// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package reflect implements run-time reflection, allowing a program to
// manipulate objects with arbitrary types. The typical use is to take a value
// with static type interface{} and extract its dynamic type information by
// calling TypeOf, which returns a Type.
//
// A call to ValueOf returns a Value representing the run-time data.
// Zero takes a Type and returns a Value representing a zero value
// for that type.
//
// See "The Laws of Reflection" for an introduction to reflection in Go:
// https://golang.org/doc/articles/laws_of_reflection.html
package reflect
import (
"runtime"
"strconv"
"sync"
"unicode"
"unicode/utf8"
"unsafe"
)
// Type is the representation of a Go type.
//
// Not all methods apply to all kinds of types. Restrictions,
// if any, are noted in the documentation for each method.
// Use the Kind method to find out the kind of type before
// calling kind-specific methods. Calling a method
// inappropriate to the kind of type causes a run-time panic.
//
// Type values are comparable, such as with the == operator,
// so they can be used as map keys.
// Two Type values are equal if they represent identical types.
type Type interface {
// Methods applicable to all types.
// Align returns the alignment in bytes of a value of
// this type when allocated in memory.
Align() int
// FieldAlign returns the alignment in bytes of a value of
// this type when used as a field in a struct.
FieldAlign() int
// Method returns the i'th method in the type's method set.
// It panics if i is not in the range [0, NumMethod()).
//
// For a non-interface type T or *T, the returned Method's Type and Func
// fields describe a function whose first argument is the receiver.
//
// For an interface type, the returned Method's Type field gives the
// method signature, without a receiver, and the Func field is nil.
//
// Only exported methods are accessible and they are sorted in
// lexicographic order.
Method(int) Method
// MethodByName returns the method with that name in the type's
// method set and a boolean indicating if the method was found.
//
// For a non-interface type T or *T, the returned Method's Type and Func
// fields describe a function whose first argument is the receiver.
//
// For an interface type, the returned Method's Type field gives the
// method signature, without a receiver, and the Func field is nil.
MethodByName(string) (Method, bool)
// NumMethod returns the number of exported methods in the type's method set.
NumMethod() int
// Name returns the type's name within its package for a defined type.
// For other (non-defined) types it returns the empty string.
Name() string
// PkgPath returns a defined type's package path, that is, the import path
// that uniquely identifies the package, such as "encoding/base64".
// If the type was predeclared (string, error) or not defined (*T, struct{},
// []int, or A where A is an alias for a non-defined type), the package path
// will be the empty string.
PkgPath() string
// Size returns the number of bytes needed to store
// a value of the given type; it is analogous to unsafe.Sizeof.
Size() uintptr
// String returns a string representation of the type.
// The string representation may use shortened package names
// (e.g., base64 instead of "encoding/base64") and is not
// guaranteed to be unique among types. To test for type identity,
// compare the Types directly.
String() string
// Kind returns the specific kind of this type.
Kind() Kind
// Implements reports whether the type implements the interface type u.
Implements(u Type) bool
// AssignableTo reports whether a value of the type is assignable to type u.
AssignableTo(u Type) bool
// ConvertibleTo reports whether a value of the type is convertible to type u.
ConvertibleTo(u Type) bool
// Comparable reports whether values of this type are comparable.
Comparable() bool
// Methods applicable only to some types, depending on Kind.
// The methods allowed for each kind are:
//
// Int*, Uint*, Float*, Complex*: Bits
// Array: Elem, Len
// Chan: ChanDir, Elem
// Func: In, NumIn, Out, NumOut, IsVariadic.
// Map: Key, Elem
// Ptr: Elem
// Slice: Elem
// Struct: Field, FieldByIndex, FieldByName, FieldByNameFunc, NumField
// Bits returns the size of the type in bits.
// It panics if the type's Kind is not one of the
// sized or unsized Int, Uint, Float, or Complex kinds.
Bits() int
// ChanDir returns a channel type's direction.
// It panics if the type's Kind is not Chan.
ChanDir() ChanDir
// IsVariadic reports whether a function type's final input parameter
// is a "..." parameter. If so, t.In(t.NumIn() - 1) returns the parameter's
// implicit actual type []T.
//
// For concreteness, if t represents func(x int, y ... float64), then
//
// t.NumIn() == 2
// t.In(0) is the reflect.Type for "int"
// t.In(1) is the reflect.Type for "[]float64"
// t.IsVariadic() == true
//
// IsVariadic panics if the type's Kind is not Func.
IsVariadic() bool
// Elem returns a type's element type.
// It panics if the type's Kind is not Array, Chan, Map, Ptr, or Slice.
Elem() Type
// Field returns a struct type's i'th field.
// It panics if the type's Kind is not Struct.
// It panics if i is not in the range [0, NumField()).
Field(i int) StructField
// FieldByIndex returns the nested field corresponding
// to the index sequence. It is equivalent to calling Field
// successively for each index i.
// It panics if the type's Kind is not Struct.
FieldByIndex(index []int) StructField
// FieldByName returns the struct field with the given name
// and a boolean indicating if the field was found.
FieldByName(name string) (StructField, bool)
// FieldByNameFunc returns the struct field with a name
// that satisfies the match function and a boolean indicating if
// the field was found.
//
// FieldByNameFunc considers the fields in the struct itself
// and then the fields in any embedded structs, in breadth first order,
// stopping at the shallowest nesting depth containing one or more
// fields satisfying the match function. If multiple fields at that depth
// satisfy the match function, they cancel each other
// and FieldByNameFunc returns no match.
// This behavior mirrors Go's handling of name lookup in
// structs containing embedded fields.
FieldByNameFunc(match func(string) bool) (StructField, bool)
// In returns the type of a function type's i'th input parameter.
// It panics if the type's Kind is not Func.
// It panics if i is not in the range [0, NumIn()).
In(i int) Type
// Key returns a map type's key type.
// It panics if the type's Kind is not Map.
Key() Type
// Len returns an array type's length.
// It panics if the type's Kind is not Array.
Len() int
// NumField returns a struct type's field count.
// It panics if the type's Kind is not Struct.
NumField() int
// NumIn returns a function type's input parameter count.
// It panics if the type's Kind is not Func.
NumIn() int
// NumOut returns a function type's output parameter count.
// It panics if the type's Kind is not Func.
NumOut() int
// Out returns the type of a function type's i'th output parameter.
// It panics if the type's Kind is not Func.
// It panics if i is not in the range [0, NumOut()).
Out(i int) Type
common() *rtype
uncommon() *uncommonType
}
// BUG(rsc): FieldByName and related functions consider struct field names to be equal
// if the names are equal, even if they are unexported names originating
// in different packages. The practical effect of this is that the result of
// t.FieldByName("x") is not well defined if the struct type t contains
// multiple fields named x (embedded from different packages).
// FieldByName may return one of the fields named x or may report that there are none.
// See https://golang.org/issue/4876 for more details.
/*
* These data structures are known to the compiler (../../cmd/internal/gc/reflect.go).
* A few are known to ../runtime/type.go to convey to debuggers.
* They are also known to ../runtime/type.go.
*/
// A Kind represents the specific kind of type that a Type represents.
// The zero Kind is not a valid kind.
type Kind uint
const (
Invalid Kind = iota
Bool
Int
Int8
Int16
Int32
Int64
Uint
Uint8
Uint16
Uint32
Uint64
Uintptr
Float32
Float64
Complex64
Complex128
Array
Chan
Func
Interface
Map
Ptr
Slice
String
Struct
UnsafePointer
)
// tflag is used by an rtype to signal what extra type information is
// available in the memory directly following the rtype value.
//
// tflag values must be kept in sync with copies in:
// cmd/compile/internal/gc/reflect.go
// cmd/link/internal/ld/decodesym.go
// runtime/type.go
type tflag uint8
const (
// tflagUncommon means that there is a pointer, *uncommonType,
// just beyond the outer type structure.
//
// For example, if t.Kind() == Struct and t.tflag&tflagUncommon != 0,
// then t has uncommonType data and it can be accessed as:
//
// type tUncommon struct {
// structType
// u uncommonType
// }
// u := &(*tUncommon)(unsafe.Pointer(t)).u
tflagUncommon tflag = 1 << 0
// tflagExtraStar means the name in the str field has an
// extraneous '*' prefix. This is because for most types T in
// a program, the type *T also exists and reusing the str data
// saves binary size.
tflagExtraStar tflag = 1 << 1
// tflagNamed means the type has a name.
tflagNamed tflag = 1 << 2
)
// rtype is the common implementation of most values.
// It is embedded in other struct types.
//
// rtype must be kept in sync with ../runtime/type.go:/^type._type.
type rtype struct {
size uintptr
ptrdata uintptr // number of bytes in the type that can contain pointers
hash uint32 // hash of type; avoids computation in hash tables
tflag tflag // extra type information flags
align uint8 // alignment of variable with this type
fieldAlign uint8 // alignment of struct field with this type
kind uint8 // enumeration for C
alg *typeAlg // algorithm table
gcdata *byte // garbage collection data
str nameOff // string form
ptrToThis typeOff // type for pointer to this type, may be zero
}
// a copy of runtime.typeAlg
type typeAlg struct {
// function for hashing objects of this type
// (ptr to object, seed) -> hash
hash func(unsafe.Pointer, uintptr) uintptr
// function for comparing objects of this type
// (ptr to object A, ptr to object B) -> ==?
equal func(unsafe.Pointer, unsafe.Pointer) bool
}
// Method on non-interface type
type method struct {
name nameOff // name of method
mtyp typeOff // method type (without receiver)
ifn textOff // fn used in interface call (one-word receiver)
tfn textOff // fn used for normal method call
}
// uncommonType is present only for defined types or types with methods
// (if T is a defined type, the uncommonTypes for T and *T have methods).
// Using a pointer to this struct reduces the overall size required
// to describe a non-defined type with no methods.
type uncommonType struct {
pkgPath nameOff // import path; empty for built-in types like int, string
mcount uint16 // number of methods
xcount uint16 // number of exported methods
moff uint32 // offset from this uncommontype to [mcount]method
_ uint32 // unused
}
// ChanDir represents a channel type's direction.
type ChanDir int
const (
RecvDir ChanDir = 1 << iota // <-chan
SendDir // chan<-
BothDir = RecvDir | SendDir // chan
)
// arrayType represents a fixed array type.
type arrayType struct {
rtype
elem *rtype // array element type
slice *rtype // slice type
len uintptr
}
// chanType represents a channel type.
type chanType struct {
rtype
elem *rtype // channel element type
dir uintptr // channel direction (ChanDir)
}
// funcType represents a function type.
//
// A *rtype for each in and out parameter is stored in an array that
// directly follows the funcType (and possibly its uncommonType). So
// a function type with one method, one input, and one output is:
//
// struct {
// funcType
// uncommonType
// [2]*rtype // [0] is in, [1] is out
// }
type funcType struct {
rtype
inCount uint16
outCount uint16 // top bit is set if last input parameter is ...
