"unsafe"
)
+const bigEndian = false // can be smarter if we find a big-endian machine
const ptrSize = unsafe.Sizeof((*byte)(nil))
const cannotSet = "cannot set value obtained from unexported struct field"
// 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.
-//
-// The fields of Value are exported so that clients can copy and
-// pass Values around, but they should not be edited or inspected
-// directly. A future language change may make it possible not to
-// export these fields while still keeping Values usable as values.
type Value struct {
- Internal interface{}
- InternalMethod int
+ // typ holds the type of the value represented by a Value.
+ typ *commonType
+
+ // val holds the 1-word representation of the value.
+ // If flag's flagIndir bit is set, then val is a pointer to the data.
+ // Otherwise val is a word holding the actual data.
+ // When the data is smaller than a word, it begins at
+ // the first byte (in the memory address sense) of val.
+ // We use unsafe.Pointer so that the garbage collector
+ // knows that val could be a pointer.
+ val unsafe.Pointer
+
+ // flag holds metadata about the value.
+ // The lowest bits are flag bits:
+ // - flagRO: obtained via unexported field, so read-only
+ // - flagIndir: val holds a pointer to the data
+ // - flagAddr: v.CanAddr is true (implies flagIndir)
+ // - flagMethod: v is a method value.
+ // The next five bits give the Kind of the value.
+ // This repeats typ.Kind() except for method values.
+ // The remaining 23+ bits give a method number for method values.
+ // If flag.kind() != Func, code can assume that flagMethod is unset.
+ // If typ.size > ptrSize, code can assume that flagIndir is set.
+ flag
+
+ // A method value represents a curried method invocation
+ // like r.Read for some receiver r. The typ+val+flag bits describe
+ // the receiver r, but the flag's Kind bits say Func (methods are
+ // functions), and the top bits of the flag give the method number
+ // in r's type's method table.
+}
+
+type flag uintptr
+
+const (
+ flagRO flag = 1 << iota
+ flagIndir
+ flagAddr
+ flagMethod
+ flagKindShift = iota
+ flagKindWidth = 5 // there are 27 kinds
+ flagKindMask flag = 1<<flagKindWidth - 1
+ flagMethodShift = flagKindShift + flagKindWidth
+)
+
+func (f flag) kind() Kind {
+ return Kind((f >> flagKindShift) & flagKindMask)
}
// A ValueError occurs when a Value method is invoked on
// An iword is the word that would be stored in an
// interface to represent a given value v. Specifically, if v is
// bigger than a pointer, its word is a pointer to v's data.
-// Otherwise, its word is a zero uintptr with the data stored
-// in the leading bytes.
-type iword uintptr
+// Otherwise, its word holds the data stored
+// in its leading bytes (so is not a pointer).
+// Because the value sometimes holds a pointer, we use
+// unsafe.Pointer to represent it, so that if iword appears
+// in a struct, the garbage collector knows that might be
+// a pointer.
+type iword unsafe.Pointer
+
+func (v Value) iword() iword {
+ if v.flag&flagIndir != 0 && v.typ.size <= ptrSize {
+ // Have indirect but want direct word.
+ return loadIword(v.val, v.typ.size)
+ }
+ return iword(v.val)
+}
-func loadIword(p unsafe.Pointer, size uintptr) iword {
+// loadIword loads n bytes at p from memory into an iword.
+func loadIword(p unsafe.Pointer, n uintptr) iword {
// Run the copy ourselves instead of calling memmove
- // to avoid moving v to the heap.
- w := iword(0)
- switch size {
+ // to avoid moving w to the heap.
+ var w iword
+ switch n {
default:
- panic("reflect: internal error: loadIword of " + strconv.Itoa(int(size)) + "-byte value")
+ panic("reflect: internal error: loadIword of " + strconv.Itoa(int(n)) + "-byte value")
case 0:
case 1:
*(*uint8)(unsafe.Pointer(&w)) = *(*uint8)(p)
return w
}
-func storeIword(p unsafe.Pointer, w iword, size uintptr) {
+// storeIword stores n bytes from w into p.
+func storeIword(p unsafe.Pointer, w iword, n uintptr) {
// Run the copy ourselves instead of calling memmove
- // to avoid moving v to the heap.
- switch size {
+ // to avoid moving w to the heap.
+ switch n {
default:
- panic("reflect: internal error: storeIword of " + strconv.Itoa(int(size)) + "-byte value")
+ panic("reflect: internal error: storeIword of " + strconv.Itoa(int(n)) + "-byte value")
case 0:
case 1:
*(*uint8)(p) = *(*uint8)(unsafe.Pointer(&w))
word iword
}
-// Regarding the implementation of Value:
-//
-// The Internal interface is a true interface value in the Go sense,
-// but it also serves as a (type, address) pair in which one cannot
-// be changed separately from the other. That is, it serves as a way
-// to prevent unsafe mutations of the Internal state even though
-// we cannot (yet?) hide the field while preserving the ability for
-// clients to make copies of Values.
-//
-// The internal method converts a Value into the expanded internalValue struct.
-// If we could avoid exporting fields we'd probably make internalValue the
-// definition of Value.
-//
-// If a Value is addressable (CanAddr returns true), then the Internal
-// interface value holds a pointer to the actual field data, and Set stores
-// through that pointer. If a Value is not addressable (CanAddr returns false),
-// then the Internal interface value holds the actual value.
-//
-// In addition to whether a value is addressable, we track whether it was
-// obtained by using an unexported struct field. Such values are allowed
-// to be read, mainly to make fmt.Print more useful, but they are not
-// allowed to be written. We call such values read-only.
-//
-// A Value can be set (via the Set, SetUint, etc. methods) only if it is both
-// addressable and not read-only.
-//
-// The two permission bits - addressable and read-only - are stored in
-// the bottom two bits of the type pointer in the interface value.
-//
-// ordinary value: Internal = value
-// addressable value: Internal = value, Internal.typ |= flagAddr
-// read-only value: Internal = value, Internal.typ |= flagRO
-// addressable, read-only value: Internal = value, Internal.typ |= flagAddr | flagRO
-//
-// It is important that the read-only values have the extra bit set
-// (as opposed to using the bit to mean writable), because client code
-// can grab the interface field and try to use it. Having the extra bit
-// set makes the type pointer compare not equal to any real type,
-// so that a client cannot, say, write through v.Internal.(*int).
-// The runtime routines that access interface types reject types with
-// low bits set.
-//
-// If a Value fv = v.Method(i), then fv = v with the InternalMethod
-// field set to i+1. Methods are never addressable.
-//
-// All in all, this is a lot of effort just to avoid making this new API
-// depend on a language change we'll probably do anyway, but
-// it's helpful to keep the two separate, and much of the logic is
-// necessary to implement the Interface method anyway.
-
-const (
- flagAddr uint32 = 1 << iota // holds address of value
- flagRO // read-only
-
- reflectFlags = 3
-)
-
-// An internalValue is the unpacked form of a Value.
-// The zero Value unpacks to a zero internalValue
-type internalValue struct {
- typ *commonType // type of value
- kind Kind // kind of value
- flag uint32
- word iword
- addr unsafe.Pointer
- rcvr iword
- method bool
- nilmethod bool
-}
-
-func (v Value) internal() internalValue {
- var iv internalValue
- eface := *(*emptyInterface)(unsafe.Pointer(&v.Internal))
- p := uintptr(unsafe.Pointer(eface.typ))
- iv.typ = toCommonType((*runtime.Type)(unsafe.Pointer(p &^ reflectFlags)))
- if iv.typ == nil {
- return iv
- }
- iv.flag = uint32(p & reflectFlags)
- iv.word = eface.word
- if iv.flag&flagAddr != 0 {
- iv.addr = unsafe.Pointer(iv.word)
- iv.typ = iv.typ.Elem().common()
- if iv.typ.size <= ptrSize {
- iv.word = loadIword(iv.addr, iv.typ.size)
- }
- } else {
- if iv.typ.size > ptrSize {
- iv.addr = unsafe.Pointer(iv.word)
- }
+// mustBe panics if f's kind is not expected.
+// Making this a method on flag instead of on Value
+// (and embedding flag in Value) means that we can write
+// the very clear v.mustBe(Bool) and have it compile into
+// v.flag.mustBe(Bool), which will only bother to copy the
+// single important word for the receiver.
+func (f flag) mustBe(expected Kind) {
+ k := f.kind()
+ if k != expected {
+ panic(&ValueError{methodName(), k})
}
- iv.kind = iv.typ.Kind()
-
- // Is this a method? If so, iv describes the receiver.
- // Rewrite to describe the method function.
- if v.InternalMethod != 0 {
- // If this Value is a method value (x.Method(i) for some Value x)
- // then we will invoke it using the interface form of the method,
- // which always passes the receiver as a single word.
