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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:14:23 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:14:23 +0000
commit73df946d56c74384511a194dd01dbe099584fd1a (patch)
treefd0bcea490dd81327ddfbb31e215439672c9a068 /src/reflect/value.go
parentInitial commit. (diff)
downloadgolang-1.16-upstream.tar.xz
golang-1.16-upstream.zip
Adding upstream version 1.16.10.upstream/1.16.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/reflect/value.go')
-rw-r--r--src/reflect/value.go2858
1 files changed, 2858 insertions, 0 deletions
diff --git a/src/reflect/value.go b/src/reflect/value.go
new file mode 100644
index 0000000..1f185b5
--- /dev/null
+++ b/src/reflect/value.go
@@ -0,0 +1,2858 @@
+// 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 (
+ "internal/unsafeheader"
+ "math"
+ "runtime"
+ "unsafe"
+)
+
+const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
+
+// 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.
+//
+// A Value can be used concurrently by multiple goroutines provided that
+// the underlying Go value can be used concurrently for the equivalent
+// direct operations.
+//
+// To compare two Values, compare the results of the Interface method.
+// Using == on two Values does not compare the underlying values
+// they represent.
+type Value struct {
+ // typ holds the type of the value represented by a Value.
+ typ *rtype
+
+ // Pointer-valued data or, if flagIndir is set, pointer to data.
+ // Valid when either flagIndir is set or typ.pointers() is true.
+ ptr unsafe.Pointer
+
+ // flag holds metadata about the value.
+ // The lowest bits are flag bits:
+ // - flagStickyRO: obtained via unexported not embedded field, so read-only
+ // - flagEmbedRO: obtained via unexported embedded 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 ifaceIndir(typ), 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 (
+ flagKindWidth = 5 // there are 27 kinds
+ flagKindMask flag = 1<<flagKindWidth - 1
+ flagStickyRO flag = 1 << 5
+ flagEmbedRO flag = 1 << 6
+ flagIndir flag = 1 << 7
+ flagAddr flag = 1 << 8
+ flagMethod flag = 1 << 9
+ flagMethodShift = 10
+ flagRO flag = flagStickyRO | flagEmbedRO
+)
+
+func (f flag) kind() Kind {
+ return Kind(f & flagKindMask)
+}
+
+func (f flag) ro() flag {
+ if f&flagRO != 0 {
+ return flagStickyRO
+ }
+ return 0
+}
+
+// pointer returns the underlying pointer represented by v.
+// v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
+// if v.Kind() == Ptr, the base type must not be go:notinheap.
+func (v Value) pointer() unsafe.Pointer {
+ if v.typ.size != ptrSize || !v.typ.pointers() {
+ panic("can't call pointer on a non-pointer Value")
+ }
+ if v.flag&flagIndir != 0 {
+ return *(*unsafe.Pointer)(v.ptr)
+ }
+ return v.ptr
+}
+
+// packEface converts v to the empty interface.
+func packEface(v Value) interface{} {
+ t := v.typ
+ var i interface{}
+ e := (*emptyInterface)(unsafe.Pointer(&i))
+ // First, fill in the data portion of the interface.
+ switch {
+ case ifaceIndir(t):
+ if v.flag&flagIndir == 0 {
+ panic("bad indir")
+ }
+ // Value is indirect, and so is the interface we're making.
+ ptr := v.ptr
+ if v.flag&flagAddr != 0 {
+ // TODO: pass safe boolean from valueInterface so
+ // we don't need to copy if safe==true?
+ c := unsafe_New(t)
+ typedmemmove(t, c, ptr)
+ ptr = c
+ }
+ e.word = ptr
+ case v.flag&flagIndir != 0:
+ // Value is indirect, but interface is direct. We need
+ // to load the data at v.ptr into the interface data word.
+ e.word = *(*unsafe.Pointer)(v.ptr)
+ default:
+ // Value is direct, and so is the interface.
+ e.word = v.ptr
+ }
+ // Now, fill in the type portion. We're very careful here not
+ // to have any operation between the e.word and e.typ assignments
+ // that would let the garbage collector observe the partially-built
+ // interface value.
+ e.typ = t
+ return i
+}
+
+// unpackEface converts the empty interface i to a Value.
+func unpackEface(i interface{}) Value {
+ e := (*emptyInterface)(unsafe.Pointer(&i))
+ // NOTE: don't read e.word until we know whether it is really a pointer or not.
+ t := e.typ
+ if t == nil {
+ return Value{}
+ }
+ f := flag(t.Kind())
+ if ifaceIndir(t) {
+ f |= flagIndir
+ }
+ return Value{t, e.word, f}
+}
+
+// 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) Error() 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()
+}
+
+// methodNameSkip is like methodName, but skips another stack frame.
+// This is a separate function so that reflect.flag.mustBe will be inlined.
+func methodNameSkip() string {
+ pc, _, _, _ := runtime.Caller(3)
+ f := runtime.FuncForPC(pc)
+ if f == nil {
+ return "unknown method"
+ }
+ return f.Name()
+}
+
+// emptyInterface is the header for an interface{} value.
+type emptyInterface struct {
+ typ *rtype
+ word unsafe.Pointer
+}
+
+// nonEmptyInterface is the header for an interface value with methods.
+type nonEmptyInterface struct {
+ // see ../runtime/iface.go:/Itab
+ itab *struct {
+ ityp *rtype // static interface type
+ typ *rtype // dynamic concrete type
+ hash uint32 // copy of typ.hash
+ _ [4]byte
+ fun [100000]unsafe.Pointer // method table
+ }
+ word unsafe.Pointer
+}
+
+// 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) {
+ // TODO(mvdan): use f.kind() again once mid-stack inlining gets better
+ if Kind(f&flagKindMask) != expected {
+ panic(&ValueError{methodName(), f.kind()})
+ }
+}
+
+// mustBeExported panics if f records that the value was obtained using
+// an unexported field.
+func (f flag) mustBeExported() {
+ if f == 0 || f&flagRO != 0 {
+ f.mustBeExportedSlow()
+ }
+}
+
+func (f flag) mustBeExportedSlow() {
+ if f == 0 {
+ panic(&ValueError{methodNameSkip(), Invalid})
+ }
+ if f&flagRO != 0 {
+ panic("reflect: " + methodNameSkip() + " using value obtained using unexported field")
+ }
+}
+
+// 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&flagRO != 0 || f&flagAddr == 0 {
+ f.mustBeAssignableSlow()
+ }
+}
+
+func (f flag) mustBeAssignableSlow() {
+ if f == 0 {
+ panic(&ValueError{methodNameSkip(), Invalid})
+ }
+ // Assignable if addressable and not read-only.
+ if f&flagRO != 0 {
+ panic("reflect: " + methodNameSkip() + " using value obtained using unexported field")
+ }
+ if f&flagAddr == 0 {
+ panic("reflect: " + methodNameSkip() + " using unaddressable value")
+ }
+}
+
+// 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 {
+ if v.flag&flagAddr == 0 {
+ panic("reflect.Value.Addr of unaddressable value")
+ }
+ // Preserve flagRO instead of using v.flag.ro() so that
+ // v.Addr().Elem() is equivalent to v (#32772)
+ fl := v.flag & flagRO
+ return Value{v.typ.ptrTo(), v.ptr, fl | flag(Ptr)}
+}
+
+// Bool returns v's underlying value.
+// It panics if v's kind is not Bool.
+func (v Value) Bool() bool {
+ v.mustBe(Bool)
+ return *(*bool)(v.ptr)
+}
+
+// Bytes returns v's underlying value.
+// It panics if v's underlying value is not a slice of bytes.
+func (v Value) Bytes() []byte {
+ v.mustBe(Slice)
+ if v.typ.Elem().Kind() != Uint8 {
+ panic("reflect.Value.Bytes of non-byte slice")
+ }
+ // Slice is always bigger than a word; assume flagIndir.
+ return *(*[]byte)(v.ptr)
+}
+
+// runes returns v's underlying value.
+// It panics if v's underlying value is not a slice of runes (int32s).
+func (v Value) runes() []rune {
+ v.mustBe(Slice)
+ if v.typ.Elem().Kind() != Int32 {
+ panic("reflect.Value.Bytes of non-rune slice")
+ }
+ // Slice is always bigger than a word; assume flagIndir.
+ return *(*[]rune)(v.ptr)
+}
+
+// CanAddr reports whether 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, or the result of dereferencing a pointer.
+// If CanAddr returns false, calling Addr will panic.
+func (v Value) CanAddr() bool {
+ return v.flag&flagAddr != 0
+}
+
+// CanSet reports whether the value of v can be changed.
+// A Value can be changed only if it is addressable and was not
+// obtained by the use of unexported struct fields.
+// If CanSet returns false, calling Set or any type-specific
+// setter (e.g., SetBool, SetInt) will panic.
+func (v Value) CanSet() bool {
+ return v.flag&(flagAddr|flagRO) == flagAddr
+}
+
+// Call calls the function v with the input arguments in.
+// For example, if len(in) == 3, v.Call(in) represents the Go call v(in[0], in[1], in[2]).
+// Call panics if v's Kind is not Func.
+// It returns the output results as Values.
+// As in Go, each input argument must be assignable to the
+// type of the function's corresponding input parameter.
+// 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 {
+ v.mustBe(Func)
+ v.mustBeExported()
+ return v.call("Call", in)
+}
+
+// CallSlice calls the variadic function v with the input arguments in,
+// assigning the slice in[len(in)-1] to v's final variadic argument.
+// For example, if len(in) == 3, v.CallSlice(in) represents the Go call v(in[0], in[1], in[2]...).
+// CallSlice panics if v's Kind is not Func or if v is not variadic.
+// It returns the output results as Values.
+// 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 {
+ v.mustBe(Func)
+ v.mustBeExported()
+ return v.call("CallSlice", in)
+}
+
+var callGC bool // for testing; see TestCallMethodJump
+
+func (v Value) call(op string, in []Value) []Value {
+ // Get function pointer, type.
