diff options
Diffstat (limited to 'libgo/go/reflect/value.go')
| -rw-r--r-- | libgo/go/reflect/value.go | 1396 |
1 files changed, 683 insertions, 713 deletions
diff --git a/libgo/go/reflect/value.go b/libgo/go/reflect/value.go index dbdfa09242f..b57ed462c84 100644 --- a/libgo/go/reflect/value.go +++ b/libgo/go/reflect/value.go @@ -11,6 +11,7 @@ import ( "unsafe" ) +const bigEndian = false // can be smarter if we find a big-endian machine const ptrSize = unsafe.Sizeof((*byte)(nil)) const cannotSet = "cannot set value obtained from unexported struct field" @@ -53,14 +54,54 @@ func memmove(adst, asrc unsafe.Pointer, n uintptr) { // its String method returns "<invalid Value>", and all other methods panic. // Most functions and methods never return an invalid value. // If one does, its documentation states the conditions explicitly. -// -// The fields of Value are exported so that clients can copy and -// pass Values around, but they should not be edited or inspected -// directly. A future language change may make it possible not to -// export these fields while still keeping Values usable as values. type Value struct { - Internal interface{} - InternalMethod int + // typ holds the type of the value represented by a Value. + typ *commonType + + // val holds the 1-word representation of the value. + // If flag's flagIndir bit is set, then val is a pointer to the data. + // Otherwise val is a word holding the actual data. + // When the data is smaller than a word, it begins at + // the first byte (in the memory address sense) of val. + // We use unsafe.Pointer so that the garbage collector + // knows that val could be a pointer. + val unsafe.Pointer + + // flag holds metadata about the value. + // The lowest bits are flag bits: + // - flagRO: obtained via unexported field, so read-only + // - flagIndir: val holds a pointer to the data + // - flagAddr: v.CanAddr is true (implies flagIndir) + // - flagMethod: v is a method value. + // The next five bits give the Kind of the value. + // This repeats typ.Kind() except for method values. + // The remaining 23+ bits give a method number for method values. + // If flag.kind() != Func, code can assume that flagMethod is unset. + // If typ.size > ptrSize, code can assume that flagIndir is set. + flag + + // A method value represents a curried method invocation + // like r.Read for some receiver r. The typ+val+flag bits describe + // the receiver r, but the flag's Kind bits say Func (methods are + // functions), and the top bits of the flag give the method number + // in r's type's method table. +} + +type flag uintptr + +const ( + flagRO flag = 1 << iota + flagIndir + flagAddr + flagMethod + flagKindShift = iota + flagKindWidth = 5 // there are 27 kinds + flagKindMask flag = 1<<flagKindWidth - 1 + flagMethodShift = flagKindShift + flagKindWidth +) + +func (f flag) kind() Kind { + return Kind((f >> flagKindShift) & flagKindMask) } // A ValueError occurs when a Value method is invoked on @@ -92,17 +133,30 @@ func methodName() string { // An iword is the word that would be stored in an // interface to represent a given value v. Specifically, if v is // bigger than a pointer, its word is a pointer to v's data. -// Otherwise, its word is a zero uintptr with the data stored -// in the leading bytes. -type iword uintptr +// Otherwise, its word holds the data stored +// in its leading bytes (so is not a pointer). +// Because the value sometimes holds a pointer, we use +// unsafe.Pointer to represent it, so that if iword appears +// in a struct, the garbage collector knows that might be +// a pointer. +type iword unsafe.Pointer + +func (v Value) iword() iword { + if v.flag&flagIndir != 0 && (v.kind() == Ptr || v.kind() == UnsafePointer) { + // Have indirect but want direct word. + return loadIword(v.val, v.typ.size) + } + return iword(v.val) +} -func loadIword(p unsafe.Pointer, size uintptr) iword { +// loadIword loads n bytes at p from memory into an iword. +func loadIword(p unsafe.Pointer, n uintptr) iword { // Run the copy ourselves instead of calling memmove - // to avoid moving v to the heap. - w := iword(0) - switch size { + // to avoid moving w to the heap. + var w iword + switch n { default: - panic("reflect: internal error: loadIword of " + strconv.Itoa(int(size)) + "-byte value") + panic("reflect: internal error: loadIword of " + strconv.Itoa(int(n)) + "-byte value") case 0: case 1: *(*uint8)(unsafe.Pointer(&w)) = *(*uint8)(p) @@ -124,12 +178,13 @@ func loadIword(p unsafe.Pointer, size uintptr) iword { return w } -func storeIword(p unsafe.Pointer, w iword, size uintptr) { +// storeIword stores n bytes from w into p. +func storeIword(p unsafe.Pointer, w iword, n uintptr) { // Run the copy ourselves instead of calling memmove - // to avoid moving v to the heap. - switch size { + // to avoid moving w to the heap. + switch n { default: - panic("reflect: internal error: storeIword of " + strconv.Itoa(int(size)) + "-byte value") + panic("reflect: internal error: storeIword of " + strconv.Itoa(int(n)) + "-byte value") case 0: case 1: *(*uint8)(p) = *(*uint8)(unsafe.Pointer(&w)) @@ -166,237 +221,42 @@ type nonEmptyInterface struct { word iword } -// Regarding the implementation of Value: -// -// The Internal interface is a true interface value in the Go sense, -// but it also serves as a (type, address) pair in which one cannot -// be changed separately from the other. That is, it serves as a way -// to prevent unsafe mutations of the Internal state even though -// we cannot (yet?) hide the field while preserving the ability for -// clients to make copies of Values. -// -// The internal method converts a Value into the expanded internalValue struct. -// If we could avoid exporting fields we'd probably make internalValue the -// definition of Value. -// -// If a Value is addressable (CanAddr returns true), then the Internal -// interface value holds a pointer to the actual field data, and Set stores -// through that pointer. If a Value is not addressable (CanAddr returns false), -// then the Internal interface value holds the actual value. -// -// In addition to whether a value is addressable, we track whether it was -// obtained by using an unexported struct field. Such values are allowed -// to be read, mainly to make fmt.Print more useful, but they are not -// allowed to be written. We call such values read-only. -// -// A Value can be set (via the Set, SetUint, etc. methods) only if it is both -// addressable and not read-only. -// -// The two permission bits - addressable and read-only - are stored in -// the bottom two bits of the type pointer in the interface value. -// -// ordinary value: Internal = value -// addressable value: Internal = value, Internal.typ |= flagAddr -// read-only value: Internal = value, Internal.typ |= flagRO -// addressable, read-only value: Internal = value, Internal.typ |= flagAddr | flagRO -// -// It is important that the read-only values have the extra bit set -// (as opposed to using the bit to mean writable), because client code -// can grab the interface field and try to use it. Having the extra bit -// set makes the type pointer compare not equal to any real type, -// so that a client cannot, say, write through v.Internal.