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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package reflect
import (
"math"
"runtime"
"unsafe"
)
const ptrSize = uintptr(unsafe.Sizeof((*byte)(nil)))
const cannotSet = "cannot set value obtained from unexported struct field"
type addr unsafe.Pointer
// TODO: This will have to go away when
// the new gc goes in.
func memmove(adst, asrc addr, n uintptr) {
dst := uintptr(adst)
src := uintptr(asrc)
switch {
case src < dst && src+n > dst:
// byte copy backward
// careful: i is unsigned
for i := n; i > 0; {
i--
*(*byte)(addr(dst + i)) = *(*byte)(addr(src + i))
}
case (n|src|dst)&(ptrSize-1) != 0:
// byte copy forward
for i := uintptr(0); i < n; i++ {
*(*byte)(addr(dst + i)) = *(*byte)(addr(src + i))
}
default:
// word copy forward
for i := uintptr(0); i < n; i += ptrSize {
*(*uintptr)(addr(dst + i)) = *(*uintptr)(addr(src + i))
}
}
}
// Value is the reflection interface to a Go value.
//
// Not all methods apply to all kinds of values. Restrictions,
// if any, are noted in the documentation for each method.
// Use the Kind method to find out the kind of value before
// calling kind-specific methods. Calling a method
// inappropriate to the kind of type causes a run time panic.
//
// The zero Value represents no value.
// Its IsValid method returns false, its Kind method returns Invalid,
// its String method returns "<invalid Value>", and all other methods panic.
// Most functions and methods never return an invalid value.
// If one does, its documentation states the conditions explicitly.
type Value struct {
Internal valueInterface
}
// TODO(rsc): This implementation of Value is a just a fa├žade
// in front of the old implementation, now called valueInterface.
// A future CL will change it to a real implementation.
// Changing the API is already a big enough step for one CL.
// A ValueError occurs when a Value method is invoked on
// a Value that does not support it. Such cases are documented
// in the description of each method.
type ValueError struct {
Method string
Kind Kind
}
func (e *ValueError) String() string {
if e.Kind == 0 {
return "reflect: call of " + e.Method + " on zero Value"
}
return "reflect: call of " + e.Method + " on " + e.Kind.String() + " Value"
}
// methodName returns the name of the calling method,
// assumed to be two stack frames above.
func methodName() string {
pc, _, _, _ := runtime.Caller(2)
f := runtime.FuncForPC(pc)
if f == nil {
return "unknown method"
}
return f.Name()
}
func (v Value) internal() valueInterface {
vi := v.Internal
if vi == nil {
panic(&ValueError{methodName(), 0})
}
return vi
}
func (v Value) panicIfNot(want Kind) valueInterface {
vi := v.Internal
if vi == nil {
panic(&ValueError{methodName(), 0})
}
if k := vi.Kind(); k != want {
panic(&ValueError{methodName(), k})
}
return vi
}
func (v Value) panicIfNots(wants []Kind) valueInterface {
vi := v.Internal
if vi == nil {
panic(&ValueError{methodName(), 0})
}
k := vi.Kind()
for _, want := range wants {
if k == want {
return vi
}
}
panic(&ValueError{methodName(), k})
}
// Addr returns a pointer value representing the address of v.
// It panics if CanAddr() returns false.
// Addr is typically used to obtain a pointer to a struct field
// or slice element in order to call a method that requires a
// pointer receiver.
func (v Value) Addr() Value {
return v.internal().Addr()
}
// Bool returns v's underlying value.
// It panics if v's kind is not Bool.
func (v Value) Bool() bool {
u := v.panicIfNot(Bool).(*boolValue)
return u.Get()
}
// CanAddr returns true if the value's address can be obtained with Addr.
// Such values are called addressable. A value is addressable if it is
// an element of a slice, an element of an addressable array,
// a field of an addressable struct, the result of dereferencing a pointer,
// or the result of a call to NewValue, MakeChan, MakeMap, or Zero.
// If CanAddr returns false, calling Addr will panic.
func (v Value) CanAddr() bool {
return v.internal().CanAddr()
}
// CanSet returns true if the value of v can be changed.
// Values obtained by the use of unexported struct fields
// can be read but not set.
// If CanSet returns false, calling Set or any type-specific
// setter (e.g., SetBool, SetInt64) will panic.
func (v Value) CanSet() bool {
return v.internal().CanSet()
}
// Call calls the function v with the input parameters in.
// It panics if v's Kind is not Func.
// It returns the output parameters as Values.
func (v Value) Call(in []Value) []Value {
return v.panicIfNot(Func).(*funcValue).Call(in)
}
var capKinds = []Kind{Array, Chan, Slice}
type capper interface {
Cap() int
}
// Cap returns v's capacity.
// It panics if v's Kind is not Array, Chan, or Slice.
func (v Value) Cap() int {
return v.panicIfNots(capKinds).(capper).Cap()
}
// Close closes the channel v.
// It panics if v's Kind is not Chan.
func (v Value) Close() {
v.panicIfNot(Chan).(*chanValue).Close()
}
var complexKinds = []Kind{Complex64, Complex128}
// Complex returns v's underlying value, as a complex128.
// It panics if v's Kind is not Complex64 or Complex128
func (v Value) Complex() complex128 {
return v.panicIfNots(complexKinds).(*complexValue).Get()
}
var interfaceOrPtr = []Kind{Interface, Ptr}
type elemer interface {
Elem() Value
}
// Elem returns the value that the interface v contains
// or that the pointer v points to.
// It panics if v's Kind is not Interface or Ptr.
// It returns the zero Value if v is nil.
func (v Value) Elem() Value {
return v.panicIfNots(interfaceOrPtr).(elemer).Elem()
}
// Field returns the i'th field of the struct v.
// It panics if v's Kind is not Struct.
func (v Value) Field(i int) Value {
return v.panicIfNot(Struct).(*structValue).Field(i)
}
// FieldByIndex returns the nested field corresponding to index.
// It panics if v's Kind is not struct.
func (v Value) FieldByIndex(index []int) Value {
return v.panicIfNot(Struct).(*structValue).FieldByIndex(index)
}
// FieldByName returns the struct field with the given name.
// It returns the zero Value if no field was found.
// It panics if v's Kind is not struct.
func (v Value) FieldByName(name string) Value {
return v.panicIfNot(Struct).(*structValue).FieldByName(name)
}
// FieldByNameFunc returns the struct field with a name
// that satisfies the match function.
// It panics if v's Kind is not struct.
// It returns the zero Value if no field was found.
func (v Value) FieldByNameFunc(match func(string) bool) Value {
return v.panicIfNot(Struct).(*structValue).FieldByNameFunc(match)
}
var floatKinds = []Kind{Float32, Float64}
// Float returns v's underlying value, as an float64.