+ t := (*funcType)(unsafe.Pointer(v.typ))
+ var (
+ fn unsafe.Pointer
+ rcvr Value
+ rcvrtype *rtype
+ )
+ if v.flag&flagMethod != 0 {
+ rcvr = v
+ rcvrtype, t, fn = methodReceiver(op, v, int(v.flag)>>flagMethodShift)
+ } else if v.flag&flagIndir != 0 {
+ fn = *(*unsafe.Pointer)(v.ptr)
+ } else {
+ fn = v.ptr
+ }
+
+ if fn == nil {
+ panic("reflect.Value.Call: call of nil function")
+ }
+
+ isSlice := op == "CallSlice"
+ n := t.NumIn()
+ if isSlice {
+ if !t.IsVariadic() {
+ panic("reflect: CallSlice of non-variadic function")
+ }
+ if len(in) < n {
+ panic("reflect: CallSlice with too few input arguments")
+ }
+ if len(in) > n {
+ panic("reflect: CallSlice with too many input arguments")
+ }
+ } else {
+ if t.IsVariadic() {
+ n--
+ }
+ if len(in) < n {
+ panic("reflect: Call with too few input arguments")
+ }
+ if !t.IsVariadic() && len(in) > n {
+ panic("reflect: Call with too many input arguments")
+ }
+ }
+ for _, x := range in {
+ if x.Kind() == Invalid {
+ panic("reflect: " + op + " using zero Value argument")
+ }
+ }
+ for i := 0; i < n; i++ {
+ if xt, targ := in[i].Type(), t.In(i); !xt.AssignableTo(targ) {
+ panic("reflect: " + op + " using " + xt.String() + " as type " + targ.String())
+ }
+ }
+ if !isSlice && t.IsVariadic() {
+ // prepare slice for remaining values
+ m := len(in) - n
+ slice := MakeSlice(t.In(n), m, m)
+ elem := t.In(n).Elem()
+ for i := 0; i < m; i++ {
+ x := in[n+i]
+ if xt := x.Type(); !xt.AssignableTo(elem) {
+ panic("reflect: cannot use " + xt.String() + " as type " + elem.String() + " in " + op)
+ }
+ slice.Index(i).Set(x)
+ }
+ origIn := in
+ in = make([]Value, n+1)
+ copy(in[:n], origIn)
+ in[n] = slice
+ }
+
+ nin := len(in)
+ if nin != t.NumIn() {
+ panic("reflect.Value.Call: wrong argument count")
+ }
+ nout := t.NumOut()
+
+ // Compute frame type.
+ frametype, _, retOffset, _, framePool := funcLayout(t, rcvrtype)
+
+ // Allocate a chunk of memory for frame.
+ var args unsafe.Pointer
+ if nout == 0 {
+ args = framePool.Get().(unsafe.Pointer)
+ } else {
+ // Can't use pool if the function has return values.
+ // We will leak pointer to args in ret, so its lifetime is not scoped.
+ args = unsafe_New(frametype)
+ }
+ off := uintptr(0)
+
+ // Copy inputs into args.
+ if rcvrtype != nil {
+ storeRcvr(rcvr, args)
+ off = ptrSize
+ }
+ for i, v := range in {
+ v.mustBeExported()
+ targ := t.In(i).(*rtype)
+ a := uintptr(targ.align)
+ off = (off + a - 1) &^ (a - 1)
+ n := targ.size
+ if n == 0 {
+ // Not safe to compute args+off pointing at 0 bytes,
+ // because that might point beyond the end of the frame,
+ // but we still need to call assignTo to check assignability.
+ v.assignTo("reflect.Value.Call", targ, nil)
+ continue
+ }
+ addr := add(args, off, "n > 0")
+ v = v.assignTo("reflect.Value.Call", targ, addr)
+ if v.flag&flagIndir != 0 {
+ typedmemmove(targ, addr, v.ptr)
+ } else {
+ *(*unsafe.Pointer)(addr) = v.ptr
+ }
+ off += n
+ }
+
+ // Call.
+ call(frametype, fn, args, uint32(frametype.size), uint32(retOffset))
+
+ // For testing; see TestCallMethodJump.
+ if callGC {
+ runtime.GC()
+ }
+
+ var ret []Value
+ if nout == 0 {
+ typedmemclr(frametype, args)
+ framePool.Put(args)
+ } else {
+ // Zero the now unused input area of args,
+ // because the Values returned by this function contain pointers to the args object,
+ // and will thus keep the args object alive indefinitely.
+ typedmemclrpartial(frametype, args, 0, retOffset)
+
+ // Wrap Values around return values in args.
+ ret = make([]Value, nout)
+ off = retOffset
+ for i := 0; i < nout; i++ {
+ tv := t.Out(i)
+ a := uintptr(tv.Align())
+ off = (off + a - 1) &^ (a - 1)
+ if tv.Size() != 0 {
+ fl := flagIndir | flag(tv.Kind())
+ ret[i] = Value{tv.common(), add(args, off, "tv.Size() != 0"), fl}
+ // Note: this does introduce false sharing between results -
+ // if any result is live, they are all live.
+ // (And the space for the args is live as well, but as we've
+ // cleared that space it isn't as big a deal.)
+ } else {
+ // For zero-sized return value, args+off may point to the next object.
+ // In this case, return the zero value instead.
+ ret[i] = Zero(tv)
+ }
+ off += tv.Size()
+ }
+ }
+
+ return ret
+}
+
+// callReflect is the call implementation used by a function
+// returned by MakeFunc. In many ways it is the opposite of the
+// method Value.call above. The method above converts a call using Values
+// into a call of a function with a concrete argument frame, while
+// callReflect converts a call of a function with a concrete argument
+// frame into a call using Values.
+// It is in this file so that it can be next to the call method above.
+// The remainder of the MakeFunc implementation is in makefunc.go.
+//
+// NOTE: This function must be marked as a "wrapper" in the generated code,
+// so that the linker can make it work correctly for panic and recover.
+// The gc compilers know to do that for the name "reflect.callReflect".
+//
+// ctxt is the "closure" generated by MakeFunc.
+// frame is a pointer to the arguments to that closure on the stack.
+// retValid points to a boolean which should be set when the results
+// section of frame is set.
+func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer, retValid *bool) {
+ ftyp := ctxt.ftyp
+ f := ctxt.fn
+
+ // Copy argument frame into Values.
+ ptr := frame
+ off := uintptr(0)
+ in := make([]Value, 0, int(ftyp.inCount))
+ for _, typ := range ftyp.in() {
+ off += -off & uintptr(typ.align-1)
+ v := Value{typ, nil, flag(typ.Kind())}
+ if ifaceIndir(typ) {
+ // value cannot be inlined in interface data.
+ // Must make a copy, because f might keep a reference to it,
+ // and we cannot let f keep a reference to the stack frame
+ // after this function returns, not even a read-only reference.
+ v.ptr = unsafe_New(typ)
+ if typ.size > 0 {
+ typedmemmove(typ, v.ptr, add(ptr, off, "typ.size > 0"))
+ }
+ v.flag |= flagIndir
+ } else {
+ v.ptr = *(*unsafe.Pointer)(add(ptr, off, "1-ptr"))
+ }
+ in = append(in, v)
+ off += typ.size
+ }
+
+ // Call underlying function.
+ out := f(in)
+ numOut := ftyp.NumOut()
+ if len(out) != numOut {
+ panic("reflect: wrong return count from function created by MakeFunc")
+ }
+
+ // Copy results back into argument frame.
+ if numOut > 0 {
+ off += -off & (ptrSize - 1)
+ for i, typ := range ftyp.out() {
+ v := out[i]
+ if v.typ == nil {
+ panic("reflect: function created by MakeFunc using " + funcName(f) +
+ " returned zero Value")
+ }
+ if v.flag&flagRO != 0 {
+ panic("reflect: function created by MakeFunc using " + funcName(f) +
+ " returned value obtained from unexported field")
+ }
+ off += -off & uintptr(typ.align-1)
+ if typ.size == 0 {
+ continue
+ }
+ addr := add(ptr, off, "typ.size > 0")
+
+ // Convert v to type typ if v is assignable to a variable
+ // of type t in the language spec.
+ // See issue 28761.
+ if typ.Kind() == Interface {
+ // We must clear the destination before calling assignTo,
+ // in case assignTo writes (with memory barriers) to the
+ // target location used as scratch space. See issue 39541.
+ *(*uintptr)(addr) = 0
+ *(*uintptr)(add(addr, ptrSize, "typ.size == 2*ptrSize")) = 0
+ }
+ v = v.assignTo("reflect.MakeFunc", typ, addr)
+
+ // We are writing to stack. No write barrier.
+ if v.flag&flagIndir != 0 {
+ memmove(addr, v.ptr, typ.size)
+ } else {
+ *(*uintptr)(addr) = uintptr(v.ptr)
+ }
+ off += typ.size
+ }
+ }
+
+ // Announce that the return values are valid.
+ // After this point the runtime can depend on the return values being valid.
+ *retValid = true
+
+ // We have to make sure that the out slice lives at least until
+ // the runtime knows the return values are valid. Otherwise, the
+ // return values might not be scanned by anyone during a GC.
+ // (out would be dead, and the return slots not yet alive.)
+ runtime.KeepAlive(out)
+
+ // runtime.getArgInfo expects to be able to find ctxt on the
+ // stack when it finds our caller, makeFuncStub. Make sure it
+ // doesn't get garbage collected.
+ runtime.KeepAlive(ctxt)
+}
+
+// methodReceiver returns information about the receiver
+// described by v. The Value v may or may not have the
+// flagMethod bit set, so the kind cached in v.flag should
+// not be used.
+// The return value rcvrtype gives the method's actual receiver type.
+// The return value t gives the method type signature (without the receiver).
+// The return value fn is a pointer to the method code.
+func methodReceiver(op string, v Value, methodIndex int) (rcvrtype *rtype, t *funcType, fn unsafe.Pointer) {
+ i := methodIndex
+ if v.typ.Kind() == Interface {
+ tt := (*interfaceType)(unsafe.Pointer(v.typ))
+ if uint(i) >= uint(len(tt.methods)) {
+ panic("reflect: internal error: invalid method index")
+ }
+ m := &tt.methods[i]
+ if !tt.nameOff(m.name).isExported() {
+ panic("reflect: " + op + " of unexported method")
+ }
+ iface := (*nonEmptyInterface)(v.ptr)
+ if iface.itab == nil {
+ panic("reflect: " + op + " of method on nil interface value")
+ }
+ rcvrtype = iface.itab.typ
+ fn = unsafe.Pointer(&iface.itab.fun[i])
+ t = (*funcType)(unsafe.Pointer(tt.typeOff(m.typ)))
+ } else {
+ rcvrtype = v.typ
+ ms := v.typ.exportedMethods()
+ if uint(i) >= uint(len(ms)) {
+ panic("reflect: internal error: invalid method index")
+ }
+ m := ms[i]
+ if !v.typ.nameOff(m.name).isExported() {
+ panic("reflect: " + op + " of unexported method")
+ }
+ ifn := v.typ.textOff(m.ifn)
+ fn = unsafe.Pointer(&ifn)
+ t = (*funcType)(unsafe.Pointer(v.typ.typeOff(m.mtyp)))
+ }
+ return
+}
+
+// v is a method receiver. Store at p the word which is used to
+// encode that receiver at the start of the argument list.
+// Reflect uses the "interface" calling convention for
+// methods, which always uses one word to record the receiver.
+func storeRcvr(v Value, p unsafe.Pointer) {
+ t := v.typ
+ if t.Kind() == Interface {
+ // the interface data word becomes the receiver word
+ iface := (*nonEmptyInterface)(v.ptr)
+ *(*unsafe.Pointer)(p) = iface.word
+ } else if v.flag&flagIndir != 0 && !ifaceIndir(t) {
+ *(*unsafe.Pointer)(p) = *(*unsafe.Pointer)(v.ptr)
+ } else {
+ *(*unsafe.Pointer)(p) = v.ptr
+ }
+}
+
+// align returns the result of rounding x up to a multiple of n.
