1808 lines
50 KiB
Go
1808 lines
50 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 bigEndian = false // can be smarter if we find a big-endian machine
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const ptrSize = 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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// 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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type Value struct {
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// typ holds the type of the value represented by a Value.
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typ *commonType
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// val holds the 1-word representation of the value.
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// If flag's flagIndir bit is set, then val is a pointer to the data.
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// Otherwise val is a word holding the actual data.
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// When the data is smaller than a word, it begins at
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// the first byte (in the memory address sense) of val.
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// We use unsafe.Pointer so that the garbage collector
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// knows that val could be a pointer.
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val 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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// - flagRO: obtained via unexported 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 typ.size > ptrSize, 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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flagRO flag = 1 << iota
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flagIndir
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flagAddr
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flagMethod
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flagKindShift = iota
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flagKindWidth = 5 // there are 27 kinds
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flagKindMask flag = 1<<flagKindWidth - 1
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flagMethodShift = flagKindShift + flagKindWidth
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)
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func (f flag) kind() Kind {
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return Kind((f >> flagKindShift) & flagKindMask)
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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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// 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 holds the data stored
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// in its leading bytes (so is not a pointer).
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// Because the value sometimes holds a pointer, we use
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// unsafe.Pointer to represent it, so that if iword appears
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// in a struct, the garbage collector knows that might be
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// a pointer.
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type iword unsafe.Pointer
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func (v Value) iword() iword {
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if v.flag&flagIndir != 0 && (v.kind() == Ptr || v.kind() == UnsafePointer) {
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// Have indirect but want direct word.
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return loadIword(v.val, v.typ.size)
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}
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return iword(v.val)
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}
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// loadIword loads n bytes at p from memory into an iword.
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func loadIword(p unsafe.Pointer, n uintptr) iword {
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// Run the copy ourselves instead of calling memmove
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// to avoid moving w to the heap.
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var w iword
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switch n {
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default:
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panic("reflect: internal error: loadIword of " + strconv.Itoa(int(n)) + "-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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// storeIword stores n bytes from w into p.
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func storeIword(p unsafe.Pointer, w iword, n uintptr) {
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// Run the copy ourselves instead of calling memmove
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// to avoid moving w to the heap.
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switch n {
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default:
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panic("reflect: internal error: storeIword of " + strconv.Itoa(int(n)) + "-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 *runtimeType
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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 *runtimeType // 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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// 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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k := f.kind()
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if k != expected {
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panic(&ValueError{methodName(), k})
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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(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(methodName() + " using value obtained using unexported field")
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}
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if f&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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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.val, (v.flag & flagRO) | flag(Ptr)<<flagKindShift}
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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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if v.flag&flagIndir != 0 {
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return *(*bool)(v.val)
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}
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return *(*bool)(unsafe.Pointer(&v.val))
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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.val)
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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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return v.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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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.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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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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func (v Value) call(method 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 iword
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)
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if v.flag&flagMethod != 0 {
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i := int(v.flag) >> flagMethodShift
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if v.typ.Kind() == Interface {
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tt := (*interfaceType)(unsafe.Pointer(v.typ))
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if i < 0 || i >= len(tt.methods) {
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panic("reflect: broken Value")
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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(method + " of unexported method")
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}
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t = toCommonType(m.typ)
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iface := (*nonEmptyInterface)(v.val)
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if iface.itab == nil {
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panic(method + " of method on nil interface value")
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}
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fn = iface.itab.fun[i]
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rcvr = iface.word
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} else {
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ut := v.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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panic(method + " of unexported method")
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}
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fn = m.tfn
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t = toCommonType(m.mtyp)
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rcvr = v.iword()
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}
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} else if v.flag&flagIndir != 0 {
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fn = *(*unsafe.Pointer)(v.val)
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} else {
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fn = v.val
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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 := method == "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: " + 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
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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 " + method)
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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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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(iword)
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*p = rcvr
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params[0] = unsafe.Pointer(p)
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off = 1
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}
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first_pointer := false
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for i, pv := range in {
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pv.mustBeExported()
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targ := t.In(i).(*commonType)
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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.val
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params[off] = unsafe.Pointer(p)
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} else {
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params[off] = pv.val
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}
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if i == 0 && Kind(targ.kind) != Ptr && v.flag&flagMethod == 0 && isMethod(v.typ) {
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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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first_pointer = true
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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, first_pointer, pp, pr)
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return ret
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}
|
|
|
|
// 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 {
|
|
k := v.kind()
|
|
switch k {
|
|
case Array:
|
|
return v.typ.Len()
|
|
case Chan:
|
|
return int(chancap(*(*iword)(v.iword())))
|
|
case Slice:
|
|
// Slice is always bigger than a word; assume flagIndir.
