botbuilder-dialogs/src/memory/pathResolvers/atPathResolver.ts

A dialog stack based conversation manager for Microsoft BotBuilder.

/**
 * @module botbuilder-dialogs
 */
/**
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */
import { AliasPathResolver } from './aliasPathResolver';

/**
 * Maps @@ => turn.recognized.entitites.xxx[0]
 */
export class AtPathResolver extends AliasPathResolver {
    private readonly _prefix = 'turn.recognized.entities.';
    private readonly _delims = ['.', '['];

    /**
     * Initializes a new instance of the [AtPathResolver](xref:botbuilder-dialogs.AtPathResolver) class.
     */
    constructor() {
        super('@', '');
    }

    /**
     * Transforms the path.
     *
     * @param path Path to inspect.
     * @returns The transformed path.
     */
    transformPath(path: string): string {
        path = path.trim();
        if (path.startsWith('@') && path.length > 1 && !path.startsWith('@@')) {
            let end = -1;
            for (let i = 0; i < this._delims.length; i++) {
                const indexOfDelim = path.indexOf(this._delims[i]);
                if (indexOfDelim >= 0) {
                    end = indexOfDelim;
                    break;
                }
            }
            if (end == -1) {
                end = path.length;
            }
            const property = path.substr(1, end - 1);
            const suffix = path.substr(end);
            path = `${this._prefix}${property}.first()${suffix}`;
        }

        return path;
    }
}