| // 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 reflectlite implements lightweight version of reflect, not using |
| // any package except for "runtime" and "unsafe". |
| package reflectlite |
| |
| import ( |
| "internal/unsafeheader" |
| "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. |
| |
| // 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 |
| |
| // 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 |
| |
| // Comparable reports whether values of this type are comparable. |
| Comparable() bool |
| |
| // 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 |
| |
| // Elem returns a type's element type. |
| // It panics if the type's Kind is not Ptr. |
| Elem() Type |
| |
| common() *rtype |
| uncommon() *uncommonType |
| } |
| |
| /* |
| * 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 |
| |
| // tflagRegularMemory means that equal and hash functions can treat |
| // this type as a single region of t.size bytes. |
| tflagRegularMemory tflag = 1 << 3 |
| ) |
| |
| // 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 |
| // function for comparing objects of this type |
| // (ptr to object A, ptr to object B) -> ==? |
| equal func(unsafe.Pointer, unsafe.Pointer) bool |
| gcdata *byte // garbage collection data |
| str nameOff // string form |
| ptrToThis typeOff // type for pointer to this type, may be zero |
| } |
| |
| // 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 |
| // function for hashing keys (ptr to key, seed) -> hash |
| hasher func(unsafe.Pointer, uintptr) uintptr |
| 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 := (*unsafeheader.String)(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 := (*unsafeheader.String)(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() |
| } |
| |
| /* |
| * The compiler knows the exact layout of all the data structures above. |
| * The compiler does not know about the data structures and methods below. |
| */ |
| |
| const ( |
| kindDirectIface = 1 << 5 |
| kindGCProg = 1 << 6 // Type.gc points to GC program |
| kindMask = (1 << 5) - 1 |
| ) |
| |
| 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 |
| |
| 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) 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) 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) PkgPath() string { |
| if t.tflag&tflagNamed == 0 { |
| return "" |
| } |
| ut := t.uncommon() |
| if ut == nil { |
| return "" |
| } |
| return t.nameOff(ut.pkgPath).name() |
| } |
| |
| func (t *rtype) hasName() bool { |
| return t.tflag&tflagNamed != 0 |
| } |
| |
| func (t *rtype) Name() string { |
| if !t.hasName() { |
| 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) 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) 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: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 : 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) |
| } |
| |
| // NumMethod returns the number of interface methods in the type's method set. |
| func (t *interfaceType) NumMethod() int { return len(t.methods) } |
| |
| // 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) |
| } |
| |
| 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) Comparable() bool { |
| return t.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.hasName() && V.hasName() || 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 |
| } |
| |
| type structTypeUncommon struct { |
| structType |
| u uncommonType |
| } |
| |
| // 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 |
| } |
| |
| // ifaceIndir reports whether t is stored indirectly in an interface value. |
| func ifaceIndir(t *rtype) bool { |
| return t.kind&kindDirectIface == 0 |
| } |