2381 lines
66 KiB
Go
2381 lines
66 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package reflect
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import (
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"math"
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"runtime"
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"unsafe"
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)
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const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
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const cannotSet = "cannot set value obtained from unexported struct field"
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// Value is the reflection interface to a Go value.
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//
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// Not all methods apply to all kinds of values. Restrictions,
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// if any, are noted in the documentation for each method.
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// Use the Kind method to find out the kind of value before
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// calling kind-specific methods. Calling a method
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// inappropriate to the kind of type causes a run time panic.
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//
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// The zero Value represents no value.
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// Its IsValid method returns false, its Kind method returns Invalid,
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// its String method returns "<invalid Value>", and all other methods panic.
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// Most functions and methods never return an invalid value.
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// If one does, its documentation states the conditions explicitly.
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//
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// A Value can be used concurrently by multiple goroutines provided that
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// the underlying Go value can be used concurrently for the equivalent
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// direct operations.
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//
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// Using == on two Values does not compare the underlying values
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// they represent, but rather the contents of the Value structs.
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// To compare two Values, compare the results of the Interface method.
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type Value struct {
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// typ holds the type of the value represented by a Value.
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typ *rtype
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// Pointer-valued data or, if flagIndir is set, pointer to data.
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// Valid when either flagIndir is set or typ.pointers() is true.
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ptr unsafe.Pointer
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// flag holds metadata about the value.
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// The lowest bits are flag bits:
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// - flagStickyRO: obtained via unexported not embedded field, so read-only
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// - flagEmbedRO: obtained via unexported embedded field, so read-only
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// - flagIndir: val holds a pointer to the data
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// - flagAddr: v.CanAddr is true (implies flagIndir)
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// - flagMethod: v is a method value.
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// The next five bits give the Kind of the value.
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// This repeats typ.Kind() except for method values.
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// The remaining 23+ bits give a method number for method values.
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// If flag.kind() != Func, code can assume that flagMethod is unset.
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// If ifaceIndir(typ), code can assume that flagIndir is set.
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flag
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// A method value represents a curried method invocation
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// like r.Read for some receiver r. The typ+val+flag bits describe
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// the receiver r, but the flag's Kind bits say Func (methods are
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// functions), and the top bits of the flag give the method number
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// in r's type's method table.
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}
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type flag uintptr
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const (
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flagKindWidth = 5 // there are 27 kinds
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flagKindMask flag = 1<<flagKindWidth - 1
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flagStickyRO flag = 1 << 5
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flagEmbedRO flag = 1 << 6
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flagIndir flag = 1 << 7
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flagAddr flag = 1 << 8
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flagMethod flag = 1 << 9
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flagMethodFn flag = 1 << 10 // gccgo: first fn parameter is always pointer
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flagMethodShift = 11
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flagRO flag = flagStickyRO | flagEmbedRO
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)
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func (f flag) kind() Kind {
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return Kind(f & flagKindMask)
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}
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// pointer returns the underlying pointer represented by v.
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// v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
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func (v Value) pointer() unsafe.Pointer {
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if v.typ.size != ptrSize || !v.typ.pointers() {
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panic("can't call pointer on a non-pointer Value")
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}
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if v.flag&flagIndir != 0 {
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return *(*unsafe.Pointer)(v.ptr)
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}
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return v.ptr
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}
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// packEface converts v to the empty interface.
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func packEface(v Value) interface{} {
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t := v.typ
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var i interface{}
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e := (*emptyInterface)(unsafe.Pointer(&i))
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// First, fill in the data portion of the interface.
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switch {
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case ifaceIndir(t):
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if v.flag&flagIndir == 0 {
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panic("bad indir")
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}
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// Value is indirect, and so is the interface we're making.
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ptr := v.ptr
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if v.flag&flagAddr != 0 {
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// TODO: pass safe boolean from valueInterface so
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// we don't need to copy if safe==true?
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c := unsafe_New(t)
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typedmemmove(t, c, ptr)
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ptr = c
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}
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e.word = ptr
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case v.flag&flagIndir != 0:
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// Value is indirect, but interface is direct. We need
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// to load the data at v.ptr into the interface data word.