// It panics if v's Kind is not Float32 or Float64
func (v Value) Float() float64 {
return v.panicIfNots(floatKinds).(*floatValue).Get()
}
var arrayOrSlice = []Kind{Array, Slice}
// Index returns v's i'th element.
// It panics if v's Kind is not Array or Slice.
func (v Value) Index(i int) Value {
return v.panicIfNots(arrayOrSlice).(arrayOrSliceValue).Elem(i)
}
var intKinds = []Kind{Int, Int8, Int16, Int32, Int64}
// Int returns v's underlying value, as an int64.
// It panics if v's Kind is not a sized or unsized Int kind.
func (v Value) Int() int64 {
return v.panicIfNots(intKinds).(*intValue).Get()
}
// Interface returns v's value as an interface{}.
// If v is a method obtained by invoking Value.Method
// (as opposed to Type.Method), Interface cannot return an
// interface value, so it panics.
func (v Value) Interface() interface{} {
return v.internal().Interface()
}
// InterfaceData returns the interface v's value as a uintptr pair.
// It panics if v's Kind is not Interface.
func (v Value) InterfaceData() [2]uintptr {
return v.panicIfNot(Interface).(*interfaceValue).Get()
}
var nilKinds = []Kind{Chan, Func, Interface, Map, Ptr, Slice}
type isNiller interface {
IsNil() bool
}
// IsNil returns true if v is a nil value.
// It panics if v's Kind is not Chan, Func, Interface, Map, Ptr, or Slice.
func (v Value) IsNil() bool {
return v.panicIfNots(nilKinds).(isNiller).IsNil()
}
// IsValid returns true if v represents a value.
// It returns false if v is the zero Value.
// If IsValid returns false, all other methods except String panic.
// Most functions and methods never return an invalid value.
// If one does, its documentation states the conditions explicitly.
func (v Value) IsValid() bool {
return v.Internal != nil
}
// Kind returns v's Kind.
// If v is the zero Value (IsValid returns false), Kind returns Invalid.
func (v Value) Kind() Kind {
if v.Internal == nil {
return Invalid
}
return v.internal().Kind()
}
var lenKinds = []Kind{Array, Chan, Map, Slice}
type lenner interface {
Len() int
}
// Len returns v's length.
// It panics if v's Kind is not Array, Chan, Map, or Slice.
func (v Value) Len() int {
return v.panicIfNots(lenKinds).(lenner).Len()
}
// MapIndex returns the value associated with key in the map v.
// It panics if v's Kind is not Map.
// It returns the zero Value if key is not found in the map.
func (v Value) MapIndex(key Value) Value {
return v.panicIfNot(Map).(*mapValue).Elem(key)
}
// MapKeys returns a slice containing all the keys present in the map,
// in unspecified order.
// It panics if v's Kind is not Map.
func (v Value) MapKeys() []Value {
return v.panicIfNot(Map).(*mapValue).Keys()
}
// Method returns a function value corresponding to v's i'th method.
// The arguments to a Call on the returned function should not include
// a receiver; the returned function will always use v as the receiver.
func (v Value) Method(i int) Value {
return v.internal().Method(i)
}
// NumField returns the number of fields in the struct v.
// It panics if v's Kind is not Struct.
func (v Value) NumField() int {
return v.panicIfNot(Struct).(*structValue).NumField()
}
// OverflowComplex returns true if the complex128 x cannot be represented by v's type.
// It panics if v's Kind is not Complex64 or Complex128.
func (v Value) OverflowComplex(x complex128) bool {
return v.panicIfNots(complexKinds).(*complexValue).Overflow(x)
}
// OverflowFloat returns true if the float64 x cannot be represented by v's type.
// It panics if v's Kind is not Float32 or Float64.
func (v Value) OverflowFloat(x float64) bool {
return v.panicIfNots(floatKinds).(*floatValue).Overflow(x)
}
// OverflowInt returns true if the int64 x cannot be represented by v's type.
// It panics if v's Kind is not a sized or unsized Int kind.
func (v Value) OverflowInt(x int64) bool {
return v.panicIfNots(intKinds).(*intValue).Overflow(x)
}
// OverflowUint returns true if the uint64 x cannot be represented by v's type.
// It panics if v's Kind is not a sized or unsized Uint kind.
func (v Value) OverflowUint(x uint64) bool {
return v.panicIfNots(uintKinds).(*uintValue).Overflow(x)
}
var pointerKinds = []Kind{Chan, Func, Map, Ptr, Slice, UnsafePointer}
type uintptrGetter interface {
Get() uintptr
}
// Pointer returns v's value as a uintptr.
// It returns uintptr instead of unsafe.Pointer so that
// code using reflect cannot obtain unsafe.Pointers
// without importing the unsafe package explicitly.
// It panics if v's Kind is not Chan, Func, Map, Ptr, Slice, or UnsafePointer.
func (v Value) Pointer() uintptr {
return v.panicIfNots(pointerKinds).(uintptrGetter).Get()
}
// Recv receives and returns a value from the channel v.
// It panics if v's Kind is not Chan.
// The receive blocks until a value is ready.
// The boolean value ok is true if the value x corresponds to a send
// on the channel, false if it is a zero value received because the channel is closed.
func (v Value) Recv() (x Value, ok bool) {
return v.panicIfNot(Chan).(*chanValue).Recv()
}
// Send sends x on the channel v.
// It panics if v's kind is not Chan or if x's type is not the same type as v's element type.
func (v Value) Send(x Value) {
v.panicIfNot(Chan).(*chanValue).Send(x)
}
// Set assigns x to the value v; x must have the same type as v.
// It panics if CanSet() returns false or if x is the zero Value.
func (v Value) Set(x Value) {
x.internal()
v.internal().SetValue(x)
}
// SetBool sets v's underlying value.
// It panics if v's Kind is not Bool or if CanSet() is false.
func (v Value) SetBool(x bool) {
v.panicIfNot(Bool).(*boolValue).Set(x)
}
// SetComplex sets v's underlying value to x.
// It panics if v's Kind is not Complex64 or Complex128, or if CanSet() is false.
func (v Value) SetComplex(x complex128) {
v.panicIfNots(complexKinds).(*complexValue).Set(x)
}
// SetFloat sets v's underlying value to x.
// It panics if v's Kind is not Float32 or Float64, or if CanSet() is false.
func (v Value) SetFloat(x float64) {
v.panicIfNots(floatKinds).(*floatValue).Set(x)
}
// SetInt sets v's underlying value to x.
// It panics if v's Kind is not a sized or unsized Int kind, or if CanSet() is false.
func (v Value) SetInt(x int64) {
v.panicIfNots(intKinds).(*intValue).Set(x)
}
// SetLen sets v's length to n.
