tom-weatherhead/thaw-grammar

// tom-weatherhead/thaw-grammar/src/languages/scheme/domain-object-model/lambda-expression.ts

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

import { IEnvironmentFrame } from '../../../common/domain-object-model/environment-frame';
import { IExpression } from '../../../common/domain-object-model/iexpression';
import { IGlobalInfo } from '../../../common/domain-object-model/iglobal-info';
import { IVariable } from '../../../common/domain-object-model/variable';
import { ISExpression } from '../../lisp/domain-object-model/isexpression';

import { Closure } from './closure';

const typenameLambdaExpression = 'LambdaExpression';

export function isLambdaExpression(obj: unknown): obj is LambdaExpression {
    const le = obj as LambdaExpression;

    return typeof le !== 'undefined' && le.typename === typenameLambdaExpression;
}

export class LambdaExpression implements IExpression<ISExpression> {
    public readonly typename: string = typenameLambdaExpression;

    constructor(
        public readonly argList: IVariable<ISExpression>[],
        public readonly body: IExpression<ISExpression>,
        public readonly line = 0,
        public readonly column = 0
    ) {}

    public toString(): string {
        return `(lambda ${this.argList} ${this.body})`;
    }

    public evaluate(
        globalInfo: IGlobalInfo<ISExpression>,
        localEnvironment?: IEnvironmentFrame<ISExpression>,
        // eslint-disable-next-line @typescript-eslint/no-unused-vars
        options?: unknown
    ): ISExpression {
        options;

        return new Closure(
            this.argList,
            this.body,
            ifDefinedThenElse(localEnvironment, globalInfo.globalEnvironment),
            this.line,
            this.column
        );
    }
}