}
// imethod represents a method on an interface type
type imethod struct {
name nameOff // name of method
typ typeOff // .(*FuncType) underneath
}
// interfaceType represents an interface type.
type interfaceType struct {
rtype
pkgPath name // import path
methods []imethod // sorted by hash
}
// mapType represents a map type.
type mapType struct {
rtype
key *rtype // map key type
elem *rtype // map element (value) type
bucket *rtype // internal bucket structure
keysize uint8 // size of key slot
valuesize uint8 // size of value slot
bucketsize uint16 // size of bucket
flags uint32
}
// ptrType represents a pointer type.
type ptrType struct {
rtype
elem *rtype // pointer element (pointed at) type
}
// sliceType represents a slice type.
type sliceType struct {
rtype
elem *rtype // slice element type
}
// Struct field
type structField struct {
name name // name is always non-empty
typ *rtype // type of field
offsetEmbed uintptr // byte offset of field<<1 | isEmbedded
}
func (f *structField) offset() uintptr {
return f.offsetEmbed >> 1
}
func (f *structField) embedded() bool {
return f.offsetEmbed&1 != 0
}
// structType represents a struct type.
type structType struct {
rtype
pkgPath name
fields []structField // sorted by offset
}
// name is an encoded type name with optional extra data.
//
// The first byte is a bit field containing:
//
// 1<<0 the name is exported
// 1<<1 tag data follows the name
// 1<<2 pkgPath nameOff follows the name and tag
//
// The next two bytes are the data length:
//
// l := uint16(data[1])<<8 | uint16(data[2])
//
// Bytes [3:3+l] are the string data.
//
// If tag data follows then bytes 3+l and 3+l+1 are the tag length,
// with the data following.
//
// If the import path follows, then 4 bytes at the end of
// the data form a nameOff. The import path is only set for concrete
// methods that are defined in a different package than their type.
//
// If a name starts with "*", then the exported bit represents
// whether the pointed to type is exported.
type name struct {
bytes *byte
}
func (n name) data(off int, whySafe string) *byte {
return (*byte)(add(unsafe.Pointer(n.bytes), uintptr(off), whySafe))
}
func (n name) isExported() bool {
return (*n.bytes)&(1<<0) != 0
}
func (n name) nameLen() int {
return int(uint16(*n.data(1, "name len field"))<<8 | uint16(*n.data(2, "name len field")))
}
func (n name) tagLen() int {
if *n.data(0, "name flag field")&(1<<1) == 0 {
return 0
}
off := 3 + n.nameLen()
return int(uint16(*n.data(off, "name taglen field"))<<8 | uint16(*n.data(off+1, "name taglen field")))
}
func (n name) name() (s string) {
if n.bytes == nil {
return
}
b := (*[4]byte)(unsafe.Pointer(n.bytes))
hdr := (*stringHeader)(unsafe.Pointer(&s))
hdr.Data = unsafe.Pointer(&b[3])
hdr.Len = int(b[1])<<8 | int(b[2])
return s
}
func (n name) tag() (s string) {
tl := n.tagLen()
if tl == 0 {
return ""
}
nl := n.nameLen()
hdr := (*stringHeader)(unsafe.Pointer(&s))
hdr.Data = unsafe.Pointer(n.data(3+nl+2, "non-empty string"))
hdr.Len = tl
return s
}
func (n name) pkgPath() string {
if n.bytes == nil || *n.data(0, "name flag field")&(1<<2) == 0 {
return ""
}
off := 3 + n.nameLen()
if tl := n.tagLen(); tl > 0 {
off += 2 + tl
}
var nameOff int32
// Note that this field may not be aligned in memory,
// so we cannot use a direct int32 assignment here.
copy((*[4]byte)(unsafe.Pointer(&nameOff))[:], (*[4]byte)(unsafe.Pointer(n.data(off, "name offset field")))[:])
pkgPathName := name{(*byte)(resolveTypeOff(unsafe.Pointer(n.bytes), nameOff))}
return pkgPathName.name()
}
// round n up to a multiple of a. a must be a power of 2.
func round(n, a uintptr) uintptr {
return (n + a - 1) &^ (a - 1)
}
func newName(n, tag string, exported bool) name {
if len(n) > 1<<16-1 {
panic("reflect.nameFrom: name too long: " + n)
}
if len(tag) > 1<<16-1 {
panic("reflect.nameFrom: tag too long: " + tag)
}
var bits byte
l := 1 + 2 + len(n)
if exported {
bits |= 1 << 0
}
if len(tag) > 0 {
l += 2 + len(tag)
bits |= 1 << 1
}
b := make([]byte, l)
b[0] = bits
b[1] = uint8(len(n) >> 8)
b[2] = uint8(len(n))
copy(b[3:], n)
if len(tag) > 0 {
tb := b[3+len(n):]
tb[0] = uint8(len(tag) >> 8)
tb[1] = uint8(len(tag))
copy(tb[2:], tag)
}
return name{bytes: &b[0]}
}
/*
* The compiler knows the exact layout of all the data structures above.
* The compiler does not know about the data structures and methods below.
*/
// Method represents a single method.
type Method struct {
// Name is the method name.
// PkgPath is the package path that qualifies a lower case (unexported)
// method name. It is empty for upper case (exported) method names.
// The combination of PkgPath and Name uniquely identifies a method
// in a method set.
// See https://golang.org/ref/spec#Uniqueness_of_identifiers
Name string
PkgPath string
Type Type // method type
Func Value // func with receiver as first argument
Index int // index for Type.Method
}
const (
kindDirectIface = 1 << 5
kindGCProg = 1 << 6 // Type.gc points to GC program
kindMask = (1 << 5) - 1
)
// String returns the name of k.
func (k Kind) String() string {
if int(k) < len(kindNames) {
return kindNames[k]
}
return "kind" + strconv.Itoa(int(k))
}
var kindNames = []string{
Invalid: "invalid",
Bool: "bool",
Int: "int",
Int8: "int8",
Int16: "int16",
Int32: "int32",
Int64: "int64",
Uint: "uint",
Uint8: "uint8",
Uint16: "uint16",
Uint32: "uint32",
Uint64: "uint64",
Uintptr: "uintptr",
Float32: "float32",
Float64: "float64",
Complex64: "complex64",
Complex128: "complex128",
Array: "array",
Chan: "chan",
Func: "func",
Interface: "interface",
Map: "map",
Ptr: "ptr",
Slice: "slice",
String: "string",
Struct: "struct",
UnsafePointer: "unsafe.Pointer",
}
func (t *uncommonType) methods() []method {
if t.mcount == 0 {
return nil
}
return (*[1 << 16]method)(add(unsafe.Pointer(t), uintptr(t.moff), "t.mcount > 0"))[:t.mcount:t.mcount]
}
func (t *uncommonType) exportedMethods() []method {
if t.xcount == 0 {
return nil
}
return (*[1 << 16]method)(add(unsafe.Pointer(t), uintptr(t.moff), "t.xcount > 0"))[:t.xcount:t.xcount]
}
// resolveNameOff resolves a name offset from a base pointer.
// The (*rtype).nameOff method is a convenience wrapper for this function.
// Implemented in the runtime package.
func resolveNameOff(ptrInModule unsafe.Pointer, off int32) unsafe.Pointer
// resolveTypeOff resolves an *rtype offset from a base type.
// The (*rtype).typeOff method is a convenience wrapper for this function.
// Implemented in the runtime package.
func resolveTypeOff(rtype unsafe.Pointer, off int32) unsafe.Pointer
// resolveTextOff resolves an function pointer offset from a base type.
// The (*rtype).textOff method is a convenience wrapper for this function.
// Implemented in the runtime package.
func resolveTextOff(rtype unsafe.Pointer, off int32) unsafe.Pointer
// addReflectOff adds a pointer to the reflection lookup map in the runtime.
// It returns a new ID that can be used as a typeOff or textOff, and will
// be resolved correctly. Implemented in the runtime package.
func addReflectOff(ptr unsafe.Pointer) int32
// resolveReflectType adds a name to the reflection lookup map in the runtime.
// It returns a new nameOff that can be used to refer to the pointer.
func resolveReflectName(n name) nameOff {
return nameOff(addReflectOff(unsafe.Pointer(n.bytes)))
}
// resolveReflectType adds a *rtype to the reflection lookup map in the runtime.
// It returns a new typeOff that can be used to refer to the pointer.
func resolveReflectType(t *rtype) typeOff {
return typeOff(addReflectOff(unsafe.Pointer(t)))
}
// resolveReflectText adds a function pointer to the reflection lookup map in
// the runtime. It returns a new textOff that can be used to refer to the
// pointer.
func resolveReflectText(ptr unsafe.Pointer) textOff {
return textOff(addReflectOff(ptr))
}
type nameOff int32 // offset to a name
type typeOff int32 // offset to an *rtype
type textOff int32 // offset from top of text section
func (t *rtype) nameOff(off nameOff) name {
return name{(*byte)(resolveNameOff(unsafe.Pointer(t), int32(off)))}
}
func (t *rtype) typeOff(off typeOff) *rtype {
return (*rtype)(resolveTypeOff(unsafe.Pointer(t), int32(off)))
}
func (t *rtype) textOff(off textOff) unsafe.Pointer {
return resolveTextOff(unsafe.Pointer(t), int32(off))
}
func (t *rtype) uncommon() *uncommonType {
if t.tflag&tflagUncommon == 0 {
return nil
}
switch t.Kind() {
case Struct:
return &(*structTypeUncommon)(unsafe.Pointer(t)).u
case Ptr:
type u struct {
ptrType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
case Func:
type u struct {
funcType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
case Slice:
type u struct {
sliceType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
case Array:
type u struct {
arrayType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
case Chan:
type u struct {
chanType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
case Map:
type u struct {
mapType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
case Interface:
type u struct {
interfaceType
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
default:
type u struct {
rtype
u uncommonType
}
return &(*u)(unsafe.Pointer(t)).u
}
}
func (t *rtype) String() string {
s := t.nameOff(t.str).name()
if t.tflag&tflagExtraStar != 0 {
return s[1:]
}
return s
}
func (t *rtype) Size() uintptr { return t.size }
func (t *rtype) Bits() int {
if t == nil {
panic("reflect: Bits of nil Type")
}
k := t.Kind()
if k < Int || k > Complex128 {
panic("reflect: Bits of non-arithmetic Type " + t.String())
}
return int(t.size) * 8
}
func (t *rtype) Align() int { return int(t.align) }
func (t *rtype) FieldAlign() int { return int(t.fieldAlign) }
func (t *rtype) Kind() Kind { return Kind(t.kind & kindMask) }
func (t *rtype) pointers() bool { return t.ptrdata != 0 }
func (t *rtype) common() *rtype { return t }
func (t *rtype) exportedMethods() []method {
ut := t.uncommon()
if ut == nil {
return nil
}
return ut.exportedMethods()
}
func (t *rtype) NumMethod() int {
if t.Kind() == Interface {
tt := (*interfaceType)(unsafe.Pointer(t))
return tt.NumMethod()
}
return len(t.exportedMethods())
}
func (t *rtype) Method(i int) (m Method) {
if t.Kind() == Interface {
tt := (*interfaceType)(unsafe.Pointer(t))
return tt.Method(i)
}
methods := t.exportedMethods()
if i < 0 || i >= len(methods) {
panic("reflect: Method index out of range")
}
p := methods[i]
pname := t.nameOff(p.name)
m.Name = pname.name()
fl := flag(Func)
mtyp := t.typeOff(p.mtyp)
ft := (*funcType)(unsafe.Pointer(mtyp))
in := make([]Type, 0, 1+len(ft.in()))
in = append(in, t)
for _, arg := range ft.in() {
in = append(in, arg)
}
out := make([]Type, 0, len(ft.out()))
for _, ret := range ft.out() {
out = append(out, ret)
}
mt := FuncOf(in, out, ft.IsVariadic())
m.Type = mt
tfn := t.textOff(p.tfn)
fn := unsafe.Pointer(&tfn)
m.Func = Value{mt.(*rtype), fn, fl}
m.Index = i
return m
}
func (t *rtype) MethodByName(name string) (m Method, ok bool) {
if t.Kind() == Interface {
tt := (*interfaceType)(unsafe.Pointer(t))
return tt.MethodByName(name)
}
ut := t.uncommon()
if ut == nil {
return Method{}, false
}
// TODO(mdempsky): Binary search.
