1692 lines
47 KiB
Go
1692 lines
47 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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"strconv"
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"unsafe"
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)
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const ptrSize = uintptr(unsafe.Sizeof((*byte)(nil)))
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const cannotSet = "cannot set value obtained from unexported struct field"
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// TODO: This will have to go away when
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// the new gc goes in.
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func memmove(adst, asrc unsafe.Pointer, n uintptr) {
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dst := uintptr(adst)
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src := uintptr(asrc)
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switch {
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case src < dst && src+n > dst:
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// byte copy backward
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// careful: i is unsigned
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for i := n; i > 0; {
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i--
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*(*byte)(unsafe.Pointer(dst + i)) = *(*byte)(unsafe.Pointer(src + i))
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}
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case (n|src|dst)&(ptrSize-1) != 0:
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// byte copy forward
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for i := uintptr(0); i < n; i++ {
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*(*byte)(unsafe.Pointer(dst + i)) = *(*byte)(unsafe.Pointer(src + i))
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}
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default:
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// word copy forward
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for i := uintptr(0); i < n; i += ptrSize {
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*(*uintptr)(unsafe.Pointer(dst + i)) = *(*uintptr)(unsafe.Pointer(src + i))
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}
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}
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}
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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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// The fields of Value are exported so that clients can copy and
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// pass Values around, but they should not be edited or inspected
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// directly. A future language change may make it possible not to
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// export these fields while still keeping Values usable as values.
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type Value struct {
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Internal interface{}
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InternalMethod int
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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) String() 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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// An iword is the word that would be stored in an
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// interface to represent a given value v. Specifically, if v is
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// bigger than a pointer, its word is a pointer to v's data.
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// Otherwise, its word is a zero uintptr with the data stored
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// in the leading bytes.
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type iword uintptr
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func loadIword(p unsafe.Pointer, size uintptr) iword {
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// Run the copy ourselves instead of calling memmove
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// to avoid moving v to the heap.
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w := iword(0)
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switch size {
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default:
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panic("reflect: internal error: loadIword of " + strconv.Itoa(int(size)) + "-byte value")
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case 0:
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case 1:
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*(*uint8)(unsafe.Pointer(&w)) = *(*uint8)(p)
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case 2:
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*(*uint16)(unsafe.Pointer(&w)) = *(*uint16)(p)
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case 3:
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*(*[3]byte)(unsafe.Pointer(&w)) = *(*[3]byte)(p)
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case 4:
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*(*uint32)(unsafe.Pointer(&w)) = *(*uint32)(p)
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case 5:
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*(*[5]byte)(unsafe.Pointer(&w)) = *(*[5]byte)(p)
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case 6:
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*(*[6]byte)(unsafe.Pointer(&w)) = *(*[6]byte)(p)
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case 7:
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*(*[7]byte)(unsafe.Pointer(&w)) = *(*[7]byte)(p)
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case 8:
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*(*uint64)(unsafe.Pointer(&w)) = *(*uint64)(p)
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}
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return w
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}
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func storeIword(p unsafe.Pointer, w iword, size uintptr) {
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// Run the copy ourselves instead of calling memmove
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// to avoid moving v to the heap.
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switch size {
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default:
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panic("reflect: internal error: storeIword of " + strconv.Itoa(int(size)) + "-byte value")
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case 0:
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case 1:
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*(*uint8)(p) = *(*uint8)(unsafe.Pointer(&w))
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case 2:
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*(*uint16)(p) = *(*uint16)(unsafe.Pointer(&w))
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case 3:
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*(*[3]byte)(p) = *(*[3]byte)(unsafe.Pointer(&w))
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case 4:
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*(*uint32)(p) = *(*uint32)(unsafe.Pointer(&w))
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case 5:
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*(*[5]byte)(p) = *(*[5]byte)(unsafe.Pointer(&w))
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case 6:
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*(*[6]byte)(p) = *(*[6]byte)(unsafe.Pointer(&w))
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case 7:
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*(*[7]byte)(p) = *(*[7]byte)(unsafe.Pointer(&w))
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case 8:
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*(*uint64)(p) = *(*uint64)(unsafe.Pointer(&w))
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}
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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 *runtime.Type
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word iword
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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.c:/Itab
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itab *struct {
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typ *runtime.Type // dynamic concrete type
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fun [100000]unsafe.Pointer // method table
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}
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word iword
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}
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// Regarding the implementation of Value:
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//
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// The Internal interface is a true interface value in the Go sense,
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// but it also serves as a (type, address) pair in whcih one cannot
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// be changed separately from the other. That is, it serves as a way
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// to prevent unsafe mutations of the Internal state even though
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// we cannot (yet?) hide the field while preserving the ability for
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// clients to make copies of Values.
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//
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// The internal method converts a Value into the expanded internalValue struct.
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// If we could avoid exporting fields we'd probably make internalValue the
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// definition of Value.
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//
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// If a Value is addressable (CanAddr returns true), then the Internal
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// interface value holds a pointer to the actual field data, and Set stores
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// through that pointer. If a Value is not addressable (CanAddr returns false),
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// then the Internal interface value holds the actual value.
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//
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// In addition to whether a value is addressable, we track whether it was
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// obtained by using an unexported struct field. Such values are allowed
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// to be read, mainly to make fmt.Print more useful, but they are not
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// allowed to be written. We call such values read-only.
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//
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// A Value can be set (via the Set, SetUint, etc. methods) only if it is both
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// addressable and not read-only.
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//
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// The two permission bits - addressable and read-only - are stored in
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// the bottom two bits of the type pointer in the interface value.
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//
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// ordinary value: Internal = value
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// addressable value: Internal = value, Internal.typ |= flagAddr
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// read-only value: Internal = value, Internal.typ |= flagRO
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// addressable, read-only value: Internal = value, Internal.typ |= flagAddr | flagRO
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//
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// It is important that the read-only values have the extra bit set
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// (as opposed to using the bit to mean writable), because client code
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// can grab the interface field and try to use it. Having the extra bit
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// set makes the type pointer compare not equal to any real type,
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// so that a client cannot, say, write through v.Internal.(*int).
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// The runtime routines that access interface types reject types with
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// low bits set.
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//
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// If a Value fv = v.Method(i), then fv = v with the InternalMethod
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// field set to i+1. Methods are never addressable.
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//
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// All in all, this is a lot of effort just to avoid making this new API
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// depend on a language change we'll probably do anyway, but
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// it's helpful to keep the two separate, and much of the logic is
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// necessary to implement the Interface method anyway.
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const (
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flagAddr uint32 = 1 << iota // holds address of value
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flagRO // read-only
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reflectFlags = 3
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)
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// An internalValue is the unpacked form of a Value.