- // Record that information.
- i := v.InternalMethod - 1
- if iv.kind == Interface {
- it := (*interfaceType)(unsafe.Pointer(iv.typ))
- if i < 0 || i >= len(it.methods) {
- panic("reflect: broken Value")
- }
- m := &it.methods[i]
- if m.pkgPath != nil {
- iv.flag |= flagRO
- }
- iv.typ = toCommonType(m.typ)
- iface := (*nonEmptyInterface)(iv.addr)
- if iface.itab == nil {
- iv.word = 0
- iv.nilmethod = true
- } else {
- iv.word = iword(iface.itab.fun[i])
- }
- iv.rcvr = iface.word
- } else {
- ut := iv.typ.uncommon()
- if ut == nil || i < 0 || i >= len(ut.methods) {
- panic("reflect: broken Value")
- }
- m := &ut.methods[i]
- if m.pkgPath != nil {
- iv.flag |= flagRO
- }
- iv.typ = toCommonType(m.mtyp)
- iv.rcvr = iv.word
- iv.word = iword(m.ifn)
- }
- iv.kind = Func
- iv.method = true
- iv.flag &^= flagAddr
- iv.addr = nil
- }
-
- return iv
}
-// packValue returns a Value with the given flag bits, type, and interface word.
-func packValue(flag uint32, typ *runtime.Type, word iword) Value {
- if typ == nil {
- panic("packValue")
+// mustBeExported panics if f records that the value was obtained using
+// an unexported field.
+func (f flag) mustBeExported() {
+ if f == 0 {
+ panic(&ValueError{methodName(), 0})
}
- t := uintptr(unsafe.Pointer(typ))
- t |= uintptr(flag)
- eface := emptyInterface{(*runtime.Type)(unsafe.Pointer(t)), word}
- return Value{Internal: *(*interface{})(unsafe.Pointer(&eface))}
-}
-
-var dummy struct {
- b bool
- x interface{}
-}
-
-// Dummy annotation marking that the value x escapes,
-// for use in cases where the reflect code is so clever that
-// the compiler cannot follow.
-func escapes(x interface{}) {
- if dummy.b {
- dummy.x = x
- }
-}
-
-// valueFromAddr returns a Value using the given type and address.
-func valueFromAddr(flag uint32, typ Type, addr unsafe.Pointer) Value {
- // TODO(rsc): Eliminate this terrible hack.
- // The escape analysis knows that addr is a pointer
- // but it doesn't see addr get passed to anything
- // that keeps it. packValue keeps it, but packValue
- // takes a uintptr (iword(addr)), and integers (non-pointers)
- // are assumed not to matter. The escapes function works
- // because return values always escape (for now).
- escapes(addr)
-
- if flag&flagAddr != 0 {
- // Addressable, so the internal value is
- // an interface containing a pointer to the real value.
- return packValue(flag, PtrTo(typ).runtimeType(), iword(addr))
- }
-
- var w iword
- if n := typ.Size(); n <= ptrSize {
- // In line, so the interface word is the actual value.
- w = loadIword(addr, n)
- } else {
- // Not in line: the interface word is the address.
- w = iword(addr)
- }
- return packValue(flag, typ.runtimeType(), w)
-}
-
-// valueFromIword returns a Value using the given type and interface word.
-func valueFromIword(flag uint32, typ Type, w iword) Value {
- if flag&flagAddr != 0 {
- panic("reflect: internal error: valueFromIword addressable")
- }
- return packValue(flag, typ.runtimeType(), w)
-}
-
-func (iv internalValue) mustBe(want Kind) {
- if iv.kind != want {
- panic(&ValueError{methodName(), iv.kind})
- }
-}
-
-func (iv internalValue) mustBeExported() {
- if iv.kind == 0 {
- panic(&ValueError{methodName(), iv.kind})
- }
- if iv.flag&flagRO != 0 {
+ if f&flagRO != 0 {
panic(methodName() + " using value obtained using unexported field")
}
}
-func (iv internalValue) mustBeAssignable() {
- if iv.kind == 0 {
- panic(&ValueError{methodName(), iv.kind})
+// mustBeAssignable panics if f records that the value is not assignable,
+// which is to say that either it was obtained using an unexported field
+// or it is not addressable.
+func (f flag) mustBeAssignable() {
+ if f == 0 {
+ panic(&ValueError{methodName(), Invalid})
}
// Assignable if addressable and not read-only.
- if iv.flag&flagRO != 0 {
+ if f&flagRO != 0 {
panic(methodName() + " using value obtained using unexported field")
}
- if iv.flag&flagAddr == 0 {
+ if f&flagAddr == 0 {
panic(methodName() + " using unaddressable value")
}
}
// or slice element in order to call a method that requires a
// pointer receiver.
func (v Value) Addr() Value {
- iv := v.internal()
- if iv.flag&flagAddr == 0 {
+ if v.flag&flagAddr == 0 {
panic("reflect.Value.Addr of unaddressable value")
}
- return valueFromIword(iv.flag&flagRO, PtrTo(iv.typ.toType()), iword(iv.addr))
+ return Value{v.typ.ptrTo(), v.val, (v.flag & flagRO) | flag(Ptr)<<flagKindShift}
}
// Bool returns v's underlying value.
// It panics if v's kind is not Bool.
func (v Value) Bool() bool {
- iv := v.internal()
- iv.mustBe(Bool)
- return *(*bool)(unsafe.Pointer(&iv.word))
+ v.mustBe(Bool)
+ if v.flag&flagIndir != 0 {
+ return *(*bool)(v.val)
+ }
+ return *(*bool)(unsafe.Pointer(&v.val))
}
// Bytes returns v's underlying value.
// It panics if v's underlying value is not a slice of bytes.
func (v Value) Bytes() []byte {
- iv := v.internal()
- iv.mustBe(Slice)
- typ := iv.typ.toType()
- if typ.Elem().Kind() != Uint8 {
+ v.mustBe(Slice)
+ if v.typ.Elem().Kind() != Uint8 {
panic("reflect.Value.Bytes of non-byte slice")
}
- return *(*[]byte)(iv.addr)
+ // Slice is always bigger than a word; assume flagIndir.
+ return *(*[]byte)(v.val)
}
// CanAddr returns true if the value's address can be obtained with Addr.
// a field of an addressable struct, or the result of dereferencing a pointer.
// If CanAddr returns false, calling Addr will panic.
func (v Value) CanAddr() bool {
- iv := v.internal()
- return iv.flag&flagAddr != 0
+ return v.flag&flagAddr != 0
}
// CanSet returns true if the value of v can be changed.
// If CanSet returns false, calling Set or any type-specific
// setter (e.g., SetBool, SetInt64) will panic.
func (v Value) CanSet() bool {
- iv := v.internal()
- return iv.flag&(flagAddr|flagRO) == flagAddr
+ return v.flag&(flagAddr|flagRO) == flagAddr
}
// Call calls the function v with the input arguments in.
// If v is a variadic function, Call creates the variadic slice parameter
// itself, copying in the corresponding values.
func (v Value) Call(in []Value) []Value {
- iv := v.internal()
- iv.mustBe(Func)
- iv.mustBeExported()
- return iv.call("Call", in)
+ v.mustBe(Func)
+ v.mustBeExported()
+ return v.call("Call", in)
}
// CallSlice calls the variadic function v with the input arguments in,
// As in Go, each input argument must be assignable to the
// type of the function's corresponding input parameter.
func (v Value) CallSlice(in []Value) []Value {
- iv := v.internal()
- iv.mustBe(Func)
- iv.mustBeExported()
- return iv.call("CallSlice", in)
-}
-
-func (iv internalValue) call(method string, in []Value) []Value {
- if iv.word == 0 {
- if iv.nilmethod {
- panic("reflect.Value.Call: call of method on nil interface value")
+ v.mustBe(Func)
+ v.mustBeExported()
+ return v.call("CallSlice", in)
+}
+
+func (v Value) call(method string, in []Value) []Value {
+ // Get function pointer, type.
