common/hcl/tag.go

71 lines
1.3 KiB
Go

package hcl
import (
"errors"
"fmt"
"reflect"
"strings"
)
const (
ElementTypeAttribute ElementType = "attr"
ElementTypeBlock ElementType = "block"
ElementTypeLabel ElementType = "label"
ElementTypeRemain ElementType = "remain"
)
var ErrNoHclTag = errors.New("no hcl tag")
type ElementType string
type FieldMeta struct {
Name string
Type ElementType
Optional bool
Ignore bool
}
func ExtractFieldMeta(t reflect.StructField, readTagName, writeTagName string) (FieldMeta, error) {
hclTag, present := t.Tag.Lookup(readTagName)
if !present {
return FieldMeta{}, ErrNoHclTag
}
cfg := FieldMeta{
Name: t.Name,
Type: ElementTypeAttribute,
}
if hclWriteTag, present := t.Tag.Lookup(writeTagName); present && hclWriteTag == "-" {
cfg.Ignore = true
return cfg, nil
}
split := strings.Split(hclTag, ",")
if len(split) > 0 && split[0] != "" {
cfg.Name = split[0]
}
if len(split) > 1 {
switch split[1] {
case "":
fallthrough
case "attr":
cfg.Type = ElementTypeAttribute
case "optional":
cfg.Optional = true
case "label":
cfg.Type = ElementTypeLabel
case "block":
cfg.Type = ElementTypeBlock
case "remain":
cfg.Type = ElementTypeRemain
default:
return FieldMeta{}, fmt.Errorf("unknown element type %q", split[1])
}
}
return cfg, nil
}