tom-weatherhead/thaw-grammar

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

import { ifDefinedThenElse } from 'thaw-common-utilities.ts';

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

const typenameSetUsage = 'SetUsage';

export function isSetUsage<T>(obj: unknown): obj is SetUsage<T> {
    const setUsage = obj as SetUsage<T>;

    return typeof setUsage !== 'undefined' && setUsage.typename === typenameSetUsage;
}

export class SetUsage<T> implements IExpression<T> {
    public readonly typename: string = typenameSetUsage;

    constructor(
        public readonly variableName: IVariable<T>,
        public readonly expression: IExpression<T>
    ) {}

    public toString(): string {
        return `(set ${this.variableName} ${this.expression})`;
    }

    public evaluate(
        globalInfo: IGlobalInfo<T>,
        localEnvironment?: IEnvironmentFrame<T>,
        options?: unknown
    ): T {
        const expressionValue = this.expression.evaluate(globalInfo, localEnvironment, options);

        // If the variable is not already defined in a local env, we may have to assign it to the global env.

        // console.log(`SetUsage<T>.Evaluate() : var is ${this.variableName.Name}; value is ${expressionValue}`);
        ifDefinedThenElse(localEnvironment, globalInfo.globalEnvironment).addBubbleDown(
            this.variableName,
            expressionValue
        );

        return expressionValue;
    }
}