for i, p := range ut.exportedMethods() {
if t.nameOff(p.name).name() == name {
return t.Method(i), true
}
}
return Method{}, false
}
func (t *rtype) PkgPath() string {
if t.tflag&tflagNamed == 0 {
return ""
}
ut := t.uncommon()
if ut == nil {
return ""
}
return t.nameOff(ut.pkgPath).name()
}
func hasPrefix(s, prefix string) bool {
return len(s) >= len(prefix) && s[:len(prefix)] == prefix
}
func (t *rtype) Name() string {
if t.tflag&tflagNamed == 0 {
return ""
}
s := t.String()
i := len(s) - 1
for i >= 0 && s[i] != '.' {
i--
}
return s[i+1:]
}
func (t *rtype) ChanDir() ChanDir {
if t.Kind() != Chan {
panic("reflect: ChanDir of non-chan type")
}
tt := (*chanType)(unsafe.Pointer(t))
return ChanDir(tt.dir)
}
func (t *rtype) IsVariadic() bool {
if t.Kind() != Func {
panic("reflect: IsVariadic of non-func type")
}
tt := (*funcType)(unsafe.Pointer(t))
return tt.outCount&(1<<15) != 0
}
func (t *rtype) Elem() Type {
switch t.Kind() {
case Array:
tt := (*arrayType)(unsafe.Pointer(t))
return toType(tt.elem)
case Chan:
tt := (*chanType)(unsafe.Pointer(t))
return toType(tt.elem)
case Map:
tt := (*mapType)(unsafe.Pointer(t))
return toType(tt.elem)
case Ptr:
tt := (*ptrType)(unsafe.Pointer(t))
return toType(tt.elem)
case Slice:
tt := (*sliceType)(unsafe.Pointer(t))
return toType(tt.elem)
}
panic("reflect: Elem of invalid type")
}
func (t *rtype) Field(i int) StructField {
if t.Kind() != Struct {
panic("reflect: Field of non-struct type")
}
tt := (*structType)(unsafe.Pointer(t))
return tt.Field(i)
}
func (t *rtype) FieldByIndex(index []int) StructField {
if t.Kind() != Struct {
panic("reflect: FieldByIndex of non-struct type")
}
tt := (*structType)(unsafe.Pointer(t))
return tt.FieldByIndex(index)
}
func (t *rtype) FieldByName(name string) (StructField, bool) {
if t.Kind() != Struct {
panic("reflect: FieldByName of non-struct type")
}
tt := (*structType)(unsafe.Pointer(t))
return tt.FieldByName(name)
}
func (t *rtype) FieldByNameFunc(match func(string) bool) (StructField, bool) {
if t.Kind() != Struct {
panic("reflect: FieldByNameFunc of non-struct type")
}
tt := (*structType)(unsafe.Pointer(t))
return tt.FieldByNameFunc(match)
}
func (t *rtype) In(i int) Type {
if t.Kind() != Func {
panic("reflect: In of non-func type")
}
tt := (*funcType)(unsafe.Pointer(t))
return toType(tt.in()[i])
}
func (t *rtype) Key() Type {
if t.Kind() != Map {
panic("reflect: Key of non-map type")
}
tt := (*mapType)(unsafe.Pointer(t))
return toType(tt.key)
}
func (t *rtype) Len() int {
if t.Kind() != Array {
panic("reflect: Len of non-array type")
}
tt := (*arrayType)(unsafe.Pointer(t))
return int(tt.len)
}
func (t *rtype) NumField() int {
if t.Kind() != Struct {
panic("reflect: NumField of non-struct type")
}
tt := (*structType)(unsafe.Pointer(t))
return len(tt.fields)
}
func (t *rtype) NumIn() int {
if t.Kind() != Func {
panic("reflect: NumIn of non-func type")
}
tt := (*funcType)(unsafe.Pointer(t))
return int(tt.inCount)
}
func (t *rtype) NumOut() int {
if t.Kind() != Func {
panic("reflect: NumOut of non-func type")
}
tt := (*funcType)(unsafe.Pointer(t))
return len(tt.out())
}
func (t *rtype) Out(i int) Type {
if t.Kind() != Func {
panic("reflect: Out of non-func type")
}
tt := (*funcType)(unsafe.Pointer(t))
return toType(tt.out()[i])
}
func (t *funcType) in() []*rtype {
uadd := unsafe.Sizeof(*t)
if t.tflag&tflagUncommon != 0 {
uadd += unsafe.Sizeof(uncommonType{})
}
if t.inCount == 0 {
return nil
}
return (*[1 << 20]*rtype)(add(unsafe.Pointer(t), uadd, "t.inCount > 0"))[:t.inCount]
}
func (t *funcType) out() []*rtype {
uadd := unsafe.Sizeof(*t)
if t.tflag&tflagUncommon != 0 {
uadd += unsafe.Sizeof(uncommonType{})
}
outCount := t.outCount & (1<<15 - 1)
if outCount == 0 {
return nil
}
return (*[1 << 20]*rtype)(add(unsafe.Pointer(t), uadd, "outCount > 0"))[t.inCount : t.inCount+outCount]
}
// add returns p+x.
//
// The whySafe string is ignored, so that the function still inlines
// as efficiently as p+x, but all call sites should use the string to
// record why the addition is safe, which is to say why the addition
// does not cause x to advance to the very end of p's allocation
// and therefore point incorrectly at the next block in memory.
func add(p unsafe.Pointer, x uintptr, whySafe string) unsafe.Pointer {
return unsafe.Pointer(uintptr(p) + x)
}
func (d ChanDir) String() string {
switch d {
case SendDir:
return "chan<-"
case RecvDir:
return "<-chan"
case BothDir:
return "chan"
}
return "ChanDir" + strconv.Itoa(int(d))
}
// Method returns the i'th method in the type's method set.
func (t *interfaceType) Method(i int) (m Method) {
if i < 0 || i >= len(t.methods) {
return
}
p := &t.methods[i]
pname := t.nameOff(p.name)
m.Name = pname.name()
if !pname.isExported() {
m.PkgPath = pname.pkgPath()
if m.PkgPath == "" {
m.PkgPath = t.pkgPath.name()
}
}
m.Type = toType(t.typeOff(p.typ))
m.Index = i
return
}
// NumMethod returns the number of interface methods in the type's method set.
func (t *interfaceType) NumMethod() int { return len(t.methods) }
// MethodByName method with the given name in the type's method set.
func (t *interfaceType) MethodByName(name string) (m Method, ok bool) {
if t == nil {
return
}
var p *imethod
for i := range t.methods {
p = &t.methods[i]
if t.nameOff(p.name).name() == name {
return t.Method(i), true
}
}
return
}
// A StructField describes a single field in a struct.
type StructField struct {
// Name is the field name.
Name string
// PkgPath is the package path that qualifies a lower case (unexported)
// field name. It is empty for upper case (exported) field names.
// See https://golang.org/ref/spec#Uniqueness_of_identifiers
PkgPath string
Type Type // field type
Tag StructTag // field tag string
Offset uintptr // offset within struct, in bytes
Index []int // index sequence for Type.FieldByIndex
Anonymous bool // is an embedded field
}
// A StructTag is the tag string in a struct field.
//
// By convention, tag strings are a concatenation of
// optionally space-separated key:"value" pairs.
// Each key is a non-empty string consisting of non-control
// characters other than space (U+0020 ' '), quote (U+0022 '"'),
// and colon (U+003A ':'). Each value is quoted using U+0022 '"'
// characters and Go string literal syntax.
type StructTag string
// Get returns the value associated with key in the tag string.
// If there is no such key in the tag, Get returns the empty string.
// If the tag does not have the conventional format, the value
// returned by Get is unspecified. To determine whether a tag is
// explicitly set to the empty string, use Lookup.
func (tag StructTag) Get(key string) string {
v, _ := tag.Lookup(key)
return v
}
// Lookup returns the value associated with key in the tag string.
// If the key is present in the tag the value (which may be empty)
// is returned. Otherwise the returned value will be the empty string.
// The ok return value reports whether the value was explicitly set in
// the tag string. If the tag does not have the conventional format,
// the value returned by Lookup is unspecified.
func (tag StructTag) Lookup(key string) (value string, ok bool) {
// When modifying this code, also update the validateStructTag code
// in cmd/vet/structtag.go.
for tag != "" {
// Skip leading space.
i := 0
for i < len(tag) && tag[i] == ' ' {
i++
}
tag = tag[i:]
if tag == "" {
break
}
// Scan to colon. A space, a quote or a control character is a syntax error.
// Strictly speaking, control chars include the range [0x7f, 0x9f], not just
// [0x00, 0x1f], but in practice, we ignore the multi-byte control characters
// as it is simpler to inspect the tag's bytes than the tag's runes.
i = 0
for i < len(tag) && tag[i] > ' ' && tag[i] != ':' && tag[i] != '"' && tag[i] != 0x7f {
i++
}
if i == 0 || i+1 >= len(tag) || tag[i] != ':' || tag[i+1] != '"' {
break
}
name := string(tag[:i])
tag = tag[i+1:]
// Scan quoted string to find value.
i = 1
for i < len(tag) && tag[i] != '"' {
if tag[i] == '\\' {
i++
}
i++
}
if i >= len(tag) {
break
}
qvalue := string(tag[:i+1])
tag = tag[i+1:]
if key == name {
value, err := strconv.Unquote(qvalue)
if err != nil {
break
}
return value, true
}
}
return "", false
}
// Field returns the i'th struct field.
func (t *structType) Field(i int) (f StructField) {
if i < 0 || i >= len(t.fields) {
panic("reflect: Field index out of bounds")
}
p := &t.fields[i]
f.Type = toType(p.typ)
f.Name = p.name.name()
f.Anonymous = p.embedded()
if !p.name.isExported() {
f.PkgPath = t.pkgPath.name()
}
if tag := p.name.tag(); tag != "" {
f.Tag = StructTag(tag)
}
f.Offset = p.offset()
// NOTE(rsc): This is the only allocation in the interface
// presented by a reflect.Type. It would be nice to avoid,
// at least in the common cases, but we need to make sure
// that misbehaving clients of reflect cannot affect other
// uses of reflect. One possibility is CL 5371098, but we
// postponed that ugliness until there is a demonstrated
// need for the performance. This is issue 2320.
f.Index = []int{i}
return
}
// TODO(gri): Should there be an error/bool indicator if the index
// is wrong for FieldByIndex?