|
|
return (*SliceHeader)(v.val).Cap
|
|
}
|
|
panic(&ValueError{"reflect.Value.Cap", k})
|
|
}
|
|
|
|
// Close closes the channel v.
|
|
// It panics if v's Kind is not Chan.
|
|
func (v Value) Close() {
|
|
v.mustBe(Chan)
|
|
v.mustBeExported()
|
|
chanclose(*(*iword)(v.iword()))
|
|
}
|
|
|
|
// Complex returns v's underlying value, as a complex128.
|
|
// It panics if v's Kind is not Complex64 or Complex128
|
|
func (v Value) Complex() complex128 {
|
|
k := v.kind()
|
|
switch k {
|
|
case Complex64:
|
|
if v.flag&flagIndir != 0 {
|
|
return complex128(*(*complex64)(v.val))
|
|
}
|
|
return complex128(*(*complex64)(unsafe.Pointer(&v.val)))
|
|
case Complex128:
|
|
// complex128 is always bigger than a word; assume flagIndir.
|
|
return *(*complex128)(v.val)
|
|
}
|
|
panic(&ValueError{"reflect.Value.Complex", k})
|
|
}
|
|
|
|
// 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 (
|
|
typ *commonType
|
|
val unsafe.Pointer
|
|
)
|
|
if v.typ.NumMethod() == 0 {
|
|
eface := (*emptyInterface)(v.val)
|
|
if eface.typ == nil {
|
|
// nil interface value
|
|
return Value{}
|
|
}
|
|
typ = toCommonType(eface.typ)
|
|
val = unsafe.Pointer(eface.word)
|
|
} else {
|
|
iface := (*nonEmptyInterface)(v.val)
|
|
if iface.itab == nil {
|
|
// nil interface value
|
|
return Value{}
|
|
}
|
|
typ = toCommonType(iface.itab.typ)
|
|
val = unsafe.Pointer(iface.word)
|
|
}
|
|
fl := v.flag & flagRO
|
|
fl |= flag(typ.Kind()) << flagKindShift
|
|
if typ.Kind() != Ptr && typ.Kind() != UnsafePointer {
|
|
fl |= flagIndir
|
|
}
|
|
return Value{typ, val, fl}
|
|
|
|
case Ptr:
|
|
val := v.val
|
|
if v.flag&flagIndir != 0 {
|
|
val = *(*unsafe.Pointer)(val)
|
|
}
|
|
// The returned value's address is v's value.
|
|
if val == nil {
|
|
return Value{}
|
|
}
|
|
tt := (*ptrType)(unsafe.Pointer(v.typ))
|
|
typ := toCommonType(tt.elem)
|
|
fl := v.flag&flagRO | flagIndir | flagAddr
|
|
fl |= flag(typ.Kind() << flagKindShift)
|
|
return Value{typ, val, fl}
|
|
}
|
|
panic(&ValueError{"reflect.Value.Elem", k})
|
|
}
|
|
|
|
// Field returns the i'th field of the struct v.
|
|
// It panics if v's Kind is not Struct or i is out of range.
|
|
func (v Value) Field(i int) Value {
|
|
v.mustBe(Struct)
|
|
tt := (*structType)(unsafe.Pointer(v.typ))
|
|
if i < 0 || i >= len(tt.fields) {
|
|
panic("reflect: Field index out of range")
|
|
}
|
|
field := &tt.fields[i]
|
|
typ := toCommonType(field.typ)
|
|
|
|
// Inherit permission bits from v.
|
|
fl := v.flag & (flagRO | flagIndir | flagAddr)
|
|
// Using an unexported field forces flagRO.
|
|
if field.pkgPath != nil {
|
|
fl |= flagRO
|
|
}
|
|
fl |= flag(typ.Kind()) << flagKindShift
|
|
|
|
var val unsafe.Pointer
|
|
switch {
|
|
case fl&flagIndir != 0:
|
|
// Indirect. Just bump pointer.
|
|
val = unsafe.Pointer(uintptr(v.val) + field.offset)
|
|
case bigEndian:
|
|
// Direct. Discard leading bytes.
|
|
val = unsafe.Pointer(uintptr(v.val) << (field.offset * 8))
|
|
default:
|
|
// Direct. Discard leading bytes.
|
|
val = unsafe.Pointer(uintptr(v.val) >> (field.offset * 8))
|
|
}
|
|
|
|
return Value{typ, val, fl}
|
|
}
|
|
|
|
// FieldByIndex returns the nested field corresponding to index.