(*int). -// The runtime routines that access interface types reject types with -// low bits set. -// -// If a Value fv = v.Method(i), then fv = v with the InternalMethod -// field set to i+1. Methods are never addressable. -// -// All in all, this is a lot of effort just to avoid making this new API -// depend on a language change we'll probably do anyway, but -// it's helpful to keep the two separate, and much of the logic is -// necessary to implement the Interface method anyway. - -const ( - flagAddr uint32 = 1 << iota // holds address of value - flagRO // read-only - - reflectFlags = 3 -) - -// An internalValue is the unpacked form of a Value. -// The zero Value unpacks to a zero internalValue -type internalValue struct { - typ *commonType // type of value - kind Kind // kind of value - flag uint32 - word iword - addr unsafe.Pointer - rcvr iword - method bool - nilmethod bool -} - -func (v Value) internal() internalValue { - var iv internalValue - eface := *(*emptyInterface)(unsafe.Pointer(&v.Internal)) - p := uintptr(unsafe.Pointer(eface.typ)) - iv.typ = toCommonType((*runtime.Type)(unsafe.Pointer(p &^ reflectFlags))) - if iv.typ == nil { - return iv - } - iv.flag = uint32(p & reflectFlags) - iv.word = eface.word - if iv.flag&flagAddr != 0 { - iv.addr = unsafe.Pointer(uintptr(iv.word)) - iv.typ = iv.typ.Elem().common() - if Kind(iv.typ.kind) == Ptr || Kind(iv.typ.kind) == UnsafePointer { - iv.word = loadIword(iv.addr, iv.typ.size) - } - } else { - if Kind(iv.typ.kind) != Ptr && Kind(iv.typ.kind) != UnsafePointer { - iv.addr = unsafe.Pointer(uintptr(iv.word)) - } +// mustBe panics if f's kind is not expected. +// Making this a method on flag instead of on Value +// (and embedding flag in Value) means that we can write +// the very clear v.mustBe(Bool) and have it compile into +// v.flag.mustBe(Bool), which will only bother to copy the +// single important word for the receiver. +func (f flag) mustBe(expected Kind) { + k := f.kind() + if k != expected { + panic(&ValueError{methodName(), k}) } - iv.kind = iv.typ.Kind() - - // Is this a method? If so, iv describes the receiver. - // Rewrite to describe the method function. - if v.InternalMethod != 0 { - // If this Value is a method value (x.Method(i) for some Value x) - // then we will invoke it using the interface form of the method, - // which always passes the receiver as a single word. - // Record that information. - i := v.InternalMethod - 1 - if iv.kind == Interface { - it := (*interfaceType)(unsafe.Pointer(iv.typ)) - if i < 0 || i >= len(it.methods) { - panic("reflect: broken Value") - } - m := &it.methods[i] - if m.pkgPath != nil { - iv.flag |= flagRO - } - iv.typ = toCommonType(m.typ) - iface := (*nonEmptyInterface)(iv.addr) - if iface.itab == nil { - iv.word = 0 - iv.nilmethod = true - } else { - iv.word = iword(uintptr(iface.itab.fun[i])) - } - iv.rcvr = iface.word - } else { - ut := iv.typ.uncommon() - if ut == nil || i < 0 || i >= len(ut.methods) { - panic("reflect: broken Value") - } - m := &ut.methods[i] - if m.pkgPath != nil { - iv.flag |= flagRO - } - iv.typ = toCommonType(m.mtyp) - iv.rcvr = iv.word - iv.word = iword(uintptr(m.tfn)) - } - if iv.word != 0 { - p := new(iword) - *p = iv.word - iv.word = iword(uintptr(unsafe.Pointer(p))) - } - iv.kind = Func - iv.method = true - iv.flag &^= flagAddr - iv.addr = unsafe.Pointer(uintptr(iv.word)) - } - - return iv } -// packValue returns a Value with the given flag bits, type, and interface word. -func packValue(flag uint32, typ *runtime.Type, word iword) Value { - if typ == nil { - panic("packValue") +// mustBeExported panics if f records that the value was obtained using +// an unexported field. +func (f flag) mustBeExported() { + if f == 0 { + panic(&ValueError{methodName(), 0}) } - t := uintptr(unsafe.Pointer(typ)) - t |= uintptr(flag) - eface := emptyInterface{(*runtime.Type)(unsafe.Pointer(t)), word} - return Value{Internal: *(*interface{})(unsafe.Pointer(&eface))} -} - -var dummy struct { - b bool - x interface{} -} - -// Dummy annotation marking that the value x escapes, -// for use in cases where the reflect code is so clever that -// the compiler cannot follow. -func escapes(x interface{}) { - if dummy.b { - dummy.x = x - } -} - -// valueFromAddr returns a Value using the given type and address. -func valueFromAddr(flag uint32, typ Type, addr unsafe.Pointer) Value { - // TODO(rsc): Eliminate this terrible hack. - // The escape analysis knows that addr is a pointer - // but it doesn't see addr get passed to anything - // that keeps it. packValue keeps it, but packValue - // takes a uintptr (iword(addr)), and integers (non-pointers) - // are assumed not to matter. The escapes function works - // because return values always escape (for now). - escapes(addr) - - if flag&flagAddr != 0 { - // Addressable, so the internal value is - // an interface containing a pointer to the real value. - return packValue(flag, PtrTo(typ).runtimeType(), iword(uintptr(addr))) - } - - var w iword - if k := typ.Kind(); k == Ptr || k == UnsafePointer { - // In line, so the interface word is the actual value. - w = loadIword(addr, typ.Size()) - } else { - // Not in line: the interface word is the address. - w = iword(uintptr(addr)) - } - return packValue(flag, typ.runtimeType(), w) -} - -// valueFromIword returns a Value using the given type and interface word. -func valueFromIword(flag uint32, typ Type, w iword) Value { - if flag&flagAddr != 0 { - panic("reflect: internal error: valueFromIword addressable") - } - return packValue(flag, typ.runtimeType(), w) -} - -func (iv internalValue) mustBe(want Kind) { - if iv.kind != want { - panic(&ValueError{methodName(), iv.kind}) - } -} - -func (iv internalValue) mustBeExported() { - if iv.kind == 0 { - panic(&ValueError{methodName(), iv.kind}) - } - if iv.flag&flagRO != 0 { + if f&flagRO != 0 { panic(methodName() + " using value obtained using unexported field") } } -func (iv internalValue) mustBeAssignable() { - if iv.kind == 0 { - panic(&ValueError{methodName(), iv.kind}) +// mustBeAssignable panics if f records that the value is not assignable, +// which is to say that either it was obtained using an unexported field +// or it is not addressable. +func (f flag) mustBeAssignable() { + if f == 0 { + panic(&ValueError{methodName(), Invalid}) } // Assignable if addressable and not read-only. - if iv.flag&flagRO != 0 { + if f&flagRO != 0 { panic(methodName() + " using value obtained using unexported field") } - if iv.flag&flagAddr == 0 { + if f&flagAddr == 0 { panic(methodName() + " using unaddressable value") } } @@ -407,31 +267,31 @@ func (iv internalValue) mustBeAssignable() { // or slice element in order to call a method that requires a // pointer receiver. func (v Value) Addr() Value { - iv := v.internal() - if iv.flag&flagAddr == 0 { + if v.flag&flagAddr == 0 { panic("reflect.Value.Addr of unaddressable value") } - return valueFromIword(iv.flag&flagRO, PtrTo(iv.typ.toType()), iword(uintptr(iv.addr))) + return Value{v.typ.ptrTo(), v.val, (v.flag & flagRO) | flag(Ptr)<<flagKindShift} } // Bool returns v's underlying value. // It panics if v's kind is not Bool. func (v Value) Bool() bool { - iv := v.internal() - iv.mustBe(Bool) - return *(*bool)(unsafe.Pointer(iv.addr)) + v.mustBe(Bool) + if v.flag&flagIndir != 0 { + return *(*bool)(v.val) + } + return *(*bool)(unsafe.Pointer(&v.val)) } // Bytes returns v's underlying value. // It panics if v's underlying value is not a slice of bytes. func (v Value) Bytes() []byte { - iv := v.internal() - iv.mustBe(Slice) - typ := iv.typ.toType() - if typ.Elem().Kind() != Uint8 { + v.mustBe(Slice) + if v.typ.Elem().Kind() != Uint8 { panic("reflect.Value.Bytes of non-byte slice") } - return *(*[]byte)(iv.addr) + // Slice is always bigger than a word; assume flagIndir. + return *(*[]byte)(v.val) } // CanAddr returns true if the value's address can be obtained with Addr. @@ -440,8 +300,7 @@ func (v Value) Bytes() []byte { // a field of an addressable struct, or the result of dereferencing a pointer. // If CanAddr returns false, calling Addr will panic. func (v Value) CanAddr() bool { - iv := v.internal() - return iv.flag&flagAddr != 0 + return v.flag&flagAddr != 0 } // CanSet returns true if the value of v can be changed. @@ -450,8 +309,7 @@ func (v Value) CanAddr() bool { // If CanSet returns false, calling Set or any type-specific // setter (e.g., SetBool, SetInt64) will panic. func (v Value) CanSet() bool { - iv := v.internal() - return iv.flag&(flagAddr|flagRO) == flagAddr + return v.flag&(flagAddr|flagRO) == flagAddr } // Call calls the function v with the input arguments in. @@ -463,10 +321,9 @@ func (v Value) CanSet() bool { // If v is a variadic function, Call creates the variadic slice parameter // itself, copying in the corresponding values. func (v Value) Call(in []Value) []Value { - iv := v.internal() - iv.mustBe(Func) - iv.mustBeExported() - return iv.call("Call", in) + v.mustBe(Func) + v.mustBeExported() + return v.call("Call", in) } // CallSlice calls the variadic function v with the input arguments in, @@ -477,22 +334,60 @@ func (v Value) Call(in []Value) []Value { // As in Go, each input argument must be assignable to the // type of the function's