| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package reflect |
| |
| import ( |
| "math" |
| "runtime" |
| "strconv" |
| "unsafe" |
| ) |
| |
| const ptrSize = unsafe.Sizeof((*byte)(nil)) |
| const cannotSet = "cannot set value obtained from unexported struct field" |
| |
| // TODO: This will have to go away when |
| // the new gc goes in. |
| func memmove(adst, asrc unsafe.Pointer, n uintptr) { |
| dst := uintptr(adst) |
| src := uintptr(asrc) |
| switch { |
| case src < dst && src+n > dst: |
| // byte copy backward |
| // careful: i is unsigned |
| for i := n; i > 0; { |
| i-- |
| *(*byte)(unsafe.Pointer(dst + i)) = *(*byte)(unsafe.Pointer(src + i)) |
| } |
| case (n|src|dst)&(ptrSize-1) != 0: |
| // byte copy forward |
| for i := uintptr(0); i < n; i++ { |
| *(*byte)(unsafe.Pointer(dst + i)) = *(*byte)(unsafe.Pointer(src + i)) |
| } |
| default: |
| // word copy forward |
| for i := uintptr(0); i < n; i += ptrSize { |
| *(*uintptr)(unsafe.Pointer(dst + i)) = *(*uintptr)(unsafe.Pointer(src + i)) |
| } |
| } |
| } |
| |
| // Value is the reflection interface to a Go value. |
| // |
| // Not all methods apply to all kinds of values. Restrictions, |
| // if any, are noted in the documentation for each method. |
| // Use the Kind method to find out the kind of value before |
| // calling kind-specific methods. Calling a method |
| // inappropriate to the kind of type causes a run time panic. |
| // |
| // The zero Value represents no value. |
| // Its IsValid method returns false, its Kind method returns Invalid, |
| // 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 |
| } |
| |
| // A ValueError occurs when a Value method is invoked on |
| // a Value that does not support it. Such cases are documented |
| // in the description of each method. |
| type ValueError struct { |
| Method string |
| Kind Kind |
| } |
| |
| func (e *ValueError) String() string { |
| if e.Kind == 0 { |
| return "reflect: call of " + e.Method + " on zero Value" |
| } |
| return "reflect: call of " + e.Method + " on " + e.Kind.String() + " Value" |
| } |
| |
| // methodName returns the name of the calling method, |
| // assumed to be two stack frames above. |
| func methodName() string { |
| pc, _, _, _ := runtime.Caller(2) |
| f := runtime.FuncForPC(pc) |
| if f == nil { |
| return "unknown method" |
| } |
| return f.Name() |
| } |
| |
| // 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 |
| |
| func loadIword(p unsafe.Pointer, size uintptr) iword { |
| // Run the copy ourselves instead of calling memmove |
| // to avoid moving v to the heap. |
| w := iword(0) |
| switch size { |
| default: |
| panic("reflect: internal error: loadIword of " + strconv.Itoa(int(size)) + "-byte value") |
| case 0: |
| case 1: |
| *(*uint8)(unsafe.Pointer(&w)) = *(*uint8)(p) |
| case 2: |
| *(*uint16)(unsafe.Pointer(&w)) = *(*uint16)(p) |
| case 3: |
| *(*[3]byte)(unsafe.Pointer(&w)) = *(*[3]byte)(p) |
| case 4: |
| *(*uint32)(unsafe.Pointer(&w)) = *(*uint32)(p) |
| case 5: |
| *(*[5]byte)(unsafe.Pointer(&w)) = *(*[5]byte)(p) |
| case 6: |
| *(*[6]byte)(unsafe.Pointer(&w)) = *(*[6]byte)(p) |
| case 7: |
| *(*[7]byte)(unsafe.Pointer(&w)) = *(*[7]byte)(p) |
| case 8: |
| *(*uint64)(unsafe.Pointer(&w)) = *(*uint64)(p) |
| } |
| return w |
| } |
| |
| func storeIword(p unsafe.Pointer, w iword, size uintptr) { |
| // Run the copy ourselves instead of calling memmove |
| // to avoid moving v to the heap. |
| switch size { |
| default: |
| panic("reflect: internal error: storeIword of " + strconv.Itoa(int(size)) + "-byte value") |
| case 0: |
| case 1: |
| *(*uint8)(p) = *(*uint8)(unsafe.Pointer(&w)) |
| case 2: |
| *(*uint16)(p) = *(*uint16)(unsafe.Pointer(&w)) |
| case 3: |
| *(*[3]byte)(p) = *(*[3]byte)(unsafe.Pointer(&w)) |
| case 4: |
| *(*uint32)(p) = *(*uint32)(unsafe.Pointer(&w)) |
| case 5: |
| *(*[5]byte)(p) = *(*[5]byte)(unsafe.Pointer(&w)) |
| case 6: |
| *(*[6]byte)(p) = *(*[6]byte)(unsafe.Pointer(&w)) |
| case 7: |
| *(*[7]byte)(p) = *(*[7]byte)(unsafe.Pointer(&w)) |
| case 8: |
| *(*uint64)(p) = *(*uint64)(unsafe.Pointer(&w)) |
| } |
| } |
| |
| // emptyInterface is the header for an interface{} value. |
| type emptyInterface struct { |
| typ *runtime.Type |
| word iword |
| } |
| |
| // nonEmptyInterface is the header for a interface value with methods. |
| type nonEmptyInterface struct { |
| // see ../runtime/iface.c:/Itab |