|
|
// It panics if v's Kind is not struct.
|
|
func (v Value) FieldByIndex(index []int) Value {
|
|
v.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 {
|
|
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 {
|
|
v.mustBe(Struct)
|
|
if f, ok := v.typ.FieldByNameFunc(match); ok {
|
|
return v.FieldByIndex(f.Index)
|
|
}
|
|
return Value{}
|
|
}
|
|
|
|
// Float returns v's underlying value, as 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:
|
|
if v.flag&flagIndir != 0 {
|
|
return float64(*(*float32)(v.val))
|
|
}
|
|
return float64(*(*float32)(unsafe.Pointer(&v.val)))
|
|
case Float64:
|
|
if v.flag&flagIndir != 0 {
|
|
return *(*float64)(v.val)
|
|
}
|
|
return *(*float64)(unsafe.Pointer(&v.val))
|
|
}
|
|
panic(&ValueError{"reflect.Value.Float", k})
|
|
}
|
|
|
|
// Index returns v's i'th element.
|
|
// It panics if v's Kind is not Array or Slice or i is out of range.
|
|
func (v Value) Index(i int) Value {
|
|
k := v.kind()
|
|
switch k {
|
|
case Array:
|
|
tt := (*arrayType)(unsafe.Pointer(v.typ))
|
|
if i < 0 || i > int(tt.len) {
|
|
panic("reflect: array index out of range")
|
|
}
|
|
typ := toCommonType(tt.elem)
|
|
fl := v.flag & (flagRO | flagIndir | flagAddr) // bits same as overall array
|
|
fl |= flag(typ.Kind()) << flagKindShift
|
|
offset := uintptr(i) * typ.size
|
|
|
|
var val unsafe.Pointer
|
|
switch {
|
|
case fl&flagIndir != 0:
|
|
// Indirect. Just bump pointer.
|
|
val = unsafe.Pointer(uintptr(v.val) + offset)
|
|
case bigEndian:
|
|
// Direct. Discard leading bytes.
|
|
val = unsafe.Pointer(uintptr(v.val) << (offset * 8))
|
|
default:
|
|
// Direct. Discard leading bytes.
|
|
val = unsafe.Pointer(uintptr(v.val) >> (offset * 8))
|
|
}
|
|
return Value{typ, val, fl}
|
|
|
|
case Slice:
|
|
// Element flag same as Elem of Ptr.
|
|
// Addressable, indirect, possibly read-only.
|
|
fl := flagAddr | flagIndir | v.flag&flagRO
|
|
s := (*SliceHeader)(v.val)
|
|
if i < 0 || i >= s.Len {
|
|
panic("reflect: slice index out of range")
|
|
}
|
|
tt := (*sliceType)(unsafe.Pointer(v.typ))
|
|
typ := toCommonType(tt.elem)
|
|
fl |= flag(typ.Kind()) << flagKindShift
|
|
val := unsafe.Pointer(s.Data + uintptr(i)*typ.size)
|
|
return Value{typ, val, fl}
|
|
}
|
|
panic(&ValueError{"reflect.Value.Index", k})
|
|
}
|
|
|
|
// Int returns v's underlying value, as an int64.
|
|
// It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64.
|
|
func (v Value) Int() int64 {
|
|
k := v.kind()
|
|
var p unsafe.Pointer
|
|
if v.flag&flagIndir != 0 {
|
|
p = v.val
|
|
} else {
|
|
// The escape analysis is good enough that &v.val
|
|
// does not trigger a heap allocation.
|
|
p = unsafe.Pointer(&v.val)
|
|
}
|
|
switch k {
|
|
case Int:
|
|
return int64(*(*int)(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", k})
|
|
}
|
|
|
|
// CanInterface returns true if Interface can be used without panicking.
|
|
func (v Value) CanInterface() bool {
|
|
if v.flag == 0 {
|
|
panic(&ValueError{"reflect.Value.CanInterface", Invalid})
|
|
}
|
|
return v.flag&(flagMethod|flagRO) == 0
|
|
}
|
|
|
|
// Interface returns v's current value as an interface{}.
|
|
// It is equivalent to:
|
|
// var i interface{} = (v's underlying value)
|
|
// If v is a method obtained by invoking Value.Method
|
|
// (as opposed to Type.Method), Interface cannot return an
|
|
// interface value, so it panics.
