tom-weatherhead/thaw-grammar

// tom-weatherhead/thaw-grammar/src/common/domain-object-model/begin-usage.ts

import { IEnvironmentFrame } from './environment-frame';
import { IExpression } from './iexpression';
import { IGlobalInfo } from './iglobal-info';

const typenameBeginUsage = 'BeginUsage';

export function isBeginUsage<T>(obj: unknown): obj is BeginUsage<T> {
    const beginUsage = obj as BeginUsage<T>;

    return typeof beginUsage !== 'undefined' && beginUsage.typename === typenameBeginUsage;
}

export class BeginUsage<T> implements IExpression<T> {
    public readonly typename: string = typenameBeginUsage;

    constructor(
        public readonly firstExpression: IExpression<T>,
        public readonly expressionList: IExpression<T>[]
    ) {}

    public toString(): string {
        return `(begin ${this.firstExpression} ${this.expressionList})`;
    }

    public evaluate(
        globalInfo: IGlobalInfo<T>,
        localEnvironment?: IEnvironmentFrame<T>,
        options?: unknown
    ): T {
        return this.expressionList.reduce(
            // eslint-disable-next-line @typescript-eslint/no-unused-vars
            (previousResult: T, expression: IExpression<T>) =>
                expression.evaluate(globalInfo, localEnvironment, options),
            this.firstExpression.evaluate(globalInfo, localEnvironment, options)
        );
    }
}