| itab *struct { |
| ityp *runtime.Type // static interface type |
| typ *runtime.Type // dynamic concrete type |
| link unsafe.Pointer |
| bad int32 |
| unused int32 |
| fun [100000]unsafe.Pointer // method table |
| } |
| 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(iv.word) |
| iv.typ = iv.typ.Elem().common() |
| if iv.typ.size <= ptrSize { |
| iv.word = loadIword(iv.addr, iv.typ.size) |
| } |
| } else { |
| if iv.typ.size > ptrSize { |
| iv.addr = unsafe.Pointer(iv.word) |
| } |
| } |
| 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(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(m.ifn) |
| } |
| iv.kind = Func |
| iv.method = true |
| iv.flag &^= flagAddr |
| iv.addr = nil |
| } |
| |
| 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") |
| } |
| t := uintptr(unsafe.Pointer(typ)) |
| t |= uintptr(flag) |
| eface := emptyInterface{(*runtime.Type)(unsafe.Pointer(t)), word} |
| return Value{Internal: *(*interface{})(unsafe.Pointer(&eface))} |
| } |
| |
| // valueFromAddr returns a Value using the given type and address. |
| func valueFromAddr(flag uint32, typ Type, addr unsafe.Pointer) Value { |
| 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(addr)) |
| } |
| |
| var w iword |
| if n := typ.Size(); n <= ptrSize { |
| // In line, so the interface word is the actual value. |
| w = loadIword(addr, n) |
| } else { |
| // Not in line: the interface word is the address. |
| w = iword(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 { |
| panic(methodName() + " using value obtained using unexported field") |
| } |
| } |
| |
| func (iv internalValue) mustBeAssignable() { |
| if iv.kind == 0 { |
| panic(&ValueError{methodName(), iv.kind}) |
| } |
| // Assignable if addressable and not read-only. |
| if iv.flag&flagRO != 0 { |
| panic(methodName() + " using value obtained using unexported field") |
| } |
| if iv.flag&flagAddr == 0 { |
| panic(methodName() + " using unaddressable value") |
| } |
| } |
| |
| // Addr returns a pointer value representing the address of v. |
| // It panics if CanAddr() returns false. |
| // Addr is typically used to obtain a pointer to a struct field |
| // 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 { |
| panic("reflect.Value.Addr of unaddressable value") |
| } |
| return valueFromIword(iv.flag&flagRO, PtrTo(iv.typ.toType()), iword(iv.addr)) |
| } |
| |
| // 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.word)) |
| } |
| |
| // CanAddr returns true if the value's address can be obtained with Addr. |
| // Such values are called addressable. A value is addressable if it is |
| // an element of a slice, an element of an addressable array, |
| // 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 |
| } |
| |
| // CanSet returns true if the value of v can be changed. |
| // A Value can be changed only if it is addressable and was not |
| // obtained by the use of unexported struct fields. |
| // 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 |
| } |
| |
| // Call calls the function v with the input arguments in. |
| // For example, if len(in) == 3, v.Call(in) represents the Go call v(in[0], in[1], in[2]). |
| // Call panics if v's Kind is not Func. |
| // It returns the output results as Values. |
| // As in Go, each input argument must be assignable to the |
| // type of the function's corresponding input parameter. |
| // 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) |
| } |
| |
| // CallSlice calls the variadic function v with the input arguments in, |
| // assigning the slice in[len(in)-1] to v's final variadic argument. |
| // For example, if len(in) == 3, v.Call(in) represents the Go call v(in[0], in[1], in[2]...). |
| // Call panics if v's Kind is not Func or if v is not variadic. |
| // It returns the output results as Values. |
| // 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") |
| } |
| panic("reflect.Value.Call: call of nil function") |
| } |
| |
| isSlice := method == "CallSlice" |
| t := iv.typ |
| n := t.NumIn() |
| if isSlice { |
| if !t.IsVariadic() { |
| panic("reflect: CallSlice of non-variadic function") |
| } |
| if len(in) < n { |
| panic("reflect: CallSlice with too few input arguments") |
| } |
| if len(in) > n { |
| panic("reflect: CallSlice with too many input arguments") |
| } |
| } else { |
| if t.IsVariadic() { |
| n-- |
| } |
| if len(in) < n { |