|
|
// It also 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 v.flag&flagMethod != 0 {
|
|
panic("reflect.Value.Interface: cannot create interface value for method with bound receiver")
|
|
}
|
|
|
|
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")
|
|
}
|
|
|
|
k := v.kind()
|
|
if k == 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.val)
|
|
}
|
|
return *(*interface {
|
|
M()
|
|
})(v.val)
|
|
}
|
|
|
|
// Non-interface value.
|
|
var eface emptyInterface
|
|
eface.typ = v.typ.runtimeType()
|
|
eface.word = v.iword()
|
|
|
|
if v.flag&flagIndir != 0 && v.typ.size > ptrSize {
|
|
// eface.word is a pointer to the actual data,
|
|
// which might be changed. We need to return
|
|
// a pointer to unchanging data, so make a copy.
|
|
ptr := unsafe_New(v.typ)
|
|
memmove(ptr, unsafe.Pointer(eface.word), v.typ.size)
|
|
eface.word = iword(ptr)
|
|
}
|
|
|
|
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 {
|
|
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.val)
|
|
}
|
|
|
|
// IsNil returns true if v is a nil value.
|
|
// It panics if v's Kind is not Chan, Func, Interface, Map, Ptr, or Slice.
|
|
func (v Value) IsNil() bool {
|
|
k := v.kind()
|
|
switch k {
|
|
case Chan, Func, Map, Ptr:
|
|
if v.flag&flagMethod != 0 {
|
|
panic("reflect: IsNil of method Value")
|
|
}
|
|
ptr := v.val
|
|
if v.flag&flagIndir != 0 {
|
|
ptr = *(*unsafe.Pointer)(ptr)
|
|
}
|
|
return ptr == nil
|
|
case Interface, Slice:
|
|
// Both interface and slice are nil if first word is 0.
|
|
// Both are always bigger than a word; assume flagIndir.
|
|
return *(*unsafe.Pointer)(v.val) == nil
|
|
}
|
|
panic(&ValueError{"reflect.Value.IsNil", k})
|
|
}
|
|
|
|
// 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.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 int(chanlen(*(*iword)(v.iword())))
|
|
case Map:
|
|
return int(maplen(*(*iword)(v.iword())))
|
|
case Slice:
|
|
// Slice is bigger than a word; assume flagIndir.
|
|
return (*SliceHeader)(v.val).Len
|
|
case String:
|
|
// String is bigger than a word; assume flagIndir.
|
|
return (*StringHeader)(v.val).Len
|
|
}
|
|
panic(&ValueError{"reflect.Value.Len", k})
|
|
}
|
|
|
|
// 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", toCommonType(tt.key), nil)
|
|
|
|
word, ok := mapaccess(v.typ.runtimeType(), *(*iword)(v.iword()), key.iword())
|
|
if !ok {
|
|
return Value{}
|
|
}
|
|
typ := toCommonType(tt.elem)
|
|
fl := (v.flag | key.flag) & flagRO
|
|
if typ.Kind() != Ptr && typ.Kind() != UnsafePointer {
|
|
fl |= flagIndir
|
|
}
|
|
fl |= flag(typ.Kind()) << flagKindShift
|
|
return Value{typ, unsafe.Pointer(word), fl}
|
|
}
|
|
|
|
// MapKeys returns a slice containing all the keys present in the map,
|
|
// 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 := toCommonType(tt.key)
|
|
|
|
fl := v.flag & flagRO
|
|
fl |= flag(keyType.Kind()) << flagKindShift
|
|
if keyType.Kind() != Ptr && keyType.Kind() != UnsafePointer {
|
|
fl |= flagIndir
|
|
}
|
|
|
|
m := *(*iword)(v.iword())
|
|
mlen := int32(0)
|
|
if m != nil {
|
|
mlen = maplen(m)
|
|
}
|
|
it := mapiterinit(v.typ.runtimeType(), m)
|
|
a := make([]Value, mlen)
|
|
var i int
|
|
for i = 0; i < len(a); i++ {
|
|
keyWord, ok := mapiterkey(it)
|
|
if !ok {
|
|
break
|
|
}
|
|
a[i] = Value{keyType, unsafe.Pointer(keyWord), 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.
|
|
func (v Value) Method(i int) Value {
|
|
if v.typ == nil {
|
|
panic(&ValueError{"reflect.Value.Method", Invalid})
|
|
}
|
|
if v.flag&flagMethod != 0 || i < 0 || i >= v.typ.NumMethod() {
|
|
panic("reflect: Method index out of range")
|
|
}
|
|
fl := v.flag & (flagRO | flagAddr | flagIndir)
|
|
fl |= flag(Func) << flagKindShift
|
|
fl |= flag(i)<<flagMethodShift | flagMethod
|
|
return Value{v.typ, v.val, fl}
|
|
}
|
|
|
|
// NumMethod returns the number of methods in the value's method set.
