Validate layout of node_choices

Author: ahoppen

Sources/SwiftSyntax/Raw/RawSyntaxValidation.swift.gyb

@@ -24,13 +24,71 @@
 /// Results in an assertion failure if the layout is invalid.
 func validateLayout(layout: RawSyntaxBuffer, as kind: SyntaxKind) {
 #if DEBUG
-  func _verify<Node: RawSyntaxNodeProtocol>(_ raw: RawSyntax?, as _: Node.Type, file: StaticString = #file, line: UInt = #line) {
-    assert(raw != nil, file: file, line: line)
-    assert(Node.isKindOf(raw!), file: file, line: line)
+  enum ValidationError: CustomStringConvertible {
+    case expectedNonNil(expectedKind: RawSyntaxNodeProtocol.Type, file: StaticString, line: UInt)
+    case kindMismatch(expectedKind: RawSyntaxNodeProtocol.Type, actualKind: SyntaxKind, file: StaticString, line: UInt)
+
+    var description: String {
+      switch self {
+      case .expectedNonNil(expectedKind: let expectedKind, file: _, line: _):
+        return "Expected non-nil node of type \(expectedKind) but received nil"
+      case .kindMismatch(expectedKind: let expectedKind, actualKind: let actualKind, file: _, line: _):
+        return "Expected node of type \(expectedKind) but received \(actualKind)"
+      }
+    }
+
+    var fileAndLine: (StaticString, UInt) {
+      switch self {
+      case .expectedNonNil(expectedKind: _, file: let file, line: let line):
+        return (file, line)
+      case .kindMismatch(expectedKind: _, actualKind: _, file: let file, line: let line):
+        return (file, line)
+      }
+    }
   }
-  func _verify<Node: RawSyntaxNodeProtocol>(_ raw: RawSyntax?, as _: Node?.Type, file: StaticString = #file, line: UInt = #line) {
-    raw.map { assert(Node.isKindOf($0), file: file, line: line) }
+
+  func verify<Node: RawSyntaxNodeProtocol>(_ raw: RawSyntax?, as _: Node.Type, file: StaticString = #file, line: UInt = #line) -> ValidationError? {
+    guard let raw = raw else {
+      return .expectedNonNil(expectedKind: Node.self, file: file, line: line)
+    }
+    guard Node.isKindOf(raw) else {
+      return .kindMismatch(expectedKind: Node.self, actualKind: raw.kind, file: file, line: line)
+    }
+    return nil
   }
+
+  func verify<Node: RawSyntaxNodeProtocol>(_ raw: RawSyntax?, as _: Node?.Type, file: StaticString = #file, line: UInt = #line) -> ValidationError? {
+    if raw != nil {
+      return verify(raw, as: Node.self, file: file, line: line)
+    }
+    return nil
+  }
+
+  func assertNoError(_ nodeKind: SyntaxKind, _ index: Int, _ error: ValidationError?) {
+    if let error = error {
+      let (file, line) = error.fileAndLine
+      assertionFailure("""
+        Error validating child at index \(index) of \(nodeKind):
+        \(error.description)
+        """, file: file, line: line)
+        _ = 1
+    }
+  }
+
+  func assertAnyHasNoError(_ nodeKind: SyntaxKind, _ index: Int, _ errors: [ValidationError?]) {
+    let nonNilErrors = errors.compactMap({ $0 })
+    if nonNilErrors.count == errors.count, let firstError = nonNilErrors.first {
+      let (file, line) = firstError.fileAndLine
+      assertionFailure("""
+        Error validating child at index \(index) of \(nodeKind):
+        Node did not satisfy any node choice requirement.
+        Validation failures:
+        \(nonNilErrors.map({ "- \($0.description)" }).joined(separator: "\n") )
+        """, file: file, line: line)
+      _ = 1
+    }
+  }
+
   switch kind {
   case .unknown:
     break
@@ -41,11 +99,19 @@ func validateLayout(layout: RawSyntaxBuffer, as kind: SyntaxKind) {
 %   if node.is_buildable() or node.is_missing():
     assert(layout.count == ${len(node.children)})
 %     for (idx, child) in enumerate(node.children):
-    _verify(layout[${idx}], as: Raw${child.type_name}${"?" if child.is_optional else ""}.self)
+%       if child.node_choices:
+    assertAnyHasNoError(kind, ${idx}, [
+%         for node_choice in child.node_choices:
+    verify(layout[${idx}], as: Raw${child.type_name}${"?" if child.is_optional else ""}.self),
+%         end
+    ])
+%       else:
+    assertNoError(kind, ${idx}, verify(layout[${idx}], as: Raw${child.type_name}${"?" if child.is_optional else ""}.self))
+%       end
 %     end
 %   elif node.is_syntax_collection():
-    for element in layout {
-      _verify(element, as: Raw${node.collection_element_type}.self)
+    for (index, element) in layout.enumerated() {
+      assertNoError(kind, index, verify(element, as: Raw${node.collection_element_type}.self))
     }
 %   end
     break