reflection

package
v0.0.0-...-0bbd9cc Latest Latest
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 Go to latest Published: Sep 15, 2012 License: MIT Imports: 7 Imported by: 0

Documentation

Index

Examples

Constants

This section is empty.

Variables

View Source 
var TypeOfError = reflect.TypeOf(func(error) {}).In(0)

TypeOfError is the built-in error type

Functions

func CanStringToValueOfType 

func CanStringToValueOfType(t reflect.Type) bool

func CopyExportedStructFields 

func CopyExportedStructFields(src, dst interface{}) (copied int)

func DereferenceValue 

func DereferenceValue(v reflect.Value) (result reflect.Value, ok bool)

DereferenceValue recursively dereferences v if it is a pointer or interface. It will return ok == false if nil is encountered.

func ExportedStructFields 

func ExportedStructFields(s interface{}) map[string]interface{}

func FindFlattenedStructField 

func FindFlattenedStructField(t reflect.Type, matchFunc MatchStructFieldFunc) *reflect.StructField

func IsDeepNil 

func IsDeepNil(i interface{}) bool

Non nil interfaces can wrap nil values. Comparing the interface to nil, won't return if the wrapped value is nil.

func IsDefaultValue 

func IsDefaultValue(value interface{}) bool

func IsExportedName 

func IsExportedName(name string) bool

func NewInstance 

func NewInstance(prototype interface{}) interface{}

Creates a new zero valued instance of prototype

func StringToValueOfType 

func StringToValueOfType(s string, t reflect.Type) (interface{}, error)

func VisitStruct 

func VisitStruct(strct interface{}, visitor StructVisitor) error

VisitStruct visits recursively all exported fields of a struct and reports them via StructVisitor methods. If a StructVisitor method returns an error, the visitation is aborted and the error returned as result. Pointers and interfaces are dereferenced silently until a non nil value is found. Structs that are embedded anonymously are inlined so that their fields are reported as fields of the embedding struct at the same depth. Anonymous struct fields that are not structs themselves are omitted. Struct fields with the tag gostart:"-" are ignored.

Example (DeepAnonymousStructFields) 
type A struct {
	A0 interface{}
	A1 int
}
type B struct {
	B0 bool
	A
	B1 bool
}
type C struct {
	A
	C0 string
	*B
	C1 string
}
type exampleStruct struct {
	C
}
val := &exampleStruct{
	C: C{
		A:  A{A0: 0, A1: 1},
		C0: "C0",
		B: &B{
			B0: false,
			A:  A{A0: 0, A1: 1},
			B1: true,
		},
		C1: "C1",
	},
}
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: A0 int = 0)
  StructField(1: A1 int = 1)
  StructField(2: C0 string = "C0")
  StructField(3: B0 bool = false)
  StructField(4: A0 int = 0)
  StructField(5: A1 int = 1)
  StructField(6: B1 bool = true)
  StructField(7: C1 string = "C1")
EndStruct(reflection.exampleStruct)
Example (DeepStructFields) 
type A struct {
	A0 interface{}
	A1 int
}
type B struct {
	B0 bool
	A  A
	B1 bool
}
type C struct {
	A  A
	C0 string
	B  *B
	C1 string
}
type exampleStruct struct {
	C C
}
val := &exampleStruct{
	C: C{
		A:  A{A0: 0, A1: 1},
		C0: "C0",
		B: &B{
			B0: false,
			A:  A{A0: 0, A1: 1},
			B1: true,
		},
		C1: "C1",
	},
}
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: C reflection.C)
  BeginStruct(reflection.C)
    StructField(0: A reflection.A)
    BeginStruct(reflection.A)
      StructField(0: A0 int = 0)
      StructField(1: A1 int = 1)
    EndStruct(reflection.A)
    StructField(1: C0 string = "C0")
    StructField(2: B reflection.B)
    BeginStruct(reflection.B)
      StructField(0: B0 bool = false)
      StructField(1: A reflection.A)
      BeginStruct(reflection.A)
        StructField(0: A0 int = 0)
        StructField(1: A1 int = 1)
      EndStruct(reflection.A)
      StructField(2: B1 bool = true)
    EndStruct(reflection.B)
    StructField(3: C1 string = "C1")
  EndStruct(reflection.C)
EndStruct(reflection.exampleStruct)
Example (FlatAnonymousStructFields) 
type A struct {
	A0 int
	A1 interface{}
	A2 int
}
type B struct {
	B0 bool
	B1 bool
}
type exampleStruct struct {
	A
	*B
}
val := &exampleStruct{
	A: A{A0: 0, A1: 1, A2: 2},
	B: &B{B0: false, B1: true},
}
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: A0 int = 0)
  StructField(1: A1 int = 1)
  StructField(2: A2 int = 2)
  StructField(3: B0 bool = false)
  StructField(4: B1 bool = true)
EndStruct(reflection.exampleStruct)
Example (FlatStructWithMap) 
type exampleStruct struct {
	X         int
	IntMap    map[string]int
	StringMap map[string]string
}
val := &exampleStruct{
	X:         9,
	IntMap:    map[string]int{"1": 1, "2": 2},
	StringMap: map[string]string{"1": "Hello", "2": "World"},
}
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: X int = 9)
  StructField(1: IntMap map[string]int = map[string]int{"1":1, "2":2})
  BeginMap(map[string]int)
    MapField("1": int = 1)
    MapField("2": int = 2)
  EndMap(map[string]int)
  StructField(2: StringMap map[string]string = map[string]string{"1":"Hello", "2":"World"})
  BeginMap(map[string]string)
    MapField("1": string = "Hello")
    MapField("2": string = "World")
  EndMap(map[string]string)
EndStruct(reflection.exampleStruct)
Example (FlatStructWithSliceAndArray) 
type exampleStruct struct {
	X      int
	hidden bool
	Slice  []int
	Array  [3]int
}
val := &exampleStruct{
	X:     9,
	Slice: []int{1, 2},
	Array: [...]int{1, 2, 3},
}
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: X int = 9)
  StructField(1: Slice []int)
  BeginSlice([]int)
    SliceField(0: int = 1)
    SliceField(1: int = 2)
  EndSlice([]int)
  StructField(2: Array [3]int)
  BeginArray([3]int)
    ArrayField(0: int = 1)
    ArrayField(1: int = 2)
    ArrayField(2: int = 3)
  EndArray([3]int)
EndStruct(reflection.exampleStruct)
Example (LimitDepth) 
type A struct {
	A0 interface{}
	A1 int
}
type B struct {
	B0 bool
	A  A
	B1 bool
}
type C struct {
	A  A
	C0 string
	B  *B
	C1 string
}
type exampleStruct struct {
	C C
}
val := &exampleStruct{
	C: C{
		A:  A{A0: 0, A1: 1},
		C0: "C0",
		B: &B{
			B0: false,
			A:  A{A0: 0, A1: 1},
			B1: true,
		},
		C1: "C1",
	},
}
VisitStructDepth(val, NewStdLogStructVisitor(), 2)