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e.word = *(*unsafe.Pointer)(v.ptr)
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default:
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// Value is direct, and so is the interface.
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e.word = v.ptr
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}
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// Now, fill in the type portion. We're very careful here not
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// to have any operation between the e.word and e.typ assignments
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// that would let the garbage collector observe the partially-built
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// interface value.
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e.typ = t
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return i
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}
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// unpackEface converts the empty interface i to a Value.
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func unpackEface(i interface{}) Value {
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e := (*emptyInterface)(unsafe.Pointer(&i))
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// NOTE: don't read e.word until we know whether it is really a pointer or not.
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t := e.typ
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if t == nil {
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return Value{}
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}
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f := flag(t.Kind())
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if ifaceIndir(t) {
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f |= flagIndir
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}
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return Value{t, unsafe.Pointer(e.word), f}
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}
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// A ValueError occurs when a Value method is invoked on
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// a Value that does not support it. Such cases are documented
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// in the description of each method.
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type ValueError struct {
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Method string
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Kind Kind
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}
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func (e *ValueError) Error() string {
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if e.Kind == 0 {
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return "reflect: call of " + e.Method + " on zero Value"
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}
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return "reflect: call of " + e.Method + " on " + e.Kind.String() + " Value"
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}
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// methodName returns the name of the calling method,
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// assumed to be two stack frames above.
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func methodName() string {
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pc, _, _, _ := runtime.Caller(2)
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f := runtime.FuncForPC(pc)
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if f == nil {
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return "unknown method"
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}
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return f.Name()
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}
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// emptyInterface is the header for an interface{} value.
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type emptyInterface struct {
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typ *rtype
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word unsafe.Pointer
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}
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// nonEmptyInterface is the header for a interface value with methods.
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type nonEmptyInterface struct {
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// see ../runtime/iface.go:/Itab
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itab *struct {
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typ *rtype // dynamic concrete type
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fun [100000]unsafe.Pointer // method table
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}
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word unsafe.Pointer
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}
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// mustBe panics if f's kind is not expected.
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// Making this a method on flag instead of on Value
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// (and embedding flag in Value) means that we can write
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// the very clear v.mustBe(Bool) and have it compile into
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// v.flag.mustBe(Bool), which will only bother to copy the
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// single important word for the receiver.
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func (f flag) mustBe(expected Kind) {
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if f.kind() != expected {
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panic(&ValueError{methodName(), f.kind()})
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}
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}
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// mustBeExported panics if f records that the value was obtained using
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// an unexported field.
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func (f flag) mustBeExported() {
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if f == 0 {
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panic(&ValueError{methodName(), 0})
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}
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if f&flagRO != 0 {
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panic("reflect: " + methodName() + " using value obtained using unexported field")
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}
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}
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// mustBeAssignable panics if f records that the value is not assignable,
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// which is to say that either it was obtained using an unexported field
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// or it is not addressable.
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func (f flag) mustBeAssignable() {
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if f == 0 {
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panic(&ValueError{methodName(), Invalid})
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}
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// Assignable if addressable and not read-only.
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if f&flagRO != 0 {
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panic("reflect: " + methodName() + " using value obtained using unexported field")
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}
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if f&flagAddr == 0 {
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panic("reflect: " + methodName() + " using unaddressable value")
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}
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}
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// Addr returns a pointer value representing the address of v.
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// It panics if CanAddr() returns false.
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// Addr is typically used to obtain a pointer to a struct field
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// or slice element in order to call a method that requires a
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// pointer receiver.
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func (v Value) Addr() Value {
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if v.flag&flagAddr == 0 {
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panic("reflect.Value.Addr of unaddressable value")
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}
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return Value{v.typ.ptrTo(), v.ptr, (v.flag & flagRO) | flag(Ptr)}
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}
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// Bool returns v's underlying value.
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// It panics if v's kind is not Bool.
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func (v Value) Bool() bool {
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v.mustBe(Bool)
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return *(*bool)(v.ptr)
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}
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// Bytes returns v's underlying value.
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// It panics if v's underlying value is not a slice of bytes.
