58 lines
1.8 KiB
Plaintext
58 lines
1.8 KiB
Plaintext
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow strict
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*/
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import type { ASTValidationContext } from '../ValidationContext';
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import { GraphQLError } from '../../error/GraphQLError';
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import type { DirectiveNode } from '../../language/ast';
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import type { ASTVisitor } from '../../language/visitor';
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export function duplicateDirectiveMessage(directiveName: string): string {
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return (
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`The directive "${directiveName}" can only be used once at ` +
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'this location.'
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);
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}
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/**
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* Unique directive names per location
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*
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* A GraphQL document is only valid if all directives at a given location
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* are uniquely named.
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*/
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export function UniqueDirectivesPerLocation(
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context: ASTValidationContext,
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): ASTVisitor {
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return {
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// Many different AST nodes may contain directives. Rather than listing
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// them all, just listen for entering any node, and check to see if it
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// defines any directives.
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enter(node) {
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// Flow can't refine that node.directives will only contain directives,
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// so we cast so the rest of the code is well typed.
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const directives: ?$ReadOnlyArray<DirectiveNode> = (node: any).directives;
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if (directives) {
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const knownDirectives = Object.create(null);
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for (const directive of directives) {
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const directiveName = directive.name.value;
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if (knownDirectives[directiveName]) {
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context.reportError(
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new GraphQLError(duplicateDirectiveMessage(directiveName), [
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knownDirectives[directiveName],
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directive,
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]),
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);
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} else {
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knownDirectives[directiveName] = directive;
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}
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}
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}
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},
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};
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}
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