+// n must be a power of two.
+func align(x, n uintptr) uintptr {
+ return (x + n - 1) &^ (n - 1)
+}
+
+// callMethod is the call implementation used by a function returned
+// by makeMethodValue (used by v.Method(i).Interface()).
+// It is a streamlined version of the usual reflect call: the caller has
+// already laid out the argument frame for us, so we don't have
+// to deal with individual Values for each argument.
+// It is in this file so that it can be next to the two similar functions above.
+// The remainder of the makeMethodValue implementation is in makefunc.go.
+//
+// NOTE: This function must be marked as a "wrapper" in the generated code,
+// so that the linker can make it work correctly for panic and recover.
+// The gc compilers know to do that for the name "reflect.callMethod".
+//
+// ctxt is the "closure" generated by makeVethodValue.
+// frame is a pointer to the arguments to that closure on the stack.
+// retValid points to a boolean which should be set when the results
+// section of frame is set.
+func callMethod(ctxt *methodValue, frame unsafe.Pointer, retValid *bool) {
+ rcvr := ctxt.rcvr
+ rcvrtype, t, fn := methodReceiver("call", rcvr, ctxt.method)
+ frametype, argSize, retOffset, _, framePool := funcLayout(t, rcvrtype)
+
+ // Make a new frame that is one word bigger so we can store the receiver.
+ // This space is used for both arguments and return values.
+ scratch := framePool.Get().(unsafe.Pointer)
+
+ // Copy in receiver and rest of args.
+ storeRcvr(rcvr, scratch)
+ // Align the first arg. The alignment can't be larger than ptrSize.
+ argOffset := uintptr(ptrSize)
+ if len(t.in()) > 0 {
+ argOffset = align(argOffset, uintptr(t.in()[0].align))
+ }
+ // Avoid constructing out-of-bounds pointers if there are no args.
+ if argSize-argOffset > 0 {
+ typedmemmovepartial(frametype, add(scratch, argOffset, "argSize > argOffset"), frame, argOffset, argSize-argOffset)
+ }
+
+ // Call.
+ // Call copies the arguments from scratch to the stack, calls fn,
+ // and then copies the results back into scratch.
+ call(frametype, fn, scratch, uint32(frametype.size), uint32(retOffset))
+
+ // Copy return values.
+ // Ignore any changes to args and just copy return values.
+ // Avoid constructing out-of-bounds pointers if there are no return values.
+ if frametype.size-retOffset > 0 {
+ callerRetOffset := retOffset - argOffset
+ // This copies to the stack. Write barriers are not needed.
+ memmove(add(frame, callerRetOffset, "frametype.size > retOffset"),
+ add(scratch, retOffset, "frametype.size > retOffset"),
+ frametype.size-retOffset)
+ }
+
+ // Tell the runtime it can now depend on the return values
+ // being properly initialized.
+ *retValid = true
+
+ // Clear the scratch space and put it back in the pool.
+ // This must happen after the statement above, so that the return
+ // values will always be scanned by someone.
+ typedmemclr(frametype, scratch)
+ framePool.Put(scratch)
+
+ // See the comment in callReflect.
+ runtime.KeepAlive(ctxt)
+}
+
+// funcName returns the name of f, for use in error messages.
+func funcName(f func([]Value) []Value) string {
+ pc := *(*uintptr)(unsafe.Pointer(&f))
+ rf := runtime.FuncForPC(pc)
+ if rf != nil {
+ return rf.Name()
+ }
+ return "closure"
+}
+
+// Cap returns v's capacity.
+// It panics if v's Kind is not Array, Chan, or Slice.
+func (v Value) Cap() int {
+ k := v.kind()
+ switch k {
+ case Array:
+ return v.typ.Len()
+ case Chan:
+ return chancap(v.pointer())
+ case Slice:
+ // Slice is always bigger than a word; assume flagIndir.
+ return (*unsafeheader.Slice)(v.ptr).Cap
+ }
+ panic(&ValueError{"reflect.Value.Cap", v.kind()})
+}
+
+// Close closes the channel v.
+// It panics if v's Kind is not Chan.
+func (v Value) Close() {
+ v.mustBe(Chan)
+ v.mustBeExported()
+ chanclose(v.pointer())
+}
+
+// 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 {
+ k := v.kind()
+ switch k {
+ case Complex64:
+ return complex128(*(*complex64)(v.ptr))
+ case Complex128:
+ return *(*complex128)(v.ptr)
+ }
+ panic(&ValueError{"reflect.Value.Complex", v.kind()})
+}
+
+// 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 {
+ k := v.kind()
+ switch k {
+ case Interface:
+ var eface interface{}
+ if v.typ.NumMethod() == 0 {
+ eface = *(*interface{})(v.ptr)
+ } else {
+ eface = (interface{})(*(*interface {
+ M()
+ })(v.ptr))
+ }
+ x := unpackEface(eface)
+ if x.flag != 0 {
+ x.flag |= v.flag.ro()
+ }
+ return x
+ case Ptr:
+ ptr := v.ptr
+ if v.flag&flagIndir != 0 {
+ ptr = *(*unsafe.Pointer)(ptr)
+ }
+ // The returned value's address is v's value.
+ if ptr == nil {
+ return Value{}
+ }
+ tt := (*ptrType)(unsafe.Pointer(v.typ))
+ typ := tt.elem
+ fl := v.flag&flagRO | flagIndir | flagAddr
+ fl |= flag(typ.Kind())
+ return Value{typ, ptr, fl}
+ }
+ panic(&ValueError{"reflect.Value.Elem", v.kind()})
+}
+
+// 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 {
+ if v.kind() != Struct {
+ panic(&ValueError{"reflect.Value.Field", v.kind()})
+ }
+ tt := (*structType)(unsafe.Pointer(v.typ))
+ if uint(i) >= uint(len(tt.fields)) {
+ panic("reflect: Field index out of range")
+ }
+ field := &tt.fields[i]
+ typ := field.typ
+
+ // Inherit permission bits from v, but clear flagEmbedRO.
+ fl := v.flag&(flagStickyRO|flagIndir|flagAddr) | flag(typ.Kind())
+ // Using an unexported field forces flagRO.
+ if !field.name.isExported() {
+ if field.embedded() {
+ fl |= flagEmbedRO
+ } else {
+ fl |= flagStickyRO
+ }
+ }
+ // Either flagIndir is set and v.ptr points at struct,
+ // or flagIndir is not set and v.ptr is the actual struct data.
+ // In the former case, we want v.ptr + offset.
+ // In the latter case, we must have field.offset = 0,
+ // so v.ptr + field.offset is still the correct address.
+ ptr := add(v.ptr, field.offset(), "same as non-reflect &v.field")
+ return Value{typ, ptr, 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 {
+ if len(index) == 1 {
+ return v.Field(index[0])
+ }
+ v.mustBe(Struct)
+ for i, x := range index {
+ if i > 0 {
+ if v.Kind() == Ptr && v.typ.Elem().Kind() == Struct {
+ if v.IsNil() {
+ panic("reflect: indirection through nil pointer to embedded struct")
+ }
+ v = v.Elem()
+ }
+ }
+ v = v.Field(x)
+ }
+ return v
+}
+
+// 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 {
+ v.mustBe(Struct)
+ if f, ok := v.typ.FieldByName(name); ok {
+ return v.FieldByIndex(f.Index)
+ }
+ return Value{}
+}
+
+// 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 {
+ if f, ok := v.typ.FieldByNameFunc(match); ok {
+ return v.FieldByIndex(f.Index)
+ }
+ return Value{}
+}
+
+// Float returns v's underlying value, as a float64.
+// It panics if v's Kind is not Float32 or Float64
+func (v Value) Float() float64 {
+ k := v.kind()
+ switch k {
+ case Float32:
+ return float64(*(*float32)(v.ptr))
+ case Float64:
+ return *(*float64)(v.ptr)
+ }
+ panic(&ValueError{"reflect.Value.Float", v.kind()})
+}
+
+var uint8Type = TypeOf(uint8(0)).(*rtype)
+
+// Index returns v's i'th element.
+// It panics if v's Kind is not Array, Slice, or String or i is out of range.
+func (v Value) Index(i int) Value {
+ switch v.kind() {
+ case Array:
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ if uint(i) >= uint(tt.len) {
+ panic("reflect: array index out of range")
+ }
+ typ := tt.elem
+ offset := uintptr(i) * typ.size
+
+ // Either flagIndir is set and v.ptr points at array,
+ // or flagIndir is not set and v.ptr is the actual array data.
+ // In the former case, we want v.ptr + offset.
+ // In the latter case, we must be doing Index(0), so offset = 0,
+ // so v.ptr + offset is still the correct address.
+ val := add(v.ptr, offset, "same as &v[i], i < tt.len")
+ fl := v.flag&(flagIndir|flagAddr) | v.flag.ro() | flag(typ.Kind()) // bits same as overall array
+ return Value{typ, val, fl}
+
+ case Slice:
+ // Element flag same as Elem of Ptr.
+ // Addressable, indirect, possibly read-only.
+ s := (*unsafeheader.Slice)(v.ptr)
+ if uint(i) >= uint(s.Len) {
+ panic("reflect: slice index out of range")
+ }
+ tt := (*sliceType)(unsafe.Pointer(v.typ))
+ typ := tt.elem
+ val := arrayAt(s.Data, i, typ.size, "i < s.Len")
+ fl := flagAddr | flagIndir | v.flag.ro() | flag(typ.Kind())
+ return Value{typ, val, fl}
+
+ case String:
+ s := (*unsafeheader.String)(v.ptr)
+ if uint(i) >= uint(s.Len) {
+ panic("reflect: string index out of range")
+ }
+ p := arrayAt(s.Data, i, 1, "i < s.Len")
+ fl := v.flag.ro() | flag(Uint8) | flagIndir
+ return Value{uint8Type, p, fl}
+ }
+ panic(&ValueError{"reflect.Value.Index", v.kind()})
+}
+
+// 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 {
+ k := v.kind()
+ p := v.ptr
+ switch k {
+ case Int:
+ return int64(*(*int)(p))
+ case Int8:
+ return int64(*(*int8)(p))
+ case Int16:
+ return int64(*(*int16)(p))
+ case Int32:
+ return int64(*(*int32)(p))
+ case Int64:
+ return *(*int64)(p)
+ }
+ panic(&ValueError{"reflect.Value.Int", v.kind()})
+}
+
+// CanInterface reports whether Interface can be used without panicking.
+func (v Value) CanInterface() bool {
+ if v.flag == 0 {
+ panic(&ValueError{"reflect.Value.CanInterface", Invalid})
+ }
+ return v.flag&flagRO == 0
+}
+
+// Interface returns v's current value as an interface{}.
+// It is equivalent to:
+// var i interface{} = (v's underlying value)
+// It panics if the Value was obtained by accessing
+// unexported struct fields.