// It panics if v's Kind is not Slice.
func (v Value) SetLen(n int) {
v.panicIfNot(Slice).(*sliceValue).SetLen(n)
}
// SetMapIndex sets the value associated with key in the map v to val.
// It panics if v's Kind is not Map.
// If val is the zero Value, SetMapIndex deletes the key from the map.
func (v Value) SetMapIndex(key, val Value) {
v.panicIfNot(Map).(*mapValue).SetElem(key, val)
}
// SetUint sets v's underlying value to x.
// It panics if v's Kind is not a sized or unsized Uint kind, or if CanSet() is false.
func (v Value) SetUint(x uint64) {
v.panicIfNots(uintKinds).(*uintValue).Set(x)
}
// SetPointer sets the unsafe.Pointer value v to x.
// It panics if v's Kind is not UnsafePointer.
func (v Value) SetPointer(x unsafe.Pointer) {
v.panicIfNot(UnsafePointer).(*unsafePointerValue).Set(x)
}
// SetString sets v's underlying value to x.
// It panics if v's Kind is not String or if CanSet() is false.
func (v Value) SetString(x string) {
v.panicIfNot(String).(*stringValue).Set(x)
}
// BUG(rsc): Value.Slice should allow slicing arrays.
// Slice returns a slice of v.
// It panics if v's Kind is not Slice.
func (v Value) Slice(beg, end int) Value {
return v.panicIfNot(Slice).(*sliceValue).Slice(beg, end)
}
// String returns the string v's underlying value, as a string.
// String is a special case because of Go's String method convention.
// Unlike the other getters, it does not panic if v's Kind is not String.
// Instead, it returns a string of the form "<T value>" where T is v's type.
func (v Value) String() string {
vi := v.Internal
if vi == nil {
return "<invalid Value>"
}
if vi.Kind() == String {
return vi.(*stringValue).Get()
}
return "<" + vi.Type().String() + " Value>"
}
// TryRecv attempts to receive a value from the channel v but will not block.
// It panics if v's Kind is not Chan.
// If the receive cannot finish without blocking, x is the zero Value.
// The boolean ok is true if the value x corresponds to a send
// on the channel, false if it is a zero value received because the channel is closed.
func (v Value) TryRecv() (x Value, ok bool) {
return v.panicIfNot(Chan).(*chanValue).TryRecv()
}
// TrySend attempts to send x on the channel v but will not block.
// It panics if v's Kind is not Chan.
// It returns true if the value was sent, false otherwise.
func (v Value) TrySend(x Value) bool {
return v.panicIfNot(Chan).(*chanValue).TrySend(x)
}
// Type returns v's type.
func (v Value) Type() Type {
return v.internal().Type()
}
var uintKinds = []Kind{Uint, Uint8, Uint16, Uint32, Uint64, Uintptr}
// Uint returns v's underlying value, as a uint64.
// It panics if v's Kind is not a sized or unsized Uint kind.
func (v Value) Uint() uint64 {
return v.panicIfNots(uintKinds).(*uintValue).Get()
}
// UnsafeAddr returns a pointer to v's data.
// It is for advanced clients that also import the "unsafe" package.
func (v Value) UnsafeAddr() uintptr {
return v.internal().UnsafeAddr()
}
// valueInterface is the common interface to reflection values.
// The implementations of Value (e.g., arrayValue, structValue)
// have additional type-specific methods.
type valueInterface interface {
// Type returns the value's type.
Type() Type
// Interface returns the value as an interface{}.
Interface() interface{}
// CanSet returns true if the value can be changed.
// Values obtained by the use of non-exported struct fields
// can be used in Get but not Set.
// If CanSet returns false, calling the type-specific Set will panic.
CanSet() bool
// SetValue assigns v to the value; v must have the same type as the value.
SetValue(v Value)
// CanAddr returns true if the value's address can be obtained with Addr.
// Such values are called addressable. A value is addressable if it is
// an element of a slice, an element of an addressable array,
// a field of an addressable struct, the result of dereferencing a pointer,
// or the result of a call to NewValue, MakeChan, MakeMap, or Zero.
// If CanAddr returns false, calling Addr will panic.
CanAddr() bool
// Addr returns the address of the value.
// If the value is not addressable, Addr panics.
// Addr is typically used to obtain a pointer to a struct field or slice element
// in order to call a method that requires a pointer receiver.
Addr() Value
// UnsafeAddr returns a pointer to the underlying data.
// It is for advanced clients that also import the "unsafe" package.
UnsafeAddr() uintptr
// Method returns a funcValue corresponding to the value's i'th method.
// The arguments to a Call on the returned funcValue
// should not include a receiver; the funcValue will use
// the value as the receiver.
Method(i int) Value
Kind() Kind
getAddr() addr
}
// flags for value
const (
canSet uint32 = 1 << iota // can set value (write to *v.addr)
canAddr // can take address of value
canStore // can store through value (write to **v.addr)
)
// value is the common implementation of most values.
// It is embedded in other, public struct types, but always
// with a unique tag like "uint" or "float" so that the client cannot
// convert from, say, *uintValue to *floatValue.
type value struct {
typ Type
addr addr
flag uint32
}
func (v *value) Type() Type { return v.typ }
func (v *value) Kind() Kind { return v.typ.Kind() }
func (v *value) Addr() Value {
if !v.CanAddr() {
panic("reflect: cannot take address of value")
}
a := v.addr
flag := canSet
if v.CanSet() {
flag |= canStore
}
// We could safely set canAddr here too -
// the caller would get the address of a -
// but it doesn't match the Go model.
// The language doesn't let you say &&v.
return newValue(PtrTo(v.typ), addr(&a), flag)
}
func (v *value) UnsafeAddr() uintptr { return uintptr(v.addr) }
func (v *value) getAddr() addr { return v.addr }
func (v *value) Interface() interface{} {
typ := v.typ
if typ.Kind() == Interface {
// There are two different representations of interface values,
// one if the interface type has methods and one if it doesn't.
