Files
moby/libnetwork/options/options.go
Sebastiaan van Stijn b453aa65fa update go:build tags to use go1.22
commit a0807e7cfe configured golangci-lint
to use go1.23 semantics, which alowed linters like `copyloopvar` to lint
using thee correct semantics.

go1.22 now creates a copy of variables when assigned in a loop; make sure we
don't have files that may downgrade semantics to go1.21 in case that also means
disabling that feature; https://go.dev/ref/spec#Go_1.22

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2024-11-12 14:02:09 +01:00

87 lines
2.7 KiB
Go

// FIXME(thaJeztah): remove once we are a module; the go:build directive prevents go from downgrading language version to go1.16:
//go:build go1.22
// Package options provides a way to pass unstructured sets of options to a
// component expecting a strongly-typed configuration structure.
package options
import (
"fmt"
"reflect"
)
// NoSuchFieldError is the error returned when the generic parameters hold a
// value for a field absent from the destination structure.
type NoSuchFieldError struct {
Field string
Type string
}
func (e NoSuchFieldError) Error() string {
return fmt.Sprintf("no field %q in type %q", e.Field, e.Type)
}
// CannotSetFieldError is the error returned when the generic parameters hold a
// value for a field that cannot be set in the destination structure.
type CannotSetFieldError struct {
Field string
Type string
}
func (e CannotSetFieldError) Error() string {
return fmt.Sprintf("cannot set field %q of type %q", e.Field, e.Type)
}
// TypeMismatchError is the error returned when the type of the generic value
// for a field mismatches the type of the destination structure.
type TypeMismatchError struct {
Field string
ExpectType string
ActualType string
}
func (e TypeMismatchError) Error() string {
return fmt.Sprintf("type mismatch, field %s require type %v, actual type %v", e.Field, e.ExpectType, e.ActualType)
}
// Generic is a basic type to store arbitrary settings.
type Generic map[string]any
// GenerateFromModel takes the generic options, and tries to build a new
// instance of the model's type by matching keys from the generic options to
// fields in the model.
//
// The return value is of the same type than the model (including a potential
// pointer qualifier).
func GenerateFromModel(options Generic, model interface{}) (interface{}, error) {
modType := reflect.TypeOf(model)
// If the model is of pointer type, we need to dereference for New.
resType := reflect.TypeOf(model)
if modType.Kind() == reflect.Ptr {
resType = resType.Elem()
}
// Populate the result structure with the generic layout content.
res := reflect.New(resType)
for name, value := range options {
field := res.Elem().FieldByName(name)
if !field.IsValid() {
return nil, NoSuchFieldError{name, resType.String()}
}
if !field.CanSet() {
return nil, CannotSetFieldError{name, resType.String()}
}
if reflect.TypeOf(value) != field.Type() {
return nil, TypeMismatchError{name, field.Type().String(), reflect.TypeOf(value).String()}
}
field.Set(reflect.ValueOf(value))
}
// If the model is not of pointer type, return content of the result.
if modType.Kind() == reflect.Ptr {
return res.Interface(), nil
}
return res.Elem().Interface(), nil
}