+func (v Value) Interface() (i interface{}) {
+ return valueInterface(v, true)
+}
+
+func valueInterface(v Value, safe bool) interface{} {
+ if v.flag == 0 {
+ panic(&ValueError{"reflect.Value.Interface", Invalid})
+ }
+ 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 v.flag&flagMethod != 0 {
+ v = makeMethodValue("Interface", v)
+ }
+
+ if v.kind() == Interface {
+ // Special case: return the element inside the interface.
+ // Empty interface has one layout, all interfaces with
+ // methods have a second layout.
+ if v.NumMethod() == 0 {
+ return *(*interface{})(v.ptr)
+ }
+ return *(*interface {
+ M()
+ })(v.ptr)
+ }
+
+ // TODO: pass safe to packEface so we don't need to copy if safe==true?
+ return packEface(v)
+}
+
+// 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 {
+ // TODO: deprecate this
+ 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.
+ // Interface value is always bigger than a word; assume flagIndir.
+ return *(*[2]uintptr)(v.ptr)
+}
+
+// IsNil reports whether its argument v is nil. The argument must be
+// a chan, func, interface, map, pointer, or slice value; if it is
+// not, IsNil panics. Note that IsNil is not always equivalent to a
+// regular comparison with nil in Go. For example, if v was created
+// by calling ValueOf with an uninitialized interface variable i,
+// i==nil will be true but v.IsNil will panic as v will be the zero
+// Value.
+func (v Value) IsNil() bool {
+ k := v.kind()
+ switch k {
+ case Chan, Func, Map, Ptr, UnsafePointer:
+ if v.flag&flagMethod != 0 {
+ return false
+ }
+ ptr := v.ptr
+ 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.
+ // Both are always bigger than a word; assume flagIndir.
+ return *(*unsafe.Pointer)(v.ptr) == nil
+ }
+ panic(&ValueError{"reflect.Value.IsNil", v.kind()})
+}
+
+// IsValid reports whether 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.flag != 0
+}
+
+// IsZero reports whether v is the zero value for its type.
+// It panics if the argument is invalid.
+func (v Value) IsZero() bool {
+ switch v.kind() {
+ case Bool:
+ return !v.Bool()
+ case Int, Int8, Int16, Int32, Int64:
+ return v.Int() == 0
+ case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+ return v.Uint() == 0
+ case Float32, Float64:
+ return math.Float64bits(v.Float()) == 0
+ case Complex64, Complex128:
+ c := v.Complex()
+ return math.Float64bits(real(c)) == 0 && math.Float64bits(imag(c)) == 0
+ case Array:
+ for i := 0; i < v.Len(); i++ {
+ if !v.Index(i).IsZero() {
+ return false
+ }
+ }
+ return true
+ case Chan, Func, Interface, Map, Ptr, Slice, UnsafePointer:
+ return v.IsNil()
+ case String:
+ return v.Len() == 0
+ case Struct:
+ for i := 0; i < v.NumField(); i++ {
+ if !v.Field(i).IsZero() {
+ return false
+ }
+ }
+ return true
+ default:
+ // This should never happens, but will act as a safeguard for
+ // later, as a default value doesn't makes sense here.
+ panic(&ValueError{"reflect.Value.IsZero", v.Kind()})
+ }
+}
+
+// Kind returns v's Kind.
+// If v is the zero Value (IsValid returns false), Kind returns Invalid.
+func (v Value) Kind() 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 {
+ k := v.kind()
+ switch k {
+ case Array:
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ return int(tt.len)
+ case Chan:
+ return chanlen(v.pointer())
+ case Map:
+ return maplen(v.pointer())
+ case Slice:
+ // Slice is bigger than a word; assume flagIndir.
+ return (*unsafeheader.Slice)(v.ptr).Len
+ case String:
+ // String is bigger than a word; assume flagIndir.
+ return (*unsafeheader.String)(v.ptr).Len
+ }
+ panic(&ValueError{"reflect.Value.Len", v.kind()})
+}
+
+// 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 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 {
+ v.mustBe(Map)
+ tt := (*mapType)(unsafe.Pointer(v.typ))
+
+ // 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. This is consistent with the
+ // behavior for structs, which allow read but not write
+ // of unexported fields.
+ key = key.assignTo("reflect.Value.MapIndex", tt.key, nil)
+
+ var k unsafe.Pointer
+ if key.flag&flagIndir != 0 {
+ k = key.ptr
+ } else {
+ k = unsafe.Pointer(&key.ptr)
+ }
+ e := mapaccess(v.typ, v.pointer(), k)
+ if e == nil {
+ return Value{}
+ }
+ typ := tt.elem
+ fl := (v.flag | key.flag).ro()
+ fl |= flag(typ.Kind())
+ return copyVal(typ, fl, e)
+}
+
+// MapKeys returns a slice containing all the keys present in the map,
+// in unspecified order.
+// 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 {
+ v.mustBe(Map)
+ tt := (*mapType)(unsafe.Pointer(v.typ))
+ keyType := tt.key
+
+ fl := v.flag.ro() | flag(keyType.Kind())
+
+ m := v.pointer()
+ mlen := int(0)
+ if m != nil {
+ mlen = maplen(m)
+ }
+ it := mapiterinit(v.typ, m)
+ a := make([]Value, mlen)
+ var i int
+ for i = 0; i < len(a); i++ {
+ key := mapiterkey(it)
+ if key == nil {
+ // Someone deleted an entry from the map since we
+ // called maplen above. It's a data race, but nothing
+ // we can do about it.
+ break
+ }
+ a[i] = copyVal(keyType, fl, key)
+ mapiternext(it)
+ }
+ return a[:i]
+}
+
+// A MapIter is an iterator for ranging over a map.
+// See Value.MapRange.
+type MapIter struct {
+ m Value
+ it unsafe.Pointer
+}
+
+// Key returns the key of the iterator's current map entry.
+func (it *MapIter) Key() Value {
+ if it.it == nil {
+ panic("MapIter.Key called before Next")
+ }
+ if mapiterkey(it.it) == nil {
+ panic("MapIter.Key called on exhausted iterator")
+ }
+
+ t := (*mapType)(unsafe.Pointer(it.m.typ))
+ ktype := t.key
+ return copyVal(ktype, it.m.flag.ro()|flag(ktype.Kind()), mapiterkey(it.it))
+}
+
+// Value returns the value of the iterator's current map entry.
+func (it *MapIter) Value() Value {
+ if it.it == nil {
+ panic("MapIter.Value called before Next")
+ }
+ if mapiterkey(it.it) == nil {
+ panic("MapIter.Value called on exhausted iterator")
+ }
+
+ t := (*mapType)(unsafe.Pointer(it.m.typ))
+ vtype := t.elem
+ return copyVal(vtype, it.m.flag.ro()|flag(vtype.Kind()), mapiterelem(it.it))
+}
+
+// Next advances the map iterator and reports whether there is another
+// entry. It returns false when the iterator is exhausted; subsequent
+// calls to Key, Value, or Next will panic.
+func (it *MapIter) Next() bool {
+ if it.it == nil {
+ it.it = mapiterinit(it.m.typ, it.m.pointer())
+ } else {
+ if mapiterkey(it.it) == nil {
+ panic("MapIter.Next called on exhausted iterator")
+ }
+ mapiternext(it.it)
+ }
+ return mapiterkey(it.it) != nil
+}
+
+// MapRange returns a range iterator for a map.
+// It panics if v's Kind is not Map.
+//
+// Call Next to advance the iterator, and Key/Value to access each entry.
+// Next returns false when the iterator is exhausted.
+// MapRange follows the same iteration semantics as a range statement.
+//
+// Example:
+//
+// iter := reflect.ValueOf(m).MapRange()
+// for iter.Next() {
+// k := iter.Key()
+// v := iter.Value()
+// ...
+// }
+//
+func (v Value) MapRange() *MapIter {
+ v.mustBe(Map)
+ return &MapIter{m: v}
+}
+
+// copyVal returns a Value containing the map key or value at ptr,
+// allocating a new variable as needed.
+func copyVal(typ *rtype, fl flag, ptr unsafe.Pointer) Value {
+ if ifaceIndir(typ) {
+ // Copy result so future changes to the map
+ // won't change the underlying value.
+ c := unsafe_New(typ)
+ typedmemmove(typ, c, ptr)
+ return Value{typ, c, fl | flagIndir}
+ }
+ return Value{typ, *(*unsafe.Pointer)(ptr), fl}
+}
+
+// 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.
+// Method panics if i is out of range or if v is a nil interface value.
+func (v Value) Method(i int) Value {
+ if v.typ == nil {
+ panic(&ValueError{"reflect.Value.Method", Invalid})
+ }
+ if v.flag&flagMethod != 0 || uint(i) >= uint(v.typ.NumMethod()) {
+ panic("reflect: Method index out of range")
+ }
+ if v.typ.Kind() == Interface && v.IsNil() {
+ panic("reflect: Method on nil interface value")
+ }
+ fl := v.flag.ro() | (v.flag & flagIndir)
+ fl |= flag(Func)
+ fl |= flag(i)<<flagMethodShift | flagMethod
+ return Value{v.typ, v.ptr, fl}
+}
+
+// NumMethod returns the number of exported methods in the value's method set.
+func (v Value) NumMethod() int {
+ if v.typ == nil {
+ panic(&ValueError{"reflect.Value.NumMethod", Invalid})
+ }
+ if v.flag&flagMethod != 0 {
+ return 0
+ }
+ return v.typ.NumMethod()
+}
+
+// MethodByName returns a function value corresponding to the method
+// of v with the given name.
+// The arguments to a Call on the returned function should not include
+// 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 {
+ if v.typ == nil {
+ panic(&ValueError{"reflect.Value.MethodByName", Invalid})
+ }
+ if v.flag&flagMethod != 0 {
+ 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 {
+ v.mustBe(Struct)
+ tt := (*structType)(unsafe.Pointer(v.typ))
+ return len(tt.fields)
+}
+
+// OverflowComplex reports whether 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 {
+ k := v.kind()
+ switch k {
+ case Complex64:
+ return overflowFloat32(real(x)) || overflowFloat32(imag(x))
+ case Complex128:
+ return false
+ }
+ panic(&ValueError{"reflect.Value.OverflowComplex", v.kind()})
+}
+
+// OverflowFloat reports whether 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 {
+ k := v.kind()
+ switch k {
+ case Float32:
+ return overflowFloat32(x)
+ case Float64:
+ return false
+ }
+ panic(&ValueError{"reflect.Value.OverflowFloat", v.kind()})
+}
+
+func overflowFloat32(x float64) bool {
+ if x < 0 {
+ x = -x
+ }
+ return math.MaxFloat32 < x && x <= math.MaxFloat64
+}
+
+// OverflowInt reports whether 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 {
+ k := v.kind()
+ switch k {
+ case Int, Int8, Int16, Int32, Int64:
+ bitSize := v.typ.size * 8
+ trunc := (x << (64 - bitSize)) >> (64 - bitSize)
+ return x != trunc
+ }
+ panic(&ValueError{"reflect.Value.OverflowInt", v.kind()})
+}
+
+// OverflowUint reports whether 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 {
+ k := v.kind()
+ switch k {
+ case Uint, Uintptr, Uint8, Uint16, Uint32, Uint64:
+ bitSize := v.typ.size * 8
+ trunc := (x << (64 - bitSize)) >> (64 - bitSize)
+ return x != trunc
+ }
+ panic(&ValueError{"reflect.Value.OverflowUint", v.kind()})
+}
+
+//go:nocheckptr
+// This prevents inlining Value.Pointer when -d=checkptr is enabled,
+// which ensures cmd/compile can recognize unsafe.Pointer(v.Pointer())
+// and make an exception.