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func (v Value) Bytes() []byte {
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v.mustBe(Slice)
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if v.typ.Elem().Kind() != Uint8 {
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panic("reflect.Value.Bytes of non-byte slice")
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}
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// Slice is always bigger than a word; assume flagIndir.
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return *(*[]byte)(v.ptr)
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}
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// runes returns v's underlying value.
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// It panics if v's underlying value is not a slice of runes (int32s).
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func (v Value) runes() []rune {
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v.mustBe(Slice)
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if v.typ.Elem().Kind() != Int32 {
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panic("reflect.Value.Bytes of non-rune slice")
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}
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// Slice is always bigger than a word; assume flagIndir.
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return *(*[]rune)(v.ptr)
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}
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// CanAddr reports whether the value's address can be obtained with Addr.
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// Such values are called addressable. A value is addressable if it is
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// an element of a slice, an element of an addressable array,
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// a field of an addressable struct, or the result of dereferencing a pointer.
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// If CanAddr returns false, calling Addr will panic.
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func (v Value) CanAddr() bool {
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return v.flag&flagAddr != 0
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}
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// CanSet reports whether the value of v can be changed.
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// A Value can be changed only if it is addressable and was not
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// obtained by the use of unexported struct fields.
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// If CanSet returns false, calling Set or any type-specific
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// setter (e.g., SetBool, SetInt) will panic.
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func (v Value) CanSet() bool {
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return v.flag&(flagAddr|flagRO) == flagAddr
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}
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// Call calls the function v with the input arguments in.
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// For example, if len(in) == 3, v.Call(in) represents the Go call v(in[0], in[1], in[2]).
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// Call panics if v's Kind is not Func.
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// It returns the output results as Values.
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// As in Go, each input argument must be assignable to the
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// type of the function's corresponding input parameter.
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// If v is a variadic function, Call creates the variadic slice parameter
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// itself, copying in the corresponding values.
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func (v Value) Call(in []Value) []Value {
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v.mustBe(Func)
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v.mustBeExported()
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return v.call("Call", in)
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}
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// CallSlice calls the variadic function v with the input arguments in,
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// assigning the slice in[len(in)-1] to v's final variadic argument.
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// For example, if len(in) == 3, v.CallSlice(in) represents the Go call v(in[0], in[1], in[2]...).
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// CallSlice panics if v's Kind is not Func or if v is not variadic.
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// It returns the output results as Values.
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// As in Go, each input argument must be assignable to the
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// type of the function's corresponding input parameter.
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func (v Value) CallSlice(in []Value) []Value {
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v.mustBe(Func)
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v.mustBeExported()
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return v.call("CallSlice", in)
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}
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var callGC bool // for testing; see TestCallMethodJump
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func (v Value) call(op string, in []Value) []Value {
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// Get function pointer, type.
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t := v.typ
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var (
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fn unsafe.Pointer
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rcvr Value
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)
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if v.flag&flagMethod != 0 {
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rcvr = v
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_, t, fn = methodReceiver(op, v, int(v.flag)>>flagMethodShift)
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} else if v.flag&flagIndir != 0 {
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fn = *(*unsafe.Pointer)(v.ptr)
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} else {
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fn = v.ptr
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}
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if fn == nil {
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panic("reflect.Value.Call: call of nil function")
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}
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isSlice := op == "CallSlice"
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n := t.NumIn()
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if isSlice {
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if !t.IsVariadic() {
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panic("reflect: CallSlice of non-variadic function")
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}
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if len(in) < n {
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panic("reflect: CallSlice with too few input arguments")
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}
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if len(in) > n {
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panic("reflect: CallSlice with too many input arguments")
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}
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} else {
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if t.IsVariadic() {
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n--
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}
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if len(in) < n {
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panic("reflect: Call with too few input arguments")
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}
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if !t.IsVariadic() && len(in) > n {
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panic("reflect: Call with too many input arguments")
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}
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}
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for _, x := range in {
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if x.Kind() == Invalid {
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panic("reflect: " + op + " using zero Value argument")
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}
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}
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for i := 0; i < n; i++ {
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if xt, targ := in[i].Type(), t.In(i); !xt.AssignableTo(targ) {
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panic("reflect: " + op + " using " + xt.String() + " as type " + targ.String())
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}
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}
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if !isSlice && t.IsVariadic() {
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// prepare slice for remaining values
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m := len(in) - n
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slice := MakeSlice(t.In(n), m, m)
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elem := t.In(n).Elem()
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for i := 0; i < m; i++ {
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x := in[n+i]
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if xt := x.Type(); !xt.AssignableTo(elem) {
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panic("reflect: cannot use " + xt.String() + " as type " + elem.String() + " in " + op)
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}
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slice.Index(i).Set(x)
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}
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origIn := in
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in = make([]Value, n+1)
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copy(in[:n], origIn)
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in[n] = slice
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}
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nin := len(in)
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if nin != t.NumIn() {
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panic("reflect.Value.Call: wrong argument count")
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}
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nout := t.NumOut()
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if v.flag&flagMethod != 0 {
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nin++
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}
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firstPointer := len(in) > 0 && t.In(0).Kind() != Ptr && v.flag&flagMethodFn != 0
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params := make([]unsafe.Pointer, nin)
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off := 0
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if v.flag&flagMethod != 0 {
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// Hard-wired first argument.
