jiuyiUniapp/service/node_modules/hermes-parser/dist/transform/SimpleTransform.js.flow

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2025-02-13 09:59:20 +08:00
/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow strict
* @format
*/
'use strict';
import type {VisitorKeysType} from '../traverse/getVisitorKeys';
import type {ESNode, Program} from 'hermes-estree';
import {SimpleTraverser} from '../traverse/SimpleTraverser';
import {
nodeWith,
removeNodeOnParent,
replaceNodeOnParent,
} from './astNodeMutationHelpers';
/**
* Transform callback
* @param node The node we are visiting
* @returns
* - return input node, signals no changes were made will continue to the next node.
* - return new node, the old node will be replaced in the AST. The new node and its
* children are then traversed.
* - return null, signals the node should be deleted from the AST.
*/
export type TransformCallback = (node: ESNode) => ESNode | null;
export type TransformOptions = $ReadOnly<{
/** The callback function which is called on entering each node. */
transform: TransformCallback,
/** The set of visitor keys to use for traversal. Defaults to the Flow ESTree visitor keys */
visitorKeys?: ?VisitorKeysType,
}>;
function setParentPointer(node: ESNode, parent: ?ESNode): void {
if (parent != null) {
// $FlowExpectedError[cannot-write]
node.parent = parent;
}
}
/**
* A simple class to recursively tranform AST trees.
*/
export class SimpleTransform {
/**
* Transform the given AST tree.
* @param rootNode The root node to traverse.
* @param options The option object.
* @return The modified rootNode or a new node if the rootNode was transformed directly.
*/
transform(rootNode: ESNode, options: TransformOptions): ESNode | null {
let resultRootNode: ESNode | null = rootNode;
SimpleTraverser.traverse(rootNode, {
enter: (node: ESNode, parent: ?ESNode) => {
// Ensure the parent pointers are correctly set before entering the node.
setParentPointer(node, parent);
const resultNode = options.transform(node);
if (resultNode !== node) {
let traversedResultNode = null;
if (resultNode != null) {
// Ensure the new node has the correct parent pointers before recursing again.
setParentPointer(resultNode, parent);
traversedResultNode = this.transform(resultNode, options);
}
if (parent == null) {
if (node !== rootNode) {
throw new Error(
'SimpleTransform infra error: Parent not set on non root node, this should not be possible',
);
}
resultRootNode = traversedResultNode;
} else if (traversedResultNode == null) {
removeNodeOnParent(node, parent, options.visitorKeys);
} else {
replaceNodeOnParent(
node,
parent,
traversedResultNode,
options.visitorKeys,
);
setParentPointer(traversedResultNode, parent);
}
throw SimpleTraverser.Skip;
}
},
leave(_node: ESNode) {},
visitorKeys: options.visitorKeys,
});
return resultRootNode;
}
/**
* Transform the given AST tree.
* @param node The root node to traverse.
* @param options The option object.
*/
static transform(node: ESNode, options: TransformOptions): ESNode | null {
return new SimpleTransform().transform(node, options);
}
static transformProgram(
program: Program,
options: TransformOptions,
): Program {
const result = SimpleTransform.transform(program, options);
if (result?.type === 'Program') {
return result;
}
throw new Error('SimpleTransform.transformProgram: Expected program node.');
}
/**
* Return a new AST node with the given properties overrided if needed.
*
* This function takes care to only create new nodes when needed. Referential equality of nodes
* is important as its used to know if a node should be re-traversed.
*
* @param node The base AST node.
* @param overrideProps New properties to apply to the node.
* @return Either the orginal node if the properties matched the existing node or a new node with
* the new properties.
*/
static nodeWith<T: ESNode>(
node: T,
overrideProps: Partial<T>,
visitorKeys?: VisitorKeysType,
): T {
return nodeWith<T>(node, overrideProps, visitorKeys);
}
}