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: C reflection.C)
  BeginStruct(reflection.C)
    StructField(0: A reflection.A)
    BeginStruct(reflection.A)
    EndStruct(reflection.A)
    StructField(1: C0 string = "C0")
    StructField(2: B reflection.B)
    BeginStruct(reflection.B)
    EndStruct(reflection.B)
    StructField(3: C1 string = "C1")
  EndStruct(reflection.C)
EndStruct(reflection.exampleStruct)
Example (SimpleFlatPtrsStruct) 
type exampleStruct struct {
	X *int
	Y **float32
	Z *string
	N **string
	I interface{}
}
val := &exampleStruct{
	X: new(int),
	Y: new(*float32),
	Z: nil,
	N: new(*string),
	I: new(int),
}
*val.X = 1
*val.Y = new(float32)
**val.Y = 2
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: X int = 1)
  StructField(1: Y float32 = 2)
  StructField(2: I int = 0)
EndStruct(reflection.exampleStruct)
Example (SimpleFlatStruct) 
type exampleStruct struct {
	X      int
	Y      float32
	Z      string
	hidden string
}
VisitStruct(&exampleStruct{X: 1}, NewStdLogStructVisitor())
VisitStruct(exampleStruct{Y: 2}, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.exampleStruct)
  StructField(0: X int = 1)
  StructField(1: Y float32 = 0)
  StructField(2: Z string = "")
EndStruct(reflection.exampleStruct)
BeginStruct(reflection.exampleStruct)
  StructField(0: X int = 0)
  StructField(1: Y float32 = 2)
  StructField(2: Z string = "")
EndStruct(reflection.exampleStruct)
Example (SliceOfStructInAnonymousStruct) 
type emailIdentity struct {
	Address     string
	Description string
}
type user struct {
	Name  string
	Email []emailIdentity
}
type person struct {
	user
	ExtraInfo string
}
val := &person{
	user: user{
		Name: "Erik Unger",
		Email: []emailIdentity{
			emailIdentity{Address: "erik@erikunger.com", Description: "Test"},
		},
	},
	ExtraInfo: "info",
}
VisitStruct(val, NewStdLogStructVisitor())

Output:

BeginStruct(reflection.person)
  StructField(0: Name string = "Erik Unger")
  StructField(1: Email []reflection.emailIdentity)
  BeginSlice([]reflection.emailIdentity)
    SliceField(0: reflection.emailIdentity)
    BeginStruct(reflection.emailIdentity)
      StructField(0: Address string = "erik@erikunger.com")
      StructField(1: Description string = "Test")
    EndStruct(reflection.emailIdentity)
  EndSlice([]reflection.emailIdentity)
  StructField(2: ExtraInfo string = "info")
EndStruct(reflection.person)

func VisitStructDepth 

func VisitStructDepth(strct interface{}, visitor StructVisitor, maxDepth int) error

VisitStructDepth is identical to VisitStruct except that its recursive depth is limited to maxDepth with the first depth level being zero. If maxDepth is -1, then the recursive depth is unlimited (VisitStruct).