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// The zero Value unpacks to a zero internalValue
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type internalValue struct {
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typ *commonType // type of value
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kind Kind // kind of value
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flag uint32
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word iword
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addr unsafe.Pointer
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rcvr iword
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method bool
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nilmethod bool
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}
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func (v Value) internal() internalValue {
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var iv internalValue
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eface := *(*emptyInterface)(unsafe.Pointer(&v.Internal))
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p := uintptr(unsafe.Pointer(eface.typ))
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iv.typ = toCommonType((*runtime.Type)(unsafe.Pointer(p &^ reflectFlags)))
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if iv.typ == nil {
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return iv
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}
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iv.flag = uint32(p & reflectFlags)
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iv.word = eface.word
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if iv.flag&flagAddr != 0 {
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iv.addr = unsafe.Pointer(uintptr(iv.word))
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iv.typ = iv.typ.Elem().common()
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if Kind(iv.typ.kind) == Ptr || Kind(iv.typ.kind) == UnsafePointer {
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iv.word = loadIword(iv.addr, iv.typ.size)
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}
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} else {
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if Kind(iv.typ.kind) != Ptr && Kind(iv.typ.kind) != UnsafePointer {
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iv.addr = unsafe.Pointer(uintptr(iv.word))
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}
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}
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iv.kind = iv.typ.Kind()
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// Is this a method? If so, iv describes the receiver.
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// Rewrite to describe the method function.
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if v.InternalMethod != 0 {
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// If this Value is a method value (x.Method(i) for some Value x)
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// then we will invoke it using the interface form of the method,
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// which always passes the receiver as a single word.
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// Record that information.
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i := v.InternalMethod - 1
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if iv.kind == Interface {
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it := (*interfaceType)(unsafe.Pointer(iv.typ))
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if i < 0 || i >= len(it.methods) {
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panic("reflect: broken Value")
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}
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m := &it.methods[i]
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if m.pkgPath != nil {
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iv.flag |= flagRO
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}
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iv.typ = toCommonType(m.typ)
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iface := (*nonEmptyInterface)(iv.addr)
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if iface.itab == nil {
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iv.word = 0
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iv.nilmethod = true
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} else {
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iv.word = iword(uintptr(iface.itab.fun[i]))
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}
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iv.rcvr = iface.word
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} else {
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ut := iv.typ.uncommon()
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if ut == nil || i < 0 || i >= len(ut.methods) {
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panic("reflect: broken Value")
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}
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m := &ut.methods[i]
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if m.pkgPath != nil {
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iv.flag |= flagRO
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}
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iv.typ = toCommonType(m.mtyp)
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iv.rcvr = iv.word
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iv.word = iword(uintptr(m.tfn))
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}
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if iv.word != 0 {
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p := new(iword)
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*p = iv.word
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iv.word = iword(uintptr(unsafe.Pointer(p)))
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}
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iv.kind = Func
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iv.method = true
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iv.flag &^= flagAddr
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iv.addr = unsafe.Pointer(uintptr(iv.word))
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}
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return iv
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}
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// packValue returns a Value with the given flag bits, type, and interface word.
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func packValue(flag uint32, typ *runtime.Type, word iword) Value {
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if typ == nil {
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panic("packValue")
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}
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t := uintptr(unsafe.Pointer(typ))
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t |= uintptr(flag)
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eface := emptyInterface{(*runtime.Type)(unsafe.Pointer(t)), word}
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return Value{Internal: *(*interface{})(unsafe.Pointer(&eface))}
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}
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// valueFromAddr returns a Value using the given type and address.
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func valueFromAddr(flag uint32, typ Type, addr unsafe.Pointer) Value {
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if flag&flagAddr != 0 {
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// Addressable, so the internal value is
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// an interface containing a pointer to the real value.
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return packValue(flag, PtrTo(typ).runtimeType(), iword(uintptr(addr)))
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}
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var w iword
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if k := typ.Kind(); k == Ptr || k == UnsafePointer {
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// In line, so the interface word is the actual value.
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w = loadIword(addr, typ.Size())
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} else {
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// Not in line: the interface word is the address.
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w = iword(uintptr(addr))
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}
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return packValue(flag, typ.runtimeType(), w)
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}
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// valueFromIword returns a Value using the given type and interface word.
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func valueFromIword(flag uint32, typ Type, w iword) Value {
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if flag&flagAddr != 0 {
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panic("reflect: internal error: valueFromIword addressable")
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}
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return packValue(flag, typ.runtimeType(), w)
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}
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func (iv internalValue) mustBe(want Kind) {
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if iv.kind != want {
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panic(&ValueError{methodName(), iv.kind})
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}
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}
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func (iv internalValue) mustBeExported() {
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if iv.kind == 0 {
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panic(&ValueError{methodName(), iv.kind})
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}
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if iv.flag&flagRO != 0 {
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panic(methodName() + " using value obtained using unexported field")
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}
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}
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func (iv internalValue) mustBeAssignable() {
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if iv.kind == 0 {
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panic(&ValueError{methodName(), iv.kind})
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}
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// Assignable if addressable and not read-only.
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if iv.flag&flagRO != 0 {
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panic(methodName() + " using value obtained using unexported field")
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}
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if iv.flag&flagAddr == 0 {
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panic(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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iv := v.internal()
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if iv.flag&flagAddr == 0 {
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panic("reflect.Value.Addr of unaddressable value")
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}
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return valueFromIword(iv.flag&flagRO, PtrTo(iv.typ.toType()), iword(uintptr(iv.addr)))
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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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iv := v.internal()
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iv.mustBe(Bool)
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return *(*bool)(unsafe.Pointer(iv.addr))
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}
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// CanAddr returns true if 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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iv := v.internal()
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return iv.flag&flagAddr != 0
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}
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// CanSet returns true if 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, SetInt64) will panic.