corresponding input parameter. func (v Value) CallSlice(in []Value) []Value { - iv := v.internal() - iv.mustBe(Func) - iv.mustBeExported() - return iv.call("CallSlice", in) -} - -func (iv internalValue) call(method string, in []Value) []Value { - if iv.word == 0 { - if iv.nilmethod { - panic("reflect.Value.Call: call of method on nil interface value") + v.mustBe(Func) + v.mustBeExported() + return v.call("CallSlice", in) +} + +func (v Value) call(method string, in []Value) []Value { + // Get function pointer, type. + t := v.typ + var ( + fn unsafe.Pointer + rcvr iword + ) + if v.flag&flagMethod != 0 { + i := int(v.flag) >> flagMethodShift + if v.typ.Kind() == Interface { + tt := (*interfaceType)(unsafe.Pointer(v.typ)) + if i < 0 || i >= len(tt.methods) { + panic("reflect: broken Value") + } + m := &tt.methods[i] + if m.pkgPath != nil { + panic(method + " of unexported method") + } + t = toCommonType(m.typ) + iface := (*nonEmptyInterface)(v.val) + if iface.itab == nil { + panic(method + " of method on nil interface value") + } + fn = iface.itab.fun[i] + rcvr = iface.word + } else { + ut := v.typ.uncommon() + if ut == nil || i < 0 || i >= len(ut.methods) { + panic("reflect: broken Value") + } + m := &ut.methods[i] + if m.pkgPath != nil { + panic(method + " of unexported method") + } + fn = m.tfn + t = toCommonType(m.mtyp) + rcvr = v.iword() } + } else if v.flag&flagIndir != 0 { + fn = *(*unsafe.Pointer)(v.val) + } else { + fn = v.val + } + + if fn == nil { panic("reflect.Value.Call: call of nil function") } isSlice := method == "CallSlice" - t := iv.typ n := t.NumIn() if isSlice { if !t.IsVariadic() { @@ -549,34 +444,32 @@ func (iv internalValue) call(method string, in []Value) []Value { } nout := t.NumOut() - if iv.method { + if v.flag&flagMethod != 0 { nin++ } params := make([]unsafe.Pointer, nin) delta := 0 off := 0 - if iv.method { + if v.flag&flagMethod != 0 { // Hard-wired first argument. p := new(iword) - *p = iv.rcvr + *p = rcvr params[0] = unsafe.Pointer(p) off = 1 } - first_pointer := false - for i, v := range in { - siv := v.internal() - siv.mustBeExported() + for i, pv := range in { + pv.mustBeExported() targ := t.In(i).(*commonType) - siv = convertForAssignment("reflect.Value.Call", nil, targ, siv) - if siv.addr == nil { + pv = pv.assignTo("reflect.Value.Call", targ, nil) + if pv.flag&flagIndir == 0 { p := new(unsafe.Pointer) - *p = unsafe.Pointer(uintptr(siv.word)) + *p = pv.val params[off] = unsafe.Pointer(p) } else { - params[off] = siv.addr + params[off] = pv.val } - if i == 0 && Kind(targ.kind) != Ptr && !iv.method && isMethod(iv.typ) { + if i == 0 && Kind(targ.kind) != Ptr && v.flag&flagMethod == 0 && isMethod(v.typ) { p := new(unsafe.Pointer) *p = params[off] params[off] = unsafe.Pointer(p) @@ -602,7 +495,7 @@ func (iv internalValue) call(method string, in []Value) []Value { pr = &results[0] } - call(t, *(*unsafe.Pointer)(iv.addr), iv.method, first_pointer, pp, pr) + call(t, fn, v.flag&flagMethod != 0, first_pointer, pp, pr) return ret } @@ -635,39 +528,42 @@ func isMethod(t *commonType) bool { // Cap returns v's capacity. // It panics if v's Kind is not Array, Chan, or Slice. func (v Value) Cap() int { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Array: - return iv.typ.Len() + return v.typ.Len() case Chan: - return int(chancap(*(*iword)(iv.addr))) + return int(chancap(*(*iword)(v.iword()))) case Slice: - return (*SliceHeader)(iv.addr).Cap + // Slice is always bigger than a word; assume flagIndir. + return (*SliceHeader)(v.val).Cap } - panic(&ValueError{"reflect.Value.Cap", iv.kind}) + panic(&ValueError{"reflect.Value.Cap", k}) } // Close closes the channel v. // It panics if v's Kind is not Chan. func (v Value) Close() { - iv := v.internal() - iv.mustBe(Chan) - iv.mustBeExported() - ch := *(*iword)(iv.addr) - chanclose(ch) + v.mustBe(Chan) + v.mustBeExported() + chanclose(*(*iword)(v.iword())) } // Complex returns v's underlying value, as a complex128. // It panics if v's Kind is not Complex64 or Complex128 func (v Value) Complex() complex128 { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Complex64: - return complex128(*(*complex64)(iv.addr)) + if v.flag&flagIndir != 0 { + return complex128(*(*complex64)(v.val)) + } + return complex128(*(*complex64)(unsafe.Pointer(&v.val))) case Complex128: - return *(*complex128)(iv.addr) + // complex128 is always bigger than a word; assume flagIndir. + return *(*complex128)(v.val) } - panic(&ValueError{"reflect.Value.Complex", iv.kind}) + panic(&ValueError{"reflect.Value.Complex", k}) } // Elem returns the value that the interface v contains @@ -675,90 +571,94 @@ func (v Value) Complex() complex128 { // It panics if v's Kind is not Interface or Ptr. // It returns the zero Value if v is nil. func (v Value) Elem() Value { - iv := v.internal() - return iv.Elem() -} - -func (iv internalValue) Elem() Value { - switch iv.kind { + k := v.kind() + switch k { case Interface: - // Empty interface and non-empty interface have different layouts. - // Convert to empty interface. - var eface emptyInterface - if iv.typ.NumMethod() == 0 { - eface = *(*emptyInterface)(iv.addr) + var ( + typ *commonType + val unsafe.Pointer + ) + if v.typ.NumMethod() == 0 { + eface := (*emptyInterface)(v.val) + if eface.typ == nil { + // nil interface value + return Value{} + } + typ = toCommonType(eface.typ) + val = unsafe.Pointer(eface.word) } else { - iface := (*nonEmptyInterface)(iv.addr) - if iface.itab != nil { - eface.typ = iface.itab.typ + iface := (*nonEmptyInterface)(v.val) + if iface.itab == nil { + // nil interface value + return Value{} } - eface.word = iface.word + typ = toCommonType(iface.itab.typ) + val = unsafe.Pointer(iface.word) } - if eface.typ == nil { - return Value{} + fl := v.flag & flagRO + fl |= flag(typ.Kind()) << flagKindShift + if typ.Kind() != Ptr && typ.Kind() != UnsafePointer { + fl |= flagIndir } - return valueFromIword(iv.flag&flagRO, toType(eface.typ), eface.word) + return Value{typ, val, fl} case Ptr: + val := v.val + if v.flag&flagIndir != 0 { + val = *(*unsafe.Pointer)(val) + } // The returned value's address is v's value. - if iv.word == 0 { + if val == nil { return Value{} } - return valueFromAddr(iv.flag&flagRO|flagAddr, iv.typ.Elem(), unsafe.Pointer(uintptr(iv.word))) + tt := (*ptrType)(unsafe.Pointer(v.typ)) + typ := toCommonType(tt.elem) + fl := v.flag&flagRO | flagIndir | flagAddr + fl |= flag(typ.Kind() << flagKindShift) + return Value{typ, val, fl} } - panic(&ValueError{"reflect.Value.Elem", iv.kind}) + panic(&ValueError{"reflect.Value.Elem", k}) } // Field returns the i'th field of the struct v. // It panics if v's Kind is not Struct or i is out of range. func (v Value) Field(i int) Value { - iv := v.internal() - iv.mustBe(Struct) - t := iv.typ.toType() - if i < 0 || i >= t.NumField() { + v.mustBe(Struct) + tt := (*structType)(unsafe.Pointer(v.typ)) + if i < 0 || i >= len(tt.fields) { panic("reflect: Field index out of range") } - f := t.Field(i) + field := &tt.fields[i] + typ := toCommonType(field.typ) // Inherit permission bits from v. - flag := iv.flag + fl := v.flag & (flagRO | flagIndir | flagAddr) // Using an unexported field forces flagRO. - if f.PkgPath != "" { - flag |= flagRO + if field.pkgPath != nil { + fl |= flagRO } - return valueFromValueOffset(flag, f.Type, iv, f.Offset) -} + fl |= flag(typ.Kind()) << flagKindShift -// valueFromValueOffset returns a sub-value of outer -// (outer is an array or a struct) with the given flag and type -// starting at the given byte offset into outer. -func valueFromValueOffset(flag uint32, typ Type, outer internalValue, offset uintptr) Value { - if outer.addr != nil { - return valueFromAddr(flag, typ, unsafe.Pointer(uintptr(outer.addr)+offset)) + var val unsafe.Pointer + switch { + case fl&flagIndir != 0: + // Indirect. Just bump pointer. + val = unsafe.Pointer(uintptr(v.val) + field.offset) + case bigEndian: + // Direct. Discard leading bytes. + val = unsafe.Pointer(uintptr(v.val) << (field.offset * 8)) + default: + // Direct. Discard leading bytes. + val = unsafe.Pointer(uintptr(v.val) >> (field.offset * 8)) } - // outer is so tiny it is in line. - // We have to use outer.word and derive - // the new word (it cannot possibly be bigger). - // In