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p := new(unsafe.Pointer)
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if rcvr.typ.Kind() == Interface {
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*p = unsafe.Pointer((*nonEmptyInterface)(v.ptr).word)
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} else if rcvr.typ.Kind() == Ptr || rcvr.typ.Kind() == UnsafePointer {
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*p = rcvr.pointer()
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} else {
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*p = rcvr.ptr
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}
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params[0] = unsafe.Pointer(p)
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off = 1
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}
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for i, pv := range in {
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pv.mustBeExported()
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targ := t.In(i).(*rtype)
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pv = pv.assignTo("reflect.Value.Call", targ, nil)
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if pv.flag&flagIndir == 0 {
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p := new(unsafe.Pointer)
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*p = pv.ptr
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params[off] = unsafe.Pointer(p)
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} else {
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params[off] = pv.ptr
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}
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if i == 0 && firstPointer {
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p := new(unsafe.Pointer)
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*p = params[off]
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params[off] = unsafe.Pointer(p)
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}
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off++
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}
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ret := make([]Value, nout)
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results := make([]unsafe.Pointer, nout)
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for i := 0; i < nout; i++ {
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v := New(t.Out(i))
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results[i] = unsafe.Pointer(v.Pointer())
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ret[i] = Indirect(v)
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}
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var pp *unsafe.Pointer
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if len(params) > 0 {
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pp = ¶ms[0]
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}
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var pr *unsafe.Pointer
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if len(results) > 0 {
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pr = &results[0]
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}
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call(t, fn, v.flag&flagMethod != 0, firstPointer, pp, pr)
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// For testing; see TestCallMethodJump.
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if callGC {
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runtime.GC()
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}
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return ret
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}
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|
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// methodReceiver returns information about the receiver
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// described by v. The Value v may or may not have the
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// flagMethod bit set, so the kind cached in v.flag should
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// not be used.
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// The return value rcvrtype gives the method's actual receiver type.
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// The return value t gives the method type signature (without the receiver).
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// The return value fn is a pointer to the method code.
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func methodReceiver(op string, v Value, methodIndex int) (rcvrtype, t *rtype, fn unsafe.Pointer) {
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i := methodIndex
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if v.typ.Kind() == Interface {
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tt := (*interfaceType)(unsafe.Pointer(v.typ))
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if uint(i) >= uint(len(tt.methods)) {
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panic("reflect: internal error: invalid method index")
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}
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m := &tt.methods[i]
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if m.pkgPath != nil {
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panic("reflect: " + op + " of unexported method")
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}
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iface := (*nonEmptyInterface)(v.ptr)
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if iface.itab == nil {
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panic("reflect: " + op + " of method on nil interface value")
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}
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rcvrtype = iface.itab.typ
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fn = unsafe.Pointer(&iface.itab.fun[i])
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t = m.typ
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} else {
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rcvrtype = v.typ
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ut := v.typ.uncommon()
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if ut == nil || uint(i) >= uint(len(ut.methods)) {
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panic("reflect: internal error: invalid method index")
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}
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m := &ut.methods[i]
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if m.pkgPath != nil {
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panic("reflect: " + op + " of unexported method")
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}
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fn = unsafe.Pointer(&m.tfn)
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t = m.mtyp
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}
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return
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}
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|
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// v is a method receiver. Store at p the word which is used to
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// encode that receiver at the start of the argument list.
|
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// Reflect uses the "interface" calling convention for
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// methods, which always uses one word to record the receiver.
