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reflect_rtype.go
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reflect_rtype.go
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/*
* Copyright 2009-2018 The Go Authors. All rights reserved.
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file.
*/
package reflect
import (
"bytes"
"unsafe"
)
func (t *RType) isDirectIface() bool { return t.kind&kindDirectIface == 0 } // isDirectIface reports whether t is stored indirectly in an interface value.
func (t *RType) hasPointers() bool { return t.kind&kindNoPointers == 0 }
func (t *RType) canHandleGC() bool { return t.kind&kindGCProg == 0 }
func (t *RType) isAnon() bool { return t.extraTypeFlag&hasNameFlag == 0 }
func (t *RType) hasExtraStar() bool { return t.extraTypeFlag&hasExtraStarFlag != 0 }
func (t *RType) hasInfoFlag() bool { return t.extraTypeFlag&hasExtraInfoFlag != 0 }
func (t *RType) hasName() bool { return !t.isAnon() && len(t.nameOffsetStr().name()) > 0 }
func (t *RType) nameOffset(offset int32) name {
return name{(*byte)(resolveNameOff(unsafe.Pointer(t), offset))}
}
func (t *RType) nameOffsetStr() name { return name{(*byte)(resolveNameOff(unsafe.Pointer(t), t.str))} }
func (t *RType) typeOffset(offset int32) *RType {
return (*RType)(resolveTypeOff(unsafe.Pointer(t), offset))
}
func (t *RType) textOffset(offset int32) unsafe.Pointer {
return resolveTextOff(unsafe.Pointer(t), offset)
}
func (t *RType) convToPtr() *ptrType { return (*ptrType)(unsafe.Pointer(t)) }
func (t *RType) convToStruct() *structType { return (*structType)(unsafe.Pointer(t)) }
func (t *RType) convToFn() *funcType { return (*funcType)(unsafe.Pointer(t)) }
func (t *RType) convToIface() *ifaceType { return (*ifaceType)(unsafe.Pointer(t)) }
func (t *RType) numIn() int { return int(t.convToFn().InLen) }
func (t *RType) numOut() int { return len(t.convToFn().outParams()) }
func (t *RType) ConvToMap() *mapType { return (*mapType)(unsafe.Pointer(t)) }
func (t *RType) ConvToSlice() *sliceType { return (*sliceType)(unsafe.Pointer(t)) }
func (t *RType) ConvToArray() *arrayType { return (*arrayType)(unsafe.Pointer(t)) }
func (t *RType) ifaceMethods() []ifaceMethod { return t.convToIface().methods }
func (t *RType) Deref() *RType { return (*ptrType)(unsafe.Pointer(t)).Type }
func (t *RType) NoOfIfaceMethods() int { return len(t.ifaceMethods()) }
func (t *RType) Kind() Kind { return Kind(t.kind & kindMask) }
func (t *RType) Size() uintptr { return t.size }
func (t *RType) FieldAlign() int { return int(t.fieldAlign) }
func (t *RType) Align() int { return int(t.align) }
func (t *RType) String() string { return string(t.nomen()) }
func (t *RType) IsExported() bool { return t.kind&(1<<5|1<<6) == 0 }
/**
func (t *RType) GoString() string {
result := ""
if t.hasName() {
result += "Name : " + string(t.nomen())
} else {
result += "Anonymous"
}
result += "\n\tKind : " + StringKind(t.Kind()) + " " + strconv.FormatUint(uint64(t.kind&kindMask), 10) + " " + strconv.FormatUint(uint64(t.kind), 10)
result += "\n\tSize : " + strconv.FormatUint(uint64(t.size), 10)
result += "\n\tAlign : " + strconv.FormatUint(uint64(t.align), 10)
result += "\n\tFieldAlign : " + strconv.FormatUint(uint64(t.fieldAlign), 10)
if t.Kind() == Func {
result += "\n\tParams : " + strconv.FormatInt(int64(t.numIn()), 10) + " in , " + strconv.FormatInt(int64(t.numOut()), 10) + " out."
}
if t.hasExtraStar() {
result += "*"
}
if t.isDirectIface() {
result += "\n\tInterface"
}
if t.hasPointers() {
result += "\n\tPointers"
}
if t.canHandleGC() {
result += "\n\tGCHandler"
}
if t.hasInfoFlag() {
result += "\n\tHasInfo"
}
if t.Kind() == Struct {
if n := t.NoOfIfaceMethods(); n > 0 {
result += "\n\t" + strconv.Itoa(n) + " methods vs " + strconv.Itoa(lenExportedMethods(t)) + " methods"
}
}
return result
}
**/
func (t *RType) nomen() []byte {
s := t.nameOffsetStr().name()
if t.hasExtraStar() {
return s[1:]
}
return s
}
// Implements reports whether the type implements the interface type u.
