/* Attributes */
type Attributes map[string]string

/* SetTag */
func (attrs Attributes) SetTag(tag string) {
  if tags,exists := attrs["tags"]; !exists {
    attrs["tags"] = tag		
  } else {
    attrs["tags"] = strings.Join([]string{tags,tag}," ")
  }
}

/* Tag */
func (attrs Attributes) Tag(tag string) bool {
  if tags,exists := attrs["tags"]; exists {
    for _,t := range strings.Split(tags," ") {
      if t == tag {
        return true
      }
    }
  }
  return false
}

/* SetKeyValue */
func (attrs Attributes) SetKeyValue(key,value string) {
  attrs[key] = value
}

/* KeyValue */
func (attrs Attributes) KeyValue(key, def string) string {
  if value,exists := attrs[key]; exists {
    return value
  }
  return def
}

type Ternary string

const (
  True    = Ternary("ternary'true")
  Unknown = Ternary("ternary'unknown")
  False   = Ternary("ternary'false")
)

/* SetTernary */
func (attrs Attributes) SetTernary(key string, value Ternary) {
  attrs[key] = string(ternary)
}

/* Ternary */
func (attrs Attributes) Ternary(key string) Ternary {
  if value,exists := attrs[key]; exists {
    switch Ternary(value) {
      case True,Unknown,False:
       return Ternary(value)
      break
      default:
        return True  
      break
    }
  }
  return Unknown
}

/* Form */
func (attrs Attributes) Form(key string) string {
  if value,exists := attrs[key]; exists {
    switch Ternary(value) {
      case True,Unknown,False:
        return "ternary"
      break
      default:
        return "keyvalue"
      break
    }
  } 
  for _,tag := range strings.Split(attrs["tags"]," ") {
   if tag == key {
     return "tag"
   }
  }
  return "unknown"
}