| panic("reflect: Call with too few input arguments") |
| } |
| if !t.IsVariadic() && len(in) > n { |
| panic("reflect: Call with too many input arguments") |
| } |
| } |
| for _, x := range in { |
| if x.Kind() == Invalid { |
| panic("reflect: " + method + " using zero Value argument") |
| } |
| } |
| for i := 0; i < n; i++ { |
| if xt, targ := in[i].Type(), t.In(i); !xt.AssignableTo(targ) { |
| panic("reflect: " + method + " using " + xt.String() + " as type " + targ.String()) |
| } |
| } |
| if !isSlice && t.IsVariadic() { |
| // prepare slice for remaining values |
| m := len(in) - n |
| slice := MakeSlice(t.In(n), m, m) |
| elem := t.In(n).Elem() |
| for i := 0; i < m; i++ { |
| x := in[n+i] |
| if xt := x.Type(); !xt.AssignableTo(elem) { |
| panic("reflect: cannot use " + xt.String() + " as type " + elem.String() + " in " + method) |
| } |
| slice.Index(i).Set(x) |
| } |
| origIn := in |
| in = make([]Value, n+1) |
| copy(in[:n], origIn) |
| in[n] = slice |
| } |
| |
| nin := len(in) |
| if nin != t.NumIn() { |
| panic("reflect.Value.Call: wrong argument count") |
| } |
| nout := t.NumOut() |
| |
| // Compute arg size & allocate. |
| // This computation is 5g/6g/8g-dependent |
| // and probably wrong for gccgo, but so |
| // is most of this function. |
| size := uintptr(0) |
| if iv.method { |
| // extra word for interface value |
| size += ptrSize |
| } |
| for i := 0; i < nin; i++ { |
| tv := t.In(i) |
| a := uintptr(tv.Align()) |
| size = (size + a - 1) &^ (a - 1) |
| size += tv.Size() |
| } |
| size = (size + ptrSize - 1) &^ (ptrSize - 1) |
| for i := 0; i < nout; i++ { |
| tv := t.Out(i) |
| a := uintptr(tv.Align()) |
| size = (size + a - 1) &^ (a - 1) |
| size += tv.Size() |
| } |
| |
| // size must be > 0 in order for &args[0] to be valid. |
| // the argument copying is going to round it up to |
| // a multiple of ptrSize anyway, so make it ptrSize to begin with. |
| if size < ptrSize { |
| size = ptrSize |
| } |
| |
| // round to pointer size |
| size = (size + ptrSize - 1) &^ (ptrSize - 1) |
| |
| // Copy into args. |
| // |
| // TODO(rsc): revisit when reference counting happens. |
| // The values are holding up the in references for us, |
| // but something must be done for the out references. |
| // For now make everything look like a pointer by pretending |
| // to allocate a []*int. |
| args := make([]*int, size/ptrSize) |
| ptr := uintptr(unsafe.Pointer(&args[0])) |
| off := uintptr(0) |
| if iv.method { |
| // Hard-wired first argument. |
| *(*iword)(unsafe.Pointer(ptr)) = iv.rcvr |
| off = ptrSize |
| } |
| for i, v := range in { |
| iv := v.internal() |
| iv.mustBeExported() |
| targ := t.In(i).(*commonType) |
| a := uintptr(targ.align) |
| off = (off + a - 1) &^ (a - 1) |
| n := targ.size |
| addr := unsafe.Pointer(ptr + off) |
| iv = convertForAssignment("reflect.Value.Call", addr, targ, iv) |
| if iv.addr == nil { |
| storeIword(addr, iv.word, n) |
| } else { |
| memmove(addr, iv.addr, n) |
| } |
| off += n |
| } |
| off = (off + ptrSize - 1) &^ (ptrSize - 1) |
| |
| // Call. |
| call(unsafe.Pointer(iv.word), unsafe.Pointer(ptr), uint32(size)) |
| |
| // Copy return values out of args. |
| // |
| // TODO(rsc): revisit like above. |
| ret := make([]Value, nout) |
| for i := 0; i < nout; i++ { |
| tv := t.Out(i) |
| a := uintptr(tv.Align()) |
| off = (off + a - 1) &^ (a - 1) |
| ret[i] = valueFromAddr(0, tv, unsafe.Pointer(ptr+off)) |
| off += tv.Size() |
| } |
| |
| return ret |
| } |
| |
| // 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 { |
| case Array: |
| return iv.typ.Len() |
| case Chan: |
| return int(chancap(iv.word)) |
| case Slice: |
| return (*SliceHeader)(iv.addr).Cap |
| } |
| panic(&ValueError{"reflect.Value.Cap", iv.kind}) |
| } |
| |
| // 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 := iv.word |
| chanclose(ch) |
| } |
| |
| // 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 { |
| case Complex64: |
| if iv.addr == nil { |
| return complex128(*(*complex64)(unsafe.Pointer(&iv.word))) |
| } |
| return complex128(*(*complex64)(iv.addr)) |
| case Complex128: |
| return *(*complex128)(iv.addr) |
| } |
| panic(&ValueError{"reflect.Value.Complex", iv.kind}) |
| } |
| |
| // Elem returns the value that the interface v contains |
| // or that the pointer v points to. |
| // It panics if v's Kind is not Interface or Ptr. |