// You always have to provide an Interface Kind of *Type
// Of course, providing nil, returns false
func (t *RType) Implements(u *RType) bool {
if u == nil {
return false
}
if u.Kind() != Interface {
return false
}
return t.implements(u)
}
// AssignableTo reports whether a value of the type is assignable to type u.v
// Of course, providing nil, returns false
func (t *RType) AssignableTo(u *RType) bool {
if u == nil {
return false
}
return t.directlyAssignable(u) || t.implements(u)
}
// ConvertibleTo reports whether a value of the type is convertible to type u.
// Of course, providing nil, returns false
func (t *RType) ConvertibleTo(u *RType) bool {
if u == nil {
return false
}
return t.convertible(u)
}
// PtrTo returns the pointer type with element t.
// For example, if t represents type Foo, PtrTo(t) represents *Foo.
func (t *RType) PtrTo() *RType {
if t.ptrToThis != 0 {
return t.typeOffset(t.ptrToThis)
}
// Look in known types.
typeName := byteSliceFromParams(star, t.nomen())
for _, existingType := range typesByString(typeName) {
// Attention : cannot use .Deref() here because below we need to return the pointer to the *Type
pointerType := existingType.convToPtr()
if pointerType.Type != t {
continue
}
return &pointerType.RType
}
// Create a new ptrType starting with the description of an *ptr.
proto := emptyPtrProto()
proto.str = declareReflectName(newName(typeName))
proto.ptrToThis = 0
// For the type structures linked into the binary, the
// compiler provides a good hash of the string.
// Create a good hash for the new string by using
// the FNV-1 hash's mixing function to combine the
// old hash and the new "*".
proto.hash = fnv1(t.hash, '*')
proto.Type = t
return &proto.RType
}
// directlyAssignable reports whether a value x of type V can be directly assigned (using memmove) to a value of type T.
// https://golang.org/doc/go_spec.html#Assignability
// Ignoring the interface rules (implemented elsewhere) and the ideal constant rules (no ideal constants at run time).
func (t *RType) directlyAssignable(dest *RType) bool {
// x's type V is identical to T?
if dest == t {
return true
}
// Otherwise at least one of T and V must be unnamed
// and they must have the same kind.
if dest.hasName() && t.hasName() || dest.Kind() != t.Kind() {
return false
}
// x's type T and V must have identical underlying types.
return t.haveIdenticalUnderlyingType(dest, true)
}
func (t *RType) haveIdenticalType(dest *RType, cmpTags bool) bool {
if cmpTags {
return dest == t
}
if dest.Name() != t.Name() || dest.Kind() != t.Kind() {
return false
}
return t.haveIdenticalUnderlyingType(dest, false)
}
func (t *RType) haveIdenticalUnderlyingType(dest *RType, cmpTags bool) bool {
if dest == t {
return true
}
kind := dest.Kind()
if kind != t.Kind() {
return false
}
// Non-composite types of equal kind have same underlying type (the predefined instance of the type).
if Bool <= kind && kind <= Complex128 || kind == String || kind == UnsafePointer {
return true
}
// Composite types.
switch kind {
case Array:
destArray := dest.ConvToArray()
return destArray.Len == t.ConvToArray().Len && t.haveIdenticalType(destArray.ElemType, cmpTags)
case Func:
destFn := dest.convToFn()
srcFn := t.convToFn()
if destFn.OutLen != srcFn.OutLen || destFn.InLen != srcFn.InLen {
return false
}
for i := 0; i < destFn.numIn(); i++ {
if !srcFn.inParam(i).haveIdenticalType(destFn.inParam(i), cmpTags) {
return false
}
}
for i := 0; i < destFn.numOut(); i++ {
if !srcFn.outParam(i).haveIdenticalType(destFn.outParam(i), cmpTags) {
return false
}
}
return true
case Interface:
destMethods := dest.ifaceMethods()
srcMethods := t.ifaceMethods()
// the case of "interface{}"
if len(destMethods) == 0 && len(srcMethods) == 0 {
return true
}
// Might have the same methods but still need a run time conversion.