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|
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) = unsafe.Pointer(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)
|
|
}
|
|
|
|
// 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 int(chancap(v.pointer()))
|
|
case Slice:
|
|
// Slice is always bigger than a word; assume flagIndir.
|
|
return (*sliceHeader)(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 & flagRO
|
|
}
|
|
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.pkgPath != nil {
|
|
if field.name == nil {
|
|
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 okay.
|
|
ptr := unsafe.Pointer(uintptr(v.ptr) + field.offset)
|
|
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 okay.
|
|
val := unsafe.Pointer(uintptr(v.ptr) + offset)
|
|
fl := v.flag&(flagRO|flagIndir|flagAddr) | 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 := (*sliceHeader)(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)
|
|
fl := flagAddr | flagIndir | v.flag&flagRO | flag(typ.Kind())
|
|
return Value{typ, val, fl}
|
|
|
|
case String:
|
|
s := (*stringHeader)(v.ptr)
|
|
if uint(i) >= uint(s.Len) {
|
|
panic("reflect: string index out of range")
|
|
}
|
|
p := arrayAt(s.Data, i, 1)
|
|
fl := v.flag&flagRO | 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(*(*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", 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 v.flag&flagMethod != 0 {
|
|
v = makeMethodValue("Interface", v)
|
|
}
|
|
|
|
if v.flag&flagMethodFn != 0 {
|
|
if v.typ.Kind() != Func {
|
|
panic("reflect: MethodFn of non-Func")
|
|
}
|
|
ft := (*funcType)(unsafe.Pointer(v.typ))
|
|
if ft.in[0].Kind() != Ptr {
|
|
v = makeValueMethod(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:
|
|
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
|
|
}
|
|
|
|
// 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 (*sliceHeader)(v.ptr).Len
|
|
case String:
|
|
// String is bigger than a word; assume flagIndir.
|
|
return (*stringHeader)(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) & flagRO
|
|
fl |= flag(typ.Kind())
|
|
if ifaceIndir(typ) {
|
|
// Copy result so future changes to the map
|
|
// won't change the underlying value.
|
|
c := unsafe_New(typ)
|
|
typedmemmove(typ, c, e)
|
|
return Value{typ, c, fl | flagIndir}
|
|
} else {
|
|
return Value{typ, *(*unsafe.Pointer)(e), fl}
|
|
}
|
|
}
|
|
|
|
// 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&flagRO | 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
|
|
}
|
|
if ifaceIndir(keyType) {
|
|
// Copy result so future changes to the map
|
|
// won't change the underlying value.
|
|
c := unsafe_New(keyType)
|
|
typedmemmove(keyType, c, key)
|
|
a[i] = Value{keyType, c, fl | flagIndir}
|
|
} else {
|
|
a[i] = Value{keyType, *(*unsafe.Pointer)(key), fl}
|
|
}
|
|
mapiternext(it)
|
|
}
|
|
return a[:i]
|
|
}
|
|
|
|
// 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 & (flagStickyRO | flagIndir) // Clear flagEmbedRO
|
|
fl |= flag(Func)
|
|
fl |= flag(i)<<flagMethodShift | flagMethod
|
|
return Value{v.typ, v.ptr, fl}
|
|
}
|
|
|
|
// NumMethod returns the number of 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()})
|
|
}
|
|
|
|
// 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 Chan, Map, Ptr, UnsafePointer:
|
|
return uintptr(v.pointer())
|
|
case Func:
|
|
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.typ, 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.typ, 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 {
|
|
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 := (*sliceHeader)(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 := (*sliceHeader)(v.ptr)
|
|
if n < int(s.Len) || n > int(s.Cap) {
|
|
panic("reflect: slice capacity out of range in SetCap")
|
|
}
|
|
s.Cap = n
|
|
}
|
|
|
|
// SetMapIndex sets the value associated with key in the map v to val.