| // It returns the zero Value if v is nil. |
| func (v Value) Elem() Value { |
| iv := v.internal() |
| return iv.Elem() |
| } |
| |
| func (iv internalValue) Elem() Value { |
| switch iv.kind { |
| 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) |
| } else { |
| iface := (*nonEmptyInterface)(iv.addr) |
| if iface.itab != nil { |
| eface.typ = iface.itab.typ |
| } |
| eface.word = iface.word |
| } |
| if eface.typ == nil { |
| return Value{} |
| } |
| return valueFromIword(iv.flag&flagRO, toType(eface.typ), eface.word) |
| |
| case Ptr: |
| // The returned value's address is v's value. |
| if iv.word == 0 { |
| return Value{} |
| } |
| return valueFromAddr(iv.flag&flagRO|flagAddr, iv.typ.Elem(), unsafe.Pointer(iv.word)) |
| } |
| panic(&ValueError{"reflect.Value.Elem", iv.kind}) |
| } |
| |
| // 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() { |
| panic("reflect: Field index out of range") |
| } |
| f := t.Field(i) |
| |
| // Inherit permission bits from v. |
| flag := iv.flag |
| // Using an unexported field forces flagRO. |
| if f.PkgPath != "" { |
| flag |= flagRO |
| } |
| return valueFromValueOffset(flag, f.Type, iv, f.Offset) |
| } |
| |
| // 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)) |
| } |
| |
| // 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) |
| } |
| |
| // 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) |
| for i, x := range index { |
| if i > 0 { |
| if v.Kind() == Ptr && v.Elem().Kind() == Struct { |
| v = v.Elem() |
| } |
| } |
| v = v.Field(x) |
| } |
| return v |
| } |
| |
| // FieldByName returns the struct field with the given name. |
| // It returns the zero Value if no field was found. |
| // It panics if v's Kind is not struct. |
| func (v Value) FieldByName(name string) Value { |
| iv := v.internal() |
| iv.mustBe(Struct) |
| if f, ok := iv.typ.FieldByName(name); ok { |
| return v.FieldByIndex(f.Index) |
| } |
| return Value{} |
| } |
| |
| // FieldByNameFunc returns the struct field with a name |
| // that satisfies the match function. |
| // It panics if v's Kind is not struct. |
| // It returns the zero Value if no field was found. |
| func (v Value) FieldByNameFunc(match func(string) bool) Value { |
| v.internal().mustBe(Struct) |
| if f, ok := v.Type().FieldByNameFunc(match); ok { |
| return v.FieldByIndex(f.Index) |
| } |
| return 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 { |
| case Float32: |
| return float64(*(*float32)(unsafe.Pointer(&iv.word))) |
| case Float64: |
| // If the pointer width can fit an entire float64, |
| // the value is in line when stored in an interface. |
| if iv.addr == nil { |
| return *(*float64)(unsafe.Pointer(&iv.word)) |
| } |
| // Otherwise we have a pointer. |
| return *(*float64)(iv.addr) |
| } |
| panic(&ValueError{"reflect.Value.Float", iv.kind}) |
| } |
| |
| // 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}) |
| case Array: |
| flag := iv.flag // element flag same as overall array |
| t := iv.typ.toType() |
| if i < 0 || i > t.Len() { |
| panic("reflect: array index out of range") |
| } |
| typ := t.Elem() |
| return valueFromValueOffset(flag, typ, iv, uintptr(i)*typ.Size()) |
| |
| case Slice: |
| // Element flag same as Elem of Ptr. |
| // Addressable, possibly read-only. |
| flag := iv.flag&flagRO | flagAddr |
| s := (*SliceHeader)(iv.addr) |
| 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) |
| } |
| |
| panic("not reached") |
| } |
| |
| // 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 { |
| case Int: |
| return int64(*(*int)(unsafe.Pointer(&iv.word))) |
| case Int8: |
| return int64(*(*int8)(unsafe.Pointer(&iv.word))) |
| case Int16: |
| return int64(*(*int16)(unsafe.Pointer(&iv.word))) |
| case Int32: |
| return int64(*(*int32)(unsafe.Pointer(&iv.word))) |
| case Int64: |
| if iv.addr == nil { |
| return *(*int64)(unsafe.Pointer(&iv.word)) |
| } |
| return *(*int64)(iv.addr) |
| } |
| panic(&ValueError{"reflect.Value.Int", iv.kind}) |
| } |
| |
| // 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}) |
| } |
| return v.InternalMethod == 0 && iv.flag&flagRO == 0 |
| } |
| |
| // Interface returns v's value as an interface{}. |
| // If v is a method obtained by invoking Value.Method |
| // (as opposed to Type.Method), Interface cannot return an |
| // interface value, so it panics. |
| func (v Value) Interface() interface{} { |
| return valueInterface(v, true) |