return false
case Map:
return t.ConvToMap().KeyType.haveIdenticalType(dest.ConvToMap().KeyType, cmpTags) && t.ConvToMap().ElemType.haveIdenticalType(dest.ConvToMap().ElemType, cmpTags)
case Slice:
return t.ConvToSlice().ElemType.haveIdenticalType(dest.ConvToSlice().ElemType, cmpTags)
case Ptr:
return t.Deref().haveIdenticalType(dest.Deref(), cmpTags)
case Struct:
destStruct := dest.convToStruct()
srcStruct := t.convToStruct()
if len(destStruct.fields) != len(srcStruct.fields) {
return false
}
if !bytes.Equal(destStruct.pkgPath.name(), srcStruct.pkgPath.name()) {
return false
}
for i := range destStruct.fields {
destField := &destStruct.fields[i]
srcField := &srcStruct.fields[i]
if !bytes.Equal(destField.name.name(), srcField.name.name()) {
return false
}
if !srcField.Type.haveIdenticalType(destField.Type, cmpTags) {
return false
}
if cmpTags && !bytes.Equal(destField.name.tag(), srcField.name.tag()) {
return false
}
if destField.offsetEmbed != srcField.offsetEmbed {
return false
}
}
return true
default:
return false
}
}
func (t *RType) pkg() (int32, bool) {
if !t.hasInfoFlag() {
return 0, false
}
var ut *uncommonType
switch t.Kind() {
case Struct:
ut = &(*uncommonStruct)(unsafe.Pointer(t)).u
case Ptr:
ut = &(*uncommonPtr)(unsafe.Pointer(t)).u
case Func:
ut = &(*uncommonFunc)(unsafe.Pointer(t)).u
case Slice:
ut = &(*uncommonSlice)(unsafe.Pointer(t)).u
case Array:
ut = &(*uncommonArray)(unsafe.Pointer(t)).u
case Interface:
ut = &(*uncommonInterface)(unsafe.Pointer(t)).u
default:
ut = &(*uncommonConcrete)(unsafe.Pointer(t)).u
}
return ut.pkgPath, true
}
// implements reports whether the type V implements the interface type T.
func (t *RType) implements(dest *RType) bool {
if dest.Kind() != Interface {
return false
}
destIntf := dest.convToIface()
// the case of "interface{}"
if len(destIntf.methods) == 0 {
return true
}
// The same algorithm applies in both cases, but the method tables for an interface type and a concrete type are different, so the code is duplicated.
// In both cases the algorithm is a linear scan over the two lists - T's methods and V's methods - simultaneously.
// Since method tables are stored in a unique sorted order (alphabetical, with no duplicate method names), the scan through V's methods must hit a match for each of T's methods along the way, or else V does not implement T.
// This lets us run the scan in overall linear time instead of the quadratic time a naive search would require.
// See also ../runtime/iface.go.
if t.Kind() == Interface {
srcIntf := t.convToIface()
i := 0
for j := 0; j < len(srcIntf.methods); j++ {
destMethod := &destIntf.methods[i]
destMethodName := destIntf.nameOffset(destMethod.nameOffset)
srcMethod := &srcIntf.methods[j]
srcMethodName := t.nameOffset(srcMethod.nameOffset)
if bytes.Equal(srcMethodName.name(), destMethodName.name()) &&
t.typeOffset(srcMethod.typeOffset) == destIntf.typeOffset(destMethod.typeOffset) {
if !destMethodName.isExported() {
destPkgPath := destMethodName.pkgPath()
if len(destPkgPath) == 0 {
destPkgPath = destIntf.pkgPath.name()
}
srcPkgPath := srcMethodName.pkgPath()
if len(srcPkgPath) == 0 {
srcPkgPath = srcIntf.pkgPath.name()
}
if !bytes.Equal(destPkgPath, srcPkgPath) {
continue
}
}
if i++; i >= len(destIntf.methods) {
return true
}
}
}
return false
}
vmethods, ok := methods(t)
if !ok {
return false
}
origPkgPath := make([]byte, 0)
pkg, ok := t.pkg()
if ok {
origPkgPath = t.nameOffset(pkg).name()
}
i := 0
for j := 0; j < len(vmethods); j++ {
destMethod := &destIntf.methods[i]
destMethodName := destIntf.nameOffset(destMethod.nameOffset)
srcMethod := vmethods[j]
srcMethodName := t.nameOffset(srcMethod.nameOffset)
if bytes.Equal(srcMethodName.name(), destMethodName.name()) &&
t.typeOffset(srcMethod.typeOffset) == destIntf.typeOffset(destMethod.typeOffset) {
if !destMethodName.isExported() {
destPkgPath := destMethodName.pkgPath()
if len(destPkgPath) == 0 {
destPkgPath = destIntf.pkgPath.name()
}
srcPkgPath := srcMethodName.pkgPath()
if len(srcPkgPath) == 0 {
srcPkgPath = origPkgPath
}
if !bytes.Equal(destPkgPath, srcPkgPath) {
continue
}
}
if i++; i >= len(destIntf.methods) {
return true
}
}
}
return false
}
// convertOp returns the function to convert a value of type src to a value of type dst. If the conversion is illegal, convertOp returns nil.