+
+// 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.
+//
+// If v's Kind is Func, the returned pointer is an underlying
+// code pointer, but not necessarily enough to identify a
+// single function uniquely. The only guarantee is that the
+// result is zero if and only if v is a nil func Value.
+//
+// If v's Kind is Slice, the returned pointer is to the first
+// element of the slice. If the slice is nil the returned value
+// is 0. If the slice is empty but non-nil the return value is non-zero.
+func (v Value) Pointer() uintptr {
+ // TODO: deprecate
+ k := v.kind()
+ switch k {
+ case Ptr:
+ if v.typ.ptrdata == 0 {
+ // Handle pointers to go:notinheap types directly,
+ // so we never materialize such pointers as an
+ // unsafe.Pointer. (Such pointers are always indirect.)
+ // See issue 42076.
+ return *(*uintptr)(v.ptr)
+ }
+ fallthrough
+ case Chan, Map, UnsafePointer:
+ return uintptr(v.pointer())
+ case Func:
+ if v.flag&flagMethod != 0 {
+ // As the doc comment says, the returned pointer is an
+ // underlying code pointer but not necessarily enough to
+ // identify a single function uniquely. All method expressions
+ // created via reflect have the same underlying code pointer,
+ // so their Pointers are equal. The function used here must
+ // match the one used in makeMethodValue.
+ f := methodValueCall
+ return **(**uintptr)(unsafe.Pointer(&f))
+ }
+ p := v.pointer()
+ // Non-nil func value points at data block.
+ // First word of data block is actual code.
+ if p != nil {
+ p = *(*unsafe.Pointer)(p)
+ }
+ return uintptr(p)
+
+ case Slice:
+ return (*SliceHeader)(v.ptr).Data
+ }
+ panic(&ValueError{"reflect.Value.Pointer", v.kind()})
+}
+
+// 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) {
+ v.mustBe(Chan)
+ v.mustBeExported()
+ return v.recv(false)
+}
+
+// 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("reflect: recv on send-only channel")
+ }
+ t := tt.elem
+ val = Value{t, nil, flag(t.Kind())}
+ var p unsafe.Pointer
+ if ifaceIndir(t) {
+ p = unsafe_New(t)
+ val.ptr = p
+ val.flag |= flagIndir
+ } else {
+ p = unsafe.Pointer(&val.ptr)
+ }
+ selected, ok := chanrecv(v.pointer(), nb, p)
+ if !selected {
+ val = Value{}
+ }
+ return
+}
+
+// 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.
+// As in Go, x's value must be assignable to the channel's element type.
+func (v Value) Send(x Value) {
+ v.mustBe(Chan)
+ v.mustBeExported()
+ v.send(x, false)
+}
+
+// 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("reflect: send on recv-only channel")
+ }
+ x.mustBeExported()
+ x = x.assignTo("reflect.Value.Send", tt.elem, nil)
+ var p unsafe.Pointer
+ if x.flag&flagIndir != 0 {
+ p = x.ptr
+ } else {
+ p = unsafe.Pointer(&x.ptr)
+ }
+ return chansend(v.pointer(), p, 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) {
+ v.mustBeAssignable()
+ x.mustBeExported() // do not let unexported x leak
+ var target unsafe.Pointer
+ if v.kind() == Interface {
+ target = v.ptr
+ }
+ x = x.assignTo("reflect.Set", v.typ, target)
+ if x.flag&flagIndir != 0 {
+ if x.ptr == unsafe.Pointer(&zeroVal[0]) {
+ typedmemclr(v.typ, v.ptr)
+ } else {
+ typedmemmove(v.typ, v.ptr, x.ptr)
+ }
+ } else {
+ *(*unsafe.Pointer)(v.ptr) = x.ptr
+ }
+}
+
+// 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.mustBeAssignable()
+ v.mustBe(Bool)
+ *(*bool)(v.ptr) = 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) {
+ v.mustBeAssignable()
+ v.mustBe(Slice)
+ if v.typ.Elem().Kind() != Uint8 {
+ panic("reflect.Value.SetBytes of non-byte slice")
+ }
+ *(*[]byte)(v.ptr) = x
+}
+
+// setRunes sets v's underlying value.
+// It panics if v's underlying value is not a slice of runes (int32s).
+func (v Value) setRunes(x []rune) {
+ v.mustBeAssignable()
+ v.mustBe(Slice)
+ if v.typ.Elem().Kind() != Int32 {
+ panic("reflect.Value.setRunes of non-rune slice")
+ }
+ *(*[]rune)(v.ptr) = 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.mustBeAssignable()
+ switch k := v.kind(); k {
+ default:
+ panic(&ValueError{"reflect.Value.SetComplex", v.kind()})
+ case Complex64:
+ *(*complex64)(v.ptr) = complex64(x)
+ case Complex128:
+ *(*complex128)(v.ptr) = 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.mustBeAssignable()
+ switch k := v.kind(); k {
+ default:
+ panic(&ValueError{"reflect.Value.SetFloat", v.kind()})
+ case Float32:
+ *(*float32)(v.ptr) = float32(x)
+ case Float64:
+ *(*float64)(v.ptr) = 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) {
+ v.mustBeAssignable()
+ switch k := v.kind(); k {
+ default:
+ panic(&ValueError{"reflect.Value.SetInt", v.kind()})
+ case Int:
+ *(*int)(v.ptr) = int(x)
+ case Int8:
+ *(*int8)(v.ptr) = int8(x)
+ case Int16:
+ *(*int16)(v.ptr) = int16(x)
+ case Int32:
+ *(*int32)(v.ptr) = int32(x)
+ case Int64:
+ *(*int64)(v.ptr) = x
+ }
+}
+
+// SetLen sets v's length to n.
+// It panics if v's Kind is not Slice or if n is negative or
+// greater than the capacity of the slice.
+func (v Value) SetLen(n int) {
+ v.mustBeAssignable()
+ v.mustBe(Slice)
+ s := (*unsafeheader.Slice)(v.ptr)
+ if uint(n) > uint(s.Cap) {
+ panic("reflect: slice length out of range in SetLen")
+ }
+ s.Len = n
+}
+
+// SetCap sets v's capacity to n.
+// It panics if v's Kind is not Slice or if n is smaller than the length or
+// greater than the capacity of the slice.
+func (v Value) SetCap(n int) {
+ v.mustBeAssignable()
+ v.mustBe(Slice)
+ s := (*unsafeheader.Slice)(v.ptr)
+ if n < s.Len || n > s.Cap {
+ panic("reflect: slice capacity out of range in SetCap")
+ }
+ s.Cap = n
+}
+
+// SetMapIndex sets the element associated with key in the map v to elem.
+// It panics if v's Kind is not Map.
+// If elem is the zero Value, SetMapIndex deletes the key from the map.
+// Otherwise if v holds a nil map, SetMapIndex will panic.
+// As in Go, key's elem must be assignable to the map's key type,
+// and elem's value must be assignable to the map's elem type.
+func (v Value) SetMapIndex(key, elem Value) {
+ v.mustBe(Map)
+ v.mustBeExported()
+ key.mustBeExported()
+ tt := (*mapType)(unsafe.Pointer(v.typ))
+ key = key.assignTo("reflect.Value.SetMapIndex", tt.key, nil)
+ var k unsafe.Pointer
+ if key.flag&flagIndir != 0 {
+ k = key.ptr
+ } else {
+ k = unsafe.Pointer(&key.ptr)
+ }
+ if elem.typ == nil {
+ mapdelete(v.typ, v.pointer(), k)
+ return
+ }
+ elem.mustBeExported()
+ elem = elem.assignTo("reflect.Value.SetMapIndex", tt.elem, nil)
+ var e unsafe.Pointer
+ if elem.flag&flagIndir != 0 {
+ e = elem.ptr
+ } else {
+ e = unsafe.Pointer(&elem.ptr)
+ }
+ mapassign(v.typ, v.pointer(), k, e)
+}
+
+// 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) {
+ v.mustBeAssignable()
+ switch k := v.kind(); k {
+ default:
+ panic(&ValueError{"reflect.Value.SetUint", v.kind()})
+ case Uint:
+ *(*uint)(v.ptr) = uint(x)
+ case Uint8:
+ *(*uint8)(v.ptr) = uint8(x)
+ case Uint16:
+ *(*uint16)(v.ptr) = uint16(x)
+ case Uint32:
+ *(*uint32)(v.ptr) = uint32(x)
+ case Uint64:
+ *(*uint64)(v.ptr) = x
+ case Uintptr:
+ *(*uintptr)(v.ptr) = 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) {
+ v.mustBeAssignable()
+ v.mustBe(UnsafePointer)
+ *(*unsafe.Pointer)(v.ptr) = 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.mustBeAssignable()
+ v.mustBe(String)
+ *(*string)(v.ptr) = x
+}
+
+// Slice returns v[i:j].
+// It panics if v's Kind is not Array, Slice or String, or if v is an unaddressable array,
+// or if the indexes are out of bounds.
+func (v Value) Slice(i, j int) Value {
+ var (
+ cap int
+ typ *sliceType
+ base unsafe.Pointer
+ )
+ switch kind := v.kind(); kind {
+ default:
+ panic(&ValueError{"reflect.Value.Slice", v.kind()})
+
+ case Array:
+ if v.flag&flagAddr == 0 {
+ panic("reflect.Value.Slice: slice of unaddressable array")
+ }
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ cap = int(tt.len)
+ typ = (*sliceType)(unsafe.Pointer(tt.slice))
+ base = v.ptr
+
+ case Slice:
+ typ = (*sliceType)(unsafe.Pointer(v.typ))
+ s := (*unsafeheader.Slice)(v.ptr)
+ base = s.Data
+ cap = s.Cap
+
+ case String:
+ s := (*unsafeheader.String)(v.ptr)
+ if i < 0 || j < i || j > s.Len {
+ panic("reflect.Value.Slice: string slice index out of bounds")
+ }
+ var t unsafeheader.String
+ if i < s.Len {
+ t = unsafeheader.String{Data: arrayAt(s.Data, i, 1, "i < s.Len"), Len: j - i}
+ }
+ return Value{v.typ, unsafe.Pointer(&t), v.flag}
+ }
+
+ if i < 0 || j < i || j > cap {
+ panic("reflect.Value.Slice: slice index out of bounds")
+ }
+
+ // Declare slice so that gc can see the base pointer in it.
+ var x []unsafe.Pointer
+
+ // Reinterpret as *unsafeheader.Slice to edit.