// FieldByIndex returns the nested field corresponding to index.
func (t *structType) FieldByIndex(index []int) (f StructField) {
f.Type = toType(&t.rtype)
for i, x := range index {
if i > 0 {
ft := f.Type
if ft.Kind() == Ptr && ft.Elem().Kind() == Struct {
ft = ft.Elem()
}
f.Type = ft
}
f = f.Type.Field(x)
}
return
}
// A fieldScan represents an item on the fieldByNameFunc scan work list.
type fieldScan struct {
typ *structType
index []int
}
// FieldByNameFunc returns the struct field with a name that satisfies the
// match function and a boolean to indicate if the field was found.
func (t *structType) FieldByNameFunc(match func(string) bool) (result StructField, ok bool) {
// This uses the same condition that the Go language does: there must be a unique instance
// of the match at a given depth level. If there are multiple instances of a match at the
// same depth, they annihilate each other and inhibit any possible match at a lower level.
// The algorithm is breadth first search, one depth level at a time.
// The current and next slices are work queues:
// current lists the fields to visit on this depth level,
// and next lists the fields on the next lower level.
current := []fieldScan{}
next := []fieldScan{{typ: t}}
// nextCount records the number of times an embedded type has been
// encountered and considered for queueing in the 'next' slice.
// We only queue the first one, but we increment the count on each.
// If a struct type T can be reached more than once at a given depth level,
// then it annihilates itself and need not be considered at all when we
// process that next depth level.
var nextCount map[*structType]int
// visited records the structs that have been considered already.
// Embedded pointer fields can create cycles in the graph of
// reachable embedded types; visited avoids following those cycles.
// It also avoids duplicated effort: if we didn't find the field in an
// embedded type T at level 2, we won't find it in one at level 4 either.
visited := map[*structType]bool{}
for len(next) > 0 {
current, next = next, current[:0]
count := nextCount
nextCount = nil
// Process all the fields at this depth, now listed in 'current'.
// The loop queues embedded fields found in 'next', for processing during the next
// iteration. The multiplicity of the 'current' field counts is recorded
// in 'count'; the multiplicity of the 'next' field counts is recorded in 'nextCount'.
for _, scan := range current {
t := scan.typ
if visited[t] {
// We've looked through this type before, at a higher level.
// That higher level would shadow the lower level we're now at,
// so this one can't be useful to us. Ignore it.
continue
}
visited[t] = true
for i := range t.fields {
f := &t.fields[i]
// Find name and (for embedded field) type for field f.
fname := f.name.name()
var ntyp *rtype
if f.embedded() {
// Embedded field of type T or *T.
ntyp = f.typ
if ntyp.Kind() == Ptr {
ntyp = ntyp.Elem().common()
}
}
// Does it match?
if match(fname) {
// Potential match
if count[t] > 1 || ok {
// Name appeared multiple times at this level: annihilate.
return StructField{}, false
}
result = t.Field(i)
result.Index = nil
result.Index = append(result.Index, scan.index...)
result.Index = append(result.Index, i)
ok = true
continue
}
// Queue embedded struct fields for processing with next level,
// but only if we haven't seen a match yet at this level and only
// if the embedded types haven't already been queued.
if ok || ntyp == nil || ntyp.Kind() != Struct {
continue
}
styp := (*structType)(unsafe.Pointer(ntyp))
if nextCount[styp] > 0 {
nextCount[styp] = 2 // exact multiple doesn't matter
continue
}
if nextCount == nil {
nextCount = map[*structType]int{}
}
nextCount[styp] = 1
if count[t] > 1 {
nextCount[styp] = 2 // exact multiple doesn't matter
}
var index []int
index = append(index, scan.index...)
index = append(index, i)
next = append(next, fieldScan{styp, index})
}
}
if ok {
break
}
}
return
}
// FieldByName returns the struct field with the given name
// and a boolean to indicate if the field was found.
func (t *structType) FieldByName(name string) (f StructField, present bool) {
// Quick check for top-level name, or struct without embedded fields.
hasEmbeds := false
if name != "" {
for i := range t.fields {
tf := &t.fields[i]
if tf.name.name() == name {
return t.Field(i), true
}
if tf.embedded() {
hasEmbeds = true
}
}
}
if !hasEmbeds {
return
}
return t.FieldByNameFunc(func(s string) bool { return s == name })
}
// TypeOf returns the reflection Type that represents the dynamic type of i.
// If i is a nil interface value, TypeOf returns nil.
func TypeOf(i interface{}) Type {
eface := *(*emptyInterface)(unsafe.Pointer(&i))
return toType(eface.typ)
}
// ptrMap is the cache for PtrTo.
var ptrMap sync.Map // map[*rtype]*ptrType
// PtrTo returns the pointer type with element t.
// For example, if t represents type Foo, PtrTo(t) represents *Foo.
func PtrTo(t Type) Type {
return t.(*rtype).ptrTo()
}
func (t *rtype) ptrTo() *rtype {
if t.ptrToThis != 0 {
return t.typeOff(t.ptrToThis)
}
// Check the cache.
if pi, ok := ptrMap.Load(t); ok {
return &pi.(*ptrType).rtype
}
// Look in known types.
s := "*" + t.String()
for _, tt := range typesByString(s) {
p := (*ptrType)(unsafe.Pointer(tt))
if p.elem != t {
continue
}
pi, _ := ptrMap.LoadOrStore(t, p)
return &pi.(*ptrType).rtype
}
// Create a new ptrType starting with the description
// of an *unsafe.Pointer.
var iptr interface{} = (*unsafe.Pointer)(nil)
prototype := *(**ptrType)(unsafe.Pointer(&iptr))
pp := *prototype
pp.str = resolveReflectName(newName(s, "", false))
pp.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 "*".
pp.hash = fnv1(t.hash, '*')
pp.elem = t
pi, _ := ptrMap.LoadOrStore(t, &pp)
return &pi.(*ptrType).rtype
}
// fnv1 incorporates the list of bytes into the hash x using the FNV-1 hash function.
func fnv1(x uint32, list ...byte) uint32 {
for _, b := range list {
x = x*16777619 ^ uint32(b)
}
return x
}
func (t *rtype) Implements(u Type) bool {
if u == nil {
panic("reflect: nil type passed to Type.Implements")
}
if u.Kind() != Interface {
panic("reflect: non-interface type passed to Type.Implements")
}
return implements(u.(*rtype), t)
}
func (t *rtype) AssignableTo(u Type) bool {
if u == nil {
panic("reflect: nil type passed to Type.AssignableTo")
}
uu := u.(*rtype)
return directlyAssignable(uu, t) || implements(uu, t)
}
func (t *rtype) ConvertibleTo(u Type) bool {
if u == nil {
panic("reflect: nil type passed to Type.ConvertibleTo")
}
uu := u.(*rtype)
return convertOp(uu, t) != nil
}
func (t *rtype) Comparable() bool {
return t.alg != nil && t.alg.equal != nil
}
// implements reports whether the type V implements the interface type T.
func implements(T, V *rtype) bool {
if T.Kind() != Interface {
return false
}
t := (*interfaceType)(unsafe.Pointer(T))
if len(t.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 V.Kind() == Interface {
v := (*interfaceType)(unsafe.Pointer(V))
i := 0
for j := 0; j < len(v.methods); j++ {
tm := &t.methods[i]
tmName := t.nameOff(tm.name)
vm := &v.methods[j]
vmName := V.nameOff(vm.name)
if vmName.name() == tmName.name() && V.typeOff(vm.typ) == t.typeOff(tm.typ) {
if !tmName.isExported() {
tmPkgPath := tmName.pkgPath()
if tmPkgPath == "" {
tmPkgPath = t.pkgPath.name()
}
vmPkgPath := vmName.pkgPath()
if vmPkgPath == "" {
vmPkgPath = v.pkgPath.name()
}
if tmPkgPath != vmPkgPath {
continue
}
}
if i++; i >= len(t.methods) {
return true
}
}
}
return false
}
v := V.uncommon()
if v == nil {
return false
}
i := 0
vmethods := v.methods()
for j := 0; j < int(v.mcount); j++ {
tm := &t.methods[i]
tmName := t.nameOff(tm.name)
vm := vmethods[j]
vmName := V.nameOff(vm.name)
if vmName.name() == tmName.name() && V.typeOff(vm.mtyp) == t.typeOff(tm.typ) {
if !tmName.isExported() {
tmPkgPath := tmName.pkgPath()
if tmPkgPath == "" {
tmPkgPath = t.pkgPath.name()
}
vmPkgPath := vmName.pkgPath()
if vmPkgPath == "" {
vmPkgPath = V.nameOff(v.pkgPath).name()
}
if tmPkgPath != vmPkgPath {
continue
}
}
if i++; i >= len(t.methods) {
return true
}
}
}
return false
}
// 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 directlyAssignable(T, V *rtype) bool {
// x's type V is identical to T?
if T == V {
return true
}
// Otherwise at least one of T and V must not be defined
// and they must have the same kind.
if T.Name() != "" && V.Name() != "" || T.Kind() != V.Kind() {
return false
}
// x's type T and V must have identical underlying types.
return haveIdenticalUnderlyingType(T, V, true)
}
func haveIdenticalType(T, V Type, cmpTags bool) bool {
if cmpTags {
return T == V
}
if T.Name() != V.Name() || T.Kind() != V.Kind() {
return false
}
return haveIdenticalUnderlyingType(T.common(), V.common(), false)
}
func haveIdenticalUnderlyingType(T, V *rtype, cmpTags bool) bool {
if T == V {
return true
}
kind := T.Kind()
if kind != V.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:
return T.Len() == V.Len() && haveIdenticalType(T.Elem(), V.Elem(), cmpTags)
case Chan:
// Special case:
// x is a bidirectional channel value, T is a channel type,
// and x's type V and T have identical element types.
if V.ChanDir() == BothDir && haveIdenticalType(T.Elem(), V.Elem(), cmpTags) {
return true
}
// Otherwise continue test for identical underlying type.
return V.ChanDir() == T.ChanDir() && haveIdenticalType(T.Elem(), V.Elem(), cmpTags)
case Func:
t := (*funcType)(unsafe.Pointer(T))
v := (*funcType)(unsafe.Pointer(V))
if t.outCount != v.outCount || t.inCount != v.inCount {
return false
}
for i := 0; i < t.NumIn(); i++ {
if !haveIdenticalType(t.In(i), v.In(i), cmpTags) {
return false
}
}
for i := 0; i < t.NumOut(); i++ {
if !haveIdenticalType(t.Out(i), v.Out(i), cmpTags) {
return false
}
}
return true
case Interface:
t := (*interfaceType)(unsafe.Pointer(T))
v := (*interfaceType)(unsafe.Pointer(V))
if len(t.methods) == 0 && len(v.methods) == 0 {
return true
}
// Might have the same methods but still
// need a run time conversion.
return false
case Map:
return haveIdenticalType(T.Key(), V.Key(), cmpTags) && haveIdenticalType(T.Elem(), V.Elem(), cmpTags)
case Ptr, Slice:
return haveIdenticalType(T.Elem(), V.Elem(), cmpTags)
case Struct:
t := (*structType)(unsafe.Pointer(T))
v := (*structType)(unsafe.Pointer(V))
if len(t.fields) != len(v.fields) {
return false
}
if t.pkgPath.name() != v.pkgPath.name() {
return false
}
for i := range t.fields {
tf := &t.fields[i]
vf := &v.fields[i]
if tf.name.name() != vf.name.name() {
return false
}
if !haveIdenticalType(tf.typ, vf.typ, cmpTags) {
return false
}
if cmpTags && tf.name.tag() != vf.name.tag() {
return false
}
if tf.offsetEmbed != vf.offsetEmbed {
return false
}
}
return true
}
return false
}
// typelinks is implemented in package runtime.