| } |
| |
| 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 iv.method { |
| panic("reflect.Value.Interface: cannot create interface value for method with bound receiver") |
| } |
| |
| if safe && iv.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 { |
| // Special case: return the element inside the interface. |
| // Won't recurse further because an interface cannot contain an interface. |
| if iv.IsNil() { |
| return nil |
| } |
| return iv.Elem().Interface() |
| } |
| |
| // Non-interface value. |
| var eface emptyInterface |
| eface.typ = iv.typ.runtimeType() |
| eface.word = iv.word |
| 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) |
| // 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) |
| } |
| |
| // 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 Chan, Func, Map, Ptr: |
| if iv.method { |
| panic("reflect: IsNil of method Value") |
| } |
| return iv.word == 0 |
| case Interface, Slice: |
| // Both interface and slice are nil if first word is 0. |
| return *(*uintptr)(iv.addr) == 0 |
| } |
| panic(&ValueError{"reflect.Value.IsNil", iv.kind}) |
| } |
| |
| // IsValid returns true if v represents a value. |
| // It returns false if v is the zero Value. |
| // If IsValid returns false, all other methods except String panic. |
| // Most functions and methods never return an invalid value. |
| // If one does, its documentation states the conditions explicitly. |
| func (v Value) IsValid() bool { |
| return v.Internal != nil |
| } |
| |
| // 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 |
| } |
| |
| // 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 { |
| case Array: |
| return iv.typ.Len() |
| case Chan: |
| return int(chanlen(iv.word)) |
| case Map: |
| return int(maplen(iv.word)) |
| case Slice: |
| return (*SliceHeader)(iv.addr).Len |
| case String: |
| return (*StringHeader)(iv.addr).Len |
| } |
| panic(&ValueError{"reflect.Value.Len", iv.kind}) |
| } |
| |
| // MapIndex returns the value associated with key in the map v. |
| // It panics if v's Kind is not Map. |
| // It returns the zero Value if key is not found in the map or if v represents a nil map. |
| // As in Go, the key's value must be assignable to the map's key type. |
| func (v Value) MapIndex(key Value) Value { |
| iv := v.internal() |
| iv.mustBe(Map) |
| typ := iv.typ.toType() |
| |
| // Do not require ikey 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{} |
| } |
| |
| flag := (iv.flag | ikey.flag) & flagRO |
| elemType := typ.Elem() |
| elemWord, ok := mapaccess(typ.runtimeType(), iv.word, ikey.word) |
| if !ok { |
| return Value{} |
| } |
| return valueFromIword(flag, elemType, elemWord) |
| } |
| |
| // MapKeys returns a slice containing all the keys present in the map, |
| // in unspecified order. |
| // It panics if v's Kind is not Map. |
| // It returns an empty slice if v represents a nil map. |
| func (v Value) MapKeys() []Value { |
| iv := v.internal() |
| iv.mustBe(Map) |
| keyType := iv.typ.Key() |
| |
| flag := iv.flag & flagRO |
| m := iv.word |
| mlen := int32(0) |
| if m != 0 { |
| mlen = maplen(m) |
| } |
| it := mapiterinit(iv.typ.runtimeType(), m) |
| a := make([]Value, mlen) |
| var i int |
| for i = 0; i < len(a); i++ { |
| keyWord, ok := mapiterkey(it) |
| if !ok { |
| break |
| } |
| a[i] = valueFromIword(flag, keyType, keyWord) |
| mapiternext(it) |
| } |
| return a[:i] |
| } |
| |
| // Method returns a function value corresponding to v's i'th method. |
| // The arguments to a Call on the returned function should not include |
| // a receiver; the returned function will always use v as the receiver. |
| // Method panics if i is out of range. |
| func (v Value) Method(i int) Value { |
| iv := v.internal() |
| if iv.kind == Invalid { |
| panic(&ValueError{"reflect.Value.Method", Invalid}) |
| } |
| if i < 0 || i >= iv.typ.NumMethod() { |
| panic("reflect: Method index out of range") |
| } |
| return Value{v.Internal, i + 1} |
| } |
| |
| // NumMethod returns the number of methods in the value's method set. |
| func (v Value) NumMethod() int { |
| iv := v.internal() |
| if iv.kind == Invalid { |
| panic(&ValueError{"reflect.Value.NumMethod", Invalid}) |
| } |
| return iv.typ.NumMethod() |
| } |
| |
| // MethodByName returns a function value corresponding to the method |
| // of v with the given name. |
| // The arguments to a Call on the returned function should not include |
