str/src/vm/commands/lines.ts

import {Command, ParseContext, unwrapString} from "./command.js";
import {LexInput} from "../lexer.js";
import {StrVM} from "../vm.js";
import {Awaitable} from "../../util/types.js";

export type LinesData = {}

export class Lines extends Command<LinesData> {
    attemptParse(context: ParseContext): LinesData {
        return {}
    }

    getDisplayName(): string {
        return 'lines'
    }

    isParseCandidate(token: LexInput): boolean {
        return this.isKeyword(token, 'lines')
    }

    execute(vm: StrVM, data: LinesData): Awaitable<StrVM> {
        return vm.tapInPlace(ctx =>
            ctx.replaceSubject(sub => ({
                term: 'destructured',
                value: unwrapString(sub)
                    .split('\n')
                    .map((line, idx) => ({ prefix: idx ? '\n' : undefined, value: line })),
            })))
    }
}