// It returns a slice of the sections in each module,
// and a slice of *rtype offsets in each module.
//
// The types in each module are sorted by string. That is, the first
// two linked types of the first module are:
//
// d0 := sections[0]
// t1 := (*rtype)(add(d0, offset[0][0]))
// t2 := (*rtype)(add(d0, offset[0][1]))
//
// and
//
// t1.String() < t2.String()
//
// Note that strings are not unique identifiers for types:
// there can be more than one with a given string.
// Only types we might want to look up are included:
// pointers, channels, maps, slices, and arrays.
func typelinks() (sections []unsafe.Pointer, offset [][]int32)
func rtypeOff(section unsafe.Pointer, off int32) *rtype {
return (*rtype)(add(section, uintptr(off), "sizeof(rtype) > 0"))
}
// typesByString returns the subslice of typelinks() whose elements have
// the given string representation.
// It may be empty (no known types with that string) or may have
// multiple elements (multiple types with that string).
func typesByString(s string) []*rtype {
sections, offset := typelinks()
var ret []*rtype
for offsI, offs := range offset {
section := sections[offsI]
// We are looking for the first index i where the string becomes >= s.
// This is a copy of sort.Search, with f(h) replaced by (*typ[h].String() >= s).
i, j := 0, len(offs)
for i < j {
h := i + (j-i)/2 // avoid overflow when computing h
// i ≤ h < j
if !(rtypeOff(section, offs[h]).String() >= s) {
i = h + 1 // preserves f(i-1) == false
} else {
j = h // preserves f(j) == true
}
}
// i == j, f(i-1) == false, and f(j) (= f(i)) == true => answer is i.
// Having found the first, linear scan forward to find the last.
// We could do a second binary search, but the caller is going
// to do a linear scan anyway.
for j := i; j < len(offs); j++ {
typ := rtypeOff(section, offs[j])
if typ.String() != s {
break
}
ret = append(ret, typ)
}
}
return ret
}
// The lookupCache caches ArrayOf, ChanOf, MapOf and SliceOf lookups.
var lookupCache sync.Map // map[cacheKey]*rtype
// A cacheKey is the key for use in the lookupCache.
// Four values describe any of the types we are looking for:
// type kind, one or two subtypes, and an extra integer.
type cacheKey struct {
kind Kind
t1 *rtype
t2 *rtype
extra uintptr
}
// The funcLookupCache caches FuncOf lookups.
// FuncOf does not share the common lookupCache since cacheKey is not
// sufficient to represent functions unambiguously.
var funcLookupCache struct {
sync.Mutex // Guards stores (but not loads) on m.
// m is a map[uint32][]*rtype keyed by the hash calculated in FuncOf.
// Elements of m are append-only and thus safe for concurrent reading.
m sync.Map
}
// ChanOf returns the channel type with the given direction and element type.
// For example, if t represents int, ChanOf(RecvDir, t) represents <-chan int.
//
// The gc runtime imposes a limit of 64 kB on channel element types.
// If t's size is equal to or exceeds this limit, ChanOf panics.
func ChanOf(dir ChanDir, t Type) Type {
typ := t.(*rtype)
// Look in cache.
ckey := cacheKey{Chan, typ, nil, uintptr(dir)}
if ch, ok := lookupCache.Load(ckey); ok {
return ch.(*rtype)
}
// This restriction is imposed by the gc compiler and the runtime.
if typ.size >= 1<<16 {
panic("reflect.ChanOf: element size too large")
}
// Look in known types.
// TODO: Precedence when constructing string.
var s string
switch dir {
default:
panic("reflect.ChanOf: invalid dir")
case SendDir:
s = "chan<- " + typ.String()
case RecvDir:
s = "<-chan " + typ.String()
case BothDir:
s = "chan " + typ.String()
}
for _, tt := range typesByString(s) {
ch := (*chanType)(unsafe.Pointer(tt))
if ch.elem == typ && ch.dir == uintptr(dir) {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
}
}
// Make a channel type.
var ichan interface{} = (chan unsafe.Pointer)(nil)
prototype := *(**chanType)(unsafe.Pointer(&ichan))
ch := *prototype
ch.tflag = 0
ch.dir = uintptr(dir)
ch.str = resolveReflectName(newName(s, "", false))
ch.hash = fnv1(typ.hash, 'c', byte(dir))
ch.elem = typ
ti, _ := lookupCache.LoadOrStore(ckey, &ch.rtype)
return ti.(Type)
}
func ismapkey(*rtype) bool // implemented in runtime
// MapOf returns the map type with the given key and element types.
// For example, if k represents int and e represents string,
// MapOf(k, e) represents map[int]string.
//
// If the key type is not a valid map key type (that is, if it does
// not implement Go's == operator), MapOf panics.
func MapOf(key, elem Type) Type {
ktyp := key.(*rtype)
etyp := elem.(*rtype)
if !ismapkey(ktyp) {
panic("reflect.MapOf: invalid key type " + ktyp.String())
}
// Look in cache.
ckey := cacheKey{Map, ktyp, etyp, 0}
if mt, ok := lookupCache.Load(ckey); ok {
return mt.(Type)
}
// Look in known types.
s := "map[" + ktyp.String() + "]" + etyp.String()
for _, tt := range typesByString(s) {
mt := (*mapType)(unsafe.Pointer(tt))
if mt.key == ktyp && mt.elem == etyp {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
}
}
// Make a map type.
// Note: flag values must match those used in the TMAP case
// in ../cmd/compile/internal/gc/reflect.go:dtypesym.
var imap interface{} = (map[unsafe.Pointer]unsafe.Pointer)(nil)
mt := **(**mapType)(unsafe.Pointer(&imap))
mt.str = resolveReflectName(newName(s, "", false))
mt.tflag = 0
mt.hash = fnv1(etyp.hash, 'm', byte(ktyp.hash>>24), byte(ktyp.hash>>16), byte(ktyp.hash>>8), byte(ktyp.hash))
mt.key = ktyp
mt.elem = etyp
mt.bucket = bucketOf(ktyp, etyp)
mt.flags = 0
if ktyp.size > maxKeySize {
mt.keysize = uint8(ptrSize)
mt.flags |= 1 // indirect key
} else {
mt.keysize = uint8(ktyp.size)
}
if etyp.size > maxValSize {
mt.valuesize = uint8(ptrSize)
mt.flags |= 2 // indirect value
} else {
mt.valuesize = uint8(etyp.size)
}
mt.bucketsize = uint16(mt.bucket.size)
if isReflexive(ktyp) {
mt.flags |= 4
}
if needKeyUpdate(ktyp) {
mt.flags |= 8
}
if hashMightPanic(ktyp) {
mt.flags |= 16
}
mt.ptrToThis = 0
ti, _ := lookupCache.LoadOrStore(ckey, &mt.rtype)
return ti.(Type)
}
// TODO(crawshaw): as these funcTypeFixedN structs have no methods,
// they could be defined at runtime using the StructOf function.
type funcTypeFixed4 struct {
funcType
args [4]*rtype
}
type funcTypeFixed8 struct {
funcType
args [8]*rtype
}
type funcTypeFixed16 struct {
funcType
args [16]*rtype
}
type funcTypeFixed32 struct {
funcType
args [32]*rtype
}
type funcTypeFixed64 struct {
funcType
args [64]*rtype
}
type funcTypeFixed128 struct {
funcType
args [128]*rtype
}
// FuncOf returns the function type with the given argument and result types.
// For example if k represents int and e represents string,
// FuncOf([]Type{k}, []Type{e}, false) represents func(int) string.
//
// The variadic argument controls whether the function is variadic. FuncOf
// panics if the in[len(in)-1] does not represent a slice and variadic is
// true.
func FuncOf(in, out []Type, variadic bool) Type {
if variadic && (len(in) == 0 || in[len(in)-1].Kind() != Slice) {
panic("reflect.FuncOf: last arg of variadic func must be slice")
}
// Make a func type.
var ifunc interface{} = (func())(nil)
prototype := *(**funcType)(unsafe.Pointer(&ifunc))
n := len(in) + len(out)
var ft *funcType
var args []*rtype
switch {
case n <= 4:
fixed := new(funcTypeFixed4)
args = fixed.args[:0:len(fixed.args)]
ft = &fixed.funcType
case n <= 8:
fixed := new(funcTypeFixed8)
args = fixed.args[:0:len(fixed.args)]
ft = &fixed.funcType
case n <= 16:
fixed := new(funcTypeFixed16)
args = fixed.args[:0:len(fixed.args)]
ft = &fixed.funcType
case n <= 32:
fixed := new(funcTypeFixed32)
args = fixed.args[:0:len(fixed.args)]
ft = &fixed.funcType
case n <= 64:
fixed := new(funcTypeFixed64)
args = fixed.args[:0:len(fixed.args)]
ft = &fixed.funcType
case n <= 128:
fixed := new(funcTypeFixed128)
args = fixed.args[:0:len(fixed.args)]
ft = &fixed.funcType
default:
panic("reflect.FuncOf: too many arguments")
}
*ft = *prototype
// Build a hash and minimally populate ft.
var hash uint32
for _, in := range in {
t := in.(*rtype)
args = append(args, t)
hash = fnv1(hash, byte(t.hash>>24), byte(t.hash>>16), byte(t.hash>>8), byte(t.hash))
}
if variadic {
hash = fnv1(hash, 'v')
}
hash = fnv1(hash, '.')
for _, out := range out {
t := out.(*rtype)
args = append(args, t)
hash = fnv1(hash, byte(t.hash>>24), byte(t.hash>>16), byte(t.hash>>8), byte(t.hash))
}
if len(args) > 50 {
panic("reflect.FuncOf does not support more than 50 arguments")
}
ft.tflag = 0
ft.hash = hash
ft.inCount = uint16(len(in))
ft.outCount = uint16(len(out))
if variadic {
ft.outCount |= 1 << 15
}
// Look in cache.
if ts, ok := funcLookupCache.m.Load(hash); ok {
for _, t := range ts.([]*rtype) {
if haveIdenticalUnderlyingType(&ft.rtype, t, true) {
return t
}
}
}
// Not in cache, lock and retry.
funcLookupCache.Lock()
defer funcLookupCache.Unlock()
if ts, ok := funcLookupCache.m.Load(hash); ok {
for _, t := range ts.([]*rtype) {
if haveIdenticalUnderlyingType(&ft.rtype, t, true) {
return t
}
}
}
addToCache := func(tt *rtype) Type {
var rts []*rtype
if rti, ok := funcLookupCache.m.Load(hash); ok {
rts = rti.([]*rtype)
}
funcLookupCache.m.Store(hash, append(rts, tt))
return tt
}
// Look in known types for the same string representation.
str := funcStr(ft)
for _, tt := range typesByString(str) {
if haveIdenticalUnderlyingType(&ft.rtype, tt, true) {
return addToCache(tt)
}
}
// Populate the remaining fields of ft and store in cache.
ft.str = resolveReflectName(newName(str, "", false))
ft.ptrToThis = 0
return addToCache(&ft.rtype)
}
// funcStr builds a string representation of a funcType.
func funcStr(ft *funcType) string {
repr := make([]byte, 0, 64)
repr = append(repr, "func("...)
for i, t := range ft.in() {
if i > 0 {
repr = append(repr, ", "...)