// These two representations require different expressions
// to extract correctly.
if typ.NumMethod() == 0 {
// Extract as interface value without methods.
return *(*interface{})(v.addr)
}
// Extract from v.addr as interface value with methods.
return *(*interface {
m()
})(v.addr)
}
return unsafe.Unreflect(v.typ, unsafe.Pointer(v.addr))
}
func (v *value) CanSet() bool { return v.flag&canSet != 0 }
func (v *value) CanAddr() bool { return v.flag&canAddr != 0 }
/*
* basic types
*/
// boolValue represents a bool value.
type boolValue struct {
value "bool"
}
// Get returns the underlying bool value.
func (v *boolValue) Get() bool { return *(*bool)(v.addr) }
// Set sets v to the value x.
func (v *boolValue) Set(x bool) {
if !v.CanSet() {
panic(cannotSet)
}
*(*bool)(v.addr) = x
}
// Set sets v to the value x.
func (v *boolValue) SetValue(x Value) { v.Set(x.Bool()) }
// floatValue represents a float value.
type floatValue struct {
value "float"
}
// Get returns the underlying int value.
func (v *floatValue) Get() float64 {
switch v.typ.Kind() {
case Float32:
return float64(*(*float32)(v.addr))
case Float64:
return *(*float64)(v.addr)
}
panic("reflect: invalid float kind")
}
// Set sets v to the value x.
func (v *floatValue) Set(x float64) {
if !v.CanSet() {
panic(cannotSet)
}
switch v.typ.Kind() {
default:
panic("reflect: invalid float kind")
case Float32:
*(*float32)(v.addr) = float32(x)
case Float64:
*(*float64)(v.addr) = x
}
}
// Overflow returns true if x cannot be represented by the type of v.
func (v *floatValue) Overflow(x float64) bool {
if v.typ.Size() == 8 {
return false
}
if x < 0 {
x = -x
}
return math.MaxFloat32 < x && x <= math.MaxFloat64
}
// Set sets v to the value x.
func (v *floatValue) SetValue(x Value) { v.Set(x.Float()) }
// complexValue represents a complex value.
type complexValue struct {
value "complex"
}
// Get returns the underlying complex value.
func (v *complexValue) Get() complex128 {
switch v.typ.Kind() {
case Complex64:
return complex128(*(*complex64)(v.addr))
case Complex128:
return *(*complex128)(v.addr)
}
panic("reflect: invalid complex kind")
}
// Set sets v to the value x.
func (v *complexValue) Set(x complex128) {
if !v.CanSet() {
panic(cannotSet)
}
switch v.typ.Kind() {
default:
panic("reflect: invalid complex kind")
case Complex64:
*(*complex64)(v.addr) = complex64(x)
case Complex128:
*(*complex128)(v.addr) = x
}
}
// How did we forget this one?
func (v *complexValue) Overflow(x complex128) bool {
if v.typ.Size() == 16 {
return false
}
r := real(x)
i := imag(x)
if r < 0 {
r = -r
}
if i < 0 {
i = -i
}
return math.MaxFloat32 <= r && r <= math.MaxFloat64 ||
math.MaxFloat32 <= i && i <= math.MaxFloat64
}
// Set sets v to the value x.
func (v *complexValue) SetValue(x Value) { v.Set(x.Complex()) }
// intValue represents an int value.
type intValue struct {
value "int"
}
// Get returns the underlying int value.
func (v *intValue) Get() int64 {
switch v.typ.Kind() {
case Int:
return int64(*(*int)(v.addr))
case Int8:
return int64(*(*int8)(v.addr))
case Int16:
return int64(*(*int16)(v.addr))
case Int32:
return int64(*(*int32)(v.addr))
case Int64:
return *(*int64)(v.addr)
}
panic("reflect: invalid int kind")
}
// Set sets v to the value x.
func (v *intValue) Set(x int64) {
if !v.CanSet() {
panic(cannotSet)
}
switch v.typ.Kind() {
default:
panic("reflect: invalid int kind")
case Int:
*(*int)(v.addr) = int(x)
case Int8:
*(*int8)(v.addr) = int8(x)
case Int16:
*(*int16)(v.addr) = int16(x)
case Int32:
*(*int32)(v.addr) = int32(x)
case Int64:
*(*int64)(v.addr) = x
}
}
// Set sets v to the value x.
func (v *intValue) SetValue(x Value) { v.Set(x.Int()) }
// Overflow returns true if x cannot be represented by the type of v.
func (v *intValue) Overflow(x int64) bool {
bitSize := uint(v.typ.Bits())
trunc := (x << (64 - bitSize)) >> (64 - bitSize)
return x != trunc
}
// StringHeader is the runtime representation of a string.
type StringHeader struct {
Data uintptr
Len int
}
// stringValue represents a string value.
type stringValue struct {
value "string"
}
// Get returns the underlying string value.
func (v *stringValue) Get() string { return *(*string)(v.addr) }
// Set sets v to the value x.
func (v *stringValue) Set(x string) {
if !v.CanSet() {
panic(cannotSet)
}
*(*string)(v.addr) = x
}
// Set sets v to the value x.
func (v *stringValue) SetValue(x Value) {
// Do the kind check explicitly, because x.String() does not.
v.Set(x.panicIfNot(String).(*stringValue).Get())
}
// uintValue represents a uint value.
type uintValue struct {
value "uint"
}
// Get returns the underlying uuint value.
func (v *uintValue) Get() uint64 {
switch v.typ.Kind() {
case Uint:
return uint64(*(*uint)(v.addr))
case Uint8:
return uint64(*(*uint8)(v.addr))
case Uint16:
return uint64(*(*uint16)(v.addr))
case Uint32:
return uint64(*(*uint32)(v.addr))
case Uint64:
return *(*uint64)(v.addr)
case Uintptr:
return uint64(*(*uintptr)(v.addr))
}
panic("reflect: invalid uint kind")
}
// Set sets v to the value x.
func (v *uintValue) Set(x uint64) {
if !v.CanSet() {
panic(cannotSet)
}
switch v.typ.Kind() {
default:
panic("reflect: invalid uint kind")
case Uint:
*(*uint)(v.addr) = uint(x)
case Uint8:
*(*uint8)(v.addr) = uint8(x)
case Uint16:
*(*uint16)(v.addr) = uint16(x)
case Uint32:
*(*uint32)(v.addr) = uint32(x)
case Uint64:
*(*uint64)(v.addr) = x
case Uintptr:
*(*uintptr)(v.addr) = uintptr(x)
}
}
// Overflow returns true if x cannot be represented by the type of v.
func (v *uintValue) Overflow(x uint64) bool {
bitSize := uint(v.typ.Bits())
trunc := (x << (64 - bitSize)) >> (64 - bitSize)
return x != trunc
}
// Set sets v to the value x.
func (v *uintValue) SetValue(x Value) { v.Set(x.Uint()) }
// unsafePointerValue represents an unsafe.Pointer value.
type unsafePointerValue struct {
value "unsafe.Pointer"
}
// Get returns the underlying uintptr value.