line, so not addressable. - if flag&flagAddr != 0 { - panic("reflect: internal error: misuse of valueFromValueOffset") - } - b := *(*[ptrSize]byte)(unsafe.Pointer(&outer.word)) - for i := uintptr(0); i < typ.Size(); i++ { - b[i] = b[offset+i] - } - for i := typ.Size(); i < ptrSize; i++ { - b[i] = 0 - } - w := *(*iword)(unsafe.Pointer(&b)) - return valueFromIword(flag, typ, w) + return Value{typ, val, fl} } // FieldByIndex returns the nested field corresponding to index. // It panics if v's Kind is not struct. func (v Value) FieldByIndex(index []int) Value { - v.internal().mustBe(Struct) + v.mustBe(Struct) for i, x := range index { if i > 0 { if v.Kind() == Ptr && v.Elem().Kind() == Struct { @@ -774,9 +674,8 @@ func (v Value) FieldByIndex(index []int) Value { // It returns the zero Value if no field was found. // It panics if v's Kind is not struct. func (v Value) FieldByName(name string) Value { - iv := v.internal() - iv.mustBe(Struct) - if f, ok := iv.typ.FieldByName(name); ok { + v.mustBe(Struct) + if f, ok := v.typ.FieldByName(name); ok { return v.FieldByIndex(f.Index) } return Value{} @@ -787,8 +686,8 @@ func (v Value) FieldByName(name string) Value { // It panics if v's Kind is not struct. // It returns the zero Value if no field was found. func (v Value) FieldByNameFunc(match func(string) bool) Value { - v.internal().mustBe(Struct) - if f, ok := v.Type().FieldByNameFunc(match); ok { + v.mustBe(Struct) + if f, ok := v.typ.FieldByNameFunc(match); ok { return v.FieldByIndex(f.Index) } return Value{} @@ -797,74 +696,101 @@ func (v Value) FieldByNameFunc(match func(string) bool) Value { // Float returns v's underlying value, as an float64. // It panics if v's Kind is not Float32 or Float64 func (v Value) Float() float64 { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Float32: - return float64(*(*float32)(iv.addr)) + if v.flag&flagIndir != 0 { + return float64(*(*float32)(v.val)) + } + return float64(*(*float32)(unsafe.Pointer(&v.val))) case Float64: - return *(*float64)(iv.addr) + if v.flag&flagIndir != 0 { + return *(*float64)(v.val) + } + return *(*float64)(unsafe.Pointer(&v.val)) } - panic(&ValueError{"reflect.Value.Float", iv.kind}) + panic(&ValueError{"reflect.Value.Float", k}) } // Index returns v's i'th element. // It panics if v's Kind is not Array or Slice or i is out of range. func (v Value) Index(i int) Value { - iv := v.internal() - switch iv.kind { - default: - panic(&ValueError{"reflect.Value.Index", iv.kind}) + k := v.kind() + switch k { case Array: - flag := iv.flag // element flag same as overall array - t := iv.typ.toType() - if i < 0 || i > t.Len() { + tt := (*arrayType)(unsafe.Pointer(v.typ)) + if i < 0 || i > int(tt.len) { panic("reflect: array index out of range") } - typ := t.Elem() - return valueFromValueOffset(flag, typ, iv, uintptr(i)*typ.Size()) + typ := toCommonType(tt.elem) + fl := v.flag & (flagRO | flagIndir | flagAddr) // bits same as overall array + fl |= flag(typ.Kind()) << flagKindShift + offset := uintptr(i) * typ.size + + var val unsafe.Pointer + switch { + case fl&flagIndir != 0: + // Indirect. Just bump pointer. + val = unsafe.Pointer(uintptr(v.val) + offset) + case bigEndian: + // Direct. Discard leading bytes. + val = unsafe.Pointer(uintptr(v.val) << (offset * 8)) + default: + // Direct. Discard leading bytes. + val = unsafe.Pointer(uintptr(v.val) >> (offset * 8)) + } + return Value{typ, val, fl} case Slice: // Element flag same as Elem of Ptr. - // Addressable, possibly read-only. - flag := iv.flag&flagRO | flagAddr - s := (*SliceHeader)(iv.addr) + // Addressable, indirect, possibly read-only. + fl := flagAddr | flagIndir | v.flag&flagRO + s := (*SliceHeader)(v.val) if i < 0 || i >= s.Len { panic("reflect: slice index out of range") } - typ := iv.typ.Elem() - addr := unsafe.Pointer(s.Data + uintptr(i)*typ.Size()) - return valueFromAddr(flag, typ, addr) + tt := (*sliceType)(unsafe.Pointer(v.typ)) + typ := toCommonType(tt.elem) + fl |= flag(typ.Kind()) << flagKindShift + val := unsafe.Pointer(s.Data + uintptr(i)*typ.size) + return Value{typ, val, fl} } - - panic("not reached") + panic(&ValueError{"reflect.Value.Index", k}) } // Int returns v's underlying value, as an int64. // It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64. func (v Value) Int() int64 { - iv := v.internal() - switch iv.kind { + k := v.kind() + var p unsafe.Pointer + if v.flag&flagIndir != 0 { + p = v.val + } else { + // The escape analysis is good enough that &v.val + // does not trigger a heap allocation. + p = unsafe.Pointer(&v.val) + } + switch k { case Int: - return int64(*(*int)(iv.addr)) + return int64(*(*int)(p)) case Int8: - return int64(*(*int8)(iv.addr)) + return int64(*(*int8)(p)) case Int16: - return int64(*(*int16)(iv.addr)) + return int64(*(*int16)(p)) case Int32: - return int64(*(*int32)(iv.addr)) + return int64(*(*int32)(p)) case Int64: - return *(*int64)(iv.addr) + return int64(*(*int64)(p)) } - panic(&ValueError{"reflect.Value.Int", iv.kind}) + panic(&ValueError{"reflect.Value.Int", k}) } // CanInterface returns true if Interface can be used without panicking. func (v Value) CanInterface() bool { - iv := v.internal() - if iv.kind == Invalid { - panic(&ValueError{"reflect.Value.CanInterface", iv.kind}) + if v.flag == 0 { + panic(&ValueError{"reflect.Value.CanInterface", Invalid}) } - return v.InternalMethod == 0 && iv.flag&flagRO == 0 + return v.flag&(flagMethod|flagRO) == 0 } // Interface returns v's value as an interface{}. @@ -876,75 +802,72 @@ func (v Value) Interface() interface{} { } func valueInterface(v Value, safe bool) interface{} { - iv := v.internal() - return iv.valueInterface(safe) -} - -func (iv internalValue) valueInterface(safe bool) interface{} { - if iv.kind == 0 { - panic(&ValueError{"reflect.Value.Interface", iv.kind}) + if v.flag == 0 { + panic(&ValueError{"reflect.Value.Interface", 0}) } - if iv.method { + if v.flag&flagMethod != 0 { panic("reflect.Value.Interface: cannot create interface value for method with bound receiver") } - if safe && iv.flag&flagRO != 0 { + if safe && v.flag&flagRO != 0 { // Do not allow access to unexported values via Interface, // because they might be pointers that should not be // writable or methods or function that should not be callable. panic("reflect.Value.Interface: cannot return value obtained from unexported field or method") } - if iv.kind == Interface { + + k := v.kind() + if k == Interface { // Special case: return the element inside the interface. - // Won't recurse further because an interface cannot contain an interface. - if iv.IsNil() { - return nil + // Empty interface has one layout, all interfaces with + // methods have a second layout. + if v.NumMethod() == 0 { + return *(*interface{})(v.val) } - return iv.Elem().Interface() + return *(*interface { + M() + })(v.val) } // Non-interface value. var eface emptyInterface - eface.typ = iv.typ.runtimeType() - eface.word = iv.word + eface.typ = v.typ.runtimeType() + eface.word = v.iword() return *(*interface{})(unsafe.Pointer(&eface)) } // InterfaceData returns the interface v's value as a uintptr pair. // It panics if v's Kind is not Interface. func (v Value) InterfaceData() [2]uintptr { - iv := v.internal() - iv.mustBe(Interface) + v.mustBe(Interface) // We treat this as a read operation, so we allow // it even for unexported data, because the caller // has to import "unsafe" to turn it into something // that can be abused. - return *(*[2]uintptr)(iv.addr) + // Interface value is always bigger than a word; assume flagIndir. + return *(*[2]uintptr)(v.val) } // IsNil returns true if v is a nil value. // It panics if v's Kind is not Chan, Func, Interface, Map, Ptr, or Slice. func (v Value) IsNil() bool { - return v.internal().IsNil() -} - -func (iv internalValue) IsNil() bool { - switch iv.kind { - case Ptr: - if iv.method { + k := v.kind() + switch k { + case Chan, Func, Map, Ptr: + if v.flag&flagMethod != 0 { panic("reflect: IsNil of method Value") } - return iv.word == 0 - case Chan, Func, Map: - if iv.method { - panic("reflect: IsNil of method Value") + ptr := v.val + if v.flag&flagIndir != 0 { + ptr = *(*unsafe.Pointer)(ptr) } - return *(*uintptr)(iv.addr) == 0 + return ptr == nil case Interface, Slice: // Both interface and slice are nil if first word is 0. - return *(*uintptr)(iv.addr) == 0 + // Both are always bigger than a word; assume flagIndir. + return *(*unsafe.Pointer)(v.val) == nil } - panic(&ValueError{"reflect.Value.IsNil", iv.kind}) + panic(&ValueError{"reflect.Value.IsNil", k}) } // IsValid returns true if v represents a value. @@ -953,32 +876,35 @@ func (iv internalValue) IsNil() bool { // Most functions and methods never return an invalid value. // If one does, its documentation states the conditions explicitly. func (v Value) IsValid() bool { - return v.Internal != nil + return v.flag != 0 } // Kind returns v's Kind. // If v is the zero Value (IsValid returns false), Kind returns Invalid. func (v Value) Kind() Kind { - return v.internal().kind + return v.kind() } // Len returns v's length. // It panics if v's Kind is not Array, Chan, Map, Slice, or String. func (v Value) Len() int { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Array: - return iv.typ.Len() + tt := (*arrayType)(unsafe.Pointer(v.typ)) + return int(tt.len) case Chan: - return int(chanlen(*(*iword)(iv.addr))) + return int(chanlen(*(*iword)(v.iword()))) case Map: - return int(maplen(*(*iword)(iv.addr))) + return int(maplen(*(*iword)(v.iword()))) case Slice: - return (*SliceHeader)(iv.addr).Len + // Slice is bigger than a word; assume flagIndir. + return (*SliceHeader)(v.val).Len case String: - return (*StringHeader)(iv.addr).Len + // String is bigger than a word; assume flagIndir. + return (*StringHeader)(v.val).Len } - panic(&ValueError{"reflect.Value.Len", iv.kind}) + panic(&ValueError{"reflect.Value.Len", k}) } // MapIndex returns the value associated with key in the map v. @@ -986,29 +912,29 @@ func (v Value) Len() int { // It returns the zero Value if key is not found in the map or if v represents a nil map. // As in Go, the key's value must be assignable to the map's key type. func (v Value) MapIndex(key Value) Value { - iv := v.internal() - iv.mustBe(Map) - typ := iv.typ.toType() + v.mustBe(Map) + tt := (*mapType)(unsafe.Pointer(v.typ)) - // Do not require ikey to be exported, so that DeepEqual + // Do not require key to be exported, so that DeepEqual // and other programs can use all the keys returned by // MapKeys as arguments to MapIndex. If either the map // or the key is unexported, though, the result will be - // considered unexported. - - ikey := key.internal() - ikey = convertForAssignment("reflect.Value.MapIndex", nil, typ.Key(), ikey) - if iv.word == 0 { - return Value{} - } + // considered unexported. This is consistent with the + // behavior for structs, which allow read but not write + // of unexported fields. + key = key.assignTo("reflect.Value.MapIndex", toCommonType(tt.key), nil) - flag := (iv.flag | ikey.flag) & flagRO - elemType := typ.Elem() - elemWord, ok := mapaccess(typ.runtimeType(), *(*iword)(iv.addr), ikey.word) + word, ok := mapaccess(v.typ.runtimeType(), *(*iword)(v.iword()), key.iword()) if !ok { return Value{} } - return valueFromIword(flag, elemType, elemWord) + typ := toCommonType(tt.elem) + fl := (v.flag | key.flag) & flagRO + if typ.Kind() != Ptr && typ.Kind() != UnsafePointer { + fl |= flagIndir + } + fl |= flag(typ.Kind()) << flagKindShift + return Value{typ, unsafe.Pointer(word), fl} } // MapKeys returns a slice containing all the keys present in the map, @@ -1016,17 +942,22 @@ func (v Value) MapIndex(key Value) Value { // It panics if v's Kind is not Map. // It returns an empty slice if v represents a nil map. func (v Value) MapKeys() []Value { - iv := v.internal() - iv.mustBe(Map) - keyType := iv.typ.Key() + v.mustBe(Map) + tt := (*mapType)(unsafe.Pointer(v.typ)) + keyType := toCommonType(tt.key) + + fl := v.flag & flagRO + fl |= flag(keyType.Kind()) << flagKindShift + if keyType.Kind() != Ptr && keyType.Kind() != UnsafePointer { + fl |= flagIndir + } - flag := iv.flag & flagRO - m := *(*iword)(iv.addr) + m := *(*iword)(v.iword()) mlen := int32(0) - if m != 0 { + if m != nil { mlen = maplen(m) } - it := mapiterinit(iv.typ.runtimeType(), m) + it := mapiterinit(v.typ.runtimeType(), m) a := make([]Value, mlen) var i int for i = 0; i < len(a); i++ { @@ -1034,7 +965,7 @@ func (v Value) MapKeys() []Value { if !ok { break } - a[i] = valueFromIword(flag, keyType, keyWord) + a[i] = Value{keyType, unsafe.Pointer(keyWord), fl} mapiternext(it) } return a[:i] @@ -1045,23 +976,27 @@ func (v Value) MapKeys() []Value { // a receiver; the returned function will always use v as the receiver. // Method panics if i is out of range. func (v Value) Method(i int) Value { - iv := v.internal() - if iv.kind == Invalid { + if v.typ == nil { panic(&ValueError{"reflect.Value.Method", Invalid}) } - if i < 0 || i >= iv.typ.NumMethod() { + if v.flag&flagMethod != 0 || i < 0 || i >= v.typ.NumMethod() { panic("reflect: Method index out of range") } - return Value{v.Internal, i + 1} + fl := v.flag & (flagRO | flagAddr | flagIndir) + fl |= flag(Func) << flagKindShift + fl |= flag(i)<<flagMethodShift | flagMethod + return Value{v.typ, v.val, fl} } // NumMethod returns the number of methods in the value's method set. func (v Value) NumMethod() int { - iv := v.internal() - if iv.kind == Invalid { + if v.typ == nil { panic(&ValueError{"reflect.Value.NumMethod", Invalid}) } - return iv.typ.NumMethod() + if v.flag&flagMethod != 0 { + return 0 + } + return v.typ.NumMethod() } // MethodByName returns a function value corresponding to the method @@ -1070,49 +1005,51 @@ func (v Value) NumMethod() int { // a receiver; the returned function will always use v as the receiver. // It returns the zero Value if no method was found. func (v Value) MethodByName(name string) Value { - iv := v.internal() - if iv.kind == Invalid { + if v.typ == nil { panic(&ValueError{"reflect.Value.MethodByName", Invalid}) } - m, ok := iv.typ.MethodByName(name) - if ok { - return Value{v.Internal, m.Index + 1} + if v.flag&flagMethod != 0 { + return Value{} } - return Value{} + m, ok := v.typ.MethodByName(name) + if !ok { + return Value{} + } + return v.Method(m.Index) } // NumField returns the number of fields in the struct v. // It panics if v's Kind is not Struct. func (v Value) NumField() int { - iv := v.internal() - iv.mustBe(Struct) - return iv.typ.NumField() + v.mustBe(Struct) + tt := (*structType)(unsafe.Pointer(v.typ)) + return len(tt.fields) } // OverflowComplex returns true if the complex128 x cannot be represented by v's type. // It panics if v's Kind is not Complex64 or Complex128. func (v Value) OverflowComplex(x complex128) bool { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Complex64: return overflowFloat32(real(x)) || overflowFloat32(imag(x)) case Complex128: return false } - panic(&ValueError{"reflect.Value.OverflowComplex", iv.kind}) + panic(&ValueError{"reflect.Value.OverflowComplex", k}) } // OverflowFloat returns true if the float64 x cannot be represented by v's type. // It panics if v's Kind is not Float32 or Float64. func (v Value) OverflowFloat(x float64) bool { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Float32: return overflowFloat32(x) case Float64: return false } - panic(&ValueError{"reflect.Value.OverflowFloat", iv.kind}) + panic(&ValueError{"reflect.Value.OverflowFloat", k}) } func overflowFloat32(x float64) bool { @@ -1125,27 +1062,27 @@ func overflowFloat32(x float64) bool { // OverflowInt returns true if the int64 x cannot be represented by v's type. // It panics if v's Kind is not Int, Int8, int16, Int32, or Int64. func (v Value) OverflowInt(x int64) bool { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Int, Int8, Int16, Int32, Int64: - bitSize := iv.typ.size * 8 + bitSize := v.typ.size * 8 trunc := (x << (64 - bitSize)) >> (64 - bitSize) return x != trunc } - panic(&ValueError{"reflect.Value.OverflowInt", iv.kind}) + panic(&ValueError{"reflect.Value.OverflowInt", k}) } // OverflowUint returns true if the uint64 x cannot be represented by v's type. // It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64. func (v Value) OverflowUint(x uint64) bool { - iv := v.internal() - switch iv.kind { + k := v.kind() + switch k { case Uint, Uintptr, Uint8, Uint16, Uint32, Uint64: - bitSize := iv.typ.size * 8 + bitSize := v.typ.size * 8 trunc := (x << (64 - bitSize)) >> (64 - bitSize) return x != trunc } - panic(&ValueError{"reflect.Value.OverflowUint", iv.kind}) + panic(&ValueError{"reflect.Value.OverflowUint", k}) } // Pointer returns v's value as a uintptr. @@ -1154,22 +1091,21 @@ func (v Value) OverflowUint(x uint64) bool { // without importing the unsafe package explicitly. // It panics if v's Kind is not Chan, Func, Map, Ptr, Slice, or UnsafePointer. func (v Value) Pointer() uintptr { - iv := v.internal() - switch iv.kind { - case Ptr, UnsafePointer: - if iv.kind == Func && v.InternalMethod != 0 { + k := v.kind() + switch k { + case Chan, Func, Map, Ptr, UnsafePointer: + if k == Func && v.flag&flagMethod != 0 { panic("reflect.Value.Pointer of method Value") } - return uintptr(iv.word) - case Chan, Func, Map: - if iv.kind == Func && v.InternalMethod != 0 { - panic("reflect.Value.Pointer of method Value") + p := v.val + if v.flag&flagIndir != 0 { + p = *(*unsafe.Pointer)(p) } - return *(*uintptr)(iv.addr) + return uintptr(p) case Slice: - return (*SliceHeader)(iv.addr).Data + return (*SliceHeader)(v.val).Data } - panic(&ValueError{"reflect.Value.Pointer", iv.kind}) + panic(&ValueError{"reflect.Value.Pointer", k}) } // Recv receives and returns a value from the channel v. @@ -1178,25 +1114,26 @@ func (v Value) Pointer() uintptr { // The boolean value ok is true if the value x corresponds to a send // on the channel, false if it is a zero value received because the channel is closed. func (v Value) Recv() (x Value, ok bool) { - iv := v.internal() - iv.mustBe(Chan) - iv.mustBeExported() - return iv.recv(false) + v.mustBe(Chan) + v.mustBeExported() + return v.recv(false) } -// internal recv, possibly non-blocking (nb) -func (iv internalValue) recv(nb bool) (val Value, ok bool) { - t := iv.typ.toType() - if t.ChanDir()&RecvDir == 0 { +// internal recv, possibly non-blocking (nb). +// v is known to be a channel. +func (v Value) recv(nb bool) (val Value, ok bool) { + tt := (*chanType)(unsafe.Pointer(v.typ)) + if ChanDir(tt.dir)&RecvDir == 0 { panic("recv on send-only channel") } - ch := *(*iword)(iv.addr) - if ch == 0 { - panic("recv on nil channel") - } - valWord, selected, ok := chanrecv(iv.typ.runtimeType(), ch, nb) + word, selected, ok := chanrecv(v.typ.runtimeType(), *(*iword)(v.iword()), nb) if selected { - val = valueFromIword(0, t.Elem(), valWord) + typ := toCommonType(tt.elem) + fl := flag(typ.Kind()) << flagKindShift + if typ.Kind() != Ptr && typ.Kind() != UnsafePointer { + fl |= flagIndir + } + val = Value{typ, unsafe.Pointer(word), fl} } return } @@ -1205,128 +1142,114 @@ func (iv internalValue) recv(nb bool) (val Value, ok bool) { // It panics if v's kind is not Chan or if x's type is not the same type as v's element type. // As in Go, x's value must be assignable to the channel's element type. func (v Value) Send(x Value) { - iv := v.internal() - iv.mustBe(Chan) - iv.mustBeExported() - iv.send(x, false) + v.mustBe(Chan) + v.mustBeExported() + v.send(x, false) } -// internal send, possibly non-blocking -func (iv internalValue) send(x Value, nb bool) (selected bool) { - t := iv.typ.toType() - if t.ChanDir()&SendDir == 0 { +// internal send, possibly non-blocking. +// v is known to be a channel. +func (v Value) send(x Value, nb bool) (selected bool) { + tt := (*chanType)(unsafe.Pointer(v.typ)) + if ChanDir(tt.dir)&SendDir == 0 { panic("send on recv-only channel") } - ix := x.internal() - ix.mustBeExported() // do not let unexported x leak - ix = convertForAssignment("reflect.Value.Send", nil, t.Elem(), ix) - ch := *(*iword)(iv.addr) - if ch == 0 { - panic("send on nil channel") - } - return chansend(iv.typ.runtimeType(), ch, ix.word, nb) + x.mustBeExported() + x = x.assignTo("reflect.Value.Send", toCommonType(tt.elem), nil) + return chansend(v.typ.runtimeType(), *(*iword)(v.iword()), x.iword(), nb) } // Set assigns x to the value v. // It panics if CanSet returns false. // As in Go, x's value must be assignable to v's type. func (v Value) Set(x Value) { - iv := v.internal() - ix := x.internal() - - iv.mustBeAssignable() - ix.mustBeExported() // do not let unexported x leak - - ix = convertForAssignment("reflect.Set", iv.addr, iv.typ, ix) - - n := ix.typ.size - if Kind(ix.typ.kind) == Ptr || Kind(ix.typ.kind) == UnsafePointer { - storeIword(iv.addr, ix.word, n) + v.mustBeAssignable() + x.mustBeExported() // do not let unexported x leak + var target *interface{} + if v.kind() == Interface { + target = (*interface{})(v.val) + } + x = x.assignTo("reflect.Set", v.typ, target) + if x.flag&flagIndir != 0 { + memmove(v.val, x.val, v.typ.size) } else { - memmove(iv.addr, ix.addr, n) + storeIword(v.val, iword(x.val), v.typ.size) } } // SetBool sets v's underlying value. // It panics if v's Kind is not Bool or if CanSet() is false. func (v Value) SetBool(x bool) { - iv := v.internal() - iv.mustBeAssignable() - iv.mustBe(Bool) - *(*bool)(iv.addr) = x + v.mustBeAssignable() + v.mustBe(Bool) + *(*bool)(v.val) = x } // SetBytes sets v's underlying value. // It panics if v's underlying value is not a slice of bytes. func (v Value) SetBytes(x []byte) { - iv := v.internal() - iv.mustBeAssignable() - iv.mustBe(Slice) - typ := iv.typ.toType() - if typ.Elem().Kind() != Uint8 { + v.mustBeAssignable() + v.mustBe(Slice) + if v.typ.Elem().Kind() != Uint8 { panic("reflect.Value.SetBytes of non-byte slice") } - *(*[]byte)(iv.addr) = x + *(*[]byte)(v.val) = x } // SetComplex sets v's underlying value to x. // It panics if v's Kind is not Complex64 or Complex128, or if CanSet() is false. func (v Value) SetComplex(x complex128) { - iv := v.internal() - iv.mustBeAssignable() - switch iv.kind { + v.mustBeAssignable() + switch k := v.kind(); k { default: - panic(&ValueError{"reflect.Value.SetComplex", iv.kind}) + panic(&ValueError{"reflect.Value.SetComplex", k}) case Complex64: - *(*complex64)(iv.addr) = complex64(x) + *(*complex64)(v.val) = complex64(x) case Complex128: - *(*complex128)(iv.addr) = x + *(*complex128)(v.val) = x } } // SetFloat sets v's underlying value to x. // It panics if v's Kind is not Float32 or Float64, or if CanSet() is false. func (v Value) SetFloat(x float64) { - iv := v.internal() - iv.mustBeAssignable() - switch iv.kind { + v.mustBeAssignable() + switch k := v.kind(); k { default: - panic(&ValueError{"reflect.Value.SetFloat", iv.kind}) + panic(&ValueError{"reflect.Value.SetFloat", k}) case Float32: - *(*float32)(iv.addr) = float32(x) + *(*float32)(v.val) = float32(x) case Float64: - *(*float64)(iv.addr) = x + *(*float64)(v.val) = x } } // SetInt sets v's underlying value to x. // It panics if v's Kind is not Int, Int8, Int16, Int32, or Int64, or if CanSet() is false. func (v Value) SetInt(x int64) { - iv := v.internal() - iv.mustBeAssignable() - switch iv.kind { + v.mustBeAssignable() + switch k := v.kind(); k { default: - panic(&ValueError{"reflect.Value.SetInt", iv.kind}) + panic(&ValueError{"reflect.Value.SetInt", k}) case Int: - *(*int)(iv.addr) = int(x) + *(*int)(v.val) = int(x) case Int8: - *(*int8)(iv.addr) = int8(x) + *(*int8)(v.val) = int8(x) case Int16: - *(*int16)(iv.addr) = int16(x) + *(*int16)(v.val) = int16(x) case Int32: - *(*int32)(iv.addr) = int32(x) + *(*int32)(v.val) = int32(x) case Int64: - *(*int64)(iv.addr) = x + *(*int64)(v.val) = x } } // SetLen sets v's length to n. // It panics if v's Kind is not Slice. func (v Value) SetLen(n int) { - iv := v.internal() - iv.mustBeAssignable() - iv.mustBe(Slice) - s := (*SliceHeader)(iv.addr) + v.mustBeAssignable() + v.mustBe(Slice) + s := (*SliceHeader)(v.val) if n < 0 || n > int(s.Cap) { panic("reflect: slice length out of range in SetLen") } @@ -1339,88 +1262,84 @@ func (v Value) SetLen(n int) { // As in Go, key's value must be assignable to the map's key type, // and val's value must be assignable to the map's value type. func (v Value) SetMapIndex(key, val Value) { - iv := v.internal() - ikey := key.internal() - ival := val.internal() - - iv.mustBe(Map) - iv.mustBeExported() - - ikey.mustBeExported() - ikey = convertForAssignment("reflect.Value.SetMapIndex", nil, iv.typ.Key(), ikey) - - if ival.kind != Invalid { - ival.mustBeExported() - ival = convertForAssignment("reflect.Value.SetMapIndex", nil, iv.typ.Elem(), ival) + v.mustBe(Map) + v.mustBeExported() + key.mustBeExported() + tt := (*mapType)(unsafe.Pointer(v.typ)) + key = key.assignTo("reflect.Value.SetMapIndex", toCommonType(tt.key), nil) + if val.typ != nil { + val.mustBeExported() + val = val.assignTo("reflect.Value.SetMapIndex", toCommonType(tt.elem), nil) } - - mapassign(iv.typ.runtimeType(), *(*iword)(iv.addr), ikey.word, ival.word, ival.kind != Invalid) + mapassign(v.typ.runtimeType(), *(*iword)(v.iword()), key.iword(), val.iword(), val.typ != nil) } // SetUint sets v's underlying value to x. // It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64, or if CanSet() is false. func (v Value) SetUint(x uint64) { - iv := v.internal() - iv.mustBeAssignable() - switch iv.kind { + v.mustBeAssignable() + switch k := v.kind(); k { default: - panic(&ValueError{"reflect.Value.SetUint", iv.kind}) + panic(&ValueError{"reflect.Value.SetUint", k}) case Uint: - *(*uint)(iv.addr) = uint(x) + *(*uint)(v.val) = uint(x) case Uint8: - *(*uint8)(iv.addr) = uint8(x) + *(*uint8)(v.val) = uint8(x) case Uint16: - *(*uint16)(iv.addr) = uint16(x) + *(*uint16)(v.val) = uint16(x) case Uint32: - *(*uint32)(iv.addr) = uint32(x) + *(*uint32)(v.val) = uint32(x) case Uint64: - *(*uint64)(iv.addr) = x + *(*uint64)(v.val) = x case Uintptr: - *(*uintptr)(iv.addr) = uintptr(x) + *(*uintptr)(v.val) = uintptr(x) } } // SetPointer sets the unsafe.Pointer value v to x. // It panics if v's Kind is not UnsafePointer. func (v Value) SetPointer(x unsafe.Pointer) { - iv := v.internal() - iv.mustBeAssignable() - iv.mustBe(UnsafePointer) - *(*unsafe.Pointer)(iv.addr) = x + v.mustBeAssignable() + v.mustBe(UnsafePointer) + *(*unsafe.Pointer)(v.val) = x } // SetString sets v's underlying value to x. // It panics if v's Kind is not String or if CanSet() is false. func (v Value) SetString(x string) { - iv := v.internal() - iv.mustBeAssignable() - iv.mustBe(String) - *(*string)(iv.addr) = x + v.mustBeAssignable() + v.mustBe(String) + *(*string)(v.val) = x } // Slice returns a slice of v. // It panics if v's Kind is not Array or Slice. func (v Value) Slice(beg, end int) Value { - iv := v.internal() - if iv.kind != Array && iv.kind != Slice { - panic(&ValueError{"reflect.Value.Slice", iv.kind}) - } - cap := v.Cap() - if beg < 0 || end < beg || end > cap { - panic("reflect.Value.Slice: slice index out of bounds") - } - var typ Type - var base uintptr - switch iv.kind { + var ( + cap int + typ *sliceType + base unsafe.Pointer + ) + switch k := v.kind(); k { + default: + panic(&ValueError{"reflect.Value.Slice", k}) case Array: - if iv.flag&flagAddr == 0 { + if v.flag&flagAddr == 0 { panic("reflect.Value.Slice: slice of unaddressable array") } - typ = toType((*arrayType)(unsafe.Pointer(iv.typ)).slice) - base = uintptr(iv.addr) + tt := (*arrayType)(unsafe.Pointer(v.typ)) + cap = int(tt.len) + typ = (*sliceType)(unsafe.Pointer(toCommonType(tt.slice))) + base = v.val case Slice: - typ = iv.typ.toType() - base = (*SliceHeader)(iv.addr).Data + typ = (*sliceType)(unsafe.Pointer(v.typ)) + s := (*SliceHeader)(v.val) + base = unsafe.Pointer(s.Data) + cap = s.Cap + + } + if beg < 0 || end < beg || end > cap { + panic("reflect.Value.Slice: slice index out of bounds") } // Declare slice so that gc can see the base pointer in it. @@ -1428,11 +1347,12 @@ func (v Value) Slice(beg, end int) Value { // Reinterpret as *SliceHeader to edit. s := (*SliceHeader)(unsafe.Pointer(&x)) - s.Data = base + uintptr(beg)*typ.Elem().Size() + s.Data = uintptr(base) + uintptr(beg)*toCommonType(typ.elem).Size() s.Len = end - beg s.Cap = end - beg - return valueFromAddr(iv.flag&flagRO, typ, unsafe.Pointer(&x)) + fl := v.flag&flagRO | flagIndir | flag(Slice)<<flagKindShift + return Value{typ.common(), unsafe.Pointer(&x), fl} } // String returns the string v's underlying value, as a string. @@ -1440,16 +1360,15 @@ func (v Value) Slice(beg, end int) Value { // Unlike the other getters, it does not panic if v's Kind is not String. // Instead, it returns a string of the form "<T value>" where T is v's type. func (v Value) String() string { - iv := v.internal() - switch iv.kind { + switch k := v.kind(); k { case Invalid: return "<invalid Value>" case String: - return *(*string)(iv.addr) + return *(*string)(v.val) } // If you call String on a reflect.Value of other type, it's better to // print something than to panic. Useful in debugging. - return "<" + iv.typ.String() + " Value>" + return "<" + v.typ.String() + " Value>" } // TryRecv attempts to receive a value from the channel v but will not block. @@ -1458,10 +1377,9 @@ func (v Value) String() string { // The boolean ok is true if the value x corresponds to a send // on the channel, false if it is a zero value received because the channel is closed. func (v Value) TryRecv() (x Value, ok bool) { - iv := v.internal() - iv.mustBe(Chan) - iv.mustBeExported() - return iv.recv(true) + v.mustBe(Chan) + v.mustBeExported() + return v.recv(true) } // TrySend attempts to send x on the channel v but will not block. @@ -1469,54 +1387,83 @@ func (v Value) TryRecv() (x Value, ok bool) { // It returns true if the value was sent, false otherwise. // As in Go, x's value must be assignable to the channel's element type. func (v Value) TrySend(x Value) bool { - iv := v.internal() - iv.mustBe(Chan) - iv.mustBeExported() - return iv.send(x, true) + v.mustBe(Chan) + v.mustBeExported() + return v.send(x, true) } // Type returns v's type. func (v Value) Type() Type { - t := v.internal().typ - if t == nil { + f := v.flag + if f == 0 { panic(&ValueError{"reflect.Value.Type", Invalid}) } - return t.toType() + if f&flagMethod == 0 { + // Easy case + return v.typ.toType() + } + + // Method value. + // v.typ describes the receiver, not the method type. + i := int(v.flag) >> flagMethodShift + if v.typ.Kind() == Interface { + // Method on interface. + tt := (*interfaceType)(unsafe.Pointer(v.typ)) + if i < 0 || i >= len(tt.methods) { + panic("reflect: broken Value") + } + m := &tt.methods[i] + return toCommonType(m.typ).toType() + } + // Method on concrete type. + ut := v.typ.uncommon() + if ut == nil || i < 0 || i >= len(ut.methods) { + panic("reflect: broken Value") + } + m := &ut.methods[i] + return toCommonType(m.mtyp).toType() } // Uint returns v's underlying value, as a uint64. // It panics if v's Kind is not Uint, Uintptr, Uint8, Uint16, Uint32, or Uint64. func (v Value) Uint() uint64 { - iv := v.internal() - switch iv.kind { + k := v.kind() + var p unsafe.Pointer + if v.flag&flagIndir != 0 { + p = v.val + } else { + // The escape analysis is good enough that &v.val + // does not trigger a heap allocation. + p = unsafe.Pointer(&v.val) + } + switch k { case Uint: - return uint64(*(*uint)(iv.addr)) + return uint64(*(*uint)(p)) case Uint8: - return uint64(*(*uint8)(iv.addr)) + return uint64(*(*uint8)(p)) case Uint16: - return uint64(*(*uint16)(iv.addr)) + return uint64(*(*uint16)(p)) case Uint32: - return uint64(*(*uint32)(iv.addr)) - case Uintptr: - return uint64(*(*uintptr)(iv.addr)) + return uint64(*(*uint32)(p)) case Uint64: - return *(*uint64)(iv.addr) + return uint64(*(*uint64)(p)) + case Uintptr: + return uint64(*(*uintptr)(p)) } - panic(&ValueError{"reflect.Value.Uint", iv.kind}) + panic(&ValueError{"reflect.Value.Uint", k}) } // UnsafeAddr returns a pointer to v's data. // It is for advanced clients that also import the "unsafe" package. // It panics if v is not addressable. func (v Value) UnsafeAddr() uintptr { - iv := v.internal() - if iv.kind == Invalid { - panic(&ValueError{"reflect.Value.UnsafeAddr", iv.kind}) + if v.typ == nil { + panic(&ValueError{"reflect.Value.UnsafeAddr", Invalid}) } - if iv.flag&flagAddr == 0 { + if v.flag&flagAddr == 0 { panic("reflect.Value.UnsafeAddr of unaddressable value") } - return uintptr(iv.addr) + return uintptr(v.val) } // StringHeader is the runtime representation of a string. @@ -1536,7 +1483,7 @@ type SliceHeader struct { func typesMustMatch(what string, t1, t2 Type) { if t1 != t2 { - panic("reflect: " + what + ": " + t1.String() + " != " + t2.String()) + panic(what + ": " + t1.String() + " != " + t2.String()) } } @@ -1571,7 +1518,7 @@ func grow(s Value, extra int) (Value, int, int) { // Append appends the values x to a slice s and returns the resulting slice. // As in