|
|
// It panics if v's Kind is not Map.
|
|
// If val is the zero Value, SetMapIndex deletes the key from the map.
|
|
// Otherwise if v holds a nil map, SetMapIndex will panic.
|
|
// 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) {
|
|
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 val.typ == nil {
|
|
mapdelete(v.typ, v.pointer(), k)
|
|
return
|
|
}
|
|
val.mustBeExported()
|
|
val = val.assignTo("reflect.Value.SetMapIndex", tt.elem, nil)
|
|
var e unsafe.Pointer
|
|
if val.flag&flagIndir != 0 {
|
|
e = val.ptr
|
|
} else {
|
|
e = unsafe.Pointer(&val.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 := (*sliceHeader)(v.ptr)
|
|
base = unsafe.Pointer(s.Data)
|
|
cap = s.Cap
|
|
|
|
case String:
|
|
s := (*stringHeader)(v.ptr)
|
|
if i < 0 || j < i || j > s.Len {
|
|
panic("reflect.Value.Slice: string slice index out of bounds")
|
|
}
|
|
t := stringHeader{arrayAt(s.Data, i, 1), 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 *sliceHeader to edit.
|
|
s := (*sliceHeader)(unsafe.Pointer(&x))
|
|
s.Len = j - i
|
|
s.Cap = cap - i
|
|
if cap-i > 0 {
|
|
s.Data = arrayAt(base, i, typ.elem.Size())
|
|
} else {
|
|
// do not advance pointer, to avoid pointing beyond end of slice
|
|
s.Data = base
|
|
}
|
|
|
|
fl := v.flag&flagRO | 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 := (*sliceHeader)(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 *sliceHeader to edit.
|
|
s := (*sliceHeader)(unsafe.Pointer(&x))
|
|
s.Len = j - i
|
|
s.Cap = k - i
|
|
if k-i > 0 {
|
|
s.Data = arrayAt(base, i, typ.elem.Size())
|
|
} else {
|
|
// do not advance pointer, to avoid pointing beyond end of slice
|
|
s.Data = base
|
|
}
|
|
|
|
fl := v.flag&flagRO | 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 toType(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 toType(m.typ)
|
|
}
|
|
// Method on concrete type.
|
|
ut := v.typ.uncommon()
|
|
if ut == nil || uint(i) >= uint(len(ut.methods)) {
|
|
panic("reflect: internal error: invalid method index")
|
|
}
|
|
m := &ut.methods[i]
|
|
return toType(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(*(*uint64)(p))
|
|
case Uintptr:
|
|
return uint64(*(*uintptr)(p))
|
|
}
|
|
panic(&ValueError{"reflect.Value.Uint", v.kind()})
|
|
}
|
|
|
|
// 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
|
|
}
|
|
|
|
// stringHeader is a safe version of StringHeader used within this package.
|
|
type stringHeader struct {
|
|
Data unsafe.Pointer
|
|
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
|
|
}
|
|
|
|
// sliceHeader is a safe version of SliceHeader used within this package.
|
|
type sliceHeader struct {
|
|
Data unsafe.Pointer
|
|
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, a C-array whose elements are
|
|
// eltSize wide (in bytes).
|
|
func arrayAt(p unsafe.Pointer, i int, eltSize uintptr) unsafe.Pointer {
|
|
return unsafe.Pointer(uintptr(p) + uintptr(i)*eltSize)
|
|
}
|
|
|
|
// 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.
