Initial Save

node_modules/graphql/validation/rules/UniqueDirectivesPerLocation.js.flow

@@ -0,0 +1,75 @@
+// @flow strict
+
+import { GraphQLError } from '../../error/GraphQLError';
+
+import { Kind } from '../../language/kinds';
+import { type DirectiveNode } from '../../language/ast';
+import { type ASTVisitor } from '../../language/visitor';
+
+import { specifiedDirectives } from '../../type/directives';
+
+import {
+  type SDLValidationContext,
+  type ValidationContext,
+} from '../ValidationContext';
+
+export function duplicateDirectiveMessage(directiveName: string): string {
+  return `The directive "${directiveName}" can only be used once at this location.`;
+}
+
+/**
+ * Unique directive names per location
+ *
+ * A GraphQL document is only valid if all non-repeatable directives at
+ * a given location are uniquely named.
+ */
+export function UniqueDirectivesPerLocation(
+  context: ValidationContext | SDLValidationContext,
+): ASTVisitor {
+  const uniqueDirectiveMap = Object.create(null);
+
+  const schema = context.getSchema();
+  const definedDirectives = schema
+    ? schema.getDirectives()
+    : specifiedDirectives;
+  for (const directive of definedDirectives) {
+    uniqueDirectiveMap[directive.name] = !directive.isRepeatable;
+  }
+
+  const astDefinitions = context.getDocument().definitions;
+  for (const def of astDefinitions) {
+    if (def.kind === Kind.DIRECTIVE_DEFINITION) {
+      uniqueDirectiveMap[def.name.value] = !def.repeatable;
+    }
+  }
+
+  return {
+    // Many different AST nodes may contain directives. Rather than listing
+    // them all, just listen for entering any node, and check to see if it
+    // defines any directives.
+    enter(node) {
+      // Flow can't refine that node.directives will only contain directives,
+      // so we cast so the rest of the code is well typed.
+      const directives: ?$ReadOnlyArray<DirectiveNode> = (node: any).directives;
+      if (directives) {
+        const knownDirectives = Object.create(null);
+        for (const directive of directives) {
+          const directiveName = directive.name.value;
+
+          if (uniqueDirectiveMap[directiveName]) {
+            if (knownDirectives[directiveName]) {
+              context.reportError(
+                new GraphQLError(duplicateDirectiveMessage(directiveName), [
+                  knownDirectives[directiveName],
+                  directive,
+                ]),
+              );
+            } else {
+              knownDirectives[directiveName] = directive;
+            }
+          }
+        }
+      }
+    },
+  };
+}