// Get returns uintptr, not unsafe.Pointer, so that
// programs that do not import "unsafe" cannot
// obtain a value of unsafe.Pointer type from "reflect".
func (v *unsafePointerValue) Get() uintptr { return uintptr(*(*unsafe.Pointer)(v.addr)) }
// Set sets v to the value x.
func (v *unsafePointerValue) Set(x unsafe.Pointer) {
if !v.CanSet() {
panic(cannotSet)
}
*(*unsafe.Pointer)(v.addr) = x
}
// Set sets v to the value x.
func (v *unsafePointerValue) SetValue(x Value) {
// Do the kind check explicitly, because x.UnsafePointer
// applies to more than just the UnsafePointer Kind.
v.Set(unsafe.Pointer(x.panicIfNot(UnsafePointer).(*unsafePointerValue).Get()))
}
func typesMustMatch(t1, t2 Type) {
if t1 != t2 {
panic("type mismatch: " + t1.String() + " != " + t2.String())
}
}
/*
* array
*/
// ArrayOrSliceValue is the common interface
// implemented by both arrayValue and sliceValue.
type arrayOrSliceValue interface {
valueInterface
Len() int
Cap() int
Elem(i int) Value
addr() addr
}
// grow grows the slice s so that it can hold extra more values, allocating
// more capacity if needed. It also returns the old and new slice lengths.
func grow(s Value, extra int) (Value, int, int) {
i0 := s.Len()
i1 := i0 + extra
if i1 < i0 {
panic("append: slice overflow")
}
m := s.Cap()
if i1 <= m {
return s.Slice(0, i1), i0, i1
}
if m == 0 {
m = extra
} else {
for m < i1 {
if i0 < 1024 {
m += m
} else {
m += m / 4
}
}
}
t := MakeSlice(s.Type(), i1, m)
Copy(t, s)
return t, i0, i1
}
// Append appends the values x to a slice s and returns the resulting slice.
// Each x must have the same type as s' element type.
func Append(s Value, x ...Value) Value {
s, i0, i1 := grow(s, len(x))
sa := s.panicIfNot(Slice).(*sliceValue)
for i, j := i0, 0; i < i1; i, j = i+1, j+1 {
sa.Elem(i).Set(x[j])
}
return s
}
// AppendSlice appends a slice t to a slice s and returns the resulting slice.
// The slices s and t must have the same element type.
func AppendSlice(s, t Value) Value {
s, i0, i1 := grow(s, t.Len())
Copy(s.Slice(i0, i1), t)
return s
}
// Copy copies the contents of src into dst until either
// dst has been filled or src has been exhausted.
// It returns the number of elements copied.
// Dst and src each must be a slice or array, and they
// must have the same element type.
func Copy(dst, src Value) int {
// TODO: This will have to move into the runtime
// once the real gc goes in.
de := dst.Type().Elem()
se := src.Type().Elem()
typesMustMatch(de, se)
n := dst.Len()
if xn := src.Len(); n > xn {
n = xn
}
memmove(dst.panicIfNots(arrayOrSlice).(arrayOrSliceValue).addr(),
src.panicIfNots(arrayOrSlice).(arrayOrSliceValue).addr(),
uintptr(n)*de.Size())
return n
}
// An arrayValue represents an array.
type arrayValue struct {
value "array"
}
// Len returns the length of the array.
func (v *arrayValue) Len() int { return v.typ.Len() }
// Cap returns the capacity of the array (equal to Len()).
func (v *arrayValue) Cap() int { return v.typ.Len() }
// addr returns the base address of the data in the array.
func (v *arrayValue) addr() addr { return v.value.addr }
// Set assigns x to v.
// The new value x must have the same type as v.
func (v *arrayValue) Set(x *arrayValue) {
if !v.CanSet() {
panic(cannotSet)
}
typesMustMatch(v.typ, x.typ)
Copy(Value{v}, Value{x})
}
// Set sets v to the value x.
func (v *arrayValue) SetValue(x Value) {
v.Set(x.panicIfNot(Array).(*arrayValue))
}
// Elem returns the i'th element of v.
func (v *arrayValue) Elem(i int) Value {
typ := v.typ.Elem()
n := v.Len()
if i < 0 || i >= n {
panic("array index out of bounds")
}
p := addr(uintptr(v.addr()) + uintptr(i)*typ.Size())
return newValue(typ, p, v.flag)
}
/*
* slice
*/
// runtime representation of slice
type SliceHeader struct {
Data uintptr
Len int
Cap int
}
// A sliceValue represents a slice.
type sliceValue struct {
value "slice"
}
func (v *sliceValue) slice() *SliceHeader { return (*SliceHeader)(v.value.addr) }
// IsNil returns whether v is a nil slice.
func (v *sliceValue) IsNil() bool { return v.slice().Data == 0 }
// Len returns the length of the slice.
func (v *sliceValue) Len() int { return int(v.slice().Len) }
// Cap returns the capacity of the slice.
func (v *sliceValue) Cap() int { return int(v.slice().Cap) }
// addr returns the base address of the data in the slice.
func (v *sliceValue) addr() addr { return addr(v.slice().Data) }
// SetLen changes the length of v.
// The new length n must be between 0 and the capacity, inclusive.
func (v *sliceValue) SetLen(n int) {
s := v.slice()
if n < 0 || n > int(s.Cap) {
panic("reflect: slice length out of range in SetLen")
}
s.Len = n
}
// Set assigns x to v.
// The new value x must have the same type as v.
func (v *sliceValue) Set(x *sliceValue) {
if !v.CanSet() {
panic(cannotSet)
}
typesMustMatch(v.typ, x.typ)
*v.slice() = *x.slice()
}
// Set sets v to the value x.
func (v *sliceValue) SetValue(x Value) {
v.Set(x.panicIfNot(Slice).(*sliceValue))
}
// Get returns the uintptr address of the v.Cap()'th element. This gives
// the same result for all slices of the same array.
// It is mainly useful for printing.
func (v *sliceValue) Get() uintptr {
typ := v.typ
return uintptr(v.addr()) + uintptr(v.Cap())*typ.Elem().Size()
}
// Slice returns a sub-slice of the slice v.
func (v *sliceValue) Slice(beg, end int) Value {
cap := v.Cap()
if beg < 0 || end < beg || end > cap {
panic("slice index out of bounds")
}
typ := v.typ
s := new(SliceHeader)
s.Data = uintptr(v.addr()) + uintptr(beg)*typ.Elem().Size()
s.Len = end - beg
s.Cap = cap - beg
// Like the result of Addr, we treat Slice as an
// unaddressable temporary, so don't set canAddr.
flag := canSet
if v.flag&canStore != 0 {
flag |= canStore
}
return newValue(typ, addr(s), flag)
}
// Elem returns the i'th element of v.
func (v *sliceValue) Elem(i int) Value {
typ := v.typ.Elem()
n := v.Len()
if i < 0 || i >= n {
panic("reflect: slice index out of range")
}
p := addr(uintptr(v.addr()) + uintptr(i)*typ.Size())
flag := canAddr
if v.flag&canStore != 0 {
flag |= canSet | canStore
}
return newValue(typ, p, flag)
}
// MakeSlice creates a new zero-initialized slice value
// for the specified slice type, length, and capacity.
func MakeSlice(typ Type, len, cap int) Value {
if typ.Kind() != Slice {
panic("reflect: MakeSlice of non-slice type")
}
s := &SliceHeader{
Data: uintptr(unsafe.NewArray(typ.Elem(), cap)),
Len: len,
Cap: cap,
}
return newValue(typ, addr(s), canAddr|canSet|canStore)
}
/*
* chan
*/
// A chanValue represents a chan.
type chanValue struct {
value "chan"
}
// IsNil returns whether v is a nil channel.
func (v *chanValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
// Set assigns x to v.