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func (v Value) CanSet() bool {
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iv := v.internal()
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return iv.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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iv := v.internal()
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iv.mustBe(Func)
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iv.mustBeExported()
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return iv.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.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 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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iv := v.internal()
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iv.mustBe(Func)
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iv.mustBeExported()
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return iv.call("CallSlice", in)
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}
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func (iv internalValue) call(method string, in []Value) []Value {
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if iv.word == 0 {
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if iv.nilmethod {
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panic("reflect.Value.Call: call of method on nil interface value")
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}
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panic("reflect.Value.Call: call of nil function")
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}
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isSlice := method == "CallSlice"
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t := iv.typ
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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: " + method + " 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: " + method + " 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
|
|
slice := MakeSlice(t.In(n), m, m)
|
|
elem := t.In(n).Elem()
|
|
for i := 0; i < m; i++ {
|
|
x := in[n+i]
|
|
if xt := x.Type(); !xt.AssignableTo(elem) {
|
|
panic("reflect: cannot use " + xt.String() + " as type " + elem.String() + " in " + method)
|
|
}
|
|
slice.Index(i).Set(x)
|
|
}
|
|
origIn := in
|
|
in = make([]Value, n+1)
|
|
copy(in[:n], origIn)
|
|
in[n] = slice
|
|
}
|
|
|
|
nin := len(in)
|
|
if nin != t.NumIn() {
|
|
panic("reflect.Value.Call: wrong argument count")
|
|
}
|
|
nout := t.NumOut()
|
|
|
|
if iv.method {
|
|
nin++
|
|
}
|
|
params := make([]unsafe.Pointer, nin)
|
|
delta := 0
|
|
off := 0
|
|
if iv.method {
|
|
// Hard-wired first argument.
|
|
p := new(iword)
|
|
*p = iv.rcvr
|
|
params[0] = unsafe.Pointer(p)
|
|
off = 1
|
|
}
|
|
|
|
first_pointer := false
|
|
for i, v := range in {
|
|
siv := v.internal()
|
|
siv.mustBeExported()
|
|
targ := t.In(i).(*commonType)
|
|
siv = convertForAssignment("reflect.Value.Call", nil, targ, siv)
|
|
if siv.addr == nil {
|
|
p := new(unsafe.Pointer)
|
|
*p = unsafe.Pointer(uintptr(siv.word))
|
|
params[off] = unsafe.Pointer(p)
|
|
} else {
|
|
params[off] = siv.addr
|
|
}
|
|
if i == 0 && Kind(targ.kind) != Ptr && !iv.method && isMethod(iv.typ) {
|
|
p := new(unsafe.Pointer)
|
|
*p = params[off]
|
|
params[off] = unsafe.Pointer(p)
|
|
first_pointer = true
|
|
}
|
|
off++
|
|
}
|
|
|
|
ret := make([]Value, nout)
|
|
results := make([]unsafe.Pointer, nout)
|
|
for i := 0; i < nout; i++ {
|
|
v := New(t.Out(i))
|
|
results[i] = unsafe.Pointer(v.Pointer())
|
|
ret[i] = Indirect(v)
|
|
}
|
|
|
|
call(t, *(*unsafe.Pointer)(iv.addr), iv.method, first_pointer, ¶ms[0], &results[0])
|
|
|
|
return ret
|
|
}
|
|
|
|
// gccgo specific test to see if typ is a method. We can tell by
|
|
// looking at the string to see if there is a receiver. We need this
|
|
// because for gccgo all methods take pointer receivers.
|
|
func isMethod(t *commonType) bool {
|
|
if Kind(t.kind) != Func {
|
|
return false
|
|
}
|
|
s := *t.string
|
|
parens := 0
|
|
params := 0
|
|
sawRet := false
|
|
for i, c := range s {
|
|
if c == '(' {
|
|
parens++
|
|
params++
|
|
} else if c == ')' {
|
|
parens--
|
|
} else if parens == 0 && c == ' ' && s[i + 1] != '(' && !sawRet {
|
|
params++
|
|
sawRet = true
|
|
}
|
|
}
|
|
return params > 2
|
|
}
|
|
|
|
// Cap returns v's capacity.
|
|
// It panics if v's Kind is not Array, Chan, or Slice.
|
|
func (v Value) Cap() int {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Array:
|
|
return iv.typ.Len()
|
|
case Chan:
|
|
return int(chancap(*(*iword)(iv.addr)))
|
|
case Slice:
|
|
return (*SliceHeader)(iv.addr).Cap
|
|
}
|
|
panic(&ValueError{"reflect.Value.Cap", iv.kind})
|
|
}
|
|
|
|
// Close closes the channel v.
|
|
// It panics if v's Kind is not Chan.
|
|
func (v Value) Close() {
|
|
iv := v.internal()
|
|
iv.mustBe(Chan)
|
|
iv.mustBeExported()
|
|
ch := *(*iword)(iv.addr)
|
|
chanclose(ch)
|
|
}
|
|
|
|
// Complex returns v's underlying value, as a complex128.
|
|
// It panics if v's Kind is not Complex64 or Complex128
|
|
func (v Value) Complex() complex128 {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Complex64:
|
|
return complex128(*(*complex64)(iv.addr))
|
|
case Complex128:
|
|
return *(*complex128)(iv.addr)
|
|
}
|
|
panic(&ValueError{"reflect.Value.Complex", iv.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 {
|
|
iv := v.internal()
|
|
return iv.Elem()
|
|
}
|
|
|
|
func (iv internalValue) Elem() Value {
|
|
switch iv.kind {
|
|
case Interface:
|
|
// Empty interface and non-empty interface have different layouts.
|
|
// Convert to empty interface.
|
|
var eface emptyInterface
|
|
if iv.typ.NumMethod() == 0 {
|
|
eface = *(*emptyInterface)(iv.addr)
|
|
} else {
|
|
iface := (*nonEmptyInterface)(iv.addr)
|
|
if iface.itab != nil {
|
|
eface.typ = iface.itab.typ
|
|
}
|
|
eface.word = iface.word
|
|
}
|
|
if eface.typ == nil {
|
|
return Value{}
|
|
}
|
|
return valueFromIword(iv.flag&flagRO, toType(eface.typ), eface.word)
|
|
|
|
case Ptr:
|
|
// The returned value's address is v's value.
|
|
if iv.word == 0 {
|
|
return Value{}
|
|
}
|
|
return valueFromAddr(iv.flag&flagRO|flagAddr, iv.typ.Elem(), unsafe.Pointer(uintptr(iv.word)))
|
|
}
|
|
panic(&ValueError{"reflect.Value.Elem", iv.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 {
|
|
iv := v.internal()
|
|
iv.mustBe(Struct)
|
|
t := iv.typ.toType()
|
|
if i < 0 || i >= t.NumField() {
|
|
panic("reflect: Field index out of range")
|
|
}
|
|
f := t.Field(i)
|
|
|
|
// Inherit permission bits from v.
|
|
flag := iv.flag
|
|
// Using an unexported field forces flagRO.
|
|
if f.PkgPath != "" {
|
|
flag |= flagRO
|
|
}
|
|
return valueFromValueOffset(flag, f.Type, iv, f.Offset)
|
|
}
|
|
|
|
// valueFromValueOffset returns a sub-value of outer
|
|
// (outer is an array or a struct) with the given flag and type
|
|
// starting at the given byte offset into outer.