|
|
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()
|
|
if sk != Array && sk != Slice {
|
|
panic(&ValueError{"reflect.Copy", sk})
|
|
}
|
|
src.mustBeExported()
|
|
|
|
de := dst.typ.Elem()
|
|
se := src.typ.Elem()
|
|
typesMustMatch("reflect.Copy", de, se)
|
|
|
|
var ds, ss sliceHeader
|
|
if dk == Array {
|
|
ds.Data = dst.ptr
|
|
ds.Len = dst.Len()
|
|
ds.Cap = ds.Len
|
|
} else {
|
|
ds = *(*sliceHeader)(dst.ptr)
|
|
}
|
|
if sk == Array {
|
|
ss.Data = src.ptr
|
|
ss.Len = src.Len()
|
|
ss.Cap = ss.Len
|
|
} else {
|
|
ss = *(*sliceHeader)(src.ptr)
|
|
}
|
|
|
|
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 uintptr // 0, SendDir, or RecvDir
|
|
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).
|
|
func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
|
|
// 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.
|
|
runcases := make([]runtimeSelect, len(cases))
|
|
haveDefault := false
|
|
for i, c := range cases {
|
|
rc := &runcases[i]
|
|
rc.dir = uintptr(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 == uintptr(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 := sliceHeader{unsafe_NewArray(typ.Elem().(*rtype), cap), len, cap}
|
|
return Value{typ.common(), 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")
|
|
}
|
|
ch := makechan(typ.(*rtype), uint64(buffer))
|
|
return Value{typ.common(), unsafe.Pointer(&ch), flag(Chan) | flagIndir}
|
|
}
|
|
|
|
// 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")
|
|
}
|
|
m := makemap(typ.(*rtype))
|
|
return Value{typ.common(), unsafe.Pointer(&m), flag(Map) | flagIndir}
|
|
}
|
|
|
|
// 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(rsc): Eliminate this terrible hack.
|
|
// In the call to unpackEface, i.typ doesn't escape,
|
|
// and i.word is an integer. So it looks like
|
|
// i doesn't escape. But really it does,
|
|
// because i.word is actually a pointer.
|
|
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.common()
|
|
fl := flag(t.Kind())
|
|
if ifaceIndir(t) {
|
|
return Value{t, unsafe_New(typ.(*rtype)), fl | flagIndir}
|
|
}
|
|
return Value{t, nil, fl}
|
|
}
|
|
|
|
// 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)")
|
|
}
|
|
ptr := unsafe_New(typ.(*rtype))
|
|
fl := flag(Ptr)
|
|
return Value{typ.common().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)
|
|
return Value{typ.common().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.
|
|
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.
|
|
v.typ = dst
|
|
fl := v.flag & (flagRO | flagAddr | flagIndir)
|
|
fl |= flag(dst.Kind())
|
|
return Value{dst, v.ptr, fl}
|
|
|
|
case implements(dst, v.typ):
|
|
if target == nil {
|
|
target = unsafe_New(dst)
|
|
}
|
|
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
|
|
}
|
|
}
|
|
}
|
|
|
|
// dst and src have same underlying type.
|
|
if haveIdenticalUnderlyingType(dst, src) {
|
|
return cvtDirect
|
|
}
|
|
|
|
// dst and src are unnamed 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()) {
|
|
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)(unsafe.Pointer(ptr)) = uint8(bits)
|
|
case 2:
|
|
*(*uint16)(unsafe.Pointer(ptr)) = uint16(bits)
|
|
case 4:
|
|
*(*uint32)(unsafe.Pointer(ptr)) = uint32(bits)
|
|
case 8:
|
|
*(*uint64)(unsafe.Pointer(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)(unsafe.Pointer(ptr)) = float32(v)
|
|
case 8:
|
|
*(*float64)(unsafe.Pointer(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)(unsafe.Pointer(ptr)) = complex64(v)
|
|
case 16:
|
|
*(*complex128)(unsafe.Pointer(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&flagRO, uint64(v.Int()), t)