+ t := v.typ
+ var (
+ fn unsafe.Pointer
+ rcvr iword
+ )
+ if v.flag&flagMethod != 0 {
+ i := int(v.flag) >> flagMethodShift
+ if v.typ.Kind() == Interface {
+ tt := (*interfaceType)(unsafe.Pointer(v.typ))
+ if i < 0 || i >= len(tt.methods) {
+ panic("reflect: broken Value")
+ }
+ m := &tt.methods[i]
+ if m.pkgPath != nil {
+ panic(method + " of unexported method")
+ }
+ t = toCommonType(m.typ)
+ iface := (*nonEmptyInterface)(v.val)
+ if iface.itab == nil {
+ panic(method + " of method on nil interface value")
+ }
+ fn = iface.itab.fun[i]
+ rcvr = iface.word
+ } else {
+ ut := v.typ.uncommon()
+ if ut == nil || i < 0 || i >= len(ut.methods) {
+ panic("reflect: broken Value")
+ }
+ m := &ut.methods[i]
+ if m.pkgPath != nil {
+ panic(method + " of unexported method")
+ }
+ fn = m.ifn
+ t = toCommonType(m.mtyp)
+ rcvr = v.iword()
}
+ } else if v.flag&flagIndir != 0 {
+ fn = *(*unsafe.Pointer)(v.val)
+ } else {
+ fn = v.val
+ }
+
+ if fn == nil {
panic("reflect.Value.Call: call of nil function")
}
isSlice := method == "CallSlice"
- t := iv.typ
n := t.NumIn()
if isSlice {
if !t.IsVariadic() {
// and probably wrong for gccgo, but so
// is most of this function.
size := uintptr(0)
- if iv.method {
- // extra word for interface value
+ if v.flag&flagMethod != 0 {
+ // extra word for receiver interface word
size += ptrSize
}
for i := 0; i < nin; i++ {
args := make([]*int, size/ptrSize)
ptr := uintptr(unsafe.Pointer(&args[0]))
off := uintptr(0)
- if iv.method {
+ if v.flag&flagMethod != 0 {
// Hard-wired first argument.
- *(*iword)(unsafe.Pointer(ptr)) = iv.rcvr
+ *(*iword)(unsafe.Pointer(ptr)) = rcvr
off = ptrSize
}
for i, v := range in {
- iv := v.internal()
- iv.mustBeExported()
+ v.mustBeExported()
targ := t.In(i).(*commonType)
a := uintptr(targ.align)
off = (off + a - 1) &^ (a - 1)
n := targ.size
addr := unsafe.Pointer(ptr + off)
- iv = convertForAssignment("reflect.Value.Call", addr, targ, iv)
- if iv.addr == nil {
- storeIword(addr, iv.word, n)
+ v = v.assignTo("reflect.Value.Call", targ, (*interface{})(addr))
+ if v.flag&flagIndir == 0 {
+ storeIword(addr, iword(v.val), n)
} else {
- memmove(addr, iv.addr, n)
+ memmove(addr, v.val, n)
}
off += n
}
off = (off + ptrSize - 1) &^ (ptrSize - 1)
// Call.
- call(unsafe.Pointer(iv.word), unsafe.Pointer(ptr), uint32(size))
+ call(fn, unsafe.Pointer(ptr), uint32(size))
// Copy return values out of args.
//
tv := t.Out(i)
a := uintptr(tv.Align())
off = (off + a - 1) &^ (a - 1)
- ret[i] = valueFromAddr(0, tv, unsafe.Pointer(ptr+off))
+ fl := flagIndir | flag(tv.Kind())<<flagKindShift
+ ret[i] = Value{tv.common(), unsafe.Pointer(ptr + off), fl}
off += tv.Size()
}
// Cap returns v's capacity.
// It panics if v's Kind is not Array, Chan, or Slice.
func (v Value) Cap() int {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Array:
- return iv.typ.Len()
+ return v.typ.Len()
case Chan:
- return int(chancap(iv.word))
+ return int(chancap(v.iword()))
case Slice:
- return (*SliceHeader)(iv.addr).Cap
+ // Slice is always bigger than a word; assume flagIndir.
+ return (*SliceHeader)(v.val).Cap
}
- panic(&ValueError{"reflect.Value.Cap", iv.kind})
+ panic(&ValueError{"reflect.Value.Cap", k})
}
// Close closes the channel v.
// It panics if v's Kind is not Chan.
func (v Value) Close() {
- iv := v.internal()
- iv.mustBe(Chan)
- iv.mustBeExported()
- ch := iv.word
- chanclose(ch)
+ v.mustBe(Chan)
+ v.mustBeExported()
+ chanclose(v.iword())
}
// 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 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Complex64:
- if iv.addr == nil {
- return complex128(*(*complex64)(unsafe.Pointer(&iv.word)))
+ if v.flag&flagIndir != 0 {
+ return complex128(*(*complex64)(v.val))
}
- return complex128(*(*complex64)(iv.addr))
+ return complex128(*(*complex64)(unsafe.Pointer(&v.val)))
case Complex128:
- return *(*complex128)(iv.addr)
+ // complex128 is always bigger than a word; assume flagIndir.
+ return *(*complex128)(v.val)
}
- panic(&ValueError{"reflect.Value.Complex", iv.kind})
+ panic(&ValueError{"reflect.Value.Complex", k})
}
// Elem returns the value that the interface v contains
// 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 {
- iv := v.internal()
- return iv.Elem()
-}
-
-func (iv internalValue) Elem() Value {
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Interface:
- // Empty interface and non-empty interface have different layouts.
- // Convert to empty interface.
- var eface emptyInterface
- if iv.typ.NumMethod() == 0 {
- eface = *(*emptyInterface)(iv.addr)
+ var (
+ typ *commonType
+ val unsafe.Pointer
+ )
+ if v.typ.NumMethod() == 0 {
+ eface := (*emptyInterface)(v.val)
+ if eface.typ == nil {
+ // nil interface value
+ return Value{}
+ }
+ typ = toCommonType(eface.typ)
+ val = unsafe.Pointer(eface.word)
} else {
- iface := (*nonEmptyInterface)(iv.addr)
- if iface.itab != nil {
- eface.typ = iface.itab.typ
+ iface := (*nonEmptyInterface)(v.val)
+ if iface.itab == nil {
+ // nil interface value
+ return Value{}
}
- eface.word = iface.word
+ typ = toCommonType(iface.itab.typ)
+ val = unsafe.Pointer(iface.word)
}
- if eface.typ == nil {
- return Value{}
+ fl := v.flag & flagRO
+ fl |= flag(typ.Kind()) << flagKindShift
+ if typ.size > ptrSize {
+ fl |= flagIndir
}
- return valueFromIword(iv.flag&flagRO, toType(eface.typ), eface.word)
+ return Value{typ, val, fl}
case Ptr:
+ val := v.val
+ if v.flag&flagIndir != 0 {
+ val = *(*unsafe.Pointer)(val)
+ }
// The returned value's address is v's value.
- if iv.word == 0 {
+ if val == nil {
return Value{}
}
- return valueFromAddr(iv.flag&flagRO|flagAddr, iv.typ.Elem(), unsafe.Pointer(iv.word))
+ tt := (*ptrType)(unsafe.Pointer(v.typ))
+ typ := toCommonType(tt.elem)
+ fl := v.flag&flagRO | flagIndir | flagAddr
+ fl |= flag(typ.Kind() << flagKindShift)
+ return Value{typ, val, fl}
}
- panic(&ValueError{"reflect.Value.Elem", iv.kind})
+ panic(&ValueError{"reflect.Value.Elem", k})
}
// Field returns the i'th field of the struct v.
// It panics if v's Kind is not Struct or i is out of range.
func (v Value) Field(i int) Value {
- iv := v.internal()
- iv.mustBe(Struct)
- t := iv.typ.toType()
- if i < 0 || i >= t.NumField() {
+ v.mustBe(Struct)
+ tt := (*structType)(unsafe.Pointer(v.typ))
+ if i < 0 || i >= len(tt.fields) {
panic("reflect: Field index out of range")
}
- f := t.Field(i)
+ field := &tt.fields[i]
+ typ := toCommonType(field.typ)
// Inherit permission bits from v.
- flag := iv.flag
+ fl := v.flag & (flagRO | flagIndir | flagAddr)
// Using an unexported field forces flagRO.
- if f.PkgPath != "" {
- flag |= flagRO
+ if field.pkgPath != nil {
+ fl |= flagRO
}
- return valueFromValueOffset(flag, f.Type, iv, f.Offset)
-}
+ fl |= flag(typ.Kind()) << flagKindShift
-// valueFromValueOffset returns a sub-value of outer
-// (outer is an array or a struct) with the given flag and type
-// starting at the given byte offset into outer.
-func valueFromValueOffset(flag uint32, typ Type, outer internalValue, offset uintptr) Value {
- if outer.addr != nil {
- return valueFromAddr(flag, typ, unsafe.Pointer(uintptr(outer.addr)+offset))
+ var val unsafe.Pointer
+ switch {
+ case fl&flagIndir != 0:
+ // Indirect. Just bump pointer.
+ val = unsafe.Pointer(uintptr(v.val) + field.offset)
+ case bigEndian:
+ // Direct. Discard leading bytes.
+ val = unsafe.Pointer(uintptr(v.val) << (field.offset * 8))
+ default:
+ // Direct. Discard leading bytes.
+ val = unsafe.Pointer(uintptr(v.val) >> (field.offset * 8))
}
- // outer is so tiny it is in line.
