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flowUtilityTypes.js
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flowUtilityTypes.js
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/*
* Copyright (c) 2015, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @flow
*
*/
import recast from 'recast';
const {
types: { namedTypes: types },
} = recast;
const supportedUtilityTypes = new Set(['$Exact', '$ReadOnly']);
/**
* See `supportedUtilityTypes` for which types are supported and
* https://flow.org/en/docs/types/utilities/ for which types are available.
*/
export function isSupportedUtilityType(path: NodePath): boolean {
if (types.GenericTypeAnnotation.check(path.node)) {
const idPath = path.get('id');
return !!idPath && supportedUtilityTypes.has(idPath.node.name);
}
return false;
}
/**
* Unwraps well known utility types. For example:
*
* $ReadOnly<T> => T
*/
export function unwrapUtilityType(path: NodePath): NodePath {
while (isSupportedUtilityType(path)) {
path = path.get('typeParameters', 'params', 0);
}
return path;
}