|
|
func (v Value) NumMethod() int {
|
|
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 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 {
|
|
k := v.kind()
|
|
switch k {
|
|
case Complex64:
|
|
return overflowFloat32(real(x)) || overflowFloat32(imag(x))
|
|
case Complex128:
|
|
return false
|
|
}
|
|
panic(&ValueError{"reflect.Value.OverflowComplex", k})
|
|
}
|
|
|
|
// OverflowFloat returns true if the float64 x cannot be represented by v's type.
|
|
// It panics if v's Kind is not Float32 or Float64.
|
|
func (v Value) OverflowFloat(x float64) bool {
|
|
k := v.kind()
|
|
switch k {
|
|
case Float32:
|
|
return overflowFloat32(x)
|
|
case Float64:
|
|
return false
|
|
}
|
|
panic(&ValueError{"reflect.Value.OverflowFloat", k})
|
|
}
|
|
|
|
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 {
|
|
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", k})
|
|
}
|
|
|
|
// OverflowUint returns true if the uint64 x cannot be represented by v's type.
|
|
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64.
|
|
func (v Value) OverflowUint(x uint64) bool {
|
|
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", k})
|
|
}
|
|
|
|
// 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 {
|
|
k := v.kind()
|
|
switch k {
|
|
case Chan, Func, Map, Ptr, UnsafePointer:
|
|
if k == Func && v.flag&flagMethod != 0 {
|
|
panic("reflect.Value.Pointer of method Value")
|
|
}
|
|
p := v.val
|
|
if v.flag&flagIndir != 0 {
|
|
p = *(*unsafe.Pointer)(p)
|
|
}
|
|
return uintptr(p)
|
|
case Slice:
|
|
return (*SliceHeader)(v.val).Data
|
|
}
|
|
panic(&ValueError{"reflect.Value.Pointer", k})
|
|
}
|
|
|
|
// 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("recv on send-only channel")
|
|
}
|
|
word, selected, ok := chanrecv(v.typ.runtimeType(), *(*iword)(v.iword()), nb)
|
|
if selected {
|
|
typ := toCommonType(tt.elem)
|
|
fl := flag(typ.Kind()) << flagKindShift
|
|
if typ.Kind() != Ptr && typ.Kind() != UnsafePointer {
|
|
fl |= flagIndir
|
|
}
|
|
val = Value{typ, unsafe.Pointer(word), fl}
|
|
}
|
|
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("send on recv-only channel")
|
|
}
|
|
x.mustBeExported()
|
|
x = x.assignTo("reflect.Value.Send", toCommonType(tt.elem), nil)
|
|
return chansend(v.typ.runtimeType(), *(*iword)(v.iword()), x.iword(), nb)
|
|
}
|
|
|
|
// Set assigns x to the value v.
|
|
// It panics if CanSet returns false.
|
|
// As in Go, x's value must be assignable to v's type.
|
|
func (v Value) Set(x Value) {
|
|
v.mustBeAssignable()
|
|
x.mustBeExported() // do not let unexported x leak
|
|
var target *interface{}
|
|
if v.kind() == Interface {
|
|
target = (*interface{})(v.val)
|
|
}
|
|
x = x.assignTo("reflect.Set", v.typ, target)
|
|
if x.flag&flagIndir != 0 {
|
|
memmove(v.val, x.val, v.typ.size)
|
|
} else {
|
|
storeIword(v.val, iword(x.val), v.typ.size)
|
|
}
|
|
}
|
|
|
|
// SetBool sets v's underlying value.
|
|
// It panics if v's Kind is not Bool or if CanSet() is false.
|
|
func (v Value) SetBool(x bool) {
|
|
v.mustBeAssignable()
|
|
v.mustBe(Bool)
|
|
*(*bool)(v.val) = x
|
|
}
|
|
|
|
// SetBytes sets v's underlying value.
|
|
// It panics if v's underlying value is not a slice of bytes.
|
|
func (v Value) SetBytes(x []byte) {
|
|
v.mustBeAssignable()
|
|
v.mustBe(Slice)
|
|
if v.typ.Elem().Kind() != Uint8 {
|
|
panic("reflect.Value.SetBytes of non-byte slice")
|
|
}
|
|
*(*[]byte)(v.val) = x
|
|
}
|
|
|
|
// SetComplex sets v's underlying value to x.