|
|
func valueFromValueOffset(flag uint32, typ Type, outer internalValue, offset uintptr) Value {
|
|
if outer.addr != nil {
|
|
return valueFromAddr(flag, typ, unsafe.Pointer(uintptr(outer.addr)+offset))
|
|
}
|
|
|
|
// outer is so tiny it is in line.
|
|
// We have to use outer.word and derive
|
|
// the new word (it cannot possibly be bigger).
|
|
// In line, so not addressable.
|
|
if flag&flagAddr != 0 {
|
|
panic("reflect: internal error: misuse of valueFromValueOffset")
|
|
}
|
|
b := *(*[ptrSize]byte)(unsafe.Pointer(&outer.word))
|
|
for i := uintptr(0); i < typ.Size(); i++ {
|
|
b[i] = b[offset+i]
|
|
}
|
|
for i := typ.Size(); i < ptrSize; i++ {
|
|
b[i] = 0
|
|
}
|
|
w := *(*iword)(unsafe.Pointer(&b))
|
|
return valueFromIword(flag, typ, w)
|
|
}
|
|
|
|
// FieldByIndex returns the nested field corresponding to index.
|
|
// It panics if v's Kind is not struct.
|
|
func (v Value) FieldByIndex(index []int) Value {
|
|
v.internal().mustBe(Struct)
|
|
for i, x := range index {
|
|
if i > 0 {
|
|
if v.Kind() == Ptr && v.Elem().Kind() == 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 {
|
|
iv := v.internal()
|
|
iv.mustBe(Struct)
|
|
if f, ok := iv.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 {
|
|
v.internal().mustBe(Struct)
|
|
if f, ok := v.Type().FieldByNameFunc(match); ok {
|
|
return v.FieldByIndex(f.Index)
|
|
}
|
|
return Value{}
|
|
}
|
|
|
|
// Float returns v's underlying value, as an float64.
|
|
// It panics if v's Kind is not Float32 or Float64
|
|
func (v Value) Float() float64 {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Float32:
|
|
return float64(*(*float32)(iv.addr))
|
|
case Float64:
|
|
return *(*float64)(iv.addr)
|
|
}
|
|
panic(&ValueError{"reflect.Value.Float", iv.kind})
|
|
}
|
|
|
|
// Index returns v's i'th element.
|
|
// It panics if v's Kind is not Array or Slice or i is out of range.
|
|
func (v Value) Index(i int) Value {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.Index", iv.kind})
|
|
case Array:
|
|
flag := iv.flag // element flag same as overall array
|
|
t := iv.typ.toType()
|
|
if i < 0 || i > t.Len() {
|
|
panic("reflect: array index out of range")
|
|
}
|
|
typ := t.Elem()
|
|
return valueFromValueOffset(flag, typ, iv, uintptr(i)*typ.Size())
|
|
|
|
case Slice:
|
|
// Element flag same as Elem of Ptr.
|
|
// Addressable, possibly read-only.
|
|
flag := iv.flag&flagRO | flagAddr
|
|
s := (*SliceHeader)(iv.addr)
|
|
if i < 0 || i >= s.Len {
|
|
panic("reflect: slice index out of range")
|
|
}
|
|
typ := iv.typ.Elem()
|
|
addr := unsafe.Pointer(s.Data + uintptr(i)*typ.Size())
|
|
return valueFromAddr(flag, typ, addr)
|
|
}
|
|
|
|
panic("not reached")
|
|
}
|
|
|
|
// Int returns v's underlying value, as an int64.
|
|
// It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64.
|
|
func (v Value) Int() int64 {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Int:
|
|
return int64(*(*int)(iv.addr))
|
|
case Int8:
|
|
return int64(*(*int8)(iv.addr))
|
|
case Int16:
|
|
return int64(*(*int16)(iv.addr))
|
|
case Int32:
|
|
return int64(*(*int32)(iv.addr))
|
|
case Int64:
|
|
return *(*int64)(iv.addr)
|
|
}
|
|
panic(&ValueError{"reflect.Value.Int", iv.kind})
|
|
}
|
|
|
|
// CanInterface returns true if Interface can be used without panicking.
|
|
func (v Value) CanInterface() bool {
|
|
iv := v.internal()
|
|
if iv.kind == Invalid {
|
|
panic(&ValueError{"reflect.Value.CanInterface", iv.kind})
|
|
}
|
|
// TODO(rsc): Check flagRO too. Decide what to do about asking for
|
|
// interface for a value obtained via an unexported field.
|
|
// If the field were of a known type, say chan int or *sync.Mutex,
|
|
// the caller could interfere with the data after getting the
|
|
// interface. But fmt.Print depends on being able to look.
|
|
// Now that reflect is more efficient the special cases in fmt
|
|
// might be less important.
|
|
return v.InternalMethod == 0
|
|
}
|
|
|
|
// Interface returns v's value as an interface{}.
|
|
// If v is a method obtained by invoking Value.Method
|
|
// (as opposed to Type.Method), Interface cannot return an
|
|
// interface value, so it panics.
|
|
func (v Value) Interface() interface{} {
|
|
return v.internal().Interface()
|
|
}
|
|
|
|
func (iv internalValue) Interface() interface{} {
|
|
if iv.method {
|
|
panic("reflect.Value.Interface: cannot create interface value for method with bound receiver")
|
|
}
|
|
/*
|
|
if v.flag()&noExport != 0 {
|
|
panic("reflect.Value.Interface: cannot return value obtained from unexported struct field")
|
|
}
|
|
*/
|
|
|
|
if iv.kind == Interface {
|
|
// Special case: return the element inside the interface.
|
|
// Won't recurse further because an interface cannot contain an interface.
|
|
if iv.IsNil() {
|
|
return nil
|
|
}
|
|
return iv.Elem().Interface()
|
|
}
|
|
|
|
// Non-interface value.
|
|
var eface emptyInterface
|
|
eface.typ = iv.typ.runtimeType()
|
|
eface.word = iv.word
|
|
return *(*interface{})(unsafe.Pointer(&eface))
|
|
}
|
|
|
|
// InterfaceData returns the interface v's value as a uintptr pair.
|
|
// It panics if v's Kind is not Interface.
|
|
func (v Value) InterfaceData() [2]uintptr {
|
|
iv := v.internal()
|
|
iv.mustBe(Interface)
|
|
// We treat this as a read operation, so we allow
|
|
// it even for unexported data, because the caller
|
|
// has to import "unsafe" to turn it into something
|
|
// that can be abused.
|
|
return *(*[2]uintptr)(iv.addr)
|
|
}
|
|
|
|
// IsNil returns true if v is a nil value.