Go, each x's value must be assignable to the slice's element type. func Append(s Value, x ...Value) Value { - s.internal().mustBe(Slice) + s.mustBe(Slice) s, i0, i1 := grow(s, len(x)) for i, j := i0, 0; i < i1; i, j = i+1, j+1 { s.Index(i).Set(x[j]) @@ -1582,8 +1529,8 @@ func Append(s Value, x ...Value) Value { // AppendSlice appends a slice t to a slice s and returns the resulting slice. // The slices s and t must have the same element type. func AppendSlice(s, t Value) Value { - s.internal().mustBe(Slice) - t.internal().mustBe(Slice) + s.mustBe(Slice) + t.mustBe(Slice) typesMustMatch("reflect.AppendSlice", s.Type().Elem(), t.Type().Elem()) s, i0, i1 := grow(s, t.Len()) Copy(s.Slice(i0, i1), t) @@ -1596,23 +1543,23 @@ func AppendSlice(s, t Value) Value { // Dst and src each must have kind Slice or Array, and // dst and src must have the same element type. func Copy(dst, src Value) int { - idst := dst.internal() - isrc := src.internal() - - if idst.kind != Array && idst.kind != Slice { - panic(&ValueError{"reflect.Copy", idst.kind}) + dk := dst.kind() + if dk != Array && dk != Slice { + panic(&ValueError{"reflect.Copy", dk}) } - if idst.kind == Array { - idst.mustBeAssignable() + if dk == Array { + dst.mustBeAssignable() } - idst.mustBeExported() - if isrc.kind != Array && isrc.kind != Slice { - panic(&ValueError{"reflect.Copy", isrc.kind}) + dst.mustBeExported() + + sk := src.kind() + if sk != Array && sk != Slice { + panic(&ValueError{"reflect.Copy", sk}) } - isrc.mustBeExported() + src.mustBeExported() - de := idst.typ.Elem() - se := isrc.typ.Elem() + de := dst.typ.Elem() + se := src.typ.Elem() typesMustMatch("reflect.Copy", de, se) n := dst.Len() @@ -1622,7 +1569,7 @@ func Copy(dst, src Value) int { // If sk is an in-line array, cannot take its address. // Instead, copy element by element. - if isrc.addr == nil { + if src.flag&flagIndir == 0 { for i := 0; i < n; i++ { dst.Index(i).Set(src.Index(i)) } @@ -1631,15 +1578,15 @@ func Copy(dst, src Value) int { // Copy via memmove. var da, sa unsafe.Pointer - if idst.kind == Array { - da = idst.addr + if dk == Array { + da = dst.val } else { - da = unsafe.Pointer((*SliceHeader)(idst.addr).Data) + da = unsafe.Pointer((*SliceHeader)(dst.val).Data) } - if isrc.kind == Array { - sa = isrc.addr + if sk == Array { + sa = src.val } else { - sa = unsafe.Pointer((*SliceHeader)(isrc.addr).Data) + sa = unsafe.Pointer((*SliceHeader)(src.val).Data) } memmove(da, sa, uintptr(n)*de.Size()) return n @@ -1653,7 +1600,7 @@ func Copy(dst, src Value) int { // for the specified slice type, length, and capacity. func MakeSlice(typ Type, len, cap int) Value { if typ.Kind() != Slice { - panic("reflect: MakeSlice of non-slice type") + panic("reflect.MakeSlice of non-slice type") } // Declare slice so that gc can see the base pointer in it. @@ -1665,31 +1612,31 @@ func MakeSlice(typ Type, len, cap int) Value { s.Len = len s.Cap = cap - return valueFromAddr(0, typ, unsafe.Pointer(&x)) + return Value{typ.common(), unsafe.Pointer(&x), flagIndir | flag(Slice)<<flagKindShift} } // MakeChan creates a new channel with the specified type and buffer size. func MakeChan(typ Type, buffer int) Value { if typ.Kind() != Chan { - panic("reflect: MakeChan of non-chan type") + panic("reflect.MakeChan of non-chan type") } if buffer < 0 { - panic("MakeChan: negative buffer size") + panic("reflect.MakeChan: negative buffer size") } if typ.ChanDir() != BothDir { - panic("MakeChan: unidirectional channel type") + panic("reflect.MakeChan: unidirectional channel type") } ch := makechan(typ.runtimeType(), uint32(buffer)) - return valueFromIword(0, typ, ch) + return Value{typ.common(), unsafe.Pointer(ch), flagIndir | (flag(Chan)<<flagKindShift)} } // MakeMap creates a new map of the specified type. func MakeMap(typ Type) Value { if typ.Kind() != Map { - panic("reflect: MakeMap of non-map type") + panic("reflect.MakeMap of non-map type") } m := makemap(typ.runtimeType()) - return valueFromIword(0, typ, m) + return Value{typ.common(), unsafe.Pointer(m), flagIndir | (flag(Map)<<flagKindShift)} } // Indirect returns the value that v points to. @@ -1719,7 +1666,12 @@ func ValueOf(i interface{}) Value { // For an interface value with the noAddr bit set, // the representation is identical to an empty interface. eface := *(*emptyInterface)(unsafe.Pointer(&i)) - return packValue(0, eface.typ, eface.word) + typ := toCommonType(eface.typ) + fl := flag(typ.Kind()) << flagKindShift + if typ.Kind() != Ptr && typ.Kind() != UnsafePointer { + fl |= flagIndir + } + return Value{typ, unsafe.Pointer(eface.word), fl} } // Zero returns a Value representing a zero value for the specified type. @@ -1730,10 +1682,12 @@ func Zero(typ Type) Value { if typ == nil { panic("reflect: Zero(nil)") } - if typ.Kind() == Ptr || typ.Kind() == UnsafePointer { - return valueFromIword(0, typ, 0) + t := typ.common() + fl := flag(t.Kind()) << flagKindShift + if t.Kind() == Ptr || t.Kind() == UnsafePointer { + return Value{t, nil, fl} } - return valueFromAddr(0, typ, unsafe.New(typ)) + return Value{t, unsafe.New(typ), fl | flagIndir} } // New returns a Value representing a pointer to a new zero value @@ -1743,40 +1697,42 @@ func New(typ Type) Value { panic("reflect: New(nil)") } ptr := unsafe.New(typ) - return valueFromIword(0, PtrTo(typ), iword(uintptr(ptr))) + fl := flag(Ptr) << flagKindShift + return Value{typ.common().ptrTo(), ptr, fl} } -// convertForAssignment -func convertForAssignment(what string, addr unsafe.Pointer, dst Type, iv internalValue) internalValue { - if iv.method { - panic(what + ": cannot assign method value to type " + dst.String()) +// assignTo returns a value v that can be assigned directly to typ. +// It panics if v is not assignable to typ. +// For a conversion to an interface type, target is a suggested scratch space to use. +func (v Value) assignTo(context string, dst *commonType, target *interface{}) Value { + if v.flag&flagMethod != 0 { + panic(context + ": cannot assign method value to type " + dst.String()) } - dst1 := dst.(*commonType) - if directlyAssignable(dst1, iv.typ) { + switch { + case directlyAssignable(dst, v.typ): // Overwrite type so that they match. // Same memory layout, so no harm done. - iv.typ = dst1 - return iv - } - if implements(dst1, iv.typ) { - if addr == nil { - addr = unsafe.Pointer(new(interface{})) + v.typ = dst + fl := v.flag & (flagRO | flagAddr | flagIndir) + fl |= flag(dst.Kind()) << flagKindShift + return Value{dst, v.val, fl} + + case implements(dst, v.typ): + if target == nil { + target = new(interface{}) } - x := iv.valueInterface(false) + x := valueInterface(v, false) if dst.NumMethod() == 0 { - *(*interface{})(addr) = x + *target = x } else { - ifaceE2I(dst1.runtimeType(), x, addr) + ifaceE2I(dst.runtimeType(), x, unsafe.Pointer(target)) } - iv.addr = addr - iv.word = iword(uintptr(addr)) - iv.typ = dst1 - return iv + return Value{dst, unsafe.Pointer(target), flagIndir | flag(Interface)<<flagKindShift} } // Failed. - panic(what + ": value of type " + iv.typ.String() + " is not assignable to type " + dst.String()) + panic(context + ": value of type " + v.typ.String() + " is not assignable to type " + dst.String()) } // implemented in ../pkg/runtime @@ -1787,7 +1743,7 @@ func chanrecv(t *runtime.Type, ch iword, nb bool) (val iword, selected, received func chansend(t *runtime.Type, ch iword, val iword, nb bool) bool func makechan(typ *runtime.Type, size uint32) (ch iword) -func makemap(t *runtime.Type) iword +func makemap(t *runtime.Type) (m iword) func mapaccess(t *runtime.Type, m iword, key iword) (val iword, ok bool) func mapassign(t *runtime.Type, m iword, key, val iword, ok bool) func mapiterinit(t *runtime.Type, m iword) *byte @@ -1797,3 +1753,17 @@ func maplen(m iword) int32 func call(typ *commonType, fnaddr unsafe.Pointer, isInterface bool, isMethod bool, params *unsafe.Pointer, results *unsafe.Pointer) func ifaceE2I(t *runtime.Type, src interface{}, dst unsafe.Pointer) + +// Dummy annotation marking that the value x escapes, +// for use in cases where the reflect code is so clever that +// the compiler cannot follow. +func escapes(x interface{}) { + if dummy.b { + dummy.x = x + } +} + +var dummy struct { + b bool + x interface{} +} |