- // We have to use outer.word and derive
- // the new word (it cannot possibly be bigger).
- // In line, so not addressable.
- if flag&flagAddr != 0 {
- panic("reflect: internal error: misuse of valueFromValueOffset")
- }
- b := *(*[ptrSize]byte)(unsafe.Pointer(&outer.word))
- for i := uintptr(0); i < typ.Size(); i++ {
- b[i] = b[offset+i]
- }
- for i := typ.Size(); i < ptrSize; i++ {
- b[i] = 0
- }
- w := *(*iword)(unsafe.Pointer(&b))
- return valueFromIword(flag, typ, w)
+ return Value{typ, val, fl}
}
// FieldByIndex returns the nested field corresponding to index.
// It panics if v's Kind is not struct.
func (v Value) FieldByIndex(index []int) Value {
- v.internal().mustBe(Struct)
+ v.mustBe(Struct)
for i, x := range index {
if i > 0 {
if v.Kind() == Ptr && v.Elem().Kind() == Struct {
// 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 {
- iv := v.internal()
- iv.mustBe(Struct)
- if f, ok := iv.typ.FieldByName(name); ok {
+ v.mustBe(Struct)
+ if f, ok := v.typ.FieldByName(name); ok {
return v.FieldByIndex(f.Index)
}
return Value{}
// 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 {
- v.internal().mustBe(Struct)
- if f, ok := v.Type().FieldByNameFunc(match); ok {
+ v.mustBe(Struct)
+ if f, ok := v.typ.FieldByNameFunc(match); ok {
return v.FieldByIndex(f.Index)
}
return Value{}
// 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 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Float32:
- return float64(*(*float32)(unsafe.Pointer(&iv.word)))
+ if v.flag&flagIndir != 0 {
+ return float64(*(*float32)(v.val))
+ }
+ return float64(*(*float32)(unsafe.Pointer(&v.val)))
case Float64:
- // If the pointer width can fit an entire float64,
- // the value is in line when stored in an interface.
- if iv.addr == nil {
- return *(*float64)(unsafe.Pointer(&iv.word))
+ if v.flag&flagIndir != 0 {
+ return *(*float64)(v.val)
}
- // Otherwise we have a pointer.
- return *(*float64)(iv.addr)
+ return *(*float64)(unsafe.Pointer(&v.val))
}
- panic(&ValueError{"reflect.Value.Float", iv.kind})
+ panic(&ValueError{"reflect.Value.Float", k})
}
// Index returns v's i'th element.
// It panics if v's Kind is not Array or Slice or i is out of range.
func (v Value) Index(i int) Value {
- iv := v.internal()
- switch iv.kind {
- default:
- panic(&ValueError{"reflect.Value.Index", iv.kind})
+ k := v.kind()
+ switch k {
case Array:
- flag := iv.flag // element flag same as overall array
- t := iv.typ.toType()
- if i < 0 || i > t.Len() {
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ if i < 0 || i > int(tt.len) {
panic("reflect: array index out of range")
}
- typ := t.Elem()
- return valueFromValueOffset(flag, typ, iv, uintptr(i)*typ.Size())
+ typ := toCommonType(tt.elem)
+ fl := v.flag & (flagRO | flagIndir | flagAddr) // bits same as overall array
+ fl |= flag(typ.Kind()) << flagKindShift
+ offset := uintptr(i) * typ.size
+
+ var val unsafe.Pointer
+ switch {
+ case fl&flagIndir != 0:
+ // Indirect. Just bump pointer.
+ val = unsafe.Pointer(uintptr(v.val) + offset)
+ case bigEndian:
+ // Direct. Discard leading bytes.
+ val = unsafe.Pointer(uintptr(v.val) << (offset * 8))
+ default:
+ // Direct. Discard leading bytes.
+ val = unsafe.Pointer(uintptr(v.val) >> (offset * 8))
+ }
+ return Value{typ, val, fl}
case Slice:
// Element flag same as Elem of Ptr.
- // Addressable, possibly read-only.
- flag := iv.flag&flagRO | flagAddr
- s := (*SliceHeader)(iv.addr)
+ // Addressable, indirect, possibly read-only.
+ fl := flagAddr | flagIndir | v.flag&flagRO
+ s := (*SliceHeader)(v.val)
if i < 0 || i >= s.Len {
panic("reflect: slice index out of range")
}
- typ := iv.typ.Elem()
- addr := unsafe.Pointer(s.Data + uintptr(i)*typ.Size())
- return valueFromAddr(flag, typ, addr)
+ tt := (*sliceType)(unsafe.Pointer(v.typ))
+ typ := toCommonType(tt.elem)
+ fl |= flag(typ.Kind()) << flagKindShift
+ val := unsafe.Pointer(s.Data + uintptr(i)*typ.size)
+ return Value{typ, val, fl}
}
-
- panic("not reached")
+ panic(&ValueError{"reflect.Value.Index", k})
}
// Int returns v's underlying value, as an int64.
// It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64.
func (v Value) Int() int64 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ var p unsafe.Pointer
+ if v.flag&flagIndir != 0 {
+ p = v.val
+ } else {
+ // The escape analysis is good enough that &v.val
+ // does not trigger a heap allocation.
+ p = unsafe.Pointer(&v.val)
+ }
+ switch k {
case Int:
- return int64(*(*int)(unsafe.Pointer(&iv.word)))
+ return int64(*(*int)(p))
case Int8:
- return int64(*(*int8)(unsafe.Pointer(&iv.word)))
+ return int64(*(*int8)(p))
case Int16:
- return int64(*(*int16)(unsafe.Pointer(&iv.word)))
+ return int64(*(*int16)(p))
case Int32:
- return int64(*(*int32)(unsafe.Pointer(&iv.word)))
+ return int64(*(*int32)(p))
case Int64:
- if iv.addr == nil {
- return *(*int64)(unsafe.Pointer(&iv.word))
- }
- return *(*int64)(iv.addr)
+ return int64(*(*int64)(p))
}
- panic(&ValueError{"reflect.Value.Int", iv.kind})
+ panic(&ValueError{"reflect.Value.Int", k})
}
// CanInterface returns true if Interface can be used without panicking.
func (v Value) CanInterface() bool {
- iv := v.internal()
- if iv.kind == Invalid {
- panic(&ValueError{"reflect.Value.CanInterface", iv.kind})
+ if v.flag == 0 {
+ panic(&ValueError{"reflect.Value.CanInterface", Invalid})
}
- return v.InternalMethod == 0 && iv.flag&flagRO == 0
+ return v.flag&(flagMethod|flagRO) == 0
}
// Interface returns v's value as an interface{}.
}
func valueInterface(v Value, safe bool) interface{} {
- iv := v.internal()
- return iv.valueInterface(safe)
-}
-
-func (iv internalValue) valueInterface(safe bool) interface{} {
- if iv.kind == 0 {
- panic(&ValueError{"reflect.Value.Interface", iv.kind})
+ if v.flag == 0 {
+ panic(&ValueError{"reflect.Value.Interface", 0})
}
- if iv.method {
+ if v.flag&flagMethod != 0 {
panic("reflect.Value.Interface: cannot create interface value for method with bound receiver")
}
- if safe && iv.flag&flagRO != 0 {
+ if safe && v.flag&flagRO != 0 {
// Do not allow access to unexported values via Interface,
// because they might be pointers that should not be
// writable or methods or function that should not be callable.
panic("reflect.Value.Interface: cannot return value obtained from unexported field or method")
}
- if iv.kind == Interface {
+
+ k := v.kind()
+ if k == Interface {
// Special case: return the element inside the interface.
- // Won't recurse further because an interface cannot contain an interface.
- if iv.IsNil() {
- return nil
+ // Empty interface has one layout, all interfaces with
+ // methods have a second layout.
+ if v.NumMethod() == 0 {
+ return *(*interface{})(v.val)
}
- return iv.Elem().Interface()
+ return *(*interface {
+ M()
+ })(v.val)
}
// Non-interface value.
var eface emptyInterface
- eface.typ = iv.typ.runtimeType()
- eface.word = iv.word
+ eface.typ = v.typ.runtimeType()
+ eface.word = v.iword()
return *(*interface{})(unsafe.Pointer(&eface))
}
// 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 {
- iv := v.internal()
- iv.mustBe(Interface)
+ v.mustBe(Interface)
// We treat this as a read operation, so we allow
// it even for unexported data, because the caller
// has to import "unsafe" to turn it into something
// that can be abused.
- return *(*[2]uintptr)(iv.addr)
+ // Interface value is always bigger than a word; assume flagIndir.