// The new value x must have the same type as v.
func (v *chanValue) Set(x *chanValue) {
if !v.CanSet() {
panic(cannotSet)
}
typesMustMatch(v.typ, x.typ)
*(*uintptr)(v.addr) = *(*uintptr)(x.addr)
}
// Set sets v to the value x.
func (v *chanValue) SetValue(x Value) {
v.Set(x.panicIfNot(Chan).(*chanValue))
}
// Get returns the uintptr value of v.
// It is mainly useful for printing.
func (v *chanValue) Get() uintptr { return *(*uintptr)(v.addr) }
// implemented in ../pkg/runtime/reflect.cgo
func makechan(typ *runtime.ChanType, size uint32) (ch *byte)
func chansend(ch, val *byte, selected *bool)
func chanrecv(ch, val *byte, selected *bool, ok *bool)
func chanclose(ch *byte)
func chanlen(ch *byte) int32
func chancap(ch *byte) int32
// Close closes the channel.
func (v *chanValue) Close() {
ch := *(**byte)(v.addr)
chanclose(ch)
}
func (v *chanValue) Len() int {
ch := *(**byte)(v.addr)
return int(chanlen(ch))
}
func (v *chanValue) Cap() int {
ch := *(**byte)(v.addr)
return int(chancap(ch))
}
// internal send; non-blocking if selected != nil
func (v *chanValue) send(x Value, selected *bool) {
t := v.Type()
if t.ChanDir()&SendDir == 0 {
panic("send on recv-only channel")
}
typesMustMatch(t.Elem(), x.Type())
ch := *(**byte)(v.addr)
chansend(ch, (*byte)(x.internal().getAddr()), selected)
}
// internal recv; non-blocking if selected != nil
func (v *chanValue) recv(selected *bool) (Value, bool) {
t := v.Type()
if t.ChanDir()&RecvDir == 0 {
panic("recv on send-only channel")
}
ch := *(**byte)(v.addr)
x := Zero(t.Elem())
var ok bool
chanrecv(ch, (*byte)(x.internal().getAddr()), selected, &ok)
return x, ok
}
// Send sends x on the channel v.
func (v *chanValue) Send(x Value) { v.send(x, nil) }
// Recv receives and returns a value from the channel v.
// The receive blocks until a value is ready.
// The boolean value ok is true if the value x corresponds to a send
// on the channel, false if it is a zero value received because the channel is closed.
func (v *chanValue) Recv() (x Value, ok bool) {
return v.recv(nil)
}
// TrySend attempts to sends x on the channel v but will not block.
// It returns true if the value was sent, false otherwise.
func (v *chanValue) TrySend(x Value) bool {
var selected bool
v.send(x, &selected)
return selected
}
// TryRecv attempts to receive a value from the channel v but will not block.
// If the receive cannot finish without blocking, TryRecv instead returns x == nil.
// If the receive can finish without blocking, TryRecv returns x != nil.
// The boolean value ok is true if the value x corresponds to a send
// on the channel, false if it is a zero value received because the channel is closed.
func (v *chanValue) TryRecv() (x Value, ok bool) {
var selected bool
x, ok = v.recv(&selected)
if !selected {
return Value{}, false
}
return x, ok
}
// MakeChan creates a new channel with the specified type and buffer size.
func MakeChan(typ Type, buffer int) Value {
if typ.Kind() != Chan {
panic("reflect: MakeChan of non-chan type")
}
if buffer < 0 {
panic("MakeChan: negative buffer size")
}
if typ.ChanDir() != BothDir {
panic("MakeChan: unidirectional channel type")
}
v := Zero(typ)
ch := v.panicIfNot(Chan).(*chanValue)
*(**byte)(ch.addr) = makechan((*runtime.ChanType)(unsafe.Pointer(typ.(*commonType))), uint32(buffer))
return v
}
/*
* func
*/
// A funcValue represents a function value.
type funcValue struct {
value "func"
first *value
isInterface bool
}
// IsNil returns whether v is a nil function.
func (v *funcValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
// Get returns the uintptr value of v.
// It is mainly useful for printing.
func (v *funcValue) Get() uintptr { return *(*uintptr)(v.addr) }
// Set assigns x to v.
// The new value x must have the same type as v.
func (v *funcValue) Set(x *funcValue) {
if !v.CanSet() {
panic(cannotSet)
}
typesMustMatch(v.typ, x.typ)
*(*uintptr)(v.addr) = *(*uintptr)(x.addr)
}
// Set sets v to the value x.
func (v *funcValue) SetValue(x Value) {
v.Set(x.panicIfNot(Func).(*funcValue))
}
// Method returns a funcValue corresponding to v's i'th method.
// The arguments to a Call on the returned funcValue
// should not include a receiver; the funcValue will use v
// as the receiver.
func (v *value) Method(i int) Value {
t := v.Type().uncommon()
if t == nil || i < 0 || i >= len(t.methods) {
panic("reflect: Method index out of range")
}
p := &t.methods[i]
fn := p.tfn
fv := &funcValue{value: value{toType(p.typ), addr(&fn), 0}, first: v, isInterface: false}
return Value{fv}
}
// implemented in ../pkg/runtime/*/asm.s
func call(fn, arg *byte, n uint32)
type tiny struct {
b byte
}
// Interface returns the fv as an interface value.
// If fv is a method obtained by invoking Value.Method
// (as opposed to Type.Method), Interface cannot return an
// interface value, so it panics.
func (fv *funcValue) Interface() interface{} {
if fv.first != nil {
panic("funcValue: cannot create interface value for method with bound receiver")
}
return fv.value.Interface()
}
// Call calls the function fv with input parameters in.
// It returns the function's output parameters as Values.
func (fv *funcValue) Call(in []Value) []Value {
t := fv.Type()
nin := len(in)
if fv.first != nil && !fv.isInterface {
nin++
}
if nin != t.NumIn() {
panic("funcValue: wrong argument count")
}
nout := t.NumOut()
// Compute arg size & allocate.
// This computation is 6g/8g-dependent
// and probably wrong for gccgo, but so
// is most of this function.
size := uintptr(0)
if fv.isInterface {
// extra word for interface value
size += ptrSize
}
for i := 0; i < nin; i++ {
tv := t.In(i)
a := uintptr(tv.Align())
size = (size + a - 1) &^ (a - 1)
size += tv.Size()
}
size = (size + ptrSize - 1) &^ (ptrSize - 1)
for i := 0; i < nout; i++ {
tv := t.Out(i)
a := uintptr(tv.Align())
size = (size + a - 1) &^ (a - 1)
size += tv.Size()
}
// size must be > 0 in order for &args[0] to be valid.