+ s := (*unsafeheader.Slice)(unsafe.Pointer(&x))
+ s.Len = j - i
+ s.Cap = cap - i
+ if cap-i > 0 {
+ s.Data = arrayAt(base, i, typ.elem.Size(), "i < cap")
+ } else {
+ // do not advance pointer, to avoid pointing beyond end of slice
+ s.Data = base
+ }
+
+ fl := v.flag.ro() | flagIndir | flag(Slice)
+ return Value{typ.common(), unsafe.Pointer(&x), fl}
+}
+
+// Slice3 is the 3-index form of the slice operation: it returns v[i:j:k].
+// It panics if v's Kind is not Array or Slice, or if v is an unaddressable array,
+// or if the indexes are out of bounds.
+func (v Value) Slice3(i, j, k int) Value {
+ var (
+ cap int
+ typ *sliceType
+ base unsafe.Pointer
+ )
+ switch kind := v.kind(); kind {
+ default:
+ panic(&ValueError{"reflect.Value.Slice3", v.kind()})
+
+ case Array:
+ if v.flag&flagAddr == 0 {
+ panic("reflect.Value.Slice3: slice of unaddressable array")
+ }
+ tt := (*arrayType)(unsafe.Pointer(v.typ))
+ cap = int(tt.len)
+ typ = (*sliceType)(unsafe.Pointer(tt.slice))
+ base = v.ptr
+
+ case Slice:
+ typ = (*sliceType)(unsafe.Pointer(v.typ))
+ s := (*unsafeheader.Slice)(v.ptr)
+ base = s.Data
+ cap = s.Cap
+ }
+
+ if i < 0 || j < i || k < j || k > cap {
+ panic("reflect.Value.Slice3: slice index out of bounds")
+ }
+
+ // Declare slice so that the garbage collector
+ // can see the base pointer in it.
+ var x []unsafe.Pointer
+
+ // Reinterpret as *unsafeheader.Slice to edit.
+ s := (*unsafeheader.Slice)(unsafe.Pointer(&x))
+ s.Len = j - i
+ s.Cap = k - i
+ if k-i > 0 {
+ s.Data = arrayAt(base, i, typ.elem.Size(), "i < k <= cap")
+ } else {
+ // do not advance pointer, to avoid pointing beyond end of slice
+ s.Data = base
+ }
+
+ fl := v.flag.ro() | flagIndir | flag(Slice)
+ return Value{typ.common(), unsafe.Pointer(&x), fl}
+}
+
+// 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.
+// The fmt package treats Values specially. It does not call their String
+// method implicitly but instead prints the concrete values they hold.
+func (v Value) String() string {
+ switch k := v.kind(); k {
+ case Invalid:
+ return "<invalid Value>"
+ case String:
+ return *(*string)(v.ptr)
+ }
+ // If you call String on a reflect.Value of other type, it's better to
+ // print something than to panic. Useful in debugging.
+ return "<" + v.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 delivers a value, x is the transferred value and ok is true.
+// If the receive cannot finish without blocking, x is the zero Value and ok is false.
+// If the channel is closed, x is the zero value for the channel's element type and ok is false.
+func (v Value) TryRecv() (x Value, ok bool) {
+ v.mustBe(Chan)
+ v.mustBeExported()
+ return v.recv(true)
+}
+
+// TrySend attempts to send x on the channel v but will not block.
+// It panics if v's Kind is not Chan.
+// It reports whether the value was sent.
+// As in Go, x's value must be assignable to the channel's element type.
+func (v Value) TrySend(x Value) bool {
+ v.mustBe(Chan)
+ v.mustBeExported()
+ return v.send(x, true)
+}
+
+// Type returns v's type.
+func (v Value) Type() Type {
+ f := v.flag
+ if f == 0 {
+ panic(&ValueError{"reflect.Value.Type", Invalid})
+ }
+ 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 uint(i) >= uint(len(tt.methods)) {
+ panic("reflect: internal error: invalid method index")
+ }
+ m := &tt.methods[i]
+ return v.typ.typeOff(m.typ)
+ }
+ // Method on concrete type.
+ ms := v.typ.exportedMethods()
+ if uint(i) >= uint(len(ms)) {
+ panic("reflect: internal error: invalid method index")
+ }
+ m := ms[i]
+ return v.typ.typeOff(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 {
+ k := v.kind()
+ p := v.ptr
+ switch k {
+ case Uint:
+ return uint64(*(*uint)(p))
+ case Uint8:
+ return uint64(*(*uint8)(p))
+ case Uint16:
+ return uint64(*(*uint16)(p))
+ case Uint32:
+ return uint64(*(*uint32)(p))
+ case Uint64:
+ return *(*uint64)(p)
+ case Uintptr:
+ return uint64(*(*uintptr)(p))
+ }
+ panic(&ValueError{"reflect.Value.Uint", v.kind()})
+}
+
+//go:nocheckptr
+// This prevents inlining Value.UnsafeAddr when -d=checkptr is enabled,
+// which ensures cmd/compile can recognize unsafe.Pointer(v.UnsafeAddr())
+// and make an exception.
+
+// 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 {
+ // TODO: deprecate
+ if v.typ == nil {
+ panic(&ValueError{"reflect.Value.UnsafeAddr", Invalid})
+ }
+ if v.flag&flagAddr == 0 {
+ panic("reflect.Value.UnsafeAddr of unaddressable value")
+ }
+ return uintptr(v.ptr)
+}
+
+// StringHeader is the runtime representation of a string.
+// It cannot be used safely or portably and its representation may
+// change in a later release.
+// Moreover, the Data field is not sufficient to guarantee the data
+// it references will not be garbage collected, so programs must keep
+// a separate, correctly typed pointer to the underlying data.
+type StringHeader struct {
+ Data uintptr
+ Len int
+}
+
+// SliceHeader is the runtime representation of a slice.
+// It cannot be used safely or portably and its representation may
+// change in a later release.
+// Moreover, the Data field is not sufficient to guarantee the data
+// it references will not be garbage collected, so programs must keep
+// a separate, correctly typed pointer to the underlying data.
+type SliceHeader struct {
+ Data uintptr
+ Len int
+ Cap int
+}
+
+func typesMustMatch(what string, t1, t2 Type) {
+ if t1 != t2 {
+ panic(what + ": " + t1.String() + " != " + t2.String())
+ }
+}
+
+// arrayAt returns the i-th element of p,
+// an array whose elements are eltSize bytes wide.
+// The array pointed at by p must have at least i+1 elements:
+// it is invalid (but impossible to check here) to pass i >= len,
+// because then the result will point outside the array.
+// whySafe must explain why i < len. (Passing "i < len" is fine;
+// the benefit is to surface this assumption at the call site.)
+func arrayAt(p unsafe.Pointer, i int, eltSize uintptr, whySafe string) unsafe.Pointer {
+ return add(p, uintptr(i)*eltSize, "i < len")
+}
+
+// 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("reflect.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.
+// As in Go, each x's value must be assignable to the slice's element type.
+func Append(s Value, x ...Value) Value {
+ 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])
+ }
+ 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.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)
+ 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 have kind Slice or Array, and
+// dst and src must have the same element type.
+//
+// As a special case, src can have kind String if the element type of dst is kind Uint8.
+func Copy(dst, src Value) int {
+ dk := dst.kind()
+ if dk != Array && dk != Slice {
+ panic(&ValueError{"reflect.Copy", dk})
+ }
+ if dk == Array {
+ dst.mustBeAssignable()
+ }
+ dst.mustBeExported()
+
+ sk := src.kind()
+ var stringCopy bool
+ if sk != Array && sk != Slice {
+ stringCopy = sk == String && dst.typ.Elem().Kind() == Uint8
+ if !stringCopy {
+ panic(&ValueError{"reflect.Copy", sk})
+ }
+ }
+ src.mustBeExported()
+
+ de := dst.typ.Elem()
+ if !stringCopy {
+ se := src.typ.Elem()
+ typesMustMatch("reflect.Copy", de, se)
+ }
+
+ var ds, ss unsafeheader.Slice
+ if dk == Array {
+ ds.Data = dst.ptr
+ ds.Len = dst.Len()
+ ds.Cap = ds.Len
+ } else {
+ ds = *(*unsafeheader.Slice)(dst.ptr)
+ }
+ if sk == Array {
+ ss.Data = src.ptr
+ ss.Len = src.Len()
+ ss.Cap = ss.Len
+ } else if sk == Slice {
+ ss = *(*unsafeheader.Slice)(src.ptr)
+ } else {
+ sh := *(*unsafeheader.String)(src.ptr)
+ ss.Data = sh.Data
+ ss.Len = sh.Len
+ ss.Cap = sh.Len
+ }
+
+ return typedslicecopy(de.common(), ds, ss)
+}
+
+// A runtimeSelect is a single case passed to rselect.
+// This must match ../runtime/select.go:/runtimeSelect
+type runtimeSelect struct {
+ dir SelectDir // SelectSend, SelectRecv or SelectDefault
+ typ *rtype // channel type
+ ch unsafe.Pointer // channel
+ val unsafe.Pointer // ptr to data (SendDir) or ptr to receive buffer (RecvDir)
+}
+
+// rselect runs a select. It returns the index of the chosen case.
+// If the case was a receive, val is filled in with the received value.
+// The conventional OK bool indicates whether the receive corresponds
+// to a sent value.
+//go:noescape
+func rselect([]runtimeSelect) (chosen int, recvOK bool)
+
+// A SelectDir describes the communication direction of a select case.
+type SelectDir int
+
+// NOTE: These values must match ../runtime/select.go:/selectDir.
+
+const (
+ _ SelectDir = iota
+ SelectSend // case Chan <- Send
+ SelectRecv // case <-Chan:
+ SelectDefault // default
+)
+
+// A SelectCase describes a single case in a select operation.
+// The kind of case depends on Dir, the communication direction.
+//
+// If Dir is SelectDefault, the case represents a default case.
+// Chan and Send must be zero Values.
+//
+// If Dir is SelectSend, the case represents a send operation.
+// Normally Chan's underlying value must be a channel, and Send's underlying value must be
+// assignable to the channel's element type. As a special case, if Chan is a zero Value,
+// then the case is ignored, and the field Send will also be ignored and may be either zero
+// or non-zero.
+//
+// If Dir is SelectRecv, the case represents a receive operation.
+// Normally Chan's underlying value must be a channel and Send must be a zero Value.
+// If Chan is a zero Value, then the case is ignored, but Send must still be a zero Value.
+// When a receive operation is selected, the received Value is returned by Select.
+//
+type SelectCase struct {
+ Dir SelectDir // direction of case
+ Chan Value // channel to use (for send or receive)
+ Send Value // value to send (for send)
+}
+
+// Select executes a select operation described by the list of cases.
+// Like the Go select statement, it blocks until at least one of the cases
+// can proceed, makes a uniform pseudo-random choice,
+// and then executes that case. It returns the index of the chosen case
+// and, if that case was a receive operation, the value received and a
+// boolean indicating whether the value corresponds to a send on the channel
+// (as opposed to a zero value received because the channel is closed).