}
if ft.IsVariadic() && i == int(ft.inCount)-1 {
repr = append(repr, "..."...)
repr = append(repr, (*sliceType)(unsafe.Pointer(t)).elem.String()...)
} else {
repr = append(repr, t.String()...)
}
}
repr = append(repr, ')')
out := ft.out()
if len(out) == 1 {
repr = append(repr, ' ')
} else if len(out) > 1 {
repr = append(repr, " ("...)
}
for i, t := range out {
if i > 0 {
repr = append(repr, ", "...)
}
repr = append(repr, t.String()...)
}
if len(out) > 1 {
repr = append(repr, ')')
}
return string(repr)
}
// isReflexive reports whether the == operation on the type is reflexive.
// That is, x == x for all values x of type t.
func isReflexive(t *rtype) bool {
switch t.Kind() {
case Bool, Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr, Chan, Ptr, String, UnsafePointer:
return true
case Float32, Float64, Complex64, Complex128, Interface:
return false
case Array:
tt := (*arrayType)(unsafe.Pointer(t))
return isReflexive(tt.elem)
case Struct:
tt := (*structType)(unsafe.Pointer(t))
for _, f := range tt.fields {
if !isReflexive(f.typ) {
return false
}
}
return true
default:
// Func, Map, Slice, Invalid
panic("isReflexive called on non-key type " + t.String())
}
}
// needKeyUpdate reports whether map overwrites require the key to be copied.
func needKeyUpdate(t *rtype) bool {
switch t.Kind() {
case Bool, Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr, Chan, Ptr, UnsafePointer:
return false
case Float32, Float64, Complex64, Complex128, Interface, String:
// Float keys can be updated from +0 to -0.
// String keys can be updated to use a smaller backing store.
// Interfaces might have floats of strings in them.
return true
case Array:
tt := (*arrayType)(unsafe.Pointer(t))
return needKeyUpdate(tt.elem)
case Struct:
tt := (*structType)(unsafe.Pointer(t))
for _, f := range tt.fields {
if needKeyUpdate(f.typ) {
return true
}
}
return false
default:
// Func, Map, Slice, Invalid
panic("needKeyUpdate called on non-key type " + t.String())
}
}
// hashMightPanic reports whether the hash of a map key of type t might panic.
func hashMightPanic(t *rtype) bool {
switch t.Kind() {
case Interface:
return true
case Array:
tt := (*arrayType)(unsafe.Pointer(t))
return hashMightPanic(tt.elem)
case Struct:
tt := (*structType)(unsafe.Pointer(t))
for _, f := range tt.fields {
if hashMightPanic(f.typ) {
return true
}
}
return false
default:
return false
}
}
// Make sure these routines stay in sync with ../../runtime/map.go!
// These types exist only for GC, so we only fill out GC relevant info.
// Currently, that's just size and the GC program. We also fill in string
// for possible debugging use.
const (
bucketSize uintptr = 8
maxKeySize uintptr = 128
maxValSize uintptr = 128
)
func bucketOf(ktyp, etyp *rtype) *rtype {
if ktyp.size > maxKeySize {
ktyp = PtrTo(ktyp).(*rtype)
}
if etyp.size > maxValSize {
etyp = PtrTo(etyp).(*rtype)
}
// Prepare GC data if any.
// A bucket is at most bucketSize*(1+maxKeySize+maxValSize)+2*ptrSize bytes,
// or 2072 bytes, or 259 pointer-size words, or 33 bytes of pointer bitmap.
// Note that since the key and value are known to be <= 128 bytes,
// they're guaranteed to have bitmaps instead of GC programs.
var gcdata *byte
var ptrdata uintptr
var overflowPad uintptr
// On NaCl, pad if needed to make overflow end at the proper struct alignment.
// On other systems, align > ptrSize is not possible.
if runtime.GOARCH == "amd64p32" && (ktyp.align > ptrSize || etyp.align > ptrSize) {
overflowPad = ptrSize
}
size := bucketSize*(1+ktyp.size+etyp.size) + overflowPad + ptrSize
if size&uintptr(ktyp.align-1) != 0 || size&uintptr(etyp.align-1) != 0 {
panic("reflect: bad size computation in MapOf")
}
if ktyp.ptrdata != 0 || etyp.ptrdata != 0 {
nptr := (bucketSize*(1+ktyp.size+etyp.size) + ptrSize) / ptrSize
mask := make([]byte, (nptr+7)/8)
base := bucketSize / ptrSize
if ktyp.ptrdata != 0 {
if ktyp.kind&kindGCProg != 0 {
panic("reflect: unexpected GC program in MapOf")
}
kmask := (*[16]byte)(unsafe.Pointer(ktyp.gcdata))
for i := uintptr(0); i < ktyp.ptrdata/ptrSize; i++ {
if (kmask[i/8]>>(i%8))&1 != 0 {
for j := uintptr(0); j < bucketSize; j++ {
word := base + j*ktyp.size/ptrSize + i
mask[word/8] |= 1 << (word % 8)
}
}
}
}
base += bucketSize * ktyp.size / ptrSize
if etyp.ptrdata != 0 {
if etyp.kind&kindGCProg != 0 {
panic("reflect: unexpected GC program in MapOf")
}
emask := (*[16]byte)(unsafe.Pointer(etyp.gcdata))
for i := uintptr(0); i < etyp.ptrdata/ptrSize; i++ {
if (emask[i/8]>>(i%8))&1 != 0 {
for j := uintptr(0); j < bucketSize; j++ {
word := base + j*etyp.size/ptrSize + i
mask[word/8] |= 1 << (word % 8)
}
}
}
}
base += bucketSize * etyp.size / ptrSize
base += overflowPad / ptrSize
word := base
mask[word/8] |= 1 << (word % 8)
gcdata = &mask[0]
ptrdata = (word + 1) * ptrSize
// overflow word must be last
if ptrdata != size {
panic("reflect: bad layout computation in MapOf")
}
}
b := &rtype{
align: ptrSize,
size: size,
kind: uint8(Struct),
ptrdata: ptrdata,
gcdata: gcdata,
}
if overflowPad > 0 {
b.align = 8
}
s := "bucket(" + ktyp.String() + "," + etyp.String() + ")"
b.str = resolveReflectName(newName(s, "", false))
return b
}
// SliceOf returns the slice type with element type t.
// For example, if t represents int, SliceOf(t) represents []int.
func SliceOf(t Type) Type {
typ := t.(*rtype)
// Look in cache.
ckey := cacheKey{Slice, typ, nil, 0}
if slice, ok := lookupCache.Load(ckey); ok {
return slice.(Type)
}
// Look in known types.
s := "[]" + typ.String()
for _, tt := range typesByString(s) {
slice := (*sliceType)(unsafe.Pointer(tt))
if slice.elem == typ {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
}
}
// Make a slice type.
var islice interface{} = ([]unsafe.Pointer)(nil)
prototype := *(**sliceType)(unsafe.Pointer(&islice))
slice := *prototype
slice.tflag = 0
slice.str = resolveReflectName(newName(s, "", false))
slice.hash = fnv1(typ.hash, '[')
slice.elem = typ
slice.ptrToThis = 0
ti, _ := lookupCache.LoadOrStore(ckey, &slice.rtype)
return ti.(Type)
}
// The structLookupCache caches StructOf lookups.
// StructOf does not share the common lookupCache since we need to pin
// the memory associated with *structTypeFixedN.
var structLookupCache struct {
sync.Mutex // Guards stores (but not loads) on m.
// m is a map[uint32][]Type keyed by the hash calculated in StructOf.
// Elements in m are append-only and thus safe for concurrent reading.
m sync.Map
}
type structTypeUncommon struct {
structType
u uncommonType
}
// isLetter reports whether a given 'rune' is classified as a Letter.
func isLetter(ch rune) bool {
return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
}
// isValidFieldName checks if a string is a valid (struct) field name or not.
//
// According to the language spec, a field name should be an identifier.
//
// identifier = letter { letter | unicode_digit } .
// letter = unicode_letter | "_" .
func isValidFieldName(fieldName string) bool {
for i, c := range fieldName {
if i == 0 && !isLetter(c) {
return false
}
if !(isLetter(c) || unicode.IsDigit(c)) {
return false
}
}
return len(fieldName) > 0
}
// StructOf returns the struct type containing fields.
// The Offset and Index fields are ignored and computed as they would be
// by the compiler.
//
// StructOf currently does not generate wrapper methods for embedded
// fields and panics if passed unexported StructFields.
// These limitations may be lifted in a future version.
func StructOf(fields []StructField) Type {
var (
hash = fnv1(0, []byte("struct {")...)
size uintptr
typalign uint8
comparable = true
hashable = true
methods []method
fs = make([]structField, len(fields))
repr = make([]byte, 0, 64)
fset = map[string]struct{}{} // fields' names
hasGCProg = false // records whether a struct-field type has a GCProg
)
lastzero := uintptr(0)
repr = append(repr, "struct {"...)
for i, field := range fields {
if field.Name == "" {
panic("reflect.StructOf: field " + strconv.Itoa(i) + " has no name")
}
if !isValidFieldName(field.Name) {
panic("reflect.StructOf: field " + strconv.Itoa(i) + " has invalid name")
}
if field.Type == nil {
panic("reflect.StructOf: field " + strconv.Itoa(i) + " has no type")
}
f := runtimeStructField(field)
ft := f.typ
if ft.kind&kindGCProg != 0 {
hasGCProg = true
}
// Update string and hash
name := f.name.name()
hash = fnv1(hash, []byte(name)...)
repr = append(repr, (" " + name)...)
if f.embedded() {
// Embedded field
if f.typ.Kind() == Ptr {
// Embedded ** and *interface{} are illegal
elem := ft.Elem()
if k := elem.Kind(); k == Ptr || k == Interface {
panic("reflect.StructOf: illegal embedded field type " + ft.String())
}
}
switch f.typ.Kind() {
case Interface:
ift := (*interfaceType)(unsafe.Pointer(ft))
for im, m := range ift.methods {
if ift.nameOff(m.name).pkgPath() != "" {
// TODO(sbinet). Issue 15924.
panic("reflect: embedded interface with unexported method(s) not implemented")
}
var (
mtyp = ift.typeOff(m.typ)
ifield = i
imethod = im
ifn Value
tfn Value
)
if ft.kind&kindDirectIface != 0 {
tfn = MakeFunc(mtyp, func(in []Value) []Value {
var args []Value
var recv = in[0]
if len(in) > 1 {
args = in[1:]
}
return recv.Field(ifield).Method(imethod).Call(args)
})
ifn = MakeFunc(mtyp, func(in []Value) []Value {
var args []Value
var recv = in[0]
if len(in) > 1 {
args = in[1:]
}
return recv.Field(ifield).Method(imethod).Call(args)
})
} else {
tfn = MakeFunc(mtyp, func(in []Value) []Value {
var args []Value
var recv = in[0]
if len(in) > 1 {
args = in[1:]
}
return recv.Field(ifield).Method(imethod).Call(args)
})
ifn = MakeFunc(mtyp, func(in []Value) []Value {
var args []Value
var recv = Indirect(in[0])
if len(in) > 1 {
args = in[1:]
}
return recv.Field(ifield).Method(imethod).Call(args)
})
}
methods = append(methods, method{
name: resolveReflectName(ift.nameOff(m.name)),
mtyp: resolveReflectType(mtyp),
ifn: resolveReflectText(unsafe.Pointer(&ifn)),
tfn: resolveReflectText(unsafe.Pointer(&tfn)),
})
}
case Ptr:
ptr := (*ptrType)(unsafe.Pointer(ft))
if unt := ptr.uncommon(); unt != nil {
if i > 0 && unt.mcount > 0 {
// Issue 15924.
panic("reflect: embedded type with methods not implemented if type is not first field")
}
if len(fields) > 1 {
panic("reflect: embedded type with methods not implemented if there is more than one field")
}
for _, m := range unt.methods() {
mname := ptr.nameOff(m.name)
if mname.pkgPath() != "" {
// TODO(sbinet).
