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import { WalkerBase } from './walker.js';
/**
* @typedef { import('estree').Node} Node
* @typedef { import('./walker.js').WalkerContext} WalkerContext
* @typedef {(
* this: WalkerContext,
* node: Node,
* parent: Node | null,
* key: string | number | symbol | null | undefined,
* index: number | null | undefined
* ) => void} SyncHandler
*/
export class SyncWalker extends WalkerBase {
/**
*
* @param {SyncHandler} [enter]
* @param {SyncHandler} [leave]
*/
constructor(enter, leave) {
super();
/** @type {boolean} */
this.should_skip = false;
/** @type {boolean} */
this.should_remove = false;
/** @type {Node | null} */
this.replacement = null;
/** @type {WalkerContext} */
this.context = {
skip: () => (this.should_skip = true),
remove: () => (this.should_remove = true),
replace: (node) => (this.replacement = node)
};
/** @type {SyncHandler | undefined} */
this.enter = enter;
/** @type {SyncHandler | undefined} */
this.leave = leave;
}
/**
* @template {Node} Parent
* @param {Node} node
* @param {Parent | null} parent
* @param {keyof Parent} [prop]
* @param {number | null} [index]
* @returns {Node | null}
*/
visit(node, parent, prop, index) {
if (node) {
if (this.enter) {
const _should_skip = this.should_skip;
const _should_remove = this.should_remove;
const _replacement = this.replacement;
this.should_skip = false;
this.should_remove = false;
this.replacement = null;
this.enter.call(this.context, node, parent, prop, index);
if (this.replacement) {
node = this.replacement;
this.replace(parent, prop, index, node);
}
if (this.should_remove) {
this.remove(parent, prop, index);
}
const skipped = this.should_skip;
const removed = this.should_remove;
this.should_skip = _should_skip;
this.should_remove = _should_remove;
this.replacement = _replacement;
if (skipped) return node;
if (removed) return null;
}
/** @type {keyof Node} */
let key;
for (key in node) {
/** @type {unknown} */
const value = node[key];
if (value && typeof value === 'object') {
if (Array.isArray(value)) {
const nodes = /** @type {Array<unknown>} */ (value);
for (let i = 0; i < nodes.length; i += 1) {
const item = nodes[i];
if (isNode(item)) {
if (!this.visit(item, node, key, i)) {
// removed
i--;
}
}
}
} else if (isNode(value)) {
this.visit(value, node, key, null);
}
}
}
if (this.leave) {
const _replacement = this.replacement;
const _should_remove = this.should_remove;
this.replacement = null;
this.should_remove = false;
this.leave.call(this.context, node, parent, prop, index);
if (this.replacement) {
node = this.replacement;
this.replace(parent, prop, index, node);
}
if (this.should_remove) {
this.remove(parent, prop, index);
}
const removed = this.should_remove;
this.replacement = _replacement;
this.should_remove = _should_remove;
if (removed) return null;
}
}
return node;
}
}
/**
* Ducktype a node.
*
* @param {unknown} value
* @returns {value is Node}
*/
function isNode(value) {
return (
value !== null && typeof value === 'object' && 'type' in value && typeof value.type === 'string'
);
}
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