+// Select supports a maximum of 65536 cases.
+func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
+ if len(cases) > 65536 {
+ panic("reflect.Select: too many cases (max 65536)")
+ }
+ // NOTE: Do not trust that caller is not modifying cases data underfoot.
+ // The range is safe because the caller cannot modify our copy of the len
+ // and each iteration makes its own copy of the value c.
+ var runcases []runtimeSelect
+ if len(cases) > 4 {
+ // Slice is heap allocated due to runtime dependent capacity.
+ runcases = make([]runtimeSelect, len(cases))
+ } else {
+ // Slice can be stack allocated due to constant capacity.
+ runcases = make([]runtimeSelect, len(cases), 4)
+ }
+
+ haveDefault := false
+ for i, c := range cases {
+ rc := &runcases[i]
+ rc.dir = c.Dir
+ switch c.Dir {
+ default:
+ panic("reflect.Select: invalid Dir")
+
+ case SelectDefault: // default
+ if haveDefault {
+ panic("reflect.Select: multiple default cases")
+ }
+ haveDefault = true
+ if c.Chan.IsValid() {
+ panic("reflect.Select: default case has Chan value")
+ }
+ if c.Send.IsValid() {
+ panic("reflect.Select: default case has Send value")
+ }
+
+ case SelectSend:
+ ch := c.Chan
+ if !ch.IsValid() {
+ break
+ }
+ ch.mustBe(Chan)
+ ch.mustBeExported()
+ tt := (*chanType)(unsafe.Pointer(ch.typ))
+ if ChanDir(tt.dir)&SendDir == 0 {
+ panic("reflect.Select: SendDir case using recv-only channel")
+ }
+ rc.ch = ch.pointer()
+ rc.typ = &tt.rtype
+ v := c.Send
+ if !v.IsValid() {
+ panic("reflect.Select: SendDir case missing Send value")
+ }
+ v.mustBeExported()
+ v = v.assignTo("reflect.Select", tt.elem, nil)
+ if v.flag&flagIndir != 0 {
+ rc.val = v.ptr
+ } else {
+ rc.val = unsafe.Pointer(&v.ptr)
+ }
+
+ case SelectRecv:
+ if c.Send.IsValid() {
+ panic("reflect.Select: RecvDir case has Send value")
+ }
+ ch := c.Chan
+ if !ch.IsValid() {
+ break
+ }
+ ch.mustBe(Chan)
+ ch.mustBeExported()
+ tt := (*chanType)(unsafe.Pointer(ch.typ))
+ if ChanDir(tt.dir)&RecvDir == 0 {
+ panic("reflect.Select: RecvDir case using send-only channel")
+ }
+ rc.ch = ch.pointer()
+ rc.typ = &tt.rtype
+ rc.val = unsafe_New(tt.elem)
+ }
+ }
+
+ chosen, recvOK = rselect(runcases)
+ if runcases[chosen].dir == SelectRecv {
+ tt := (*chanType)(unsafe.Pointer(runcases[chosen].typ))
+ t := tt.elem
+ p := runcases[chosen].val
+ fl := flag(t.Kind())
+ if ifaceIndir(t) {
+ recv = Value{t, p, fl | flagIndir}
+ } else {
+ recv = Value{t, *(*unsafe.Pointer)(p), fl}
+ }
+ }
+ return chosen, recv, recvOK
+}
+
+/*
+ * constructors
+ */
+
+// implemented in package runtime
+func unsafe_New(*rtype) unsafe.Pointer
+func unsafe_NewArray(*rtype, int) unsafe.Pointer
+
+// 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")
+ }
+ if len < 0 {
+ panic("reflect.MakeSlice: negative len")
+ }
+ if cap < 0 {
+ panic("reflect.MakeSlice: negative cap")
+ }
+ if len > cap {
+ panic("reflect.MakeSlice: len > cap")
+ }
+
+ s := unsafeheader.Slice{Data: unsafe_NewArray(typ.Elem().(*rtype), cap), Len: len, Cap: cap}
+ return Value{typ.(*rtype), unsafe.Pointer(&s), flagIndir | flag(Slice)}
+}
+
+// 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("reflect.MakeChan: negative buffer size")
+ }
+ if typ.ChanDir() != BothDir {
+ panic("reflect.MakeChan: unidirectional channel type")
+ }
+ t := typ.(*rtype)
+ ch := makechan(t, buffer)
+ return Value{t, ch, flag(Chan)}
+}
+
+// MakeMap creates a new map with the specified type.
+func MakeMap(typ Type) Value {
+ return MakeMapWithSize(typ, 0)
+}
+
+// MakeMapWithSize creates a new map with the specified type
+// and initial space for approximately n elements.
+func MakeMapWithSize(typ Type, n int) Value {
+ if typ.Kind() != Map {
+ panic("reflect.MakeMapWithSize of non-map type")
+ }
+ t := typ.(*rtype)
+ m := makemap(t, n)
+ return Value{t, m, flag(Map)}
+}
+
+// Indirect returns the value that v points to.
+// If v is a nil pointer, Indirect returns a zero Value.
+// If v is not a pointer, Indirect returns v.
+func Indirect(v Value) Value {
+ if v.Kind() != Ptr {
+ return v
+ }
+ return v.Elem()
+}
+
+// ValueOf returns a new Value initialized to the concrete value
+// stored in the interface i. ValueOf(nil) returns the zero Value.
+func ValueOf(i interface{}) Value {
+ if i == nil {
+ return Value{}
+ }
+
+ // TODO: Maybe allow contents of a Value to live on the stack.
+ // For now we make the contents always escape to the heap. It
+ // makes life easier in a few places (see chanrecv/mapassign
+ // comment below).
+ escapes(i)
+
+ return unpackEface(i)
+}
+
+// Zero returns a Value representing the 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.
+// The returned value is neither addressable nor settable.
+func Zero(typ Type) Value {
+ if typ == nil {
+ panic("reflect: Zero(nil)")
+ }
+ t := typ.(*rtype)
+ fl := flag(t.Kind())
+ if ifaceIndir(t) {
+ var p unsafe.Pointer
+ if t.size <= maxZero {
+ p = unsafe.Pointer(&zeroVal[0])
+ } else {
+ p = unsafe_New(t)
+ }
+ return Value{t, p, fl | flagIndir}
+ }
+ return Value{t, nil, fl}
+}
+
+// must match declarations in runtime/map.go.
+const maxZero = 1024
+
+//go:linkname zeroVal runtime.zeroVal
+var zeroVal [maxZero]byte
+
+// New returns a Value representing a pointer to a new zero value
+// for the specified type. That is, the returned Value's Type is PtrTo(typ).
+func New(typ Type) Value {
+ if typ == nil {
+ panic("reflect: New(nil)")
+ }
+ t := typ.(*rtype)
+ ptr := unsafe_New(t)
+ fl := flag(Ptr)
+ return Value{t.ptrTo(), ptr, fl}
+}
+
+// NewAt returns a Value representing a pointer to a value of the
+// specified type, using p as that pointer.
+func NewAt(typ Type, p unsafe.Pointer) Value {
+ fl := flag(Ptr)
+ t := typ.(*rtype)
+ return Value{t.ptrTo(), p, fl}
+}
+
+// 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.
+// target must be initialized memory (or nil).
+func (v Value) assignTo(context string, dst *rtype, target unsafe.Pointer) Value {
+ if v.flag&flagMethod != 0 {
+ v = makeMethodValue(context, v)
+ }
+
+ switch {
+ case directlyAssignable(dst, v.typ):
+ // Overwrite type so that they match.
+ // Same memory layout, so no harm done.
+ fl := v.flag&(flagAddr|flagIndir) | v.flag.ro()
+ fl |= flag(dst.Kind())
+ return Value{dst, v.ptr, fl}
+
+ case implements(dst, v.typ):
+ if target == nil {
+ target = unsafe_New(dst)
+ }
+ if v.Kind() == Interface && v.IsNil() {
+ // A nil ReadWriter passed to nil Reader is OK,
+ // but using ifaceE2I below will panic.
+ // Avoid the panic by returning a nil dst (e.g., Reader) explicitly.
+ return Value{dst, nil, flag(Interface)}
+ }
+ x := valueInterface(v, false)
+ if dst.NumMethod() == 0 {
+ *(*interface{})(target) = x
+ } else {
+ ifaceE2I(dst, x, target)
+ }
+ return Value{dst, target, flagIndir | flag(Interface)}
+ }
+
+ // Failed.
+ panic(context + ": value of type " + v.typ.String() + " is not assignable to type " + dst.String())
+}
+
+// Convert returns the value v converted to type t.
+// If the usual Go conversion rules do not allow conversion
+// of the value v to type t, Convert panics.
+func (v Value) Convert(t Type) Value {
+ if v.flag&flagMethod != 0 {
+ v = makeMethodValue("Convert", v)
+ }
+ op := convertOp(t.common(), v.typ)
+ if op == nil {
+ panic("reflect.Value.Convert: value of type " + v.typ.String() + " cannot be converted to type " + t.String())
+ }
+ return op(v, t)
+}
+
+// convertOp returns the function to convert a value of type src
+// to a value of type dst. If the conversion is illegal, convertOp returns nil.
+func convertOp(dst, src *rtype) func(Value, Type) Value {
+ switch src.Kind() {
+ case Int, Int8, Int16, Int32, Int64:
+ switch dst.Kind() {
+ case Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+ return cvtInt
+ case Float32, Float64:
+ return cvtIntFloat
+ case String:
+ return cvtIntString
+ }
+
+ case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+ switch dst.Kind() {
+ case Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+ return cvtUint
+ case Float32, Float64:
+ return cvtUintFloat
+ case String:
+ return cvtUintString
+ }
+
+ case Float32, Float64:
+ switch dst.Kind() {
+ case Int, Int8, Int16, Int32, Int64:
+ return cvtFloatInt
+ case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+ return cvtFloatUint
+ case Float32, Float64:
+ return cvtFloat
+ }
+
+ case Complex64, Complex128:
+ switch dst.Kind() {
+ case Complex64, Complex128:
+ return cvtComplex
+ }
+
+ case String:
+ if dst.Kind() == Slice && dst.Elem().PkgPath() == "" {
+ switch dst.Elem().Kind() {
+ case Uint8:
+ return cvtStringBytes
+ case Int32:
+ return cvtStringRunes
+ }
+ }
+
+ case Slice:
+ if dst.Kind() == String && src.Elem().PkgPath() == "" {
+ switch src.Elem().Kind() {
+ case Uint8:
+ return cvtBytesString
+ case Int32:
+ return cvtRunesString
+ }
+ }
+
+ case Chan:
+ if dst.Kind() == Chan && specialChannelAssignability(dst, src) {
+ return cvtDirect
+ }
+ }
+
+ // dst and src have same underlying type.
+ if haveIdenticalUnderlyingType(dst, src, false) {
+ return cvtDirect
+ }
+
+ // dst and src are non-defined pointer types with same underlying base type.