func (t *RType) convertible(dst *RType) bool {
destKind := dst.Kind()
srcKind := t.Kind()
switch srcKind {
case Int, Int8, Int16, Int32, Int64:
switch destKind {
case Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, UintPtr:
return true
case Float32, Float64:
return true
case String:
return true
}
case Uint, Uint8, Uint16, Uint32, Uint64, UintPtr:
switch destKind {
case Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, UintPtr:
return true
case Float32, Float64:
return true
case String:
return true
}
case Float32, Float64:
switch destKind {
case Int, Int8, Int16, Int32, Int64:
return true
case Uint, Uint8, Uint16, Uint32, Uint64, UintPtr:
return true
case Float32, Float64:
return true
}
case Complex64, Complex128:
switch destKind {
case Complex64, Complex128:
return true
}
case String:
sliceElem := dst.ConvToSlice().ElemType
if destKind == Slice && sliceElem.pkgPathLen() == 0 {
switch sliceElem.Kind() {
case Uint8:
return true
case Int32:
return true
}
}
case Slice:
sliceElem := t.ConvToSlice().ElemType
if destKind == String && sliceElem.pkgPathLen() == 0 {
switch sliceElem.Kind() {
case Uint8:
return true
case Int32:
return true
}
}
}
// dst and src have same underlying type.
if t.haveIdenticalUnderlyingType(dst, false) {
return true
}
// dst and src are unnamed pointer types with same underlying base type.
if destKind == Ptr && !dst.hasName() &&
srcKind == Ptr && !t.hasName() &&
t.Deref().haveIdenticalUnderlyingType(dst.Deref(), false) {
return true
}
return t.implements(dst)
}
func (t *RType) Comparable() bool {
return t.alg != nil && t.alg.equal != nil
}
// Methods applicable only to some types, depending on Kind.
// The methods allowed for each kind are:
//
// Int*, Uint*, Float*, Complex*: Bits
// Array: Deref, Len
// Chan: ChanDir, Deref
// Func: In, NumIn, Out, NumOut, IsVariadic.
// Map: Key, Deref
// ptr: Deref
// Slice: Deref
// Struct: Field, FieldByIndex, FieldByName, FieldByNameFunc, NumField
// Bits returns the size of the type in bits.
func (t *RType) Bits() int {
if t == nil {
return 0
}
k := t.Kind()
if k < Int || k > Complex128 {
if willPrintDebug {
println("reflect.Bits : of non-arithmetic Type.")
}
return 0
}
return int(t.size) * 8
}
func (t *RType) addTypeBits(vec *bitVector, offset uintptr) {
switch t.Kind() {
case Chan, Func, Map, Ptr, Slice, String, UnsafePointer:
// 1 pointer at start of representation
for vec.num < uint32(offset/uintptr(PtrSize)) {
appendBitVector(vec, 0)
}
appendBitVector(vec, 1)
case Interface:
// 2 pointers
for vec.num < uint32(offset/uintptr(PtrSize)) {
appendBitVector(vec, 0)
}
appendBitVector(vec, 1)
appendBitVector(vec, 1)
case Array:
// repeat inner type
tArray := t.ConvToArray()
for i := 0; i < int(tArray.Len); i++ {
if tArray.ElemType.hasPointers() {
tArray.ElemType.addTypeBits(vec, offset+uintptr(i)*tArray.ElemType.size)
}
}
case Struct:
// apply fields
structType := t.convToStruct()
for i := range structType.fields {
field := &structType.fields[i]
if field.Type.hasPointers() {
field.Type.addTypeBits(vec, offset+structFieldOffset(field))
}
}
}
}
// used only in tests
func (t *RType) PkgPath() string {
if t.isAnon() {
return ""
}
pk, ok := t.pkg()
if !ok {
return ""
}
return string(t.nameOffset(pk).name())
}
func (t *RType) pkgPathLen() int {
if t.isAnon() {
return 0
}
pk, ok := t.pkg()
if !ok {
return 0
}
return t.nameOffset(pk).nameLen()
}
func (t *RType) Name() string {
if t.isAnon() {
return ""
}
s := t.nameOffsetStr().name()
i := len(s) - 1
for i >= 0 {
if s[i] == '.' {
break
}
i--
}
// if we have extra star, and it's the full name, then set it to avoid first char (which is the star)
if t.hasExtraStar() && i == -1 {
i = 0
}
return string(s[i+1:])
}
func (t *RType) Fields(inspect InspectTypeFn) {
if t.Kind() != Struct {
if willPrintDebug {
println("reflect.Field: Requested field of non-struct type")
}
return
}
structType := (*structType)(unsafe.Pointer(t))
for i := range structType.fields {
field := &structType.fields[i]
fn := field.name
var PkgPath []byte
if !fn.isExported() {
PkgPath = structType.pkgPath.name()
}
var Tag []byte
if tag := fn.tag(); len(tag) > 0 {
Tag = tag
}
inspect(field.Type, fn.name(), Tag, PkgPath, field.offsetEmbed&1 != 0, fn.isExported(), field.offsetEmbed>>1, i)
}
}
func (t *RType) StructFields() []structField {
return t.convToStruct().fields
}