package module
Version: v1.0.2 Latest Latest

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Published: May 3, 2021 License: MIT Imports: 3 Imported by: 687



reflectwalk is a Go library for "walking" a value in Go using reflection, in the same way a directory tree can be "walked" on the filesystem. Walking a complex structure can allow you to do manipulations on unknown structures such as those decoded from JSON.



reflectwalk is a package that allows you to "walk" complex structures similar to how you may "walk" a filesystem: visiting every element one by one and calling callback functions allowing you to handle and manipulate those elements.



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var SkipEntry = errors.New("skip this entry")

SkipEntry can be returned from walk functions to skip walking the value of this field. This is only valid in the following functions:

  • Struct: skips all fields from being walked
  • StructField: skips walking the struct value


func Walk

func Walk(data, walker interface{}) (err error)

Walk takes an arbitrary value and an interface and traverses the value, calling callbacks on the interface if they are supported. The interface should implement one or more of the walker interfaces in this package, such as PrimitiveWalker, StructWalker, etc.


type ArrayWalker

type ArrayWalker interface {
	Array(reflect.Value) error
	ArrayElem(int, reflect.Value) error

ArrayWalker implementations are able to handle array elements found within complex structures.

type EnterExitWalker

type EnterExitWalker interface {
	Enter(Location) error
	Exit(Location) error

EnterExitWalker implementations are notified before and after they walk deeper into complex structures (into struct fields, into slice elements, etc.)

type InterfaceWalker

type InterfaceWalker interface {
	Interface(reflect.Value) error

InterfaceWalker implementations are able to handle interface values as they are encountered during the walk.

type Location

type Location uint
const (
	None Location = iota

func (Location) String

func (i Location) String() string

type MapWalker

type MapWalker interface {
	Map(m reflect.Value) error
	MapElem(m, k, v reflect.Value) error

MapWalker implementations are able to handle individual elements found within a map structure.

type PointerValueWalker added in v1.0.2

type PointerValueWalker interface {
	Pointer(reflect.Value) error

PointerValueWalker implementations are notified with the value of a particular pointer when a pointer is walked. Pointer is called right before PointerEnter.

type PointerWalker

type PointerWalker interface {
	PointerEnter(bool) error
	PointerExit(bool) error

PointerWalker implementations are notified when the value they're walking is a pointer or not. Pointer is called for _every_ value whether it is a pointer or not.

type PrimitiveWalker

type PrimitiveWalker interface {
	Primitive(reflect.Value) error

PrimitiveWalker implementations are able to handle primitive values within complex structures. Primitive values are numbers, strings, booleans, funcs, chans.

These primitive values are often members of more complex structures (slices, maps, etc.) that are walkable by other interfaces.

type SliceWalker

type SliceWalker interface {
	Slice(reflect.Value) error
	SliceElem(int, reflect.Value) error

SliceWalker implementations are able to handle slice elements found within complex structures.

type StructWalker

type StructWalker interface {
	Struct(reflect.Value) error
	StructField(reflect.StructField, reflect.Value) error

StructWalker is an interface that has methods that are called for structs when a Walk is done.

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