|
|
// It panics if v's Kind is not Chan, Func, Interface, Map, Ptr, or Slice.
|
|
func (v Value) IsNil() bool {
|
|
return v.internal().IsNil()
|
|
}
|
|
|
|
func (iv internalValue) IsNil() bool {
|
|
switch iv.kind {
|
|
case Ptr:
|
|
if iv.method {
|
|
panic("reflect: IsNil of method Value")
|
|
}
|
|
return iv.word == 0
|
|
case Chan, Func, Map:
|
|
if iv.method {
|
|
panic("reflect: IsNil of method Value")
|
|
}
|
|
return *(*uintptr)(iv.addr) == 0
|
|
case Interface, Slice:
|
|
// Both interface and slice are nil if first word is 0.
|
|
return *(*uintptr)(iv.addr) == 0
|
|
}
|
|
panic(&ValueError{"reflect.Value.IsNil", iv.kind})
|
|
}
|
|
|
|
// IsValid returns true if v represents a value.
|
|
// It returns false if v is the zero Value.
|
|
// If IsValid returns false, all other methods except String panic.
|
|
// Most functions and methods never return an invalid value.
|
|
// If one does, its documentation states the conditions explicitly.
|
|
func (v Value) IsValid() bool {
|
|
return v.Internal != nil
|
|
}
|
|
|
|
// Kind returns v's Kind.
|
|
// If v is the zero Value (IsValid returns false), Kind returns Invalid.
|
|
func (v Value) Kind() Kind {
|
|
return v.internal().kind
|
|
}
|
|
|
|
// Len returns v's length.
|
|
// It panics if v's Kind is not Array, Chan, Map, or Slice.
|
|
func (v Value) Len() int {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Array:
|
|
return iv.typ.Len()
|
|
case Chan:
|
|
return int(chanlen(*(*iword)(iv.addr)))
|
|
case Map:
|
|
return int(maplen(*(*iword)(iv.addr)))
|
|
case Slice:
|
|
return (*SliceHeader)(iv.addr).Len
|
|
}
|
|
panic(&ValueError{"reflect.Value.Len", iv.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 {
|
|
iv := v.internal()
|
|
iv.mustBe(Map)
|
|
typ := iv.typ.toType()
|
|
|
|
// Do not require ikey to be exported, so that DeepEqual
|
|
// and other programs can use all the keys returned by
|
|
// MapKeys as arguments to MapIndex. If either the map
|
|
// or the key is unexported, though, the result will be
|
|
// considered unexported.
|
|
|
|
ikey := key.internal()
|
|
ikey = convertForAssignment("reflect.Value.MapIndex", nil, typ.Key(), ikey)
|
|
if iv.word == 0 {
|
|
return Value{}
|
|
}
|
|
|
|
flag := (iv.flag | ikey.flag) & flagRO
|
|
elemType := typ.Elem()
|
|
elemWord, ok := mapaccess(*(*iword)(iv.addr), ikey.word)
|
|
if !ok {
|
|
return Value{}
|
|
}
|
|
return valueFromIword(flag, elemType, elemWord)
|
|
}
|
|
|
|
// 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 {
|
|
iv := v.internal()
|
|
iv.mustBe(Map)
|
|
keyType := iv.typ.Key()
|
|
|
|
flag := iv.flag & flagRO
|
|
m := *(*iword)(iv.addr)
|
|
mlen := int32(0)
|
|
if m != 0 {
|
|
mlen = maplen(m)
|
|
}
|
|
it := mapiterinit(m)
|
|
a := make([]Value, mlen)
|
|
var i int
|
|
for i = 0; i < len(a); i++ {
|
|
keyWord, ok := mapiterkey(it)
|
|
if !ok {
|
|
break
|
|
}
|
|
a[i] = valueFromIword(flag, keyType, keyWord)
|
|
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.
|
|
func (v Value) Method(i int) Value {
|
|
iv := v.internal()
|
|
if iv.kind == Invalid {
|
|
panic(&ValueError{"reflect.Value.Method", Invalid})
|
|
}
|
|
if i < 0 || i >= iv.typ.NumMethod() {
|
|
panic("reflect: Method index out of range")
|
|
}
|
|
return Value{v.Internal, i + 1}
|
|
}
|
|
|
|
// NumField returns the number of fields in the struct v.
|
|
// It panics if v's Kind is not Struct.
|
|
func (v Value) NumField() int {
|
|
iv := v.internal()
|
|
iv.mustBe(Struct)
|
|
return iv.typ.NumField()
|
|
}
|
|
|
|
// OverflowComplex returns true if the complex128 x cannot be represented by v's type.
|
|
// It panics if v's Kind is not Complex64 or Complex128.
|
|
func (v Value) OverflowComplex(x complex128) bool {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Complex64:
|
|
return overflowFloat32(real(x)) || overflowFloat32(imag(x))
|
|
case Complex128:
|
|
return false
|
|
}
|
|
panic(&ValueError{"reflect.Value.OverflowComplex", iv.kind})
|
|
}
|
|
|
|
// OverflowFloat returns true if the float64 x cannot be represented by v's type.
|
|
// It panics if v's Kind is not Float32 or Float64.
|
|
func (v Value) OverflowFloat(x float64) bool {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Float32:
|
|
return overflowFloat32(x)
|
|
case Float64:
|
|
return false
|
|
}
|
|
panic(&ValueError{"reflect.Value.OverflowFloat", iv.kind})
|
|
}
|
|
|
|
func overflowFloat32(x float64) bool {
|
|
if x < 0 {
|
|
x = -x
|
|
}
|
|
return math.MaxFloat32 <= x && x <= math.MaxFloat64
|
|
}
|
|
|
|
// OverflowInt returns true if the int64 x cannot be represented by v's type.
|
|
// It panics if v's Kind is not Int, Int8, int16, Int32, or Int64.
|
|
func (v Value) OverflowInt(x int64) bool {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Int, Int8, Int16, Int32, Int64:
|
|
bitSize := iv.typ.size * 8
|
|
trunc := (x << (64 - bitSize)) >> (64 - bitSize)
|
|
return x != trunc
|
|
}
|
|
panic(&ValueError{"reflect.Value.OverflowInt", iv.kind})
|
|
}
|
|
|
|
// OverflowUint returns true if the uint64 x cannot be represented by v's type.
|
|
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64.
|
|
func (v Value) OverflowUint(x uint64) bool {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Uint, Uintptr, Uint8, Uint16, Uint32, Uint64:
|
|
bitSize := iv.typ.size * 8
|
|
trunc := (x << (64 - bitSize)) >> (64 - bitSize)
|
|
return x != trunc
|
|
}
|
|
panic(&ValueError{"reflect.Value.OverflowUint", iv.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.