|
|
// It panics if v's Kind is not Complex64 or Complex128, or if CanSet() is false.
|
|
func (v Value) SetComplex(x complex128) {
|
|
v.mustBeAssignable()
|
|
switch k := v.kind(); k {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetComplex", k})
|
|
case Complex64:
|
|
*(*complex64)(v.val) = complex64(x)
|
|
case Complex128:
|
|
*(*complex128)(v.val) = x
|
|
}
|
|
}
|
|
|
|
// SetFloat sets v's underlying value to x.
|
|
// It panics if v's Kind is not Float32 or Float64, or if CanSet() is false.
|
|
func (v Value) SetFloat(x float64) {
|
|
v.mustBeAssignable()
|
|
switch k := v.kind(); k {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetFloat", k})
|
|
case Float32:
|
|
*(*float32)(v.val) = float32(x)
|
|
case Float64:
|
|
*(*float64)(v.val) = x
|
|
}
|
|
}
|
|
|
|
// SetInt sets v's underlying value to x.
|
|
// It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64, or if CanSet() is false.
|
|
func (v Value) SetInt(x int64) {
|
|
v.mustBeAssignable()
|
|
switch k := v.kind(); k {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetInt", k})
|
|
case Int:
|
|
*(*int)(v.val) = int(x)
|
|
case Int8:
|
|
*(*int8)(v.val) = int8(x)
|
|
case Int16:
|
|
*(*int16)(v.val) = int16(x)
|
|
case Int32:
|
|
*(*int32)(v.val) = int32(x)
|
|
case Int64:
|
|
*(*int64)(v.val) = 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.val)
|
|
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) {
|
|
v.mustBe(Map)
|
|
v.mustBeExported()
|
|
key.mustBeExported()
|
|
tt := (*mapType)(unsafe.Pointer(v.typ))
|
|
key = key.assignTo("reflect.Value.SetMapIndex", toCommonType(tt.key), nil)
|
|
if val.typ != nil {
|
|
val.mustBeExported()
|
|
val = val.assignTo("reflect.Value.SetMapIndex", toCommonType(tt.elem), nil)
|
|
}
|
|
mapassign(v.typ.runtimeType(), *(*iword)(v.iword()), key.iword(), val.iword(), val.typ != nil)
|
|
}
|
|
|
|
// SetUint sets v's underlying value to x.
|
|
// It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64, or if CanSet() is false.
|
|
func (v Value) SetUint(x uint64) {
|
|
v.mustBeAssignable()
|
|
switch k := v.kind(); k {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.SetUint", k})
|
|
case Uint:
|
|
*(*uint)(v.val) = uint(x)
|
|
case Uint8:
|
|
*(*uint8)(v.val) = uint8(x)
|
|
case Uint16:
|
|
*(*uint16)(v.val) = uint16(x)
|
|
case Uint32:
|
|
*(*uint32)(v.val) = uint32(x)
|
|
case Uint64:
|
|
*(*uint64)(v.val) = x
|
|
case Uintptr:
|
|
*(*uintptr)(v.val) = uintptr(x)
|
|
}
|
|
}
|
|
|
|
// SetPointer sets the unsafe.Pointer value v to x.
|
|
// It panics if v's Kind is not UnsafePointer.
|
|
func (v Value) SetPointer(x unsafe.Pointer) {
|
|
v.mustBeAssignable()
|
|
v.mustBe(UnsafePointer)
|
|
*(*unsafe.Pointer)(v.val) = x
|
|
}
|
|
|
|
// SetString sets v's underlying value to x.
|
|
// It panics if v's Kind is not String or if CanSet() is false.
|
|
func (v Value) SetString(x string) {
|
|
v.mustBeAssignable()
|
|
v.mustBe(String)
|
|
*(*string)(v.val) = x
|
|
}
|
|
|
|
// Slice returns a slice of v.
|
|
// It panics if v's Kind is not Array or Slice.
|
|
func (v Value) Slice(beg, end int) Value {
|
|
var (
|
|
cap int
|
|
typ *sliceType
|
|
base unsafe.Pointer
|
|
)
|
|
switch k := v.kind(); k {
|
|
default:
|
|
panic(&ValueError{"reflect.Value.Slice", k})
|
|
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(toCommonType(tt.slice)))
|
|
base = v.val
|
|
case Slice:
|
|
typ = (*sliceType)(unsafe.Pointer(v.typ))
|
|
s := (*SliceHeader)(v.val)
|
|
base = unsafe.Pointer(s.Data)
|
|
cap = s.Cap
|
|
|
|
}
|
|
if beg < 0 || end < beg || end > cap {
|
|
panic("reflect.Value.Slice: slice index out of bounds")
|
|
}
|
|
|
|
// Declare slice so that gc can see the base pointer in it.
