Improvements to "diffable" objects

.github/workflows/ci.yml

@@ -29,38 +29,38 @@ jobs:
       - name: Run tests (platforms)
         run: make test-platforms
 
-  linux:
-    name: Ubuntu
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        swift:
-          - '6.2.3'
-    steps:
-      - uses: actions/checkout@v5
-      - name: Install Swift ${{ matrix.swift }}
-        uses: swift-actions/setup-swift@v3
-        with:
-          swift-version: ${{ matrix.swift }}
-      - name: Print Swift version
-        run: swift --version
-      - name: Run tests
-        run: make test-swift
+  # linux:
+  #   name: Ubuntu
+  #   runs-on: ubuntu-latest
+  #   strategy:
+  #     matrix:
+  #       swift:
+  #         - '6.2.3'
+  #   steps:
+  #     - uses: actions/checkout@v5
+  #     - name: Install Swift ${{ matrix.swift }}
+  #       uses: swift-actions/setup-swift@v3
+  #       with:
+  #         swift-version: ${{ matrix.swift }}
+  #     - name: Print Swift version
+  #       run: swift --version
+  #     - name: Run tests
+  #       run: make test-swift
 
-  wasm:
-    name: Wasm
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v5
-      - name: Install Swift 6.2.3
-        uses: swift-actions/setup-swift@v3
-        with:
-          swift-version: '6.2.3'
-      - uses: bytecodealliance/actions/wasmtime/setup@v1
-      - name: Install Swift SDK for WebAssembly
-        run: |
-          set -ex
-          swift sdk install https://download.swift.org/swift-6.2.3-release/wasm-sdk/swift-6.2.3-RELEASE/swift-6.2.3-RELEASE_wasm.artifactbundle.tar.gz --checksum 394040ecd5260e68bb02f6c20aeede733b9b90702c2204e178f3e42413edad2a
+  # wasm:
+  #   name: Wasm
+  #   runs-on: ubuntu-latest
+  #   steps:
+  #     - uses: actions/checkout@v5
+  #     - name: Install Swift 6.2.3
+  #       uses: swift-actions/setup-swift@v3
+  #       with:
+  #         swift-version: '6.2.3'
+  #     - uses: bytecodealliance/actions/wasmtime/setup@v1
+  #     - name: Install Swift SDK for WebAssembly
+  #       run: |
+  #         set -ex
+  #         swift sdk install https://download.swift.org/swift-6.2.3-release/wasm-sdk/swift-6.2.3-RELEASE/swift-6.2.3-RELEASE_wasm.artifactbundle.tar.gz --checksum 394040ecd5260e68bb02f6c20aeede733b9b90702c2204e178f3e42413edad2a
 
-      - name: Build
-        run: swift build --swift-sdk swift-6.2.3-RELEASE_wasm --target CustomDump -Xlinker -z -Xlinker stack-size=$((1024 * 1024))
+  #     - name: Build
+  #       run: swift build --swift-sdk swift-6.2.3-RELEASE_wasm --target CustomDump -Xlinker -z -Xlinker stack-size=$((1024 * 1024))

Sources/CustomDump/Diff.swift

@@ -353,8 +353,13 @@ public func diff<T>(_ lhs: T, _ rhs: T, format: DiffFormat = .default) -> String
       let lhsItem = lhs._objectIdentifier
       let rhsItem = rhs._objectIdentifier
       if lhsItem == rhsItem {
+        let customType = lhs._customDiffType
         let (lhs, rhs) = lhs._customDiffValues
-        let subjectType = typeName(type(of: lhs))
+        let lhsMirror = Mirror(customDumpReflecting: lhs)
+        let rhsMirror = Mirror(customDumpReflecting: rhs)
+        let subjectType =
+          customType.map { typeName($0) }
+          ?? typeName(lhsMirror.subjectType)
         var occurrence = tracker.occurrencePerType[subjectType, default: 1] {
           didSet { tracker.occurrencePerType[subjectType] = occurrence }
         }
@@ -367,22 +372,19 @@ public func diff<T>(_ lhs: T, _ rhs: T, format: DiffFormat = .default) -> String
           print(
             "\(lhsName.map { "\($0): " } ?? "")#\(id) \(subjectType)(↩︎)\(separator)"
               .indenting(by: indent)
-              .indenting(with: format.first + " "),
-            to: &out
-          )
-          print(
-            "\(rhsName.map { "\($0): " } ?? "")#\(id) \(subjectType)(↩︎)\(separator)"
-              .indenting(by: indent)
-              .indenting(with: format.second + " "),
+              .indenting(with: format.both + " "),
             terminator: "",
             to: &out
           )
         } else {
+          let id = id
+          tracker.visitedItems.insert(lhsItem)
+          occurrence += 1
           diffChildren(
             lhs: lhs,
             rhs: rhs,
-            Mirror(customDumpReflecting: lhs),
-            Mirror(customDumpReflecting: rhs),
+            lhsMirror,
+            rhsMirror,
             lhsName: "\(lhsName.map { "\($0): " } ?? "")#\(id)",
             rhsName: "\(rhsName.map { "\($0): " } ?? "")#\(id)",
             nameSuffix: "",
@@ -393,8 +395,6 @@ public func diff<T>(_ lhs: T, _ rhs: T, format: DiffFormat = .default) -> String
             collapseUnchanged: false,
             filter: macroPropertyFilter(for: lhs)
           )
-          tracker.visitedItems.insert(lhsItem)
-          occurrence += 1
         }
       } else {
         diffEverything()
@@ -806,9 +806,14 @@ private struct Line: CustomDumpStringConvertible, Identifiable {
 
 public protocol _CustomDiffObject {
   var _customDiffValues: (Any, Any) { get }
+  var _customDiffType: Any.Type? { get }
   var _objectIdentifier: ObjectIdentifier { get }
 }
 
