flow like the river

VISUALIZACION/node_modules/graphql/validation/rules/UniqueDirectivesPerLocationRule.mjs

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+import { GraphQLError } from "../../error/GraphQLError.mjs";
+import { Kind } from "../../language/kinds.mjs";
+import { isTypeDefinitionNode, isTypeExtensionNode } from "../../language/predicates.mjs";
+import { specifiedDirectives } from "../../type/directives.mjs";
+
+/**
+ * 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 UniqueDirectivesPerLocationRule(context) {
+  var uniqueDirectiveMap = Object.create(null);
+  var schema = context.getSchema();
+  var definedDirectives = schema ? schema.getDirectives() : specifiedDirectives;
+
+  for (var _i2 = 0; _i2 < definedDirectives.length; _i2++) {
+    var directive = definedDirectives[_i2];
+    uniqueDirectiveMap[directive.name] = !directive.isRepeatable;
+  }
+
+  var astDefinitions = context.getDocument().definitions;
+
+  for (var _i4 = 0; _i4 < astDefinitions.length; _i4++) {
+    var def = astDefinitions[_i4];
+
+    if (def.kind === Kind.DIRECTIVE_DEFINITION) {
+      uniqueDirectiveMap[def.name.value] = !def.repeatable;
+    }
+  }
+
+  var schemaDirectives = Object.create(null);
+  var typeDirectivesMap = Object.create(null);
+  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 == null) {
+        return;
+      }
+
+      var seenDirectives;
+
+      if (node.kind === Kind.SCHEMA_DEFINITION || node.kind === Kind.SCHEMA_EXTENSION) {
+        seenDirectives = schemaDirectives;
+      } else if (isTypeDefinitionNode(node) || isTypeExtensionNode(node)) {
+        var typeName = node.name.value;
+        seenDirectives = typeDirectivesMap[typeName];
+
+        if (seenDirectives === undefined) {
+          typeDirectivesMap[typeName] = seenDirectives = Object.create(null);
+        }
+      } else {
+        seenDirectives = Object.create(null);
+      }
+
+      for (var _i6 = 0, _node$directives2 = node.directives; _i6 < _node$directives2.length; _i6++) {
+        var _directive = _node$directives2[_i6];
+        var directiveName = _directive.name.value;
+
+        if (uniqueDirectiveMap[directiveName]) {
+          if (seenDirectives[directiveName]) {
+            context.reportError(new GraphQLError("The directive \"@".concat(directiveName, "\" can only be used once at this location."), [seenDirectives[directiveName], _directive]));
+          } else {
+            seenDirectives[directiveName] = _directive;
+          }
+        }
+      }
+    }
+  };
+}