// Issue 15924.
panic("reflect: embedded interface with unexported method(s) not implemented")
}
methods = append(methods, method{
name: resolveReflectName(mname),
mtyp: resolveReflectType(ptr.typeOff(m.mtyp)),
ifn: resolveReflectText(ptr.textOff(m.ifn)),
tfn: resolveReflectText(ptr.textOff(m.tfn)),
})
}
}
if unt := ptr.elem.uncommon(); unt != nil {
for _, m := range unt.methods() {
mname := ptr.nameOff(m.name)
if mname.pkgPath() != "" {
// TODO(sbinet)
// Issue 15924.
panic("reflect: embedded interface with unexported method(s) not implemented")
}
methods = append(methods, method{
name: resolveReflectName(mname),
mtyp: resolveReflectType(ptr.elem.typeOff(m.mtyp)),
ifn: resolveReflectText(ptr.elem.textOff(m.ifn)),
tfn: resolveReflectText(ptr.elem.textOff(m.tfn)),
})
}
}
default:
if unt := ft.uncommon(); unt != nil {
if i > 0 && unt.mcount > 0 {
// Issue 15924.
panic("reflect: embedded type with methods not implemented if type is not first field")
}
if len(fields) > 1 && ft.kind&kindDirectIface != 0 {
panic("reflect: embedded type with methods not implemented for non-pointer type")
}
for _, m := range unt.methods() {
mname := ft.nameOff(m.name)
if mname.pkgPath() != "" {
// TODO(sbinet)
// Issue 15924.
panic("reflect: embedded interface with unexported method(s) not implemented")
}
methods = append(methods, method{
name: resolveReflectName(mname),
mtyp: resolveReflectType(ft.typeOff(m.mtyp)),
ifn: resolveReflectText(ft.textOff(m.ifn)),
tfn: resolveReflectText(ft.textOff(m.tfn)),
})
}
}
}
}
if _, dup := fset[name]; dup {
panic("reflect.StructOf: duplicate field " + name)
}
fset[name] = struct{}{}
hash = fnv1(hash, byte(ft.hash>>24), byte(ft.hash>>16), byte(ft.hash>>8), byte(ft.hash))
repr = append(repr, (" " + ft.String())...)
if f.name.tagLen() > 0 {
hash = fnv1(hash, []byte(f.name.tag())...)
repr = append(repr, (" " + strconv.Quote(f.name.tag()))...)
}
if i < len(fields)-1 {
repr = append(repr, ';')
}
comparable = comparable && (ft.alg.equal != nil)
hashable = hashable && (ft.alg.hash != nil)
offset := align(size, uintptr(ft.align))
if ft.align > typalign {
typalign = ft.align
}
size = offset + ft.size
f.offsetEmbed |= offset << 1
if ft.size == 0 {
lastzero = size
}
fs[i] = f
}
if size > 0 && lastzero == size {
// This is a non-zero sized struct that ends in a
// zero-sized field. We add an extra byte of padding,
// to ensure that taking the address of the final
// zero-sized field can't manufacture a pointer to the
// next object in the heap. See issue 9401.
size++
}
var typ *structType
var ut *uncommonType
if len(methods) == 0 {
t := new(structTypeUncommon)
typ = &t.structType
ut = &t.u
} else {
// A *rtype representing a struct is followed directly in memory by an
// array of method objects representing the methods attached to the
// struct. To get the same layout for a run time generated type, we
// need an array directly following the uncommonType memory.
// A similar strategy is used for funcTypeFixed4, ...funcTypeFixedN.
tt := New(StructOf([]StructField{
{Name: "S", Type: TypeOf(structType{})},
{Name: "U", Type: TypeOf(uncommonType{})},
{Name: "M", Type: ArrayOf(len(methods), TypeOf(methods[0]))},
}))
typ = (*structType)(unsafe.Pointer(tt.Elem().Field(0).UnsafeAddr()))
ut = (*uncommonType)(unsafe.Pointer(tt.Elem().Field(1).UnsafeAddr()))
copy(tt.Elem().Field(2).Slice(0, len(methods)).Interface().([]method), methods)
}
// TODO(sbinet): Once we allow embedding multiple types,
// methods will need to be sorted like the compiler does.
// TODO(sbinet): Once we allow non-exported methods, we will
// need to compute xcount as the number of exported methods.
ut.mcount = uint16(len(methods))
ut.xcount = ut.mcount
ut.moff = uint32(unsafe.Sizeof(uncommonType{}))
if len(fs) > 0 {
repr = append(repr, ' ')
}
repr = append(repr, '}')
hash = fnv1(hash, '}')
str := string(repr)
// Round the size up to be a multiple of the alignment.
size = align(size, uintptr(typalign))
// Make the struct type.
var istruct interface{} = struct{}{}
prototype := *(**structType)(unsafe.Pointer(&istruct))
*typ = *prototype
typ.fields = fs
// Look in cache.
if ts, ok := structLookupCache.m.Load(hash); ok {
for _, st := range ts.([]Type) {
t := st.common()
if haveIdenticalUnderlyingType(&typ.rtype, t, true) {
return t
}
}
}
// Not in cache, lock and retry.
structLookupCache.Lock()
defer structLookupCache.Unlock()
if ts, ok := structLookupCache.m.Load(hash); ok {
for _, st := range ts.([]Type) {
t := st.common()
if haveIdenticalUnderlyingType(&typ.rtype, t, true) {
return t
}
}
}
addToCache := func(t Type) Type {
var ts []Type
if ti, ok := structLookupCache.m.Load(hash); ok {
ts = ti.([]Type)
}
structLookupCache.m.Store(hash, append(ts, t))
return t
}
// Look in known types.
for _, t := range typesByString(str) {
if haveIdenticalUnderlyingType(&typ.rtype, t, true) {
// even if 't' wasn't a structType with methods, we should be ok
// as the 'u uncommonType' field won't be accessed except when
// tflag&tflagUncommon is set.
return addToCache(t)
}
}
typ.str = resolveReflectName(newName(str, "", false))
typ.tflag = 0
typ.hash = hash
typ.size = size
typ.ptrdata = typeptrdata(typ.common())
typ.align = typalign
typ.fieldAlign = typalign
typ.ptrToThis = 0
if len(methods) > 0 {
typ.tflag |= tflagUncommon
}
if hasGCProg {
lastPtrField := 0
for i, ft := range fs {
if ft.typ.pointers() {
lastPtrField = i
}
}
prog := []byte{0, 0, 0, 0} // will be length of prog
var off uintptr
for i, ft := range fs {
if i > lastPtrField {
// gcprog should not include anything for any field after
// the last field that contains pointer data
break
}
if !ft.typ.pointers() {
// Ignore pointerless fields.
continue
}
// Pad to start of this field with zeros.
if ft.offset() > off {
n := (ft.offset() - off) / ptrSize
prog = append(prog, 0x01, 0x00) // emit a 0 bit
if n > 1 {
prog = append(prog, 0x81) // repeat previous bit
prog = appendVarint(prog, n-1) // n-1 times
}
off = ft.offset()
}
elemGC := (*[1 << 30]byte)(unsafe.Pointer(ft.typ.gcdata))[:]
elemPtrs := ft.typ.ptrdata / ptrSize
if ft.typ.kind&kindGCProg == 0 {
// Element is small with pointer mask; use as literal bits.
mask := elemGC
// Emit 120-bit chunks of full bytes (max is 127 but we avoid using partial bytes).
var n uintptr
for n = elemPtrs; n > 120; n -= 120 {
prog = append(prog, 120)
prog = append(prog, mask[:15]...)
mask = mask[15:]
}
prog = append(prog, byte(n))
prog = append(prog, mask[:(n+7)/8]...)
} else {
// Element has GC program; emit one element.
elemProg := elemGC[4 : 4+*(*uint32)(unsafe.Pointer(&elemGC[0]))-1]
prog = append(prog, elemProg...)
}
off += ft.typ.ptrdata
}
prog = append(prog, 0)
*(*uint32)(unsafe.Pointer(&prog[0])) = uint32(len(prog) - 4)
typ.kind |= kindGCProg
typ.gcdata = &prog[0]
} else {
typ.kind &^= kindGCProg
bv := new(bitVector)
addTypeBits(bv, 0, typ.common())
if len(bv.data) > 0 {
typ.gcdata = &bv.data[0]
}
}
typ.alg = new(typeAlg)
if hashable {
typ.alg.hash = func(p unsafe.Pointer, seed uintptr) uintptr {
o := seed
for _, ft := range typ.fields {
pi := add(p, ft.offset(), "&x.field safe")
o = ft.typ.alg.hash(pi, o)
}
return o
}
}
if comparable {
typ.alg.equal = func(p, q unsafe.Pointer) bool {
for _, ft := range typ.fields {
pi := add(p, ft.offset(), "&x.field safe")
qi := add(q, ft.offset(), "&x.field safe")
if !ft.typ.alg.equal(pi, qi) {
return false
}
}
return true
}
}
switch {
case len(fs) == 1 && !ifaceIndir(fs[0].typ):
// structs of 1 direct iface type can be direct
typ.kind |= kindDirectIface
default:
typ.kind &^= kindDirectIface
}
return addToCache(&typ.rtype)
}
func runtimeStructField(field StructField) structField {
if field.PkgPath != "" {
panic("reflect.StructOf: StructOf does not allow unexported fields")
}
// Best-effort check for misuse.
// Since PkgPath is empty, not much harm done if Unicode lowercase slips through.
c := field.Name[0]
if 'a' <= c && c <= 'z' || c == '_' {
panic("reflect.StructOf: field \"" + field.Name + "\" is unexported but missing PkgPath")
}
offsetEmbed := uintptr(0)
if field.Anonymous {
offsetEmbed |= 1
}
resolveReflectType(field.Type.common()) // install in runtime
return structField{
name: newName(field.Name, string(field.Tag), true),
typ: field.Type.common(),
offsetEmbed: offsetEmbed,
}
}
// typeptrdata returns the length in bytes of the prefix of t
// containing pointer data. Anything after this offset is scalar data.