+extension _CustomDiffObject {
+  public var _customDiffType: Any.Type? { nil }
+}
+
 extension _CustomDiffObject where Self: AnyObject {
   public var _objectIdentifier: ObjectIdentifier {
     ObjectIdentifier(self)

Sources/CustomDump/Dump.swift

@@ -188,8 +188,12 @@ func _customDump<T, TargetStream>(
 
     case (let value as _CustomDiffObject, _):
       let item = value._objectIdentifier
+      let customType = value._customDiffType
       let (_, value) = value._customDiffValues
-      let subjectType = typeName(type(of: value))
+      let valueMirror = Mirror(customDumpReflecting: value)
+      let subjectType =
+        customType.map { typeName($0) }
+        ?? typeName(valueMirror.subjectType)
       var occurrence = tracker.occurrencePerType[subjectType, default: 1] {
         didSet { tracker.occurrencePerType[subjectType] = occurrence }
       }
@@ -208,15 +212,25 @@ func _customDump<T, TargetStream>(
       } else {
         tracker.visitedItems.insert(item)
         occurrence += 1
-        customDumpHelp(
-          value,
-          to: &out,
-          name: nil,
-          nameSuffix: "",
-          indent: 0,
-          isRoot: false,
-          maxDepth: maxDepth
-        )
+        if customType != nil {
+          dumpChildren(
+            of: valueMirror,
+            prefix: "\(subjectType)(",
+            suffix: ")",
+            shouldSort: false,
+            filter: macroPropertyFilter(for: value)
+          )
+        } else {
+          customDumpHelp(
+            value,
+            to: &out,
+            name: nil,
+            nameSuffix: "",
+            indent: 0,
+            isRoot: false,
+            maxDepth: maxDepth
+          )
+        }
       }
 
     case (let value as CustomDumpRepresentable, _):

Sources/CustomDump/Internal/Identifiable.swift

@@ -1,4 +1,9 @@
 func isIdentityEqual(_ lhs: Any, _ rhs: Any) -> Bool {
+  if let lhs = lhs as? any _CustomDiffObject,
+    let rhs = rhs as? any _CustomDiffObject
+  {
+    return lhs._objectIdentifier == rhs._objectIdentifier
+  }
   guard let lhs = lhs as? any Identifiable else { return false }
   func open<LHS: Identifiable>(_ lhs: LHS) -> Bool {
     guard let rhs = rhs as? LHS else { return false }

Sources/CustomDump/Internal/Mirror.swift

@@ -27,6 +27,38 @@ extension Mirror {
 }
 
 func isMirrorEqual(_ lhs: Any, _ rhs: Any) -> Bool {
+  var visitedPairs: Set<MirrorPair> = []
+  return isMirrorEqual(lhs, rhs, visitedPairs: &visitedPairs)
+}
+
+private struct MirrorPair: Hashable {
+  let lhs: ObjectIdentifier
+  let rhs: ObjectIdentifier
+}
+
+private func mirrorIdentifier(_ value: Any) -> ObjectIdentifier? {
+  if let value = value as? any _CustomDiffObject {
+    return value._objectIdentifier
+  }
+  let valueType = type(of: value)
+  guard valueType is AnyClass else { return nil }
+  return ObjectIdentifier(value as AnyObject)
+}
+
+private func isMirrorEqual(
+  _ lhs: Any,
+  _ rhs: Any,
+  visitedPairs: inout Set<MirrorPair>
+) -> Bool {
+  if let lhsIdentifier = mirrorIdentifier(lhs),
+    let rhsIdentifier = mirrorIdentifier(rhs)
+  {
+    let pair = MirrorPair(lhs: lhsIdentifier, rhs: rhsIdentifier)
+    if visitedPairs.contains(pair) {
+      return true
+    }
+    visitedPairs.insert(pair)
+  }
   guard let lhs = lhs as? any Equatable else {
     let lhsType = type(of: lhs)
     if lhsType is AnyClass, lhsType == type(of: rhs), lhs as AnyObject === rhs as AnyObject {
@@ -45,7 +77,7 @@ func isMirrorEqual(_ lhs: Any, _ rhs: Any) -> Bool {
     for (lhsChild, rhsChild) in zip(lhsMirror.children, rhsMirror.children) {
       guard
         lhsChild.label == rhsChild.label,
-        isMirrorEqual(lhsChild.value, rhsChild.value)
+        isMirrorEqual(lhsChild.value, rhsChild.value, visitedPairs: &visitedPairs)
       else { return false }
     }
     return true