ucl/repl/evaldisplay.go

package repl

import (
	"context"
	"fmt"
	"os"
	"ucl.lmika.dev/ucl"
)

type NoResults struct{}

func (r *REPL) EvalAndDisplay(ctx context.Context, expr string) error {
	res, err := r.inst.Eval(ctx, expr)
	if err != nil {
		return err
	}

	return displayResult(ctx, r.inst, res)
}

func displayResult(ctx context.Context, inst *ucl.Inst, res any) (err error) {
	switch v := res.(type) {
	case NoResults:
		return nil
	case nil:
		if _, err = fmt.Fprintln(os.Stdout, "(nil)"); err != nil {
			return err
		}
	case ucl.Listable:
		for i := 0; i < v.Len(); i++ {
			if err = displayResult(ctx, inst, v.Index(i)); err != nil {
				return err
			}
		}
	case ucl.Object:
		if _, err = fmt.Fprintln(os.Stdout, v.String()); err != nil {
			return err
		}
	default:
		if _, err = fmt.Fprintln(os.Stdout, v); err != nil {
			return err
		}
	}
	return nil
}