feature: Adds KnownDirectivesRule

Author: NeedleInAJayStack

Sources/GraphQL/Validation/Rules/KnownDirectivesRule.swift

@@ -0,0 +1,122 @@
+
+/**
+ * Known directives
+ *
+ * A GraphQL document is only valid if all `@directives` are known by the
+ * schema and legally positioned.
+ *
+ * See https://spec.graphql.org/draft/#sec-Directives-Are-Defined
+ */
+func KnownDirectivesRule(context: ValidationContext) -> Visitor {
+    var locationsMap = [String: [String]]()
+
+    let schema = context.schema
+    let definedDirectives = schema.directives
+    for directive in definedDirectives {
+        locationsMap[directive.name] = directive.locations.map { $0.rawValue }
+    }
+
+    let astDefinitions = context.ast.definitions
+    for def in astDefinitions {
+        if let directive = def as? DirectiveDefinition {
+            locationsMap[directive.name.value] = directive.locations.map { $0.value }
+        }
+    }
+
+    return Visitor(
+        enter: { node, _, _, _, ancestors in
+            if let node = node as? Directive {
+                let name = node.name.value
+                let locations = locationsMap[name]
+
+                guard let locations = locations else {
+                    context.report(
+                        error: GraphQLError(
+                            message: "Unknown directive \"@\(name)\".",
+                            nodes: [node]
+                        )
+                    )
+                    return .continue
+                }
+
+                let candidateLocation = getDirectiveLocationForASTPath(ancestors)
+                if
+                    let candidateLocation = candidateLocation,
+                    !locations.contains(candidateLocation.rawValue)
+                {
+                    context.report(
+                        error: GraphQLError(
+                            message: "Directive \"@\(name)\" may not be used on \(candidateLocation.rawValue).",
+                            nodes: [node]
+                        )
+                    )
+                }
+            }
+            return .continue
+        }
+    )
+}
+
+func getDirectiveLocationForASTPath(_ ancestors: [NodeResult]) -> DirectiveLocation? {
+    guard let last = ancestors.last, case let .node(appliedTo) = last else {
+        return nil
+    }
+
+    switch appliedTo {
+    case let appliedTo as OperationDefinition:
+        return getDirectiveLocationForOperation(appliedTo.operation)
+    case is Field:
+        return DirectiveLocation.field
+    case is FragmentSpread:
+        return DirectiveLocation.fragmentSpread
+    case is InlineFragment:
+        return DirectiveLocation.inlineFragment
+    case is FragmentDefinition:
+        return DirectiveLocation.fragmentDefinition
+    case is VariableDefinition:
+        return DirectiveLocation.variableDefinition
+    case is SchemaDefinition:
+        return DirectiveLocation.schema
+    case is ScalarTypeDefinition, is ScalarExtensionDefinition:
+        return DirectiveLocation.scalar
+    case is ObjectTypeDefinition:
+        return DirectiveLocation.object
+    case is FieldDefinition:
+        return DirectiveLocation.fieldDefinition
+    case is InterfaceTypeDefinition, is InterfaceExtensionDefinition:
+        return DirectiveLocation.interface
+    case is UnionTypeDefinition, is UnionExtensionDefinition:
+        return DirectiveLocation.union
+    case is EnumTypeDefinition, is EnumExtensionDefinition:
+        return DirectiveLocation.enum
+    case is EnumValueDefinition:
+        return DirectiveLocation.enumValue
+    case is InputObjectTypeDefinition, is InputObjectExtensionDefinition:
+        return DirectiveLocation.inputObject
+    case is InputValueDefinition:
+        guard ancestors.count >= 3 else {
+            return nil
+        }
+        let parentNode = ancestors[ancestors.count - 3]
+        guard case let .node(parentNode) = parentNode else {
+            return nil
+        }
+        return parentNode.kind == .inputObjectTypeDefinition
+            ? DirectiveLocation.inputFieldDefinition
+            : DirectiveLocation.argumentDefinition
+    // Not reachable, all possible types have been considered.
+    default:
+        return nil
+    }
+}
+
+func getDirectiveLocationForOperation(_ operation: OperationType) -> DirectiveLocation {
+    switch operation {
+    case .query:
+        return DirectiveLocation.query
+    case .mutation:
+        return DirectiveLocation.mutation
+    case .subscription:
+        return DirectiveLocation.subscription
+    }
+}

Sources/GraphQL/Validation/SpecifiedRules.swift

@@ -19,7 +19,7 @@ public let specifiedRules: [(ValidationContext) -> Visitor] = [
     UniqueVariableNamesRule,
     NoUndefinedVariablesRule,
     NoUnusedVariablesRule,
-//    KnownDirectivesRule,
+    KnownDirectivesRule,
 //    UniqueDirectivesPerLocationRule,
 //    DeferStreamDirectiveOnRootFieldRule,
 //    DeferStreamDirectiveOnValidOperationsRule,