fields

Documentation

Overview

Package fields implements a simple field system, parsing and matching selectors with sets of fields.

Index

• type Fields
• type Selector
  • func Everything() Selector
  • func OneTermEqualSelector(k, v string) Selector
  • func ParseAndTransformSelector(selector string, fn TransformFunc) (Selector, error)
  • func ParseSelector(selector string) (Selector, error)
  • func SelectorFromSet(ls Set) Selector
• type Set
  • func (ls Set) AsSelector() Selector
  • func (ls Set) Get(field string) string
  • func (ls Set) Has(field string) bool
  • func (ls Set) String() string
• type TransformFunc

Types

type Fields

type Fields interface {
	// Has returns whether the provided field exists.
	Has(field string) (exists bool)

	// Get returns the value for the provided field.
	Get(field string) (value string)
}

Fields allows you to present fields independently from their storage.

type Selector

type Selector interface {
	// Matches returns true if this selector matches the given set of fields.
	Matches(Fields) bool

	// Empty returns true if this selector does not restrict the selection space.
	Empty() bool

	// RequiresExactMatch allows a caller to introspect whether a given selector
	// requires a single specific field to be set, and if so returns the value it
	// requires.
	RequiresExactMatch(field string) (value string, found bool)

	// Transform returns a new copy of the selector after TransformFunc has been
	// applied to the entire selector, or an error if fn returns an error.
	Transform(fn TransformFunc) (Selector, error)

	// String returns a human readable string that represents this selector.
	String() string
}

Selector represents a field selector.

func Everything

func Everything() Selector

Everything returns a selector that matches all fields.

func OneTermEqualSelector

func OneTermEqualSelector(k, v string) Selector

OneTermEqualSelector returns an object that matches objects where one field/field equals one value. Cannot return an error.

func ParseAndTransformSelector

func ParseAndTransformSelector(selector string, fn TransformFunc) (Selector, error)

Parses the selector and runs them through the given TransformFunc.

func ParseSelector

func ParseSelector(selector string) (Selector, error)

ParseSelector takes a string representing a selector and returns an object suitable for matching, or an error.

func SelectorFromSet

func SelectorFromSet(ls Set) Selector

SelectorFromSet returns a Selector which will match exactly the given Set. A nil Set is considered equivalent to Everything().

type Set

type Set map[string]string

Set is a map of field:value. It implements Fields.

func (Set) AsSelector

func (ls Set) AsSelector() Selector

AsSelector converts fields into a selectors.

func (Set) Get

func (ls Set) Get(field string) string

Get returns the value in the map for the provided field.

func (Set) Has

func (ls Set) Has(field string) bool

Has returns whether the provided field exists in the map.

func (Set) String

func (ls Set) String() string

String returns all fields listed as a human readable string. Conveniently, exactly the format that ParseSelector takes.

type TransformFunc

type TransformFunc func(field, value string) (newField, newValue string, err error)

Function to transform selectors.