+ return *(*[2]uintptr)(v.val)
}
// 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.internal().IsNil()
-}
-
-func (iv internalValue) IsNil() bool {
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Chan, Func, Map, Ptr:
- if iv.method {
+ if v.flag&flagMethod != 0 {
panic("reflect: IsNil of method Value")
}
- return iv.word == 0
+ ptr := v.val
+ if v.flag&flagIndir != 0 {
+ ptr = *(*unsafe.Pointer)(ptr)
+ }
+ return ptr == nil
case Interface, Slice:
// Both interface and slice are nil if first word is 0.
- return *(*uintptr)(iv.addr) == 0
+ // Both are always bigger than a word; assume flagIndir.
+ return *(*unsafe.Pointer)(v.val) == nil
}
- panic(&ValueError{"reflect.Value.IsNil", iv.kind})
+ panic(&ValueError{"reflect.Value.IsNil", k})
}
// IsValid returns true if v represents a value.
// 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
+ return v.flag != 0
}
// Kind returns v's Kind.
// If v is the zero Value (IsValid returns false), Kind returns Invalid.
func (v Value) Kind() Kind {
- return v.internal().kind
+ return v.kind()
}
// Len returns v's length.
// It panics if v's Kind is not Array, Chan, Map, Slice, or String.
func (v Value) Len() int {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Array:
- return iv.typ.Len()
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ return int(tt.len)
case Chan:
- return int(chanlen(iv.word))
+ return int(chanlen(v.iword()))
case Map:
- return int(maplen(iv.word))
+ return int(maplen(v.iword()))
case Slice:
- return (*SliceHeader)(iv.addr).Len
+ // Slice is bigger than a word; assume flagIndir.
+ return (*SliceHeader)(v.val).Len
case String:
- return (*StringHeader)(iv.addr).Len
+ // String is bigger than a word; assume flagIndir.
+ return (*StringHeader)(v.val).Len
}
- panic(&ValueError{"reflect.Value.Len", iv.kind})
+ panic(&ValueError{"reflect.Value.Len", k})
}
// MapIndex returns the value associated with key in the map v.
// It returns the zero Value if key is not found in the map or if v represents a nil map.
// As in Go, the key's value must be assignable to the map's key type.
func (v Value) MapIndex(key Value) Value {
- iv := v.internal()
- iv.mustBe(Map)
- typ := iv.typ.toType()
+ v.mustBe(Map)
+ tt := (*mapType)(unsafe.Pointer(v.typ))
- // Do not require ikey to be exported, so that DeepEqual
+ // Do not require key to be exported, so that DeepEqual
// and other programs can use all the keys returned by
// MapKeys as arguments to MapIndex. If either the map
// or the key is unexported, though, the result will be
- // considered unexported.
-
- ikey := key.internal()
- ikey = convertForAssignment("reflect.Value.MapIndex", nil, typ.Key(), ikey)
- if iv.word == 0 {
- return Value{}
- }
+ // considered unexported. This is consistent with the
+ // behavior for structs, which allow read but not write
+ // of unexported fields.
+ key = key.assignTo("reflect.Value.MapIndex", toCommonType(tt.key), nil)
- flag := (iv.flag | ikey.flag) & flagRO
- elemType := typ.Elem()
- elemWord, ok := mapaccess(typ.runtimeType(), iv.word, ikey.word)
+ word, ok := mapaccess(v.typ.runtimeType(), v.iword(), key.iword())
if !ok {
return Value{}
}
- return valueFromIword(flag, elemType, elemWord)
+ typ := toCommonType(tt.elem)
+ fl := (v.flag | key.flag) & flagRO
+ if typ.size > ptrSize {
+ fl |= flagIndir
+ }
+ fl |= flag(typ.Kind()) << flagKindShift
+ return Value{typ, unsafe.Pointer(word), fl}
}
// MapKeys returns a slice containing all the keys present in the map,
// It panics if v's Kind is not Map.
// It returns an empty slice if v represents a nil map.
func (v Value) MapKeys() []Value {
- iv := v.internal()
- iv.mustBe(Map)
- keyType := iv.typ.Key()
+ v.mustBe(Map)
+ tt := (*mapType)(unsafe.Pointer(v.typ))
+ keyType := toCommonType(tt.key)
- flag := iv.flag & flagRO
- m := iv.word
+ fl := v.flag & flagRO
+ fl |= flag(keyType.Kind()) << flagKindShift
+ if keyType.size > ptrSize {
+ fl |= flagIndir
+ }
+
+ m := v.iword()
mlen := int32(0)
- if m != 0 {
+ if m != nil {
mlen = maplen(m)
}
- it := mapiterinit(iv.typ.runtimeType(), m)
+ it := mapiterinit(v.typ.runtimeType(), m)
a := make([]Value, mlen)
var i int
for i = 0; i < len(a); i++ {
if !ok {
break
}
- a[i] = valueFromIword(flag, keyType, keyWord)
+ a[i] = Value{keyType, unsafe.Pointer(keyWord), fl}
mapiternext(it)
}
return a[:i]
// a receiver; the returned function will always use v as the receiver.
// Method panics if i is out of range.
func (v Value) Method(i int) Value {
- iv := v.internal()
- if iv.kind == Invalid {
+ if v.typ == nil {
panic(&ValueError{"reflect.Value.Method", Invalid})
}
- if i < 0 || i >= iv.typ.NumMethod() {
+ if v.flag&flagMethod != 0 || i < 0 || i >= v.typ.NumMethod() {
panic("reflect: Method index out of range")
}
- return Value{v.Internal, i + 1}
+ fl := v.flag & (flagRO | flagAddr | flagIndir)
+ fl |= flag(Func) << flagKindShift
+ fl |= flag(i)<<flagMethodShift | flagMethod
+ return Value{v.typ, v.val, fl}
}
// NumMethod returns the number of methods in the value's method set.
func (v Value) NumMethod() int {
- iv := v.internal()
- if iv.kind == Invalid {
+ if v.typ == nil {
panic(&ValueError{"reflect.Value.NumMethod", Invalid})
}
- return iv.typ.NumMethod()
+ if v.flag&flagMethod != 0 {
+ return 0
+ }
+ return v.typ.NumMethod()
}
// MethodByName returns a function value corresponding to the method
// a receiver; the returned function will always use v as the receiver.
// It returns the zero Value if no method was found.
func (v Value) MethodByName(name string) Value {
- iv := v.internal()
- if iv.kind == Invalid {
+ if v.typ == nil {
panic(&ValueError{"reflect.Value.MethodByName", Invalid})
}
- m, ok := iv.typ.MethodByName(name)
- if ok {
- return Value{v.Internal, m.Index + 1}
+ if v.flag&flagMethod != 0 {
+ return Value{}
}
- return Value{}
+ m, ok := v.typ.MethodByName(name)
+ if !ok {
+ return Value{}
+ }
+ return v.Method(m.Index)
}
// NumField returns the number of fields in the struct v.
// It panics if v's Kind is not Struct.
func (v Value) NumField() int {
- iv := v.internal()
- iv.mustBe(Struct)
- return iv.typ.NumField()
+ v.mustBe(Struct)
+ tt := (*structType)(unsafe.Pointer(v.typ))
+ return len(tt.fields)
}
// 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 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Complex64:
return overflowFloat32(real(x)) || overflowFloat32(imag(x))
case Complex128:
return false
}
- panic(&ValueError{"reflect.Value.OverflowComplex", iv.kind})
+ panic(&ValueError{"reflect.Value.OverflowComplex", k})
}
// 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 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Float32:
return overflowFloat32(x)
case Float64:
return false
}
- panic(&ValueError{"reflect.Value.OverflowFloat", iv.kind})
+ panic(&ValueError{"reflect.Value.OverflowFloat", k})
}
func overflowFloat32(x float64) bool {
// OverflowInt returns true if the int64 x cannot be represented by v's type.
// It panics if v's Kind is not Int, Int8, int16, Int32, or Int64.
func (v Value) OverflowInt(x int64) bool {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Int, Int8, Int16, Int32, Int64:
- bitSize := iv.typ.size * 8
+ bitSize := v.typ.size * 8
trunc := (x << (64 - bitSize)) >> (64 - bitSize)
return x != trunc
}
- panic(&ValueError{"reflect.Value.OverflowInt", iv.kind})
+ panic(&ValueError{"reflect.Value.OverflowInt", k})
}
// OverflowUint returns true if the uint64 x cannot be represented by v's type.
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64.
func (v Value) OverflowUint(x uint64) bool {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Uint, Uintptr, Uint8, Uint16, Uint32, Uint64:
- bitSize := iv.typ.size * 8
+ bitSize := v.typ.size * 8
trunc := (x << (64 - bitSize)) >> (64 - bitSize)
return x != trunc
}
- panic(&ValueError{"reflect.Value.OverflowUint", iv.kind})
+ panic(&ValueError{"reflect.Value.OverflowUint", k})
}
// Pointer returns v's value as a uintptr.
