not both.
-public struct CheckoutState: Equatable, CustomStringConvertible {
+public struct CheckoutState: Equatable, Hashable {
 
     /// The revision of the checkout.
     public let revision: Revision
@@ -47,25 +47,27 @@ public struct CheckoutState: Equatable, CustomStringConvertible {
         self.init(revision: revision, version: version, branch: nil)
     }
 
-    public var description: String {
-        return version?.description ?? branch ?? revision.identifier
-    }
-
     public var isBranchOrRevisionBased: Bool {
         return version == nil
     }
-}
-
-extension CheckoutState {
 
     /// Returns requirement induced by this state.
-    public func requirement() -> PackageRequirement {
+    public var requirement: PackageRequirement {
         if let version = version {
             return .versionSet(.exact(version))
         } else if let branch = branch {
             return .revision(branch)
+        } else {
+            return .revision(revision.identifier)
         }
-        return .revision(revision.identifier)
+    }
+}
+
+// MARK: - CustomStringConvertible
+
+extension CheckoutState: CustomStringConvertible {
+    public var description: String {
+        return version?.description ?? branch ?? revision.identifier
     }
 }
 

Sources/PackageGraph/DependencyResolutionNode.swift

@@ -0,0 +1,135 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See http://swift.org/LICENSE.txt for license information
+ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import TSCBasic
+import PackageModel
+import struct TSCUtility.Version
+
+/// A node in the dependency resolution graph.
+///
+/// See the documentation of each case for more detailed descriptions of each kind and how they interact.
+///
+/// - SeeAlso: `GraphLoadingNode`
+public enum DependencyResolutionNode {
+
+    /// An empty package node.
+    ///
+    /// This node indicates that a package needs to be present, but does not indicate that any of its contents are needed.
+    ///
+    /// Empty package nodes are always leaf nodes; they have no dependencies.
+    case empty(package: PackageReference)
+
+    /// A product node.
+    ///
+    /// This node indicates that a particular product in a particular package is required.
+    ///
+    /// Product nodes always have dependencies. A product node has...
+    ///
+    /// - one implicit dependency on its own package at an exact version (as an empty package node).
+    ///   This dependency is what ensures the resolver does not select two products from the same package at different versions.
+    /// - zero or more dependencies on the product nodes of other packages.
+    ///   These are all the external products required to build all of the targets vended by this product.
+    ///   They derive from the manifest.
+    ///
+    ///   Tools versions before 5.2 do not know which products belong to which packages, so each product is required from every dependency.
+    ///   Since a non‐existant product ends up with only its implicit dependency on its own package,
+    ///   only whichever package contains the product will end up adding additional constraints.
+    ///   See `ProductFilter` and `Manifest.register(...)`.
+    case product(String, package: PackageReference)
+
+    /// A root node.
+    ///
+    /// This node indicates a root node in the graph, which is required no matter what.
+    ///
+    /// Root nodes may have dependencies. A root node has...
+    ///
+    /// - zero or more dependencies on each external product node required to build any of its targets (vended or not).
+    /// - zero or more dependencies directly on external empty package nodes.
+    ///   This special case occurs when a dependecy is declared but not used.
+    ///   It is a warning condition, and builds do not actually need these dependencies.
+    ///   However, forcing the graph to resolve and fetch them anyway allows the diagnostics passes access
+    ///   to the information needed in order to provide actionable suggestions to help the user stitch up the dependency declarations properly.
+    case root(package: PackageReference)
+
+    /// The package.
+    public var package: PackageReference {
+        switch self {
+        case .empty(let package), .product(_, let package), .root(let package):
+            return package
+        }
+    }
+
+    /// The name of the specific product if the node is a product node, otherwise `nil`.
+    public var specificProduct: String? {
+        switch self {
+        case .empty, .root:
+            return nil
+        case .product(let product, _):
+            return product
+        }
+    }
+
+    /// Assembles the product filter to use on the manifest for this node to determine its dependencies.
+    public var productFilter: ProductFilter {
+        switch self {
+        case .empty:
+            return .specific([])
+        case .product(let product, _):
+            return .specific([product])
+        case .root:
+            return .everything
+        }
+    }
+
+    /// Returns the dependency that a product has on its own package, if relevant.
+    ///
+    /// This is the constraint that requires all products from a package resolve to the same version.
+    internal func versionLock(version: Version) -> RepositoryPackageConstraint? {
+        // Don’t create a version lock for anything but a product.
+        guard specificProduct != nil else { return nil }
+        return RepositoryPackageConstraint(
+            container: package,
+            versionRequirement: .exact(version),
+            products: .specific([])
+        )
+    }
+
+    /// Returns the dependency that a product has on its own package, if relevant.
+    ///
+    /// This is the constraint that requires all products from a package resolve to the same revision.
+    internal func revisionLock(revision: String) -> RepositoryPackageConstraint? {
+        // Don’t create a revision lock for anything but a product.
+        guard specificProduct != nil else { return nil }
+        return RepositoryPackageConstraint(
+            container: package,
+            requirement: .revision(revision),
+            products: .specific([])
+        )
+    }
+}
+
+extension DependencyResolutionNode: Equatable {
+    public static func ==(lhs: DependencyResolutionNode, rhs: DependencyResolutionNode) -> Bool {
+        return (lhs.package, lhs.specificProduct) == (rhs.package, rhs.specificProduct)
+    }
+}
+
+extension DependencyResolutionNode: Hashable {
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(package)
+        hasher.combine(specificProduct)
+    }
+}
+
+extension DependencyResolutionNode: CustomStringConvertible {
+    public var description: String {
+        return "\(package.name)\(productFilter)"
+    }
+}