|
|
}
|
|
|
|
// convertOp: uintXX -> [u]intXX
|
|
func cvtUint(v Value, t Type) Value {
|
|
return makeInt(v.flag&flagRO, v.Uint(), t)
|
|
}
|
|
|
|
// convertOp: floatXX -> intXX
|
|
func cvtFloatInt(v Value, t Type) Value {
|
|
return makeInt(v.flag&flagRO, uint64(int64(v.Float())), t)
|
|
}
|
|
|
|
// convertOp: floatXX -> uintXX
|
|
func cvtFloatUint(v Value, t Type) Value {
|
|
return makeInt(v.flag&flagRO, uint64(v.Float()), t)
|
|
}
|
|
|
|
// convertOp: intXX -> floatXX
|
|
func cvtIntFloat(v Value, t Type) Value {
|
|
return makeFloat(v.flag&flagRO, float64(v.Int()), t)
|
|
}
|
|
|
|
// convertOp: uintXX -> floatXX
|
|
func cvtUintFloat(v Value, t Type) Value {
|
|
return makeFloat(v.flag&flagRO, float64(v.Uint()), t)
|
|
}
|
|
|
|
// convertOp: floatXX -> floatXX
|
|
func cvtFloat(v Value, t Type) Value {
|
|
return makeFloat(v.flag&flagRO, v.Float(), t)
|
|
}
|
|
|
|
// convertOp: complexXX -> complexXX
|
|
func cvtComplex(v Value, t Type) Value {
|
|
return makeComplex(v.flag&flagRO, v.Complex(), t)
|
|
}
|
|
|
|
// convertOp: intXX -> string
|
|
func cvtIntString(v Value, t Type) Value {
|
|
return makeString(v.flag&flagRO, string(v.Int()), t)
|
|
}
|
|
|
|
// convertOp: uintXX -> string
|
|
func cvtUintString(v Value, t Type) Value {
|
|
return makeString(v.flag&flagRO, string(v.Uint()), t)
|
|
}
|
|
|
|
// convertOp: []byte -> string
|
|
func cvtBytesString(v Value, t Type) Value {
|
|
return makeString(v.flag&flagRO, string(v.Bytes()), t)
|
|
}
|
|
|
|
// convertOp: string -> []byte
|
|
func cvtStringBytes(v Value, t Type) Value {
|
|
return makeBytes(v.flag&flagRO, []byte(v.String()), t)
|
|
}
|
|
|
|
// convertOp: []rune -> string
|
|
func cvtRunesString(v Value, t Type) Value {
|
|
return makeString(v.flag&flagRO, string(v.runes()), t)
|
|
}
|
|
|
|
// convertOp: string -> []rune
|
|
func cvtStringRunes(v Value, t Type) Value {
|
|
return makeRunes(v.flag&flagRO, []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&flagRO | f} // v.flag&flagRO|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&flagRO | flagIndir | flag(Interface)}
|
|
}
|
|
|
|
// convertOp: interface -> interface
|
|
func cvtI2I(v Value, typ Type) Value {
|
|
if v.IsNil() {
|
|
ret := Zero(typ)
|
|
ret.flag |= v.flag & flagRO
|
|
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
|
|
|
|
//go:noescape
|
|
func chanrecv(t *rtype, ch unsafe.Pointer, nb bool, val unsafe.Pointer) (selected, received bool)
|
|
|
|
//go:noescape
|
|
func chansend(t *rtype, ch unsafe.Pointer, val unsafe.Pointer, nb bool) bool
|
|
|
|
func makechan(typ *rtype, size uint64) (ch unsafe.Pointer)
|
|
func makemap(t *rtype) (m unsafe.Pointer)
|
|
|
|
//go:noescape
|
|
func mapaccess(t *rtype, m unsafe.Pointer, key unsafe.Pointer) (val unsafe.Pointer)
|
|
|
|
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 mapiternext(it unsafe.Pointer)
|
|
|
|
//go:noescape
|
|
func maplen(m unsafe.Pointer) int
|
|
func call(typ *rtype, fnaddr unsafe.Pointer, isInterface bool, isMethod bool, params *unsafe.Pointer, results *unsafe.Pointer)
|
|
|
|
func ifaceE2I(t *rtype, src interface{}, dst unsafe.Pointer)
|
|
|
|
// typedmemmove copies a value of type t to dst from src.
|
|
//go:noescape
|
|
func typedmemmove(t *rtype, dst, src unsafe.Pointer)
|
|
|
|
// 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 sliceHeader) int
|
|
|
|
//go:noescape
|
|
//extern memmove
|
|
func memmove(adst, asrc unsafe.Pointer, n 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{}
|
|
}
|