|
|
func (v Value) Pointer() uintptr {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Ptr, UnsafePointer:
|
|
if iv.kind == Func && v.InternalMethod != 0 {
|
|
panic("reflect.Value.Pointer of method Value")
|
|
}
|
|
return uintptr(iv.word)
|
|
case Chan, Func, Map:
|
|
if iv.kind == Func && v.InternalMethod != 0 {
|
|
panic("reflect.Value.Pointer of method Value")
|
|
}
|
|
return *(*uintptr)(iv.addr)
|
|
case Slice:
|
|
return (*SliceHeader)(iv.addr).Data
|
|
}
|
|
panic(&ValueError{"reflect.Value.Pointer", iv.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) {
|
|
iv := v.internal()
|
|
iv.mustBe(Chan)
|
|
iv.mustBeExported()
|
|
return iv.recv(false)
|
|
}
|
|
|
|
// internal recv, possibly non-blocking (nb)
|
|
func (iv internalValue) recv(nb bool) (val Value, ok bool) {
|
|
t := iv.typ.toType()
|
|
if t.ChanDir()&RecvDir == 0 {
|
|
panic("recv on send-only channel")
|
|
}
|
|
ch := *(*iword)(iv.addr)
|
|
if ch == 0 {
|
|
panic("recv on nil channel")
|
|
}
|
|
valWord, selected, ok := chanrecv(ch, nb)
|
|
if selected {
|
|
val = valueFromIword(0, t.Elem(), valWord)
|
|
}
|
|
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) {
|
|
iv := v.internal()
|
|
iv.mustBe(Chan)
|
|
iv.mustBeExported()
|
|
iv.send(x, false)
|
|
}
|
|
|
|
// internal send, possibly non-blocking
|
|
func (iv internalValue) send(x Value, nb bool) (selected bool) {
|
|
t := iv.typ.toType()
|
|
if t.ChanDir()&SendDir == 0 {
|
|
panic("send on recv-only channel")
|
|
}
|
|
ix := x.internal()
|
|
ix.mustBeExported() // do not let unexported x leak
|
|
ix = convertForAssignment("reflect.Value.Send", nil, t.Elem(), ix)
|
|
ch := *(*iword)(iv.addr)
|
|
if ch == 0 {
|
|
panic("send on nil channel")
|
|
}
|
|
return chansend(ch, ix.word, nb)
|
|
}
|
|
|
|
// Set assigns x to the value v.
|
|
// It panics if CanSet returns false.
|
|
// As in Go, x's value must be assignable to v's type.
|
|
func (v Value) Set(x Value) {
|
|
iv := v.internal()
|
|
ix := x.internal()
|
|
|
|
iv.mustBeAssignable()
|
|
ix.mustBeExported() // do not let unexported x leak
|
|
|
|
ix = convertForAssignment("reflect.Set", iv.addr, iv.typ, ix)
|
|
|
|
n := ix.typ.size
|
|
if Kind(ix.typ.kind) == Ptr || Kind(ix.typ.kind) == UnsafePointer {
|
|
storeIword(iv.addr, ix.word, n)
|
|
} else {
|
|
memmove(iv.addr, ix.addr, n)
|
|
}
|
|
}
|
|
|
|
// SetBool sets v's underlying value.
|
|
// It panics if v's Kind is not Bool or if CanSet() is false.
|
|
func (v Value) SetBool(x bool) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
iv.mustBe(Bool)
|
|
*(*bool)(iv.addr) = x
|
|
}
|
|
|
|
// SetComplex sets v's underlying value to x.
|
|
// It panics if v's Kind is not Complex64 or Complex128, or if CanSet() is false.
|
|
func (v Value) SetComplex(x complex128) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
switch iv.kind {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetComplex", iv.kind})
|
|
case Complex64:
|
|
*(*complex64)(iv.addr) = complex64(x)
|
|
case Complex128:
|
|
*(*complex128)(iv.addr) = x
|
|
}
|
|
}
|
|
|
|
// SetFloat sets v's underlying value to x.
|
|
// It panics if v's Kind is not Float32 or Float64, or if CanSet() is false.
|
|
func (v Value) SetFloat(x float64) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
switch iv.kind {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetFloat", iv.kind})
|
|
case Float32:
|
|
*(*float32)(iv.addr) = float32(x)
|
|
case Float64:
|
|
*(*float64)(iv.addr) = x
|
|
}
|
|
}
|
|
|
|
// SetInt sets v's underlying value to x.
|
|
// It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64, or if CanSet() is false.
|
|
func (v Value) SetInt(x int64) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
switch iv.kind {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetInt", iv.kind})
|
|
case Int:
|
|
*(*int)(iv.addr) = int(x)
|
|
case Int8:
|
|
*(*int8)(iv.addr) = int8(x)
|
|
case Int16:
|
|
*(*int16)(iv.addr) = int16(x)
|
|
case Int32:
|
|
*(*int32)(iv.addr) = int32(x)
|
|
case Int64:
|
|
*(*int64)(iv.addr) = x
|
|
}
|
|
}
|
|
|
|
// SetLen sets v's length to n.
|
|
// It panics if v's Kind is not Slice.
|
|
func (v Value) SetLen(n int) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
iv.mustBe(Slice)
|
|
s := (*SliceHeader)(iv.addr)
|
|
if n < 0 || n > int(s.Cap) {
|
|
panic("reflect: slice length out of range in SetLen")
|
|
}
|
|
s.Len = 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.
|
|
// As in Go, key's value must be assignable to the map's key type,
|
|
// and val's value must be assignable to the map's value type.
|
|
func (v Value) SetMapIndex(key, val Value) {
|
|
iv := v.internal()
|
|
ikey := key.internal()
|
|
ival := val.internal()
|
|
|
|
iv.mustBe(Map)
|
|
iv.mustBeExported()
|
|
|
|
ikey.mustBeExported()
|
|
ikey = convertForAssignment("reflect.Value.SetMapIndex", nil, iv.typ.Key(), ikey)
|
|
|
|
if ival.kind != Invalid {
|
|
ival.mustBeExported()
|
|
ival = convertForAssignment("reflect.Value.SetMapIndex", nil, iv.typ.Elem(), ival)
|
|
}
|
|
|
|
mapassign(*(*iword)(iv.addr), ikey.word, ival.word, ival.kind != Invalid)
|
|
}
|
|
|
|
// SetUint sets v's underlying value to x.
|
|
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64, or if CanSet() is false.