// 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 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ switch k {
case Chan, Func, Map, Ptr, UnsafePointer:
- if iv.kind == Func && v.InternalMethod != 0 {
+ if k == Func && v.flag&flagMethod != 0 {
panic("reflect.Value.Pointer of method Value")
}
- return uintptr(iv.word)
+ p := v.val
+ if v.flag&flagIndir != 0 {
+ p = *(*unsafe.Pointer)(p)
+ }
+ return uintptr(p)
case Slice:
- return (*SliceHeader)(iv.addr).Data
+ return (*SliceHeader)(v.val).Data
}
- panic(&ValueError{"reflect.Value.Pointer", iv.kind})
+ panic(&ValueError{"reflect.Value.Pointer", k})
}
// Recv receives and returns a value from the channel v.
// 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) {
- iv := v.internal()
- iv.mustBe(Chan)
- iv.mustBeExported()
- return iv.recv(false)
+ v.mustBe(Chan)
+ v.mustBeExported()
+ return v.recv(false)
}
-// internal recv, possibly non-blocking (nb)
-func (iv internalValue) recv(nb bool) (val Value, ok bool) {
- t := iv.typ.toType()
- if t.ChanDir()&RecvDir == 0 {
+// internal recv, possibly non-blocking (nb).
+// v is known to be a channel.
+func (v Value) recv(nb bool) (val Value, ok bool) {
+ tt := (*chanType)(unsafe.Pointer(v.typ))
+ if ChanDir(tt.dir)&RecvDir == 0 {
panic("recv on send-only channel")
}
- ch := iv.word
- if ch == 0 {
- panic("recv on nil channel")
- }
- valWord, selected, ok := chanrecv(iv.typ.runtimeType(), ch, nb)
+ word, selected, ok := chanrecv(v.typ.runtimeType(), v.iword(), nb)
if selected {
- val = valueFromIword(0, t.Elem(), valWord)
+ typ := toCommonType(tt.elem)
+ fl := flag(typ.Kind()) << flagKindShift
+ if typ.size > ptrSize {
+ fl |= flagIndir
+ }
+ val = Value{typ, unsafe.Pointer(word), fl}
}
return
}
// It panics if v's kind is not Chan or if x's type is not the same type as v's element type.
// As in Go, x's value must be assignable to the channel's element type.
func (v Value) Send(x Value) {
- iv := v.internal()
- iv.mustBe(Chan)
- iv.mustBeExported()
- iv.send(x, false)
+ v.mustBe(Chan)
+ v.mustBeExported()
+ v.send(x, false)
}
-// internal send, possibly non-blocking
-func (iv internalValue) send(x Value, nb bool) (selected bool) {
- t := iv.typ.toType()
- if t.ChanDir()&SendDir == 0 {
+// internal send, possibly non-blocking.
+// v is known to be a channel.
+func (v Value) send(x Value, nb bool) (selected bool) {
+ tt := (*chanType)(unsafe.Pointer(v.typ))
+ if ChanDir(tt.dir)&SendDir == 0 {
panic("send on recv-only channel")
}
- ix := x.internal()
- ix.mustBeExported() // do not let unexported x leak
- ix = convertForAssignment("reflect.Value.Send", nil, t.Elem(), ix)
- ch := iv.word
- if ch == 0 {
- panic("send on nil channel")
- }
- return chansend(iv.typ.runtimeType(), ch, ix.word, nb)
+ x.mustBeExported()
+ x = x.assignTo("reflect.Value.Send", toCommonType(tt.elem), nil)
+ return chansend(v.typ.runtimeType(), v.iword(), x.iword(), nb)
}
// Set assigns x to the value v.
// It panics if CanSet returns false.
// As in Go, x's value must be assignable to v's type.
func (v Value) Set(x Value) {
- iv := v.internal()
- ix := x.internal()
-
- iv.mustBeAssignable()
- ix.mustBeExported() // do not let unexported x leak
-
- ix = convertForAssignment("reflect.Set", iv.addr, iv.typ, ix)
-
- n := ix.typ.size
- if n <= ptrSize {
- storeIword(iv.addr, ix.word, n)
+ v.mustBeAssignable()
+ x.mustBeExported() // do not let unexported x leak
+ var target *interface{}
+ if v.kind() == Interface {
+ target = (*interface{})(v.val)
+ }
+ x = x.assignTo("reflect.Set", v.typ, target)
+ if x.flag&flagIndir != 0 {
+ memmove(v.val, x.val, v.typ.size)
} else {
- memmove(iv.addr, ix.addr, n)
+ storeIword(v.val, iword(x.val), v.typ.size)
}
}
// 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) {
- iv := v.internal()
- iv.mustBeAssignable()
- iv.mustBe(Bool)
- *(*bool)(iv.addr) = x
+ v.mustBeAssignable()
+ v.mustBe(Bool)
+ *(*bool)(v.val) = x
}
// SetBytes sets v's underlying value.
// It panics if v's underlying value is not a slice of bytes.
func (v Value) SetBytes(x []byte) {
- iv := v.internal()
- iv.mustBeAssignable()
- iv.mustBe(Slice)
- typ := iv.typ.toType()
- if typ.Elem().Kind() != Uint8 {
+ v.mustBeAssignable()
+ v.mustBe(Slice)
+ if v.typ.Elem().Kind() != Uint8 {
panic("reflect.Value.SetBytes of non-byte slice")
}
- *(*[]byte)(iv.addr) = x
+ *(*[]byte)(v.val) = 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) {
- iv := v.internal()
- iv.mustBeAssignable()
- switch iv.kind {
+ v.mustBeAssignable()
+ switch k := v.kind(); k {
default:
- panic(&ValueError{"reflect.Value.SetComplex", iv.kind})
+ panic(&ValueError{"reflect.Value.SetComplex", k})
case Complex64:
- *(*complex64)(iv.addr) = complex64(x)
+ *(*complex64)(v.val) = complex64(x)
case Complex128:
- *(*complex128)(iv.addr) = x
+ *(*complex128)(v.val) = 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) {
- iv := v.internal()
- iv.mustBeAssignable()
- switch iv.kind {
+ v.mustBeAssignable()
+ switch k := v.kind(); k {
default:
- panic(&ValueError{"reflect.Value.SetFloat", iv.kind})
+ panic(&ValueError{"reflect.Value.SetFloat", k})
case Float32:
- *(*float32)(iv.addr) = float32(x)
+ *(*float32)(v.val) = float32(x)
case Float64:
- *(*float64)(iv.addr) = x
+ *(*float64)(v.val) = x
}
}
// SetInt sets v's underlying value to x.
// It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64, or if CanSet() is false.
func (v Value) SetInt(x int64) {
- iv := v.internal()
- iv.mustBeAssignable()
- switch iv.kind {
+ v.mustBeAssignable()
+ switch k := v.kind(); k {
default:
- panic(&ValueError{"reflect.Value.SetInt", iv.kind})
+ panic(&ValueError{"reflect.Value.SetInt", k})
case Int:
- *(*int)(iv.addr) = int(x)
+ *(*int)(v.val) = int(x)
case Int8:
- *(*int8)(iv.addr) = int8(x)
+ *(*int8)(v.val) = int8(x)
case Int16:
- *(*int16)(iv.addr) = int16(x)
+ *(*int16)(v.val) = int16(x)
case Int32:
- *(*int32)(iv.addr) = int32(x)
+ *(*int32)(v.val) = int32(x)
case Int64:
- *(*int64)(iv.addr) = x
+ *(*int64)(v.val) = x
}
}
// SetLen sets v's length to n.
// It panics if v's Kind is not Slice.
func (v Value) SetLen(n int) {
- iv := v.internal()
- iv.mustBeAssignable()
- iv.mustBe(Slice)
- s := (*SliceHeader)(iv.addr)
+ v.mustBeAssignable()
+ v.mustBe(Slice)
+ s := (*SliceHeader)(v.val)
if n < 0 || n > int(s.Cap) {
panic("reflect: slice length out of range in SetLen")
}
// As in Go, key's value must be assignable to the map's key type,
// and val's value must be assignable to the map's value type.
func (v Value) SetMapIndex(key, val Value) {
- iv := v.internal()
- ikey := key.internal()
- ival := val.internal()
-
- iv.mustBe(Map)
- iv.mustBeExported()
-
- ikey.mustBeExported()
- ikey = convertForAssignment("reflect.Value.SetMapIndex", nil, iv.typ.Key(), ikey)
-
- if ival.kind != Invalid {
- ival.mustBeExported()
- ival = convertForAssignment("reflect.Value.SetMapIndex", nil, iv.typ.Elem(), ival)
+ v.mustBe(Map)
+ v.mustBeExported()
+ key.mustBeExported()
+ tt := (*mapType)(unsafe.Pointer(v.typ))
+ key = key.assignTo("reflect.Value.SetMapIndex", toCommonType(tt.key), nil)
+ if val.typ != nil {
+ val.mustBeExported()
+ val = val.assignTo("reflect.Value.SetMapIndex", toCommonType(tt.elem), nil)
}
-
- mapassign(iv.typ.runtimeType(), iv.word, ikey.word, ival.word, ival.kind != Invalid)
+ mapassign(v.typ.runtimeType(), v.iword(), key.iword(), val.iword(), val.typ != nil)
}
// SetUint sets v's underlying value to x.