| // a receiver; the returned function will always use v as the receiver. |
| // It returns the zero Value if no method was found. |
| func (v Value) MethodByName(name string) Value { |
| iv := v.internal() |
| if iv.kind == Invalid { |
| panic(&ValueError{"reflect.Value.MethodByName", Invalid}) |
| } |
| m, ok := iv.typ.MethodByName(name) |
| if ok { |
| return Value{v.Internal, m.Index + 1} |
| } |
| return Value{} |
| } |
| |
| // 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() |
| } |
| |
| // 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 { |
| case Complex64: |
| return overflowFloat32(real(x)) || overflowFloat32(imag(x)) |
| case Complex128: |
| return false |
| } |
| panic(&ValueError{"reflect.Value.OverflowComplex", iv.kind}) |
| } |
| |
| // 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 { |
| case Float32: |
| return overflowFloat32(x) |
| case Float64: |
| return false |
| } |
| panic(&ValueError{"reflect.Value.OverflowFloat", iv.kind}) |
| } |
| |
| func overflowFloat32(x float64) bool { |
| if x < 0 { |
| x = -x |
| } |
| return math.MaxFloat32 <= x && x <= math.MaxFloat64 |
| } |
| |
| // OverflowInt returns true if the int64 x cannot be represented by v's type. |
| // It panics if v's Kind is not Int, Int8, int16, Int32, or Int64. |
| func (v Value) OverflowInt(x int64) bool { |
| iv := v.internal() |
| switch iv.kind { |
| case Int, Int8, Int16, Int32, Int64: |
| bitSize := iv.typ.size * 8 |
| trunc := (x << (64 - bitSize)) >> (64 - bitSize) |
| return x != trunc |
| } |
| panic(&ValueError{"reflect.Value.OverflowInt", iv.kind}) |
| } |
| |
| // 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 { |
| case Uint, Uintptr, Uint8, Uint16, Uint32, Uint64: |
| bitSize := iv.typ.size * 8 |
| trunc := (x << (64 - bitSize)) >> (64 - bitSize) |
| return x != trunc |
| } |
| panic(&ValueError{"reflect.Value.OverflowUint", iv.kind}) |
| } |
| |
| // Pointer returns v's value as a uintptr. |
| // It returns uintptr instead of unsafe.Pointer so that |
| // code using reflect cannot obtain unsafe.Pointers |
| // without importing the unsafe package explicitly. |
| // It panics if v's Kind is not Chan, Func, Map, Ptr, Slice, or UnsafePointer. |
| func (v Value) Pointer() uintptr { |
| iv := v.internal() |
| switch iv.kind { |
| case Chan, Func, Map, Ptr, UnsafePointer: |
| if iv.kind == Func && v.InternalMethod != 0 { |
| panic("reflect.Value.Pointer of method Value") |
| } |
| return uintptr(iv.word) |
| case Slice: |
| return (*SliceHeader)(iv.addr).Data |
| } |
| panic(&ValueError{"reflect.Value.Pointer", iv.kind}) |
| } |
| |
| // Recv receives and returns a value from the channel v. |
| // It panics if v's Kind is not Chan. |
| // The receive blocks until a value is ready. |
| // The boolean value ok is true if the value x corresponds to a send |
| // on the channel, false if it is a zero value received because the channel is closed. |
| func (v Value) Recv() (x Value, ok bool) { |
| iv := v.internal() |
| iv.mustBe(Chan) |
| iv.mustBeExported() |
| return iv.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 { |
| panic("recv on send-only channel") |
| } |
| ch := iv.word |
| if ch == 0 { |
| panic("recv on nil channel") |
| } |
| valWord, selected, ok := chanrecv(iv.typ.runtimeType(), ch, nb) |
| if selected { |
| val = valueFromIword(0, t.Elem(), valWord) |
| } |
| return |
| } |
| |
| // Send sends x on the channel v. |
| // It panics if v's kind is not Chan or if x's type is not the same type as v's element type. |
| // As in Go, x's value must be assignable to the channel's element type. |
| func (v Value) Send(x Value) { |
| iv := v.internal() |
| iv.mustBe(Chan) |
| iv.mustBeExported() |
| iv.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 { |
| 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 := iv.word |
| if ch == 0 { |
| panic("send on nil channel") |
| } |
| return chansend(iv.typ.runtimeType(), ch, ix.word, 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 n <= ptrSize { |
| storeIword(iv.addr, ix.word, n) |
| } else { |
| memmove(iv.addr, ix.addr, n) |
| } |
| } |
| |
| // 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 |
| } |
| |
| // 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 { |
| default: |
| panic(&ValueError{"reflect.Value.SetComplex", iv.kind}) |
| case Complex64: |