+ if dst.Kind() == Ptr && dst.Name() == "" &&
+ src.Kind() == Ptr && src.Name() == "" &&
+ haveIdenticalUnderlyingType(dst.Elem().common(), src.Elem().common(), false) {
+ return cvtDirect
+ }
+
+ if implements(dst, src) {
+ if src.Kind() == Interface {
+ return cvtI2I
+ }
+ return cvtT2I
+ }
+
+ return nil
+}
+
+// makeInt returns a Value of type t equal to bits (possibly truncated),
+// where t is a signed or unsigned int type.
+func makeInt(f flag, bits uint64, t Type) Value {
+ typ := t.common()
+ ptr := unsafe_New(typ)
+ switch typ.size {
+ case 1:
+ *(*uint8)(ptr) = uint8(bits)
+ case 2:
+ *(*uint16)(ptr) = uint16(bits)
+ case 4:
+ *(*uint32)(ptr) = uint32(bits)
+ case 8:
+ *(*uint64)(ptr) = bits
+ }
+ return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
+}
+
+// makeFloat returns a Value of type t equal to v (possibly truncated to float32),
+// where t is a float32 or float64 type.
+func makeFloat(f flag, v float64, t Type) Value {
+ typ := t.common()
+ ptr := unsafe_New(typ)
+ switch typ.size {
+ case 4:
+ *(*float32)(ptr) = float32(v)
+ case 8:
+ *(*float64)(ptr) = v
+ }
+ return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
+}
+
+// makeFloat returns a Value of type t equal to v, where t is a float32 type.
+func makeFloat32(f flag, v float32, t Type) Value {
+ typ := t.common()
+ ptr := unsafe_New(typ)
+ *(*float32)(ptr) = v
+ return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
+}
+
+// makeComplex returns a Value of type t equal to v (possibly truncated to complex64),
+// where t is a complex64 or complex128 type.
+func makeComplex(f flag, v complex128, t Type) Value {
+ typ := t.common()
+ ptr := unsafe_New(typ)
+ switch typ.size {
+ case 8:
+ *(*complex64)(ptr) = complex64(v)
+ case 16:
+ *(*complex128)(ptr) = v
+ }
+ return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
+}
+
+func makeString(f flag, v string, t Type) Value {
+ ret := New(t).Elem()
+ ret.SetString(v)
+ ret.flag = ret.flag&^flagAddr | f
+ return ret
+}
+
+func makeBytes(f flag, v []byte, t Type) Value {
+ ret := New(t).Elem()
+ ret.SetBytes(v)
+ ret.flag = ret.flag&^flagAddr | f
+ return ret
+}
+
+func makeRunes(f flag, v []rune, t Type) Value {
+ ret := New(t).Elem()
+ ret.setRunes(v)
+ ret.flag = ret.flag&^flagAddr | f
+ return ret
+}
+
+// These conversion functions are returned by convertOp
+// for classes of conversions. For example, the first function, cvtInt,
+// takes any value v of signed int type and returns the value converted
+// to type t, where t is any signed or unsigned int type.
+
+// convertOp: intXX -> [u]intXX
+func cvtInt(v Value, t Type) Value {
+ return makeInt(v.flag.ro(), uint64(v.Int()), t)
+}
+
+// convertOp: uintXX -> [u]intXX
+func cvtUint(v Value, t Type) Value {
+ return makeInt(v.flag.ro(), v.Uint(), t)
+}
+
+// convertOp: floatXX -> intXX
+func cvtFloatInt(v Value, t Type) Value {
+ return makeInt(v.flag.ro(), uint64(int64(v.Float())), t)
+}
+
+// convertOp: floatXX -> uintXX
+func cvtFloatUint(v Value, t Type) Value {
+ return makeInt(v.flag.ro(), uint64(v.Float()), t)
+}
+
+// convertOp: intXX -> floatXX
+func cvtIntFloat(v Value, t Type) Value {
+ return makeFloat(v.flag.ro(), float64(v.Int()), t)
+}
+
+// convertOp: uintXX -> floatXX
+func cvtUintFloat(v Value, t Type) Value {
+ return makeFloat(v.flag.ro(), float64(v.Uint()), t)
+}
+
+// convertOp: floatXX -> floatXX
+func cvtFloat(v Value, t Type) Value {
+ if v.Type().Kind() == Float32 && t.Kind() == Float32 {
+ // Don't do any conversion if both types have underlying type float32.
+ // This avoids converting to float64 and back, which will
+ // convert a signaling NaN to a quiet NaN. See issue 36400.
+ return makeFloat32(v.flag.ro(), *(*float32)(v.ptr), t)
+ }
+ return makeFloat(v.flag.ro(), v.Float(), t)
+}
+
+// convertOp: complexXX -> complexXX
+func cvtComplex(v Value, t Type) Value {
+ return makeComplex(v.flag.ro(), v.Complex(), t)
+}
+
+// convertOp: intXX -> string
+func cvtIntString(v Value, t Type) Value {
+ s := "\uFFFD"
+ if x := v.Int(); int64(rune(x)) == x {
+ s = string(rune(x))
+ }
+ return makeString(v.flag.ro(), s, t)
+}
+
+// convertOp: uintXX -> string
+func cvtUintString(v Value, t Type) Value {
+ s := "\uFFFD"
+ if x := v.Uint(); uint64(rune(x)) == x {
+ s = string(rune(x))
+ }
+ return makeString(v.flag.ro(), s, t)
+}
+
+// convertOp: []byte -> string
+func cvtBytesString(v Value, t Type) Value {
+ return makeString(v.flag.ro(), string(v.Bytes()), t)
+}
+
+// convertOp: string -> []byte
+func cvtStringBytes(v Value, t Type) Value {
+ return makeBytes(v.flag.ro(), []byte(v.String()), t)
+}
+
+// convertOp: []rune -> string
+func cvtRunesString(v Value, t Type) Value {
+ return makeString(v.flag.ro(), string(v.runes()), t)
+}
+
+// convertOp: string -> []rune
+func cvtStringRunes(v Value, t Type) Value {
+ return makeRunes(v.flag.ro(), []rune(v.String()), t)
+}
+
+// convertOp: direct copy
+func cvtDirect(v Value, typ Type) Value {
+ f := v.flag
+ t := typ.common()
+ ptr := v.ptr
+ if f&flagAddr != 0 {
+ // indirect, mutable word - make a copy
+ c := unsafe_New(t)
+ typedmemmove(t, c, ptr)
+ ptr = c
+ f &^= flagAddr
+ }
+ return Value{t, ptr, v.flag.ro() | f} // v.flag.ro()|f == f?
+}
+
+// convertOp: concrete -> interface
+func cvtT2I(v Value, typ Type) Value {
+ target := unsafe_New(typ.common())
+ x := valueInterface(v, false)
+ if typ.NumMethod() == 0 {
+ *(*interface{})(target) = x
+ } else {
+ ifaceE2I(typ.(*rtype), x, target)
+ }
+ return Value{typ.common(), target, v.flag.ro() | flagIndir | flag(Interface)}
+}
+
+// convertOp: interface -> interface
+func cvtI2I(v Value, typ Type) Value {
+ if v.IsNil() {
+ ret := Zero(typ)
+ ret.flag |= v.flag.ro()
+ return ret
+ }
+ return cvtT2I(v.Elem(), typ)
+}
+
+// implemented in ../runtime
+func chancap(ch unsafe.Pointer) int
+func chanclose(ch unsafe.Pointer)
+func chanlen(ch unsafe.Pointer) int
+
+// Note: some of the noescape annotations below are technically a lie,
+// but safe in the context of this package. Functions like chansend
+// and mapassign don't escape the referent, but may escape anything
+// the referent points to (they do shallow copies of the referent).
+// It is safe in this package because the referent may only point
+// to something a Value may point to, and that is always in the heap
+// (due to the escapes() call in ValueOf).
+
+//go:noescape
+func chanrecv(ch unsafe.Pointer, nb bool, val unsafe.Pointer) (selected, received bool)
+
+//go:noescape
+func chansend(ch unsafe.Pointer, val unsafe.Pointer, nb bool) bool
+
+func makechan(typ *rtype, size int) (ch unsafe.Pointer)
+func makemap(t *rtype, cap int) (m unsafe.Pointer)
+
+//go:noescape
+func mapaccess(t *rtype, m unsafe.Pointer, key unsafe.Pointer) (val unsafe.Pointer)
+
+//go:noescape
+func mapassign(t *rtype, m unsafe.Pointer, key, val unsafe.Pointer)
+
+//go:noescape
+func mapdelete(t *rtype, m unsafe.Pointer, key unsafe.Pointer)
+
+// m escapes into the return value, but the caller of mapiterinit
+// doesn't let the return value escape.
+//go:noescape
+func mapiterinit(t *rtype, m unsafe.Pointer) unsafe.Pointer
+
+//go:noescape
+func mapiterkey(it unsafe.Pointer) (key unsafe.Pointer)
+
+//go:noescape
+func mapiterelem(it unsafe.Pointer) (elem unsafe.Pointer)
+
+//go:noescape
+func mapiternext(it unsafe.Pointer)
+
+//go:noescape
+func maplen(m unsafe.Pointer) int
+
+// call calls fn with a copy of the n argument bytes pointed at by arg.
+// After fn returns, reflectcall copies n-retoffset result bytes
+// back into arg+retoffset before returning. If copying result bytes back,
+// the caller must pass the argument frame type as argtype, so that
+// call can execute appropriate write barriers during the copy.
+//
+//go:linkname call runtime.reflectcall
+func call(argtype *rtype, fn, arg unsafe.Pointer, n uint32, retoffset uint32)
+
+func ifaceE2I(t *rtype, src interface{}, dst unsafe.Pointer)
+
+// memmove copies size bytes to dst from src. No write barriers are used.
+//go:noescape
+func memmove(dst, src unsafe.Pointer, size uintptr)
+
+// typedmemmove copies a value of type t to dst from src.
+//go:noescape
+func typedmemmove(t *rtype, dst, src unsafe.Pointer)
+
+// typedmemmovepartial is like typedmemmove but assumes that
+// dst and src point off bytes into the value and only copies size bytes.
+//go:noescape
+func typedmemmovepartial(t *rtype, dst, src unsafe.Pointer, off, size uintptr)
+
+// typedmemclr zeros the value at ptr of type t.
+//go:noescape
+func typedmemclr(t *rtype, ptr unsafe.Pointer)
+
+// typedmemclrpartial is like typedmemclr but assumes that
+// dst points off bytes into the value and only clears size bytes.
+//go:noescape
+func typedmemclrpartial(t *rtype, ptr unsafe.Pointer, off, size uintptr)
+
+// typedslicecopy copies a slice of elemType values from src to dst,
+// returning the number of elements copied.
+//go:noescape
+func typedslicecopy(elemType *rtype, dst, src unsafeheader.Slice) int
+
+//go:noescape
+func typehash(t *rtype, p unsafe.Pointer, h uintptr) uintptr
+
+// 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{}
+}