core/server/sandbox/convert.go

package sandbox

import (
	"fmt"

	"go.starlark.net/starlark"
)

// GoToStarlark converts a Go value (typically from JSON unmarshal) to a
// starlark.Value.  Handles nil, bool, int, int64, float64, string,
// map[string]any, []any, and their interface{} equivalents.  Unknown
// types are stringified.
func GoToStarlark(v any) starlark.Value {
	switch val := v.(type) {
	case nil:
		return starlark.None
	case bool:
		return starlark.Bool(val)
	case int:
		return starlark.MakeInt(val)
	case int64:
		return starlark.MakeInt64(val)
	case float64:
		if val == float64(int64(val)) {
			return starlark.MakeInt64(int64(val))
		}
		return starlark.Float(val)
	case string:
		return starlark.String(val)
	case map[string]any:
		return MapToDict(val)
	case []any:
		elems := make([]starlark.Value, len(val))
		for i, e := range val {
			elems[i] = GoToStarlark(e)
		}
		return starlark.NewList(elems)
	default:
		return starlark.String(fmt.Sprintf("%v", val))
	}
}

// StarlarkToGo converts a starlark.Value to a Go value suitable for
// JSON serialization.  Handles None, Bool, Int, Float, String, List,
// Dict, and Tuple.
func StarlarkToGo(v starlark.Value) any {
	switch val := v.(type) {
	case starlark.NoneType:
		return nil
	case starlark.Bool:
		return bool(val)
	case starlark.Int:
		if i, ok := val.Int64(); ok {
			return i
		}
		return val.String()
	case starlark.Float:
		return float64(val)
	case starlark.String:
		return string(val)
	case *starlark.List:
		result := make([]any, val.Len())
		for i := 0; i < val.Len(); i++ {
			result[i] = StarlarkToGo(val.Index(i))
		}
		return result
	case *starlark.Dict:
		return DictToMap(val)
	case starlark.Tuple:
		result := make([]any, len(val))
		for i, e := range val {
			result[i] = StarlarkToGo(e)
		}
		return result
	default:
		return v.String()
	}
}

// DictToMap converts a *starlark.Dict to map[string]any.
// Non-string keys are silently skipped.
func DictToMap(d *starlark.Dict) map[string]any {
	result := make(map[string]any, d.Len())
	for _, item := range d.Items() {
		k, ok := starlark.AsString(item[0])
		if !ok {
			continue
		}
		result[k] = StarlarkToGo(item[1])
	}
	return result
}

// MapToDict converts a map[string]any to *starlark.Dict.
func MapToDict(m map[string]any) *starlark.Dict {
	d := starlark.NewDict(len(m))
	for k, v := range m {
		_ = d.SetKey(starlark.String(k), GoToStarlark(v))
	}
	return d
}