| *(*complex64)(iv.addr) = complex64(x) |
| case Complex128: |
| *(*complex128)(iv.addr) = 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 { |
| default: |
| panic(&ValueError{"reflect.Value.SetFloat", iv.kind}) |
| case Float32: |
| *(*float32)(iv.addr) = float32(x) |
| case Float64: |
| *(*float64)(iv.addr) = 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 { |
| default: |
| panic(&ValueError{"reflect.Value.SetInt", iv.kind}) |
| case Int: |
| *(*int)(iv.addr) = int(x) |
| case Int8: |
| *(*int8)(iv.addr) = int8(x) |
| case Int16: |
| *(*int16)(iv.addr) = int16(x) |
| case Int32: |
| *(*int32)(iv.addr) = int32(x) |
| case Int64: |
| *(*int64)(iv.addr) = 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) |
| if n < 0 || n > int(s.Cap) { |
| panic("reflect: slice length out of range in SetLen") |
| } |
| s.Len = n |
| } |
| |
| // SetMapIndex sets the value associated with key in the map v to val. |
| // It panics if v's Kind is not Map. |
| // If val is the zero Value, SetMapIndex deletes the key from the map. |
| // As in Go, key's value must be assignable to the map's key type, |
| // and val's value must be assignable to the map's value type. |
| func (v Value) SetMapIndex(key, val Value) { |
| 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) |
| } |
| |
| mapassign(iv.typ.runtimeType(), iv.word, ikey.word, ival.word, ival.kind != Invalid) |
| } |
| |
| // 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 { |
| default: |
| panic(&ValueError{"reflect.Value.SetUint", iv.kind}) |
| case Uint: |
| *(*uint)(iv.addr) = uint(x) |
| case Uint8: |
| *(*uint8)(iv.addr) = uint8(x) |
| case Uint16: |
| *(*uint16)(iv.addr) = uint16(x) |
| case Uint32: |
| *(*uint32)(iv.addr) = uint32(x) |
| case Uint64: |
| *(*uint64)(iv.addr) = x |
| case Uintptr: |
| *(*uintptr)(iv.addr) = 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 |
| } |
| |
| // 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 |
| } |
| |
| // 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 { |
| case Array: |
| if iv.flag&flagAddr == 0 { |
| panic("reflect.Value.Slice: slice of unaddressable array") |
| } |
| typ = toType((*arrayType)(unsafe.Pointer(iv.typ)).slice) |
| base = uintptr(iv.addr) |
| case Slice: |
| typ = iv.typ.toType() |
| base = (*SliceHeader)(iv.addr).Data |
| } |
| s := new(SliceHeader) |
| s.Data = base + uintptr(beg)*typ.Elem().Size() |
| s.Len = end - beg |
| s.Cap = cap - beg |
| return valueFromAddr(iv.flag&flagRO, typ, unsafe.Pointer(s)) |
| } |
| |
| // String returns the string v's underlying value, as a string. |
| // String is a special case because of Go's String method convention. |
| // Unlike the other getters, it does not panic if v's Kind is not String. |
| // Instead, it returns a string of the form "<T value>" where T is v's type. |
| func (v Value) String() string { |
| iv := v.internal() |
| switch iv.kind { |
| case Invalid: |
| return "<invalid Value>" |
| case String: |
| return *(*string)(iv.addr) |
| } |
| return "<" + iv.typ.String() + " Value>" |
| } |
| |
| // TryRecv attempts to receive a value from the channel v but will not block. |
| // It panics if v's Kind is not Chan. |
| // If the receive cannot finish without blocking, x is the zero Value. |
| // The boolean ok is true if the value x corresponds to a send |
| // on the channel, false if it is a zero value received because the channel is closed. |
| func (v Value) TryRecv() (x Value, ok bool) { |
| iv := v.internal() |
| iv.mustBe(Chan) |
| iv.mustBeExported() |
| return iv.recv(true) |
| } |
| |
| // TrySend attempts to send x on the channel v but will not block. |
| // It panics if v's Kind is not Chan. |
| // It returns true if the value was sent, false otherwise. |
| // As in Go, x's value must be assignable to the channel's element type. |
| func (v Value) TrySend(x Value) bool { |
| iv := v.internal() |
| iv.mustBe(Chan) |
| iv.mustBeExported() |
| return iv.send(x, true) |
| } |
| |
| // Type returns v's type. |
| func (v Value) Type() Type { |
| t := v.internal().typ |
| if t == nil { |
| panic(&ValueError{"reflect.Value.Type", Invalid}) |
| } |
| return t.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 { |
| case Uint: |
| return uint64(*(*uint)(unsafe.Pointer(&iv.word))) |
| case Uint8: |
| return uint64(*(*uint8)(unsafe.Pointer(&iv.word))) |
| case Uint16: |
| return uint64(*(*uint16)(unsafe.Pointer(&iv.word))) |