|
|
func (v Value) SetUint(x uint64) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
switch iv.kind {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetUint", iv.kind})
|
|
case Uint:
|
|
*(*uint)(iv.addr) = uint(x)
|
|
case Uint8:
|
|
*(*uint8)(iv.addr) = uint8(x)
|
|
case Uint16:
|
|
*(*uint16)(iv.addr) = uint16(x)
|
|
case Uint32:
|
|
*(*uint32)(iv.addr) = uint32(x)
|
|
case Uint64:
|
|
*(*uint64)(iv.addr) = x
|
|
case Uintptr:
|
|
*(*uintptr)(iv.addr) = uintptr(x)
|
|
}
|
|
}
|
|
|
|
// SetPointer sets the unsafe.Pointer value v to x.
|
|
// It panics if v's Kind is not UnsafePointer.
|
|
func (v Value) SetPointer(x unsafe.Pointer) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
iv.mustBe(UnsafePointer)
|
|
*(*unsafe.Pointer)(iv.addr) = x
|
|
}
|
|
|
|
// SetString sets v's underlying value to x.
|
|
// It panics if v's Kind is not String or if CanSet() is false.
|
|
func (v Value) SetString(x string) {
|
|
iv := v.internal()
|
|
iv.mustBeAssignable()
|
|
iv.mustBe(String)
|
|
*(*string)(iv.addr) = x
|
|
}
|
|
|
|
// Slice returns a slice of v.
|
|
// It panics if v's Kind is not Array or Slice.
|
|
func (v Value) Slice(beg, end int) Value {
|
|
iv := v.internal()
|
|
if iv.kind != Array && iv.kind != Slice {
|
|
panic(&ValueError{"reflect.Value.Slice", iv.kind})
|
|
}
|
|
cap := v.Cap()
|
|
if beg < 0 || end < beg || end > cap {
|
|
panic("reflect.Value.Slice: slice index out of bounds")
|
|
}
|
|
var typ Type
|
|
var base uintptr
|
|
switch iv.kind {
|
|
case Array:
|
|
if iv.flag&flagAddr == 0 {
|
|
panic("reflect.Value.Slice: slice of unaddressable array")
|
|
}
|
|
typ = toType((*arrayType)(unsafe.Pointer(iv.typ)).slice)
|
|
base = uintptr(iv.addr)
|
|
case Slice:
|
|
typ = iv.typ.toType()
|
|
base = (*SliceHeader)(iv.addr).Data
|
|
}
|
|
s := new(SliceHeader)
|
|
s.Data = base + uintptr(beg)*typ.Elem().Size()
|
|
s.Len = end - beg
|
|
s.Cap = cap - beg
|
|
return valueFromAddr(iv.flag&flagRO, typ, unsafe.Pointer(s))
|
|
}
|
|
|
|
// String returns the string v's underlying value, as a string.
|
|
// String is a special case because of Go's String method convention.
|
|
// Unlike the other getters, it does not panic if v's Kind is not String.
|
|
// Instead, it returns a string of the form "<T value>" where T is v's type.
|
|
func (v Value) String() string {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Invalid:
|
|
return "<invalid Value>"
|
|
case String:
|
|
return *(*string)(iv.addr)
|
|
}
|
|
return "<" + iv.typ.String() + " Value>"
|
|
}
|
|
|
|
// TryRecv attempts to receive a value from the channel v but will not block.
|
|
// It panics if v's Kind is not Chan.
|
|
// If the receive cannot finish without blocking, x is the zero Value.
|
|
// The boolean ok is true if the value x corresponds to a send
|
|
// on the channel, false if it is a zero value received because the channel is closed.
|
|
func (v Value) TryRecv() (x Value, ok bool) {
|
|
iv := v.internal()
|
|
iv.mustBe(Chan)
|
|
iv.mustBeExported()
|
|
return iv.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 returns true if the value was sent, false otherwise.
|
|
// As in Go, x's value must be assignable to the channel's element type.
|
|
func (v Value) TrySend(x Value) bool {
|
|
iv := v.internal()
|
|
iv.mustBe(Chan)
|
|
iv.mustBeExported()
|
|
return iv.send(x, true)
|
|
}
|
|
|
|
// Type returns v's type.
|
|
func (v Value) Type() Type {
|
|
t := v.internal().typ
|
|
if t == nil {
|
|
panic(&ValueError{"reflect.Value.Type", Invalid})
|
|
}
|
|
return t.toType()
|
|
}
|
|
|
|
// Uint returns v's underlying value, as a uint64.
|
|
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64.
|
|
func (v Value) Uint() uint64 {
|
|
iv := v.internal()
|
|
switch iv.kind {
|
|
case Uint:
|
|
return uint64(*(*uint)(iv.addr))
|
|
case Uint8:
|
|
return uint64(*(*uint8)(iv.addr))
|
|
case Uint16:
|
|
return uint64(*(*uint16)(iv.addr))
|
|
case Uint32:
|
|
return uint64(*(*uint32)(iv.addr))
|
|
case Uintptr:
|
|
return uint64(*(*uintptr)(iv.addr))
|
|
case Uint64:
|
|
return *(*uint64)(iv.addr)
|
|
}
|
|
panic(&ValueError{"reflect.Value.Uint", iv.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 {
|
|
iv := v.internal()
|
|
if iv.kind == Invalid {
|
|
panic(&ValueError{"reflect.Value.UnsafeAddr", iv.kind})
|
|
}
|
|
if iv.flag&flagAddr == 0 {
|
|
panic("reflect.Value.UnsafeAddr of unaddressable value")
|
|
}
|
|
return uintptr(iv.addr)
|
|
}
|
|
|
|
// StringHeader is the runtime representation of a string.
|
|
// It cannot be used safely or portably.
|
|
type StringHeader struct {
|
|
Data uintptr
|
|
Len int
|
|
}
|
|
|
|
// SliceHeader is the runtime representation of a slice.
|
|
// It cannot be used safely or portably.
|
|
type SliceHeader struct {
|
|
Data uintptr
|
|
Len int
|
|
Cap int
|
|
}
|
|
|
|
func typesMustMatch(what string, t1, t2 Type) {
|
|
if t1 != t2 {
|
|
panic("reflect: " + what + ": " + t1.String() + " != " + t2.String())
|
|
}
|
|
}
|
|
|
|
// 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.internal().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.internal().mustBe(Slice)
|
|
t.internal().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 {
|
|
idst := dst.internal()
|
|
isrc := src.internal()
|
|
|
|
if idst.kind != Array && idst.kind != Slice {
|
|
panic(&ValueError{"reflect.Copy", idst.kind})
|
|
}
|
|
if idst.kind == Array {
|
|
idst.mustBeAssignable()
|
|
}
|
|
idst.mustBeExported()
|
|
if isrc.kind != Array && isrc.kind != Slice {
|
|
panic(&ValueError{"reflect.Copy", isrc.kind})
|
|
}
|
|
isrc.mustBeExported()
|
|
|
|
de := idst.typ.Elem()
|
|
se := isrc.typ.Elem()
|
|
typesMustMatch("reflect.Copy", de, se)
|
|
|
|
n := dst.Len()
|
|
if sn := src.Len(); n > sn {
|
|
n = sn
|
|
}
|
|
|
|
// If sk is an in-line array, cannot take its address.
