Key is used as the identity of a Label. Keys are intended to be compared by pointer only, the name should be unique for communicating with external systems, but it is not required or enforced.
type Key interface {
// Name returns the key name.
Name() string
// Description returns a string that can be used to describe the value.
Description() string
// Format is used in formatting to append the value of the label to the
// supplied buffer.
// The formatter may use the supplied buf as a scratch area to avoid
// allocations.
Format(w io.Writer, buf []byte, l Label)
}
Label holds a key and value pair. It is normally used when passing around lists of labels.
type Label struct {
// contains filtered or unexported fields
}
func Of64(k Key, v uint64) Label
Of64 creates a new label from a key and a uint64. This is often used for non uint64 values that can be packed into a uint64. This method is for implementing new key types, label creation should normally be done with the Of method of the key.
func OfString(k Key, v string) Label
OfString creates a new label from a key and a string. This method is for implementing new key types, label creation should normally be done with the Of method of the key.
func OfValue(k Key, value interface{}) Label
OfValue creates a new label from the key and value. This method is for implementing new key types, label creation should normally be done with the Of method of the key.
func (t Label) Format(f fmt.State, r rune)
Format is used for debug printing of labels.
func (t Label) Key() Key
Key returns the key of this Label.
func (t Label) Unpack64() uint64
Unpack64 assumes the label was built using LabelOf64 and returns the value that was passed to that constructor. This method is for implementing new key types, for type safety normal access should be done with the From method of the key.
func (t Label) UnpackString() string
UnpackString assumes the label was built using LabelOfString and returns the value that was passed to that constructor. This method is for implementing new key types, for type safety normal access should be done with the From method of the key.
func (t Label) UnpackValue() interface{}
UnpackValue assumes the label was built using LabelOfValue and returns the value that was passed to that constructor. This method is for implementing new key types, for type safety normal access should be done with the From method of the key.
func (t Label) Valid() bool
Valid returns true if the Label is a valid one (it has a key).
List is the interface to something that provides an iterable list of labels. Iteration should start from 0 and continue until Valid returns false.
type List interface {
// Valid returns true if the index is within range for the list.
// It does not imply the label at that index will itself be valid.
Valid(index int) bool
// Label returns the label at the given index.
Label(index int) Label
}
func Filter(l List, keys ...Key) List
func NewList(labels ...Label) List
Map is the interface to a collection of Labels indexed by key.
type Map interface {
// Find returns the label that matches the supplied key.
Find(key Key) Label
}
func MergeMaps(srcs ...Map) Map
func NewMap(labels ...Label) Map