flow like the river

VISUALIZACION/node_modules/graphql/validation/rules/UniqueDirectiveNamesRule.js

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+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.UniqueDirectiveNamesRule = UniqueDirectiveNamesRule;
+
+var _GraphQLError = require("../../error/GraphQLError.js");
+
+/**
+ * Unique directive names
+ *
+ * A GraphQL document is only valid if all defined directives have unique names.
+ */
+function UniqueDirectiveNamesRule(context) {
+  var knownDirectiveNames = Object.create(null);
+  var schema = context.getSchema();
+  return {
+    DirectiveDefinition: function DirectiveDefinition(node) {
+      var directiveName = node.name.value;
+
+      if (schema !== null && schema !== void 0 && schema.getDirective(directiveName)) {
+        context.reportError(new _GraphQLError.GraphQLError("Directive \"@".concat(directiveName, "\" already exists in the schema. It cannot be redefined."), node.name));
+        return;
+      }
+
+      if (knownDirectiveNames[directiveName]) {
+        context.reportError(new _GraphQLError.GraphQLError("There can be only one directive named \"@".concat(directiveName, "\"."), [knownDirectiveNames[directiveName], node.name]));
+      } else {
+        knownDirectiveNames[directiveName] = node.name;
+      }
+
+      return false;
+    }
+  };
+}