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64, or if CanSet() is false.
func (v Value) SetUint(x uint64) {
- iv := v.internal()
- iv.mustBeAssignable()
- switch iv.kind {
+ v.mustBeAssignable()
+ switch k := v.kind(); k {
default:
- panic(&ValueError{"reflect.Value.SetUint", iv.kind})
+ panic(&ValueError{"reflect.Value.SetUint", k})
case Uint:
- *(*uint)(iv.addr) = uint(x)
+ *(*uint)(v.val) = uint(x)
case Uint8:
- *(*uint8)(iv.addr) = uint8(x)
+ *(*uint8)(v.val) = uint8(x)
case Uint16:
- *(*uint16)(iv.addr) = uint16(x)
+ *(*uint16)(v.val) = uint16(x)
case Uint32:
- *(*uint32)(iv.addr) = uint32(x)
+ *(*uint32)(v.val) = uint32(x)
case Uint64:
- *(*uint64)(iv.addr) = x
+ *(*uint64)(v.val) = x
case Uintptr:
- *(*uintptr)(iv.addr) = uintptr(x)
+ *(*uintptr)(v.val) = uintptr(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) {
- iv := v.internal()
- iv.mustBeAssignable()
- iv.mustBe(UnsafePointer)
- *(*unsafe.Pointer)(iv.addr) = x
+ v.mustBeAssignable()
+ v.mustBe(UnsafePointer)
+ *(*unsafe.Pointer)(v.val) = 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) {
- iv := v.internal()
- iv.mustBeAssignable()
- iv.mustBe(String)
- *(*string)(iv.addr) = x
+ v.mustBeAssignable()
+ v.mustBe(String)
+ *(*string)(v.val) = x
}
// Slice returns a slice of v.
// It panics if v's Kind is not Array or Slice.
func (v Value) Slice(beg, end int) Value {
- iv := v.internal()
- if iv.kind != Array && iv.kind != Slice {
- panic(&ValueError{"reflect.Value.Slice", iv.kind})
- }
- cap := v.Cap()
- if beg < 0 || end < beg || end > cap {
- panic("reflect.Value.Slice: slice index out of bounds")
- }
- var typ Type
- var base uintptr
- switch iv.kind {
+ var (
+ cap int
+ typ *sliceType
+ base unsafe.Pointer
+ )
+ switch k := v.kind(); k {
+ default:
+ panic(&ValueError{"reflect.Value.Slice", k})
case Array:
- if iv.flag&flagAddr == 0 {
+ if v.flag&flagAddr == 0 {
panic("reflect.Value.Slice: slice of unaddressable array")
}
- typ = toType((*arrayType)(unsafe.Pointer(iv.typ)).slice)
- base = uintptr(iv.addr)
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ cap = int(tt.len)
+ typ = (*sliceType)(unsafe.Pointer(toCommonType(tt.slice)))
+ base = v.val
case Slice:
- typ = iv.typ.toType()
- base = (*SliceHeader)(iv.addr).Data
+ typ = (*sliceType)(unsafe.Pointer(v.typ))
+ s := (*SliceHeader)(v.val)
+ base = unsafe.Pointer(s.Data)
+ cap = s.Cap
+
+ }
+ if beg < 0 || end < beg || end > cap {
+ panic("reflect.Value.Slice: slice index out of bounds")
}
// Declare slice so that gc can see the base pointer in it.
// Reinterpret as *SliceHeader to edit.
s := (*SliceHeader)(unsafe.Pointer(&x))
- s.Data = base + uintptr(beg)*typ.Elem().Size()
+ s.Data = uintptr(base) + uintptr(beg)*toCommonType(typ.elem).Size()
s.Len = end - beg
s.Cap = end - beg
- return valueFromAddr(iv.flag&flagRO, typ, unsafe.Pointer(&x))
+ fl := v.flag&flagRO | flagIndir | flag(Slice)<<flagKindShift
+ return Value{typ.common(), unsafe.Pointer(&x), fl}
}
// String returns the string v's underlying value, as a string.
// 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 {
- iv := v.internal()
- switch iv.kind {
+ switch k := v.kind(); k {
case Invalid:
return "<invalid Value>"
case String:
- return *(*string)(iv.addr)
+ return *(*string)(v.val)
}
// If you call String on a reflect.Value of other type, it's better to
// print something than to panic. Useful in debugging.
- return "<" + iv.typ.String() + " Value>"
+ return "<" + v.typ.String() + " Value>"
}
// TryRecv attempts to receive a value from the channel v but will not block.
// 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) {
- iv := v.internal()
- iv.mustBe(Chan)
- iv.mustBeExported()
- return iv.recv(true)
+ v.mustBe(Chan)
+ v.mustBeExported()
+ return v.recv(true)
}
// TrySend attempts to send x on the channel v but will not block.
// It returns true if the value was sent, false otherwise.
// As in Go, x's value must be assignable to the channel's element type.
func (v Value) TrySend(x Value) bool {
- iv := v.internal()
- iv.mustBe(Chan)
- iv.mustBeExported()
- return iv.send(x, true)
+ v.mustBe(Chan)
+ v.mustBeExported()
+ return v.send(x, true)
}
// Type returns v's type.
func (v Value) Type() Type {
- t := v.internal().typ
- if t == nil {
+ f := v.flag
+ if f == 0 {
panic(&ValueError{"reflect.Value.Type", Invalid})
}
- return t.toType()
+ if f&flagMethod == 0 {
+ // Easy case
+ return v.typ
+ }
+
+ // Method value.
+ // v.typ describes the receiver, not the method type.
+ i := int(v.flag) >> flagMethodShift
+ if v.typ.Kind() == Interface {
+ // Method on interface.
+ tt := (*interfaceType)(unsafe.Pointer(v.typ))
+ if i < 0 || i >= len(tt.methods) {
+ panic("reflect: broken Value")
+ }
+ m := &tt.methods[i]
+ return toCommonType(m.typ)
+ }
+ // Method on concrete type.
+ ut := v.typ.uncommon()
+ if ut == nil || i < 0 || i >= len(ut.methods) {
+ panic("reflect: broken Value")
+ }
+ m := &ut.methods[i]
+ return toCommonType(m.mtyp)
}
// Uint returns v's underlying value, as a uint64.
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64.
func (v Value) Uint() uint64 {
- iv := v.internal()
- switch iv.kind {
+ k := v.kind()
+ var p unsafe.Pointer
+ if v.flag&flagIndir != 0 {
+ p = v.val
+ } else {
+ // The escape analysis is good enough that &v.val
+ // does not trigger a heap allocation.
+ p = unsafe.Pointer(&v.val)
+ }
+ switch k {
case Uint:
- return uint64(*(*uint)(unsafe.Pointer(&iv.word)))
+ return uint64(*(*uint)(p))
case Uint8:
- return uint64(*(*uint8)(unsafe.Pointer(&iv.word)))
+ return uint64(*(*uint8)(p))
case Uint16:
- return uint64(*(*uint16)(unsafe.Pointer(&iv.word)))
+ return uint64(*(*uint16)(p))
case Uint32:
- return uint64(*(*uint32)(unsafe.Pointer(&iv.word)))
- case Uintptr:
- return uint64(*(*uintptr)(unsafe.Pointer(&iv.word)))
+ return uint64(*(*uint32)(p))
case Uint64:
- if iv.addr == nil {
- return *(*uint64)(unsafe.Pointer(&iv.word))
- }
- return *(*uint64)(iv.addr)
+ return uint64(*(*uint64)(p))
+ case Uintptr:
+ return uint64(*(*uintptr)(p))
}
- panic(&ValueError{"reflect.Value.Uint", iv.kind})
+ panic(&ValueError{"reflect.Value.Uint", k})
}
// UnsafeAddr returns a pointer to v's data.
// It is for advanced clients that also import the "unsafe" package.