|
|
var x []byte
|
|
|
|
// Reinterpret as *SliceHeader to edit.
|
|
s := (*SliceHeader)(unsafe.Pointer(&x))
|
|
s.Data = uintptr(base) + uintptr(beg)*toCommonType(typ.elem).Size()
|
|
s.Len = end - beg
|
|
s.Cap = cap - beg
|
|
|
|
fl := v.flag&flagRO | flagIndir | flag(Slice)<<flagKindShift
|
|
return Value{typ.common(), unsafe.Pointer(&x), fl}
|
|
}
|
|
|
|
// String returns the string v's underlying value, as a string.
|
|
// 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 {
|
|
switch k := v.kind(); k {
|
|
case Invalid:
|
|
return "<invalid Value>"
|
|
case String:
|
|
return *(*string)(v.val)
|
|
}
|
|
// If you call String on a reflect.Value of other type, it's better to
|
|
// print something than to panic. Useful in debugging.
|
|
return "<" + v.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) {
|
|
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 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 {
|
|
v.mustBe(Chan)
|
|
v.mustBeExported()
|
|
return v.send(x, true)
|
|
}
|
|
|
|
// Type returns v's type.
|
|
func (v Value) Type() Type {
|
|
f := v.flag
|
|
if f == 0 {
|
|
panic(&ValueError{"reflect.Value.Type", Invalid})
|
|
}
|
|
if f&flagMethod == 0 {
|
|
// Easy case
|
|
return v.typ.toType()
|
|
}
|
|
|
|
// Method value.
|
|
// v.typ describes the receiver, not the method type.
|
|
i := int(v.flag) >> flagMethodShift
|
|
if v.typ.Kind() == Interface {
|
|
// Method on interface.
|
|
tt := (*interfaceType)(unsafe.Pointer(v.typ))
|
|
if i < 0 || i >= len(tt.methods) {
|
|
panic("reflect: broken Value")
|
|
}
|
|
m := &tt.methods[i]
|
|
return toCommonType(m.typ).toType()
|
|
}
|
|
// Method on concrete type.
|
|
ut := v.typ.uncommon()
|
|
if ut == nil || i < 0 || i >= len(ut.methods) {
|
|
panic("reflect: broken Value")
|
|
}
|
|
m := &ut.methods[i]
|
|
return toCommonType(m.mtyp).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 {
|
|
k := v.kind()
|
|
var p unsafe.Pointer
|
|
if v.flag&flagIndir != 0 {
|
|
p = v.val
|
|
} else {
|
|
// The escape analysis is good enough that &v.val
|
|
// does not trigger a heap allocation.
|
|
p = unsafe.Pointer(&v.val)
|
|
}
|
|
switch k {
|
|
case Uint:
|
|
return uint64(*(*uint)(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", k})
|
|
}
|
|
|
|
// UnsafeAddr returns a pointer to v's data.
|
|
// It is for advanced clients that also import the "unsafe" package.
|
|
// It panics if v is not addressable.
|
|
func (v Value) UnsafeAddr() uintptr {
|
|
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.val)
|
|
}
|
|
|
|
// 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(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.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)
|
|
|
|
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 src.flag&flagIndir == 0 {
|
|
for i := 0; i < n; i++ {
|
|
dst.Index(i).Set(src.Index(i))
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Copy via memmove.
|
|
var da, sa unsafe.Pointer
|
|
if dk == Array {
|
|
da = dst.val
|
|
} else {
|
|
da = unsafe.Pointer((*SliceHeader)(dst.val).Data)
|
|
}
|
|
if sk == Array {
|
|
sa = src.val
|
|
} else {
|
|
sa = unsafe.Pointer((*SliceHeader)(src.val).Data)
|
|
}
|
|
memmove(da, sa, uintptr(n)*de.Size())
|
|
return n
|
|
}
|
|
|
|
/*
|
|
* constructors
|
|
*/
|
|
|
|
// implemented in package runtime
|
|
func unsafe_New(Type) unsafe.Pointer
|
|
func unsafe_NewArray(Type, 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")
|
|
}
|
|
|
|
// Declare slice so that gc can see the base pointer in it.
|
|
var x []byte
|
|
|
|
// Reinterpret as *SliceHeader to edit.
