@dillonkearns/elm-graphql/examples/src/subscription/node_modules/graphql/validation/rules/UniqueDirectivesPerLocation.js

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'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.duplicateDirectiveMessage = duplicateDirectiveMessage;
exports.UniqueDirectivesPerLocation = UniqueDirectivesPerLocation;

var _error = require('../../error');

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * 
 */

function duplicateDirectiveMessage(directiveName) {
  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 directives at a given location
 * are uniquely named.
 */
function UniqueDirectivesPerLocation(context) {
  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: function enter(node) {
      if (node.directives) {
        var knownDirectives = Object.create(null);
        node.directives.forEach(function (directive) {
          var directiveName = directive.name.value;
          if (knownDirectives[directiveName]) {
            context.reportError(new _error.GraphQLError(duplicateDirectiveMessage(directiveName), [knownDirectives[directiveName], directive]));
          } else {
            knownDirectives[directiveName] = directive;
          }
        });
      }
    }
  };
}