adaptive-expressions/src/builtinFunctions/addProperty.ts

Common Expression Language

/**
 * @module adaptive-expressions
 */
/**
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */

import { Expression } from '../expression';
import { EvaluateExpressionDelegate, ExpressionEvaluator } from '../expressionEvaluator';
import { ExpressionType } from '../expressionType';
import { FunctionUtils } from '../functionUtils';
import { ReturnType } from '../returnType';

/**
 * Add a property and its value, or name-value pair, to a JSON object, and return the updated object.
 * If the object already exists at runtime the function throws an error.
 */
export class AddProperty extends ExpressionEvaluator {
    /**
     * Initializes a new instance of the [AddProperty](xref:adaptive-expressions.AddProperty) class.
     */
    constructor() {
        super(ExpressionType.AddProperty, AddProperty.evaluator(), ReturnType.Object, AddProperty.validator);
    }

    /**
     * @private
     */
    private static evaluator(): EvaluateExpressionDelegate {
        return FunctionUtils.applyWithError((args: any[]): any => {
            let error: string;
            const temp: any = args[0];
            const prop = String(args[1]);
            if (prop in temp) {
                error = `${prop} already exists`;
            } else {
                temp[String(args[1])] = args[2];
            }

            return { value: temp, error };
        });
    }

    /**
     * @private
     */
    private static validator(expression: Expression): void {
        FunctionUtils.validateOrder(expression, undefined, ReturnType.Object, ReturnType.String, ReturnType.Object);
    }
}