spec

Documentation

Overview

Package spec provides spec-version metadata.

For use by code that maps events using (prefixed) attribute name strings. Supports handling multiple spec versions uniformly.

Index

• Variables
• type Attribute
• type Kind
  • func (k Kind) IsRequired() bool
  • func (k Kind) String() string
• type Version
• type Versions
  • func New() *Versions
  • func WithPrefix(prefix string) *Versions
  • func (vs *Versions) FindVersion(getAttr func(string) string) (Version, error)
  • func (vs *Versions) Latest() Version
  • func (vs *Versions) Prefix() string
  • func (vs *Versions) SpecVersionNames() []string
  • func (vs *Versions) Version(name string) (Version, error)
  • func (vs *Versions) Versions() []Version

Variables

var (
	VS  *Versions
	V01 Version
	V02 Version
	V03 Version
	V1  Version
)

Built-in un-prefixed versions.

Types

type Attribute

type Attribute interface {
	Kind() Kind
	// Name of the attribute with respect to the current spec Version()
	Name() string
	// Version of the spec that this attribute belongs to
	Version() Version
	// Get the value of this attribute from an event context
	Get(ce.EventContextReader) interface{}
	// Set the value of this attribute on an event context
	Set(ce.EventContextWriter, interface{}) error
	// Delete this attribute from and event context, when possible
	Delete(ce.EventContextWriter) error
}

Attribute is a named attribute accessor. The attribute name is specific to a Version.

type Kind

type Kind uint8

Kind is a version-independent identifier for a CloudEvent context attribute.

const (
	// Required cloudevents attributes
	ID Kind = iota
	Source
	SpecVersion
	Type
	// Optional cloudevents attributes
	DataContentType
	DataSchema
	Subject
	Time
)

func (Kind) IsRequired

func (k Kind) IsRequired() bool

IsRequired returns true for attributes defined as "required" by the CE spec.

func (Kind) String

func (k Kind) String() string

String is a human-readable string, for a valid attribute name use Attribute.Name

type Version

type Version interface {
	// String name of the version, e.g. "1.0"
	String() string
	// Prefix for attribute names.
	Prefix() string
	// Attribute looks up a prefixed attribute name (case insensitive).
	// Returns nil if not found.
	Attribute(name string) Attribute
	// Attributes returns all the context attributes for this version.
	Attributes() []Attribute
	// NewContext returns a new context for this version.
	NewContext() ce.EventContext
	// Convert translates a context to this version.
	Convert(ce.EventContextConverter) ce.EventContext
	// SetAttribute sets named attribute to value.
	//
	// Name is case insensitive.
	// Does nothing if name does not start with prefix.
	SetAttribute(context ce.EventContextWriter, name string, value interface{}) error
	// Attribute looks up the attribute from kind.
	// Returns nil if not found.
	AttributeFromKind(kind Kind) Attribute
}

Version provides meta-data for a single spec-version.

type Versions

type Versions struct {
	// contains filtered or unexported fields
}

Versions contains all known versions with the same attribute prefix.

func New

func New() *Versions

New returns a set of versions

func WithPrefix

func WithPrefix(prefix string) *Versions

WithPrefix returns a set of versions with prefix added to all attribute names.

func (*Versions) FindVersion

func (vs *Versions) FindVersion(getAttr func(string) string) (Version, error)

FindVersion calls getAttr with known (prefixed) spec-version attribute names till it finds a valid version.

func (*Versions) Latest

func (vs *Versions) Latest() Version

Latest returns the latest Version

func (*Versions) Prefix

func (vs *Versions) Prefix() string

Prefix is the lowercase attribute name prefix.

func (*Versions) SpecVersionNames

func (vs *Versions) SpecVersionNames() []string

SpecVersionNames returns distinct names of the specversion attribute used in all versions, newest first. Names are prefixed.

func (*Versions) Version

func (vs *Versions) Version(name string) (Version, error)

Version returns the named version.

func (*Versions) Versions

func (vs *Versions) Versions() []Version

Versions returns the list of all known versions, most recent first.