Types

type LogStructVisitor 

type LogStructVisitor struct {
	Logger *log.Logger
}

LogStructVisitor can be used for testing and debugging VisitStruct()

func NewStdLogStructVisitor 

func NewStdLogStructVisitor() *LogStructVisitor

func (*LogStructVisitor) ArrayField 

func (self *LogStructVisitor) ArrayField(depth int, v reflect.Value, index int) error

func (*LogStructVisitor) BeginArray 

func (self *LogStructVisitor) BeginArray(depth int, v reflect.Value) error

func (*LogStructVisitor) BeginMap 

func (self *LogStructVisitor) BeginMap(depth int, v reflect.Value) error

func (*LogStructVisitor) BeginSlice 

func (self *LogStructVisitor) BeginSlice(depth int, v reflect.Value) error

func (*LogStructVisitor) BeginStruct 

func (self *LogStructVisitor) BeginStruct(depth int, v reflect.Value) error

func (*LogStructVisitor) EndArray 

func (self *LogStructVisitor) EndArray(depth int, v reflect.Value) error

func (*LogStructVisitor) EndMap 

func (self *LogStructVisitor) EndMap(depth int, v reflect.Value) error

func (*LogStructVisitor) EndSlice 

func (self *LogStructVisitor) EndSlice(depth int, v reflect.Value) error

func (*LogStructVisitor) EndStruct 

func (self *LogStructVisitor) EndStruct(depth int, v reflect.Value) error

func (*LogStructVisitor) MapField 

func (self *LogStructVisitor) MapField(depth int, v reflect.Value, key string, index int) error

func (*LogStructVisitor) SliceField 

func (self *LogStructVisitor) SliceField(depth int, v reflect.Value, index int) error

func (*LogStructVisitor) StructField 

func (self *LogStructVisitor) StructField(depth int, v reflect.Value, f reflect.StructField, index int) error

type MatchStructFieldFunc 

type MatchStructFieldFunc func(field *reflect.StructField) bool

type ModifySliceStructVisitor 

type ModifySliceStructVisitor func(depth int, v reflect.Value) (reflect.Value, error)

ModifySliceStructVisitor is a StructVisitor that calls its self function value in BeginSlice() and ignores all other StructVisitor methos. It can be used to modify the length of slices in complex structs.

func (ModifySliceStructVisitor) ArrayField 

func (self ModifySliceStructVisitor) ArrayField(depth int, v reflect.Value, index int) error

func (ModifySliceStructVisitor) BeginArray 

func (self ModifySliceStructVisitor) BeginArray(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) BeginMap 

func (self ModifySliceStructVisitor) BeginMap(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) BeginSlice 

func (self ModifySliceStructVisitor) BeginSlice(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) BeginStruct 

func (self ModifySliceStructVisitor) BeginStruct(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) EndArray 

func (self ModifySliceStructVisitor) EndArray(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) EndMap 

func (self ModifySliceStructVisitor) EndMap(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) EndSlice 

func (self ModifySliceStructVisitor) EndSlice(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) EndStruct 

func (self ModifySliceStructVisitor) EndStruct(depth int, v reflect.Value) error

func (ModifySliceStructVisitor) MapField 

func (self ModifySliceStructVisitor) MapField(depth int, v reflect.Value, key string, index int) error

func (ModifySliceStructVisitor) ModifySlice 

func (self ModifySliceStructVisitor) ModifySlice(depth int, v reflect.Value) (reflect.Value, error)

func (ModifySliceStructVisitor) SliceField 

func (self ModifySliceStructVisitor) SliceField(depth int, v reflect.Value, index int) error

func (ModifySliceStructVisitor) StructField 

func (self ModifySliceStructVisitor) StructField(depth int, v reflect.Value, f reflect.StructField, index int) error

type StructVisitor 

type StructVisitor interface {
	BeginStruct(depth int, v reflect.Value) error
	StructField(depth int, v reflect.Value, f reflect.StructField, index int) error
	EndStruct(depth int, v reflect.Value) error

	BeginSlice(depth int, v reflect.Value) error
	SliceField(depth int, v reflect.Value, index int) error
	EndSlice(depth int, v reflect.Value) error

	BeginArray(depth int, v reflect.Value) error
	ArrayField(depth int, v reflect.Value, index int) error
	EndArray(depth int, v reflect.Value) error

	BeginMap(depth int, v reflect.Value) error
	MapField(depth int, v reflect.Value, key string, index int) error
	EndMap(depth int, v reflect.Value) error
}

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