flow like the river

BACK_BACK/node_modules/graphql/validation/rules/ScalarLeafsRule.js

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+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.ScalarLeafsRule = ScalarLeafsRule;
+
+var _inspect = _interopRequireDefault(require("../../jsutils/inspect.js"));
+
+var _GraphQLError = require("../../error/GraphQLError.js");
+
+var _definition = require("../../type/definition.js");
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/**
+ * Scalar leafs
+ *
+ * A GraphQL document is valid only if all leaf fields (fields without
+ * sub selections) are of scalar or enum types.
+ */
+function ScalarLeafsRule(context) {
+  return {
+    Field: function Field(node) {
+      var type = context.getType();
+      var selectionSet = node.selectionSet;
+
+      if (type) {
+        if ((0, _definition.isLeafType)((0, _definition.getNamedType)(type))) {
+          if (selectionSet) {
+            var fieldName = node.name.value;
+            var typeStr = (0, _inspect.default)(type);
+            context.reportError(new _GraphQLError.GraphQLError("Field \"".concat(fieldName, "\" must not have a selection since type \"").concat(typeStr, "\" has no subfields."), selectionSet));
+          }
+        } else if (!selectionSet) {
+          var _fieldName = node.name.value;
+
+          var _typeStr = (0, _inspect.default)(type);
+
+          context.reportError(new _GraphQLError.GraphQLError("Field \"".concat(_fieldName, "\" of type \"").concat(_typeStr, "\" must have a selection of subfields. Did you mean \"").concat(_fieldName, " { ... }\"?"), node));
+        }
+      }
+    }
+  };
+}