// It panics if v is not addressable.
func (v Value) UnsafeAddr() uintptr {
- iv := v.internal()
- if iv.kind == Invalid {
- panic(&ValueError{"reflect.Value.UnsafeAddr", iv.kind})
+ if v.typ == nil {
+ panic(&ValueError{"reflect.Value.UnsafeAddr", Invalid})
}
- if iv.flag&flagAddr == 0 {
+ if v.flag&flagAddr == 0 {
panic("reflect.Value.UnsafeAddr of unaddressable value")
}
- return uintptr(iv.addr)
+ return uintptr(v.val)
}
// StringHeader is the runtime representation of a string.
func typesMustMatch(what string, t1, t2 Type) {
if t1 != t2 {
- panic("reflect: " + what + ": " + t1.String() + " != " + t2.String())
+ panic(what + ": " + t1.String() + " != " + t2.String())
}
}
// Append appends the values x to a slice s and returns the resulting slice.
// As in Go, each x's value must be assignable to the slice's element type.
func Append(s Value, x ...Value) Value {
- s.internal().mustBe(Slice)
+ s.mustBe(Slice)
s, i0, i1 := grow(s, len(x))
for i, j := i0, 0; i < i1; i, j = i+1, j+1 {
s.Index(i).Set(x[j])
// 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.internal().mustBe(Slice)
- t.internal().mustBe(Slice)
+ s.mustBe(Slice)
+ t.mustBe(Slice)
typesMustMatch("reflect.AppendSlice", s.Type().Elem(), t.Type().Elem())
s, i0, i1 := grow(s, t.Len())
Copy(s.Slice(i0, i1), t)
// Dst and src each must have kind Slice or Array, and
// dst and src must have the same element type.
func Copy(dst, src Value) int {
- idst := dst.internal()
- isrc := src.internal()
-
- if idst.kind != Array && idst.kind != Slice {
- panic(&ValueError{"reflect.Copy", idst.kind})
+ dk := dst.kind()
+ if dk != Array && dk != Slice {
+ panic(&ValueError{"reflect.Copy", dk})
}
- if idst.kind == Array {
- idst.mustBeAssignable()
+ if dk == Array {
+ dst.mustBeAssignable()
}
- idst.mustBeExported()
- if isrc.kind != Array && isrc.kind != Slice {
- panic(&ValueError{"reflect.Copy", isrc.kind})
+ dst.mustBeExported()
+
+ sk := src.kind()
+ if sk != Array && sk != Slice {
+ panic(&ValueError{"reflect.Copy", sk})
}
- isrc.mustBeExported()
+ src.mustBeExported()
- de := idst.typ.Elem()
- se := isrc.typ.Elem()
+ de := dst.typ.Elem()
+ se := src.typ.Elem()
typesMustMatch("reflect.Copy", de, se)
n := dst.Len()
// If sk is an in-line array, cannot take its address.
// Instead, copy element by element.
- if isrc.addr == nil {
+ if src.flag&flagIndir == 0 {
for i := 0; i < n; i++ {
dst.Index(i).Set(src.Index(i))
}
// Copy via memmove.
var da, sa unsafe.Pointer
- if idst.kind == Array {
- da = idst.addr
+ if dk == Array {
+ da = dst.val
} else {
- da = unsafe.Pointer((*SliceHeader)(idst.addr).Data)
+ da = unsafe.Pointer((*SliceHeader)(dst.val).Data)
}
- if isrc.kind == Array {
- sa = isrc.addr
+ if sk == Array {
+ sa = src.val
} else {
- sa = unsafe.Pointer((*SliceHeader)(isrc.addr).Data)
+ sa = unsafe.Pointer((*SliceHeader)(src.val).Data)
}
memmove(da, sa, uintptr(n)*de.Size())
return n
// 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")
+ panic("reflect.MakeSlice of non-slice type")
}
// Declare slice so that gc can see the base pointer in it.
s.Len = len
s.Cap = cap
- return valueFromAddr(0, typ, unsafe.Pointer(&x))
+ return Value{typ.common(), unsafe.Pointer(&x), flagIndir | flag(Slice)<<flagKindShift}
}
// 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")
+ panic("reflect.MakeChan of non-chan type")
}
if buffer < 0 {
- panic("MakeChan: negative buffer size")
+ panic("reflect.MakeChan: negative buffer size")
}
if typ.ChanDir() != BothDir {
- panic("MakeChan: unidirectional channel type")
+ panic("reflect.MakeChan: unidirectional channel type")
}
ch := makechan(typ.runtimeType(), uint32(buffer))
- return valueFromIword(0, typ, ch)
+ return Value{typ.common(), unsafe.Pointer(ch), flag(Chan) << flagKindShift}
}
// 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")
+ panic("reflect.MakeMap of non-map type")
}
m := makemap(typ.runtimeType())
- return valueFromIword(0, typ, m)
+ return Value{typ.common(), unsafe.Pointer(m), flag(Map) << flagKindShift}
}
// Indirect returns the value that v points to.
// For an interface value with the noAddr bit set,
// the representation is identical to an empty interface.
eface := *(*emptyInterface)(unsafe.Pointer(&i))
- return packValue(0, eface.typ, eface.word)
+ typ := toCommonType(eface.typ)
+ fl := flag(typ.Kind()) << flagKindShift
+ if typ.size > ptrSize {
+ fl |= flagIndir
+ }
+ return Value{typ, unsafe.Pointer(eface.word), fl}
}
// Zero returns a Value representing a zero value for the specified type.
if typ == nil {
panic("reflect: Zero(nil)")
}
- if typ.Size() <= ptrSize {
- return valueFromIword(0, typ, 0)
+ t := typ.common()
+ fl := flag(t.Kind()) << flagKindShift
+ if t.size <= ptrSize {
+ return Value{t, nil, fl}
}
- return valueFromAddr(0, typ, unsafe.New(typ))
+ return Value{t, unsafe.New(typ), fl | flagIndir}
}
// New returns a Value representing a pointer to a new zero value
panic("reflect: New(nil)")
}
ptr := unsafe.New(typ)
- return valueFromIword(0, PtrTo(typ), iword(ptr))
+ fl := flag(Ptr) << flagKindShift
+ return Value{typ.common().ptrTo(), ptr, fl}
}
-// convertForAssignment
-func convertForAssignment(what string, addr unsafe.Pointer, dst Type, iv internalValue) internalValue {
- if iv.method {
- panic(what + ": cannot assign method value to type " + dst.String())
+// assignTo returns a value v that can be assigned directly to typ.
+// It panics if v is not assignable to typ.
+// For a conversion to an interface type, target is a suggested scratch space to use.
+func (v Value) assignTo(context string, dst *commonType, target *interface{}) Value {
+ if v.flag&flagMethod != 0 {
+ panic(context + ": cannot assign method value to type " + dst.String())
}
- dst1 := dst.(*commonType)
- if directlyAssignable(dst1, iv.typ) {
+ switch {
+ case directlyAssignable(dst, v.typ):
// Overwrite type so that they match.
// Same memory layout, so no harm done.
- iv.typ = dst1
- return iv
- }
- if implements(dst1, iv.typ) {
- if addr == nil {
- addr = unsafe.Pointer(new(interface{}))
+ v.typ = dst
+ fl := v.flag & (flagRO | flagAddr | flagIndir)
+ fl |= flag(dst.Kind()) << flagKindShift
+ return Value{dst, v.val, fl}
+
+ case implements(dst, v.typ):
+ if target == nil {
+ target = new(interface{})
}
- x := iv.valueInterface(false)
+ x := valueInterface(v, false)
if dst.NumMethod() == 0 {
- *(*interface{})(addr) = x
+ *target = x
} else {
- ifaceE2I(dst1.runtimeType(), x, addr)
+ ifaceE2I(dst.runtimeType(), x, unsafe.Pointer(target))
}
- iv.addr = addr
- iv.word = iword(addr)
- iv.typ = dst1
- return iv
+ return Value{dst, unsafe.Pointer(target), flagIndir | flag(Interface)<<flagKindShift}
}
// Failed.
- panic(what + ": value of type " + iv.typ.String() + " is not assignable to type " + dst.String())
+ panic(context + ": value of type " + v.typ.String() + " is not assignable to type " + dst.String())
}
// implemented in ../pkg/runtime
func chansend(t *runtime.Type, ch iword, val iword, nb bool) bool
func makechan(typ *runtime.Type, size uint32) (ch iword)
-func makemap(t *runtime.Type) iword
+func makemap(t *runtime.Type) (m iword)
func mapaccess(t *runtime.Type, m iword, key iword) (val iword, ok bool)
func mapassign(t *runtime.Type, m iword, key, val iword, ok bool)
func mapiterinit(t *runtime.Type, m iword) *byte
func call(fn, arg unsafe.Pointer, n uint32)
func ifaceE2I(t *runtime.Type, src interface{}, dst unsafe.Pointer)
+
+// Dummy annotation marking that the value x escapes,
+// for use in cases where the reflect code is so clever that
+// the compiler cannot follow.
+func escapes(x interface{}) {
+ if dummy.b {
+ dummy.x = x
+ }
+}
+
+var dummy struct {
+ b bool
+ x interface{}
+}