|
|
// Instead, copy element by element.
|
|
if isrc.addr == nil {
|
|
for i := 0; i < n; i++ {
|
|
dst.Index(i).Set(src.Index(i))
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Copy via memmove.
|
|
var da, sa unsafe.Pointer
|
|
if idst.kind == Array {
|
|
da = idst.addr
|
|
} else {
|
|
da = unsafe.Pointer((*SliceHeader)(idst.addr).Data)
|
|
}
|
|
if isrc.kind == Array {
|
|
sa = isrc.addr
|
|
} else {
|
|
sa = unsafe.Pointer((*SliceHeader)(isrc.addr).Data)
|
|
}
|
|
memmove(da, sa, uintptr(n)*de.Size())
|
|
return n
|
|
}
|
|
|
|
/*
|
|
* constructors
|
|
*/
|
|
|
|
// MakeSlice creates a new zero-initialized slice value
|
|
// for the specified slice type, length, and capacity.
|
|
func MakeSlice(typ Type, len, cap int) Value {
|
|
if typ.Kind() != Slice {
|
|
panic("reflect: MakeSlice of non-slice type")
|
|
}
|
|
s := &SliceHeader{
|
|
Data: uintptr(unsafe.NewArray(typ.Elem(), cap)),
|
|
Len: len,
|
|
Cap: cap,
|
|
}
|
|
return valueFromAddr(0, typ, unsafe.Pointer(s))
|
|
}
|
|
|
|
// MakeChan creates a new channel with the specified type and buffer size.
|
|
func MakeChan(typ Type, buffer int) Value {
|
|
if typ.Kind() != Chan {
|
|
panic("reflect: MakeChan of non-chan type")
|
|
}
|
|
if buffer < 0 {
|
|
panic("MakeChan: negative buffer size")
|
|
}
|
|
if typ.ChanDir() != BothDir {
|
|
panic("MakeChan: unidirectional channel type")
|
|
}
|
|
ch := makechan(typ.runtimeType(), uint32(buffer))
|
|
return valueFromIword(0, typ, ch)
|
|
}
|
|
|
|
// 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.runtimeType())
|
|
return valueFromIword(0, typ, m)
|
|
}
|
|
|
|
// Indirect returns the value that v points to.
|
|
// If v is a nil pointer, Indirect returns a nil Value.
|
|
// If v is not a pointer, Indirect returns v.
|
|
func Indirect(v Value) Value {
|
|
if v.Kind() != Ptr {
|
|
return v
|
|
}
|
|
return v.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{}
|
|
}
|
|
// For an interface value with the noAddr bit set,
|
|
// the representation is identical to an empty interface.
|
|
eface := *(*emptyInterface)(unsafe.Pointer(&i))
|
|
return packValue(0, eface.typ, eface.word)
|
|
}
|
|
|
|
// Zero returns a Value representing a zero value for the specified type.
|
|
// The result is different from the zero value of the Value struct,
|
|
// which represents no value at all.
|
|
// For example, Zero(TypeOf(42)) returns a Value with Kind Int and value 0.
|
|
func Zero(typ Type) Value {
|
|
if typ == nil {
|
|
panic("reflect: Zero(nil)")
|
|
}
|
|
if typ.Kind() == Ptr || typ.Kind() == UnsafePointer {
|
|
return valueFromIword(0, typ, 0)
|
|
}
|
|
return valueFromAddr(0, typ, unsafe.New(typ))
|
|
}
|
|
|
|
// 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(t).
|
|
func New(typ Type) Value {
|
|
if typ == nil {
|
|
panic("reflect: New(nil)")
|
|
}
|
|
ptr := unsafe.New(typ)
|
|
return valueFromIword(0, PtrTo(typ), iword(uintptr(ptr)))
|
|
}
|
|
|
|
// convertForAssignment
|
|
func convertForAssignment(what string, addr unsafe.Pointer, dst Type, iv internalValue) internalValue {
|
|
if iv.method {
|
|
panic(what + ": cannot assign method value to type " + dst.String())
|
|
}
|
|
|
|
dst1 := dst.(*commonType)
|
|
if directlyAssignable(dst1, iv.typ) {
|
|
// Overwrite type so that they match.
|
|
// Same memory layout, so no harm done.
|
|
iv.typ = dst1
|
|
return iv
|
|
}
|
|
if implements(dst1, iv.typ) {
|
|
if addr == nil {
|
|
addr = unsafe.Pointer(new(interface{}))
|
|
}
|
|
x := iv.Interface()
|
|
if dst.NumMethod() == 0 {
|
|
*(*interface{})(addr) = x
|
|
} else {
|
|
ifaceE2I(dst1.runtimeType(), x, addr)
|
|
}
|
|
iv.addr = addr
|
|
iv.word = iword(uintptr(addr))
|
|
iv.typ = dst1
|
|
return iv
|
|
}
|
|
|
|
// Failed.
|
|
panic(what + ": value of type " + iv.typ.String() + " is not assignable to type " + dst.String())
|
|
}
|
|
|
|
// implemented in ../pkg/runtime
|
|
func chancap(ch iword) int32
|
|
func chanclose(ch iword)
|
|
func chanlen(ch iword) int32
|
|
func chanrecv(ch iword, nb bool) (val iword, selected, received bool)
|
|
func chansend(ch iword, val iword, nb bool) bool
|
|
|
|
func makechan(typ *runtime.Type, size uint32) (ch iword)
|
|
func makemap(t *runtime.Type) iword
|
|
func mapaccess(m iword, key iword) (val iword, ok bool)
|
|
func mapassign(m iword, key, val iword, ok bool)
|
|
func mapiterinit(m iword) *byte
|
|
func mapiterkey(it *byte) (key iword, ok bool)
|
|
func mapiternext(it *byte)
|
|
func maplen(m iword) int32
|
|
|
|
func call(typ *commonType, fnaddr unsafe.Pointer, isInterface bool, isMethod bool, params *unsafe.Pointer, results *unsafe.Pointer)
|
|
func ifaceE2I(t *runtime.Type, src interface{}, dst unsafe.Pointer)
|