|
|
s := (*SliceHeader)(unsafe.Pointer(&x))
|
|
s.Data = uintptr(unsafe_NewArray(typ.Elem(), cap))
|
|
s.Len = len
|
|
s.Cap = cap
|
|
|
|
return Value{typ.common(), unsafe.Pointer(&x), flagIndir | flag(Slice)<<flagKindShift}
|
|
}
|
|
|
|
// MakeChan creates a new channel with the specified type and buffer size.
|
|
func MakeChan(typ Type, buffer int) Value {
|
|
if typ.Kind() != Chan {
|
|
panic("reflect.MakeChan of non-chan type")
|
|
}
|
|
if buffer < 0 {
|
|
panic("reflect.MakeChan: negative buffer size")
|
|
}
|
|
if typ.ChanDir() != BothDir {
|
|
panic("reflect.MakeChan: unidirectional channel type")
|
|
}
|
|
ch := makechan(typ.runtimeType(), uint32(buffer))
|
|
return Value{typ.common(), unsafe.Pointer(ch), flagIndir | (flag(Chan) << flagKindShift)}
|
|
}
|
|
|
|
// MakeMap creates a new map of the specified type.
|
|
func MakeMap(typ Type) Value {
|
|
if typ.Kind() != Map {
|
|
panic("reflect.MakeMap of non-map type")
|
|
}
|
|
m := makemap(typ.runtimeType())
|
|
return Value{typ.common(), unsafe.Pointer(m), flagIndir | (flag(Map) << flagKindShift)}
|
|
}
|
|
|
|
// 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 packValue, eface.typ doesn't escape,
|
|
// and eface.word is an integer. So it looks like
|
|
// i (= eface) doesn't escape. But really it does,
|
|
// because eface.word is actually a pointer.
|
|
escapes(i)
|
|
|
|
// For an interface value with the noAddr bit set,
|
|
// the representation is identical to an empty interface.
|
|
eface := *(*emptyInterface)(unsafe.Pointer(&i))
|
|
typ := toCommonType(eface.typ)
|
|
fl := flag(typ.Kind()) << flagKindShift
|
|
if typ.Kind() != Ptr && typ.Kind() != UnsafePointer {
|
|
fl |= flagIndir
|
|
}
|
|
return Value{typ, unsafe.Pointer(eface.word), fl}
|
|
}
|
|
|
|
// 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)")
|
|
}
|
|
t := typ.common()
|
|
fl := flag(t.Kind()) << flagKindShift
|
|
if t.Kind() == Ptr || t.Kind() == UnsafePointer {
|
|
return Value{t, nil, fl}
|
|
}
|
|
return Value{t, unsafe_New(typ), fl | flagIndir}
|
|
}
|
|
|
|
// 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)
|
|
fl := flag(Ptr) << flagKindShift
|
|
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) << flagKindShift
|
|
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 *commonType, target *interface{}) Value {
|
|
if v.flag&flagMethod != 0 {
|
|
panic(context + ": cannot assign method value to type " + dst.String())
|
|
}
|
|
|
|
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()) << flagKindShift
|
|
return Value{dst, v.val, fl}
|
|
|
|
case implements(dst, v.typ):
|
|
if target == nil {
|
|
target = new(interface{})
|
|
}
|
|
x := valueInterface(v, false)
|
|
if dst.NumMethod() == 0 {
|
|
*target = x
|
|
} else {
|
|
ifaceE2I(dst.runtimeType(), x, unsafe.Pointer(target))
|
|
}
|
|
return Value{dst, unsafe.Pointer(target), flagIndir | flag(Interface)<<flagKindShift}
|
|
}
|
|
|
|
// Failed.
|
|
panic(context + ": value of type " + v.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(t *runtimeType, ch iword, nb bool) (val iword, selected, received bool)
|
|
func chansend(t *runtimeType, ch iword, val iword, nb bool) bool
|
|
|
|
func makechan(typ *runtimeType, size uint32) (ch iword)
|
|
func makemap(t *runtimeType) (m iword)
|
|
func mapaccess(t *runtimeType, m iword, key iword) (val iword, ok bool)
|
|
func mapassign(t *runtimeType, m iword, key, val iword, ok bool)
|
|
func mapiterinit(t *runtimeType, 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 *runtimeType, src interface{}, dst unsafe.Pointer)
|
|
|
|
// Dummy annotation marking that the value x escapes,
|
|
// for use in cases where the reflect code is so clever that
|
|
// the compiler cannot follow.
|
|
func escapes(x interface{}) {
|
|
if dummy.b {
|
|
dummy.x = x
|
|
}
|
|
}
|
|
|
|
var dummy struct {
|
|
b bool
|
|
x interface{}
|
|
}
|