// keep in sync with ../cmd/compile/internal/gc/reflect.go
func typeptrdata(t *rtype) uintptr {
switch t.Kind() {
case Struct:
st := (*structType)(unsafe.Pointer(t))
// find the last field that has pointers.
field := -1
for i := range st.fields {
ft := st.fields[i].typ
if ft.pointers() {
field = i
}
}
if field == -1 {
return 0
}
f := st.fields[field]
return f.offset() + f.typ.ptrdata
default:
panic("reflect.typeptrdata: unexpected type, " + t.String())
}
}
// See cmd/compile/internal/gc/reflect.go for derivation of constant.
const maxPtrmaskBytes = 2048
// ArrayOf returns the array type with the given count and element type.
// For example, if t represents int, ArrayOf(5, t) represents [5]int.
//
// If the resulting type would be larger than the available address space,
// ArrayOf panics.
func ArrayOf(count int, elem Type) Type {
typ := elem.(*rtype)
// Look in cache.
ckey := cacheKey{Array, typ, nil, uintptr(count)}
if array, ok := lookupCache.Load(ckey); ok {
return array.(Type)
}
// Look in known types.
s := "[" + strconv.Itoa(count) + "]" + typ.String()
for _, tt := range typesByString(s) {
array := (*arrayType)(unsafe.Pointer(tt))
if array.elem == typ {
ti, _ := lookupCache.LoadOrStore(ckey, tt)
return ti.(Type)
}
}
// Make an array type.
var iarray interface{} = [1]unsafe.Pointer{}
prototype := *(**arrayType)(unsafe.Pointer(&iarray))
array := *prototype
array.tflag = 0
array.str = resolveReflectName(newName(s, "", false))
array.hash = fnv1(typ.hash, '[')
for n := uint32(count); n > 0; n >>= 8 {
array.hash = fnv1(array.hash, byte(n))
}
array.hash = fnv1(array.hash, ']')
array.elem = typ
array.ptrToThis = 0
if typ.size > 0 {
max := ^uintptr(0) / typ.size
if uintptr(count) > max {
panic("reflect.ArrayOf: array size would exceed virtual address space")
}
}
array.size = typ.size * uintptr(count)
if count > 0 && typ.ptrdata != 0 {
array.ptrdata = typ.size*uintptr(count-1) + typ.ptrdata
}
array.align = typ.align
array.fieldAlign = typ.fieldAlign
array.len = uintptr(count)
array.slice = SliceOf(elem).(*rtype)
switch {
case typ.ptrdata == 0 || array.size == 0:
// No pointers.
array.gcdata = nil
array.ptrdata = 0
case count == 1:
// In memory, 1-element array looks just like the element.
array.kind |= typ.kind & kindGCProg
array.gcdata = typ.gcdata
array.ptrdata = typ.ptrdata
case typ.kind&kindGCProg == 0 && array.size <= maxPtrmaskBytes*8*ptrSize:
// Element is small with pointer mask; array is still small.
// Create direct pointer mask by turning each 1 bit in elem
// into count 1 bits in larger mask.
mask := make([]byte, (array.ptrdata/ptrSize+7)/8)
elemMask := (*[1 << 30]byte)(unsafe.Pointer(typ.gcdata))[:]
elemWords := typ.size / ptrSize
for j := uintptr(0); j < typ.ptrdata/ptrSize; j++ {
if (elemMask[j/8]>>(j%8))&1 != 0 {
for i := uintptr(0); i < array.len; i++ {
k := i*elemWords + j
mask[k/8] |= 1 << (k % 8)
}
}
}
array.gcdata = &mask[0]
default:
// Create program that emits one element
// and then repeats to make the array.
prog := []byte{0, 0, 0, 0} // will be length of prog
elemGC := (*[1 << 30]byte)(unsafe.Pointer(typ.gcdata))[:]
elemPtrs := typ.ptrdata / ptrSize
if typ.kind&kindGCProg == 0 {
// Element is small with pointer mask; use as literal bits.
mask := elemGC
// Emit 120-bit chunks of full bytes (max is 127 but we avoid using partial bytes).
var n uintptr
for n = elemPtrs; n > 120; n -= 120 {
prog = append(prog, 120)
prog = append(prog, mask[:15]...)
mask = mask[15:]
}
prog = append(prog, byte(n))
prog = append(prog, mask[:(n+7)/8]...)
} else {
// Element has GC program; emit one element.
elemProg := elemGC[4 : 4+*(*uint32)(unsafe.Pointer(&elemGC[0]))-1]
prog = append(prog, elemProg...)
}
// Pad from ptrdata to size.
elemWords := typ.size / ptrSize
if elemPtrs < elemWords {
// Emit literal 0 bit, then repeat as needed.
prog = append(prog, 0x01, 0x00)
if elemPtrs+1 < elemWords {
prog = append(prog, 0x81)
prog = appendVarint(prog, elemWords-elemPtrs-1)
}
}
// Repeat count-1 times.
if elemWords < 0x80 {
prog = append(prog, byte(elemWords|0x80))
} else {
prog = append(prog, 0x80)
prog = appendVarint(prog, elemWords)
}
prog = appendVarint(prog, uintptr(count)-1)
prog = append(prog, 0)
*(*uint32)(unsafe.Pointer(&prog[0])) = uint32(len(prog) - 4)
array.kind |= kindGCProg
array.gcdata = &prog[0]
array.ptrdata = array.size // overestimate but ok; must match program
}
etyp := typ.common()
esize := etyp.Size()
ealg := etyp.alg
array.alg = new(typeAlg)
if ealg.equal != nil {
eequal := ealg.equal
array.alg.equal = func(p, q unsafe.Pointer) bool {
for i := 0; i < count; i++ {
pi := arrayAt(p, i, esize, "i < count")
qi := arrayAt(q, i, esize, "i < count")
if !eequal(pi, qi) {
return false
}
}
return true
}
}
if ealg.hash != nil {
ehash := ealg.hash
array.alg.hash = func(ptr unsafe.Pointer, seed uintptr) uintptr {
o := seed
for i := 0; i < count; i++ {
o = ehash(arrayAt(ptr, i, esize, "i < count"), o)
}
return o
}
}
switch {
case count == 1 && !ifaceIndir(typ):
// array of 1 direct iface type can be direct
array.kind |= kindDirectIface
default:
array.kind &^= kindDirectIface
}
ti, _ := lookupCache.LoadOrStore(ckey, &array.rtype)
return ti.(Type)
}
func appendVarint(x []byte, v uintptr) []byte {
for ; v >= 0x80; v >>= 7 {
x = append(x, byte(v|0x80))
}
x = append(x, byte(v))
return x
}
// toType converts from a *rtype to a Type that can be returned
// to the client of package reflect. In gc, the only concern is that
// a nil *rtype must be replaced by a nil Type, but in gccgo this
// function takes care of ensuring that multiple *rtype for the same
// type are coalesced into a single Type.
func toType(t *rtype) Type {
if t == nil {
return nil
}
return t
}
type layoutKey struct {
ftyp *funcType // function signature
rcvr *rtype // receiver type, or nil if none
}
type layoutType struct {
t *rtype
argSize uintptr // size of arguments
retOffset uintptr // offset of return values.
stack *bitVector
framePool *sync.Pool
}
var layoutCache sync.Map // map[layoutKey]layoutType
// funcLayout computes a struct type representing the layout of the
// function arguments and return values for the function type t.
// If rcvr != nil, rcvr specifies the type of the receiver.
// The returned type exists only for GC, so we only fill out GC relevant info.
// Currently, that's just size and the GC program. We also fill in
// the name for possible debugging use.
func funcLayout(t *funcType, rcvr *rtype) (frametype *rtype, argSize, retOffset uintptr, stk *bitVector, framePool *sync.Pool) {
if t.Kind() != Func {
panic("reflect: funcLayout of non-func type")
}
if rcvr != nil && rcvr.Kind() == Interface {
panic("reflect: funcLayout with interface receiver " + rcvr.String())
}
k := layoutKey{t, rcvr}
if lti, ok := layoutCache.Load(k); ok {
lt := lti.(layoutType)
return lt.t, lt.argSize, lt.retOffset, lt.stack, lt.framePool
}
// compute gc program & stack bitmap for arguments
ptrmap := new(bitVector)
var offset uintptr
if rcvr != nil {
// Reflect uses the "interface" calling convention for
// methods, where receivers take one word of argument
// space no matter how big they actually are.
if ifaceIndir(rcvr) || rcvr.pointers() {
ptrmap.append(1)
} else {
ptrmap.append(0)
}
offset += ptrSize
}
for _, arg := range t.in() {
offset += -offset & uintptr(arg.align-1)
addTypeBits(ptrmap, offset, arg)
offset += arg.size
}
argSize = offset
if runtime.GOARCH == "amd64p32" {
offset += -offset & (8 - 1)
}
offset += -offset & (ptrSize - 1)
retOffset = offset
for _, res := range t.out() {
offset += -offset & uintptr(res.align-1)
addTypeBits(ptrmap, offset, res)
offset += res.size
}
offset += -offset & (ptrSize - 1)
// build dummy rtype holding gc program
x := &rtype{
align: ptrSize,
size: offset,
ptrdata: uintptr(ptrmap.n) * ptrSize,
}
if runtime.GOARCH == "amd64p32" {
x.align = 8
}
if ptrmap.n > 0 {
x.gcdata = &ptrmap.data[0]
}
var s string
if rcvr != nil {
s = "methodargs(" + rcvr.String() + ")(" + t.String() + ")"
} else {
s = "funcargs(" + t.String() + ")"
}
x.str = resolveReflectName(newName(s, "", false))
// cache result for future callers
framePool = &sync.Pool{New: func() interface{} {
return unsafe_New(x)
}}
lti, _ := layoutCache.LoadOrStore(k, layoutType{
t: x,
argSize: argSize,
retOffset: retOffset,
stack: ptrmap,
framePool: framePool,
})
lt := lti.(layoutType)
return lt.t, lt.argSize, lt.retOffset, lt.stack, lt.framePool
}
// ifaceIndir reports whether t is stored indirectly in an interface value.
func ifaceIndir(t *rtype) bool {
return t.kind&kindDirectIface == 0
}
// Layout matches runtime.gobitvector (well enough).
type bitVector struct {
n uint32 // number of bits
data []byte
}
// append a bit to the bitmap.
func (bv *bitVector) append(bit uint8) {
if bv.n%8 == 0 {
bv.data = append(bv.data, 0)
}
bv.data[bv.n/8] |= bit << (bv.n % 8)
bv.n++
}
func addTypeBits(bv *bitVector, offset uintptr, t *rtype) {
if t.ptrdata == 0 {
return
}
switch Kind(t.kind & kindMask) {
case Chan, Func, Map, Ptr, Slice, String, UnsafePointer:
// 1 pointer at start of representation
for bv.n < uint32(offset/uintptr(ptrSize)) {
bv.append(0)
}
bv.append(1)
case Interface:
// 2 pointers
for bv.n < uint32(offset/uintptr(ptrSize)) {
bv.append(0)
}
bv.append(1)
bv.append(1)
case Array:
// repeat inner type
tt := (*arrayType)(unsafe.Pointer(t))
for i := 0; i < int(tt.len); i++ {
addTypeBits(bv, offset+uintptr(i)*tt.elem.size, tt.elem)
}
case Struct:
// apply fields
tt := (*structType)(unsafe.Pointer(t))
for i := range tt.fields {
f := &tt.fields[i]
addTypeBits(bv, offset+f.offset(), f.typ)
}
}
}
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