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// @ts-check
import { WalkerBase } from './walker.js';
/** @typedef { import('estree').BaseNode} BaseNode */
/** @typedef { import('./walker').WalkerContext} WalkerContext */
/** @typedef {(
 *    this: WalkerContext,
 *    node: BaseNode,
 *    parent: BaseNode,
 *    key: string,
 *    index: number
 * ) => Promise<void>} AsyncHandler */
export class AsyncWalker extends WalkerBase {
    /**
     *
     * @param {AsyncHandler} enter
     * @param {AsyncHandler} leave
     */
    constructor(enter, leave) {
        super();
        /** @type {AsyncHandler} */
        this.enter = enter;
        /** @type {AsyncHandler} */
        this.leave = leave;
    }
    /**
     *
     * @param {BaseNode} node
     * @param {BaseNode} parent
     * @param {string} [prop]
     * @param {number} [index]
     * @returns {Promise<BaseNode>}
     */
    async 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;
                await 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;
            }
            for (const key in node) {
                const value = node[key];
                if (typeof value !== "object") {
                    continue;
                } else if (Array.isArray(value)) {
                    for (let i = 0; i < value.length; i += 1) {
                        if (value[i] !== null && typeof value[i].type === 'string') {
                            if (!(await this.visit(value[i], node, key, i))) {
                                // removed
                                i--;
                            }
                        }
                    }
                } else if (value !== null && typeof value.type === "string") {
                    await 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;
                await 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;
    }
}
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