// the argument copying is going to round it up to
// a multiple of ptrSize anyway, so make it ptrSize to begin with.
if size < ptrSize {
size = ptrSize
}
// round to pointer size
size = (size + ptrSize - 1) &^ (ptrSize - 1)
// Copy into args.
//
// TODO(rsc): revisit when reference counting happens.
// The values are holding up the in references for us,
// but something must be done for the out references.
// For now make everything look like a pointer by pretending
// to allocate a []*int.
args := make([]*int, size/ptrSize)
ptr := uintptr(unsafe.Pointer(&args[0]))
off := uintptr(0)
delta := 0
if v := fv.first; v != nil {
// Hard-wired first argument.
if fv.isInterface {
// v is a single uninterpreted word
memmove(addr(ptr), v.getAddr(), ptrSize)
off = ptrSize
} else {
// v is a real value
tv := v.Type()
typesMustMatch(t.In(0), tv)
n := tv.Size()
memmove(addr(ptr), v.getAddr(), n)
off = n
delta = 1
}
}
for i, v := range in {
tv := v.Type()
typesMustMatch(t.In(i+delta), tv)
a := uintptr(tv.Align())
off = (off + a - 1) &^ (a - 1)
n := tv.Size()
memmove(addr(ptr+off), v.internal().getAddr(), n)
off += n
}
off = (off + ptrSize - 1) &^ (ptrSize - 1)
// Call
call(*(**byte)(fv.addr), (*byte)(addr(ptr)), uint32(size))
// Copy return values out of args.
//
// TODO(rsc): revisit like above.
ret := make([]Value, nout)
for i := 0; i < nout; i++ {
tv := t.Out(i)
a := uintptr(tv.Align())
off = (off + a - 1) &^ (a - 1)
v := Zero(tv)
n := tv.Size()
memmove(v.internal().getAddr(), addr(ptr+off), n)
ret[i] = v
off += n
}
return ret
}
/*
* interface
*/
// An interfaceValue represents an interface value.
type interfaceValue struct {
value "interface"
}
// IsNil returns whether v is a nil interface value.
func (v *interfaceValue) IsNil() bool { return v.Interface() == nil }
// No single uinptr Get because v.Interface() is available.
// Get returns the two words that represent an interface in the runtime.
// Those words are useful only when playing unsafe games.
func (v *interfaceValue) Get() [2]uintptr {
return *(*[2]uintptr)(v.addr)
}
// Elem returns the concrete value stored in the interface value v.
func (v *interfaceValue) Elem() Value { return NewValue(v.Interface()) }
// ../runtime/reflect.cgo
func setiface(typ *interfaceType, x *interface{}, addr addr)
// Set assigns x to v.
func (v *interfaceValue) Set(x Value) {
i := x.Interface()
if !v.CanSet() {
panic(cannotSet)
}
// Two different representations; see comment in Get.
// Empty interface is easy.
t := (*interfaceType)(unsafe.Pointer(v.typ.(*commonType)))
if t.NumMethod() == 0 {
*(*interface{})(v.addr) = i
return
}
// Non-empty interface requires a runtime check.
setiface(t, &i, v.addr)
}
// Set sets v to the value x.
func (v *interfaceValue) SetValue(x Value) { v.Set(x) }
// Method returns a funcValue corresponding to v's i'th method.
// The arguments to a Call on the returned funcValue
// should not include a receiver; the funcValue will use v
// as the receiver.
func (v *interfaceValue) Method(i int) Value {
t := (*interfaceType)(unsafe.Pointer(v.Type().(*commonType)))
if t == nil || i < 0 || i >= len(t.methods) {
panic("reflect: Method index out of range")
}
p := &t.methods[i]
// Interface is two words: itable, data.
tab := *(**runtime.Itable)(v.addr)
data := &value{Typeof((*byte)(nil)), addr(uintptr(v.addr) + ptrSize), 0}
// Function pointer is at p.perm in the table.
fn := tab.Fn[i]
fv := &funcValue{value: value{toType(p.typ), addr(&fn), 0}, first: data, isInterface: true}
return Value{fv}
}
/*
* map
*/
// A mapValue represents a map value.
type mapValue struct {
value "map"
}
// IsNil returns whether v is a nil map value.
func (v *mapValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
// Set assigns x to v.
// The new value x must have the same type as v.
func (v *mapValue) Set(x *mapValue) {
if !v.CanSet() {
panic(cannotSet)
}
if x == nil {
*(**uintptr)(v.addr) = nil
return
}
typesMustMatch(v.typ, x.typ)
*(*uintptr)(v.addr) = *(*uintptr)(x.addr)
}
// Set sets v to the value x.
func (v *mapValue) SetValue(x Value) {
v.Set(x.panicIfNot(Map).(*mapValue))
}
// Get returns the uintptr value of v.
// It is mainly useful for printing.
func (v *mapValue) Get() uintptr { return *(*uintptr)(v.addr) }
// implemented in ../pkg/runtime/reflect.cgo
func mapaccess(m, key, val *byte) bool
func mapassign(m, key, val *byte)
func maplen(m *byte) int32
func mapiterinit(m *byte) *byte
func mapiternext(it *byte)
func mapiterkey(it *byte, key *byte) bool
func makemap(t *runtime.MapType) *byte
// Elem returns the value associated with key in the map v.
// It returns nil if key is not found in the map.
func (v *mapValue) Elem(key Value) Value {
t := v.Type()
typesMustMatch(t.Key(), key.Type())
m := *(**byte)(v.addr)
if m == nil {
return Value{}
}
newval := Zero(t.Elem())
if !mapaccess(m, (*byte)(key.internal().getAddr()), (*byte)(newval.internal().getAddr())) {
return Value{}
}
return newval
}
// SetElem sets the value associated with key in the map v to val.
// If val is nil, Put deletes the key from map.
func (v *mapValue) SetElem(key, val Value) {
t := v.Type()
typesMustMatch(t.Key(), key.Type())
var vaddr *byte
if val.IsValid() {
typesMustMatch(t.Elem(), val.Type())
vaddr = (*byte)(val.internal().getAddr())
}
m := *(**byte)(v.addr)
mapassign(m, (*byte)(key.internal().getAddr()), vaddr)
}
// Len returns the number of keys in the map v.
func (v *mapValue) Len() int {
m := *(**byte)(v.addr)
if m == nil {
return 0
}
return int(maplen(m))
}
// Keys returns a slice containing all the keys present in the map,
// in unspecified order.
func (v *mapValue) Keys() []Value {
tk := v.Type().Key()
m := *(**byte)(v.addr)
mlen := int32(0)
if m != nil {
mlen = maplen(m)
}
it := mapiterinit(m)
a := make([]Value, mlen)
var i int
for i = 0; i < len(a); i++ {
k := Zero(tk)
if !mapiterkey(it, (*byte)(k.internal().getAddr())) {
break
}
a[i] = k
mapiternext(it)
}
return a[0:i]
}
// MakeMap creates a new map of the specified type.
func MakeMap(typ Type) Value {
if typ.Kind() != Map {
panic("reflect: MakeMap of non-map type")
}
v := Zero(typ)
m := v.panicIfNot(Map).(*mapValue)
*(**byte)(m.addr) = makemap((*runtime.MapType)(unsafe.Pointer(typ.(*commonType))))
return v
}
/*
* ptr
*/
// A ptrValue represents a pointer.
type ptrValue struct {
value "ptr"
}
// IsNil returns whether v is a nil pointer.
func (v *ptrValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
// Get returns the uintptr value of v.
// It is mainly useful for printing.
func (v *ptrValue) Get() uintptr { return *(*uintptr)(v.addr) }
// Set assigns x to v.
// The new value x must have the same type as v, and x.Elem().CanSet() must be true.
func (v *ptrValue) Set(x *ptrValue) {
if x == nil {
*(**uintptr)(v.addr) = nil
return
}
if !v.CanSet() {
panic(cannotSet)
}
if x.flag&canStore == 0 {
panic("cannot copy pointer obtained from unexported struct field")
}
typesMustMatch(v.typ, x.typ)
// TODO: This will have to move into the runtime
// once the new gc goes in
*(*uintptr)(v.addr) = *(*uintptr)(x.addr)
}
// Set sets v to the value x.
func (v *ptrValue) SetValue(x Value) {
v.Set(x.panicIfNot(Ptr).(*ptrValue))
}
// PointTo changes v to point to x.
// If x is a nil Value, PointTo sets v to nil.
func (v *ptrValue) PointTo(x Value) {
if !x.IsValid() {
*(**uintptr)(v.addr) = nil
return
}
if !x.CanSet() {
panic("cannot set x; cannot point to x")
}
typesMustMatch(v.typ.Elem(), x.Type())
// TODO: This will have to move into the runtime
// once the new gc goes in.
*(*uintptr)(v.addr) = x.UnsafeAddr()
}
// Elem returns the value that v points to.
// If v is a nil pointer, Elem returns a nil Value.
func (v *ptrValue) Elem() Value {
if v.IsNil() {
return Value{}
}
flag := canAddr
if v.flag&canStore != 0 {
flag |= canSet | canStore
}
return newValue(v.typ.Elem(), *(*addr)(v.addr), flag)
}
// Indirect returns the value that v points to.
// If v is a nil pointer, Indirect returns a nil Value.
// If v is not a pointer, Indirect returns v.
func Indirect(v Value) Value {
if v.Kind() != Ptr {
return v
}
return v.panicIfNot(Ptr).(*ptrValue).Elem()
}
/*
* struct
*/
// A structValue represents a struct value.
type structValue struct {
value "struct"
}
// Set assigns x to v.
// The new value x must have the same type as v.
func (v *structValue) Set(x *structValue) {
// TODO: This will have to move into the runtime
// once the gc goes in.
if !v.CanSet() {
panic(cannotSet)
}
typesMustMatch(v.typ, x.typ)
memmove(v.addr, x.addr, v.typ.Size())
}
// Set sets v to the value x.
func (v *structValue) SetValue(x Value) {
v.Set(x.panicIfNot(Struct).(*structValue))
}
// Field returns the i'th field of the struct.
func (v *structValue) Field(i int) Value {
t := v.typ
if i < 0 || i >= t.NumField() {
panic("reflect: Field index out of range")
}
f := t.Field(i)
flag := v.flag
if f.PkgPath != "" {
// unexported field
flag &^= canSet | canStore
}
return newValue(f.Type, addr(uintptr(v.addr)+f.Offset), flag)
}
// FieldByIndex returns the nested field corresponding to index.
func (t *structValue) FieldByIndex(index []int) (v Value) {
v = Value{t}
for i, x := range index {
if i > 0 {
if v.Kind() == Ptr {
v = v.Elem()
}
if v.Kind() != Struct {
return Value{}
}
}
v = v.Field(x)
}
return
}
// FieldByName returns the struct field with the given name.
// The result is nil if no field was found.
func (t *structValue) FieldByName(name string) Value {
if f, ok := t.Type().FieldByName(name); ok {
return t.FieldByIndex(f.Index)
}
return Value{}
}
// FieldByNameFunc returns the struct field with a name that satisfies the
// match function.
// The result is nil if no field was found.
func (t *structValue) FieldByNameFunc(match func(string) bool) Value {
if f, ok := t.Type().FieldByNameFunc(match); ok {
return t.FieldByIndex(f.Index)
}
return Value{}
}
// NumField returns the number of fields in the struct.
func (v *structValue) NumField() int { return v.typ.NumField() }
/*
* constructors
*/
// NewValue returns a new Value initialized to the concrete value
// stored in the interface i. NewValue(nil) returns the zero Value.
func NewValue(i interface{}) Value {
if i == nil {
return Value{}
}
_, a := unsafe.Reflect(i)
return newValue(Typeof(i), addr(a), canSet|canAddr|canStore)
}
func newValue(typ Type, addr addr, flag uint32) Value {
v := value{typ, addr, flag}
switch typ.Kind() {
case Array:
return Value{&arrayValue{v}}
case Bool:
return Value{&boolValue{v}}
case Chan:
return Value{&chanValue{v}}
case Float32, Float64:
return Value{&floatValue{v}}
case Func:
return Value{&funcValue{value: v}}
case Complex64, Complex128:
return Value{&complexValue{v}}
case Int, Int8, Int16, Int32, Int64:
return Value{&intValue{v}}
case Interface:
return Value{&interfaceValue{v}}
case Map:
return Value{&mapValue{v}}
case Ptr:
return Value{&ptrValue{v}}
case Slice:
return Value{&sliceValue{v}}
case String:
return Value{&stringValue{v}}
case Struct:
return Value{&structValue{v}}
case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
return Value{&uintValue{v}}
case UnsafePointer:
return Value{&unsafePointerValue{v}}
}
panic("newValue" + typ.String())
}
// Zero returns a Value representing a zero value for the specified type.
// The result is different from the zero value of the Value struct,
// which represents no value at all.
// For example, Zero(Typeof(42)) returns a Value with Kind Int and value 0.
func Zero(typ Type) Value {
if typ == nil {
panic("reflect: Zero(nil)")
}
return newValue(typ, addr(unsafe.New(typ)), canSet|canAddr|canStore)
}