| case Uint32: |
| return uint64(*(*uint32)(unsafe.Pointer(&iv.word))) |
| case Uintptr: |
| return uint64(*(*uintptr)(unsafe.Pointer(&iv.word))) |
| case Uint64: |
| if iv.addr == nil { |
| return *(*uint64)(unsafe.Pointer(&iv.word)) |
| } |
| return *(*uint64)(iv.addr) |
| } |
| panic(&ValueError{"reflect.Value.Uint", iv.kind}) |
| } |
| |
| // 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 iv.flag&flagAddr == 0 { |
| panic("reflect.Value.UnsafeAddr of unaddressable value") |
| } |
| return uintptr(iv.addr) |
| } |
| |
| // StringHeader is the runtime representation of a string. |
| // It cannot be used safely or portably. |
| type StringHeader struct { |
| Data uintptr |
| Len int |
| } |
| |
| // SliceHeader is the runtime representation of a slice. |
| // It cannot be used safely or portably. |
| type SliceHeader struct { |
| Data uintptr |
| Len int |
| Cap int |
| } |
| |
| func typesMustMatch(what string, t1, t2 Type) { |
| if t1 != t2 { |
| panic("reflect: " + what + ": " + t1.String() + " != " + t2.String()) |
| } |
| } |
| |
| // grow grows the slice s so that it can hold extra more values, allocating |
| // more capacity if needed. It also returns the old and new slice lengths. |
| func grow(s Value, extra int) (Value, int, int) { |
| i0 := s.Len() |
| i1 := i0 + extra |
| if i1 < i0 { |
| panic("reflect.Append: slice overflow") |
| } |
| m := s.Cap() |
| if i1 <= m { |
| return s.Slice(0, i1), i0, i1 |
| } |
| if m == 0 { |
| m = extra |
| } else { |
| for m < i1 { |
| if i0 < 1024 { |
| m += m |
| } else { |
| m += m / 4 |
| } |
| } |
| } |
| t := MakeSlice(s.Type(), i1, m) |
| Copy(t, s) |
| return t, i0, i1 |
| } |
| |
| // Append appends the values x to a slice s and returns the resulting slice. |
| // As in Go, each x's value must be assignable to the slice's element type. |
| func Append(s Value, x ...Value) Value { |
| s.internal().mustBe(Slice) |
| s, i0, i1 := grow(s, len(x)) |
| for i, j := i0, 0; i < i1; i, j = i+1, j+1 { |
| s.Index(i).Set(x[j]) |
| } |
| return s |
| } |
| |
| // AppendSlice appends a slice t to a slice s and returns the resulting slice. |
| // The slices s and t must have the same element type. |
| func AppendSlice(s, t Value) Value { |
| s.internal().mustBe(Slice) |
| t.internal().mustBe(Slice) |
| typesMustMatch("reflect.AppendSlice", s.Type().Elem(), t.Type().Elem()) |
| s, i0, i1 := grow(s, t.Len()) |
| Copy(s.Slice(i0, i1), t) |
| return s |
| } |
| |
| // Copy copies the contents of src into dst until either |
| // dst has been filled or src has been exhausted. |
| // It returns the number of elements copied. |
| // Dst and src each must have kind Slice or Array, and |
| // dst and src must have the same element type. |
| func Copy(dst, src Value) int { |
| idst := dst.internal() |
| isrc := src.internal() |
| |
| if idst.kind != Array && idst.kind != Slice { |
| panic(&ValueError{"reflect.Copy", idst.kind}) |
| } |
| if idst.kind == Array { |
| idst.mustBeAssignable() |
| } |
| idst.mustBeExported() |
| if isrc.kind != Array && isrc.kind != Slice { |
| panic(&ValueError{"reflect.Copy", isrc.kind}) |
| } |
| isrc.mustBeExported() |
| |
| de := idst.typ.Elem() |
| se := isrc.typ.Elem() |
| typesMustMatch("reflect.Copy", de, se) |
| |
| n := dst.Len() |
| if sn := src.Len(); n > sn { |
| n = sn |
| } |
| |
| // If sk is an in-line array, cannot take its address. |
| // Instead, copy element by element. |
| if isrc.addr == nil { |
| for i := 0; i < n; i++ { |
| dst.Index(i).Set(src.Index(i)) |
| } |
| return n |
| } |
| |
| // Copy via memmove. |
| var da, sa unsafe.Pointer |
| if idst.kind == Array { |
| da = idst.addr |
| } else { |
| da = unsafe.Pointer((*SliceHeader)(idst.addr).Data) |
| } |
| if isrc.kind == Array { |
| sa = isrc.addr |
| } else { |
| sa = unsafe.Pointer((*SliceHeader)(isrc.addr).Data) |
| } |
| memmove(da, sa, uintptr(n)*de.Size()) |
| return n |
| } |
| |
| /* |
| * constructors |
| */ |
| |
| // MakeSlice creates a new zero-initialized slice value |
| // for the specified slice type, length, and capacity. |
| func MakeSlice(typ Type, len, cap int) Value { |
| if typ.Kind() != Slice { |
| panic("reflect: MakeSlice of non-slice type") |
| } |
| s := &SliceHeader{ |
| Data: uintptr(unsafe.NewArray(typ.Elem(), cap)), |
| Len: len, |
| Cap: cap, |
| } |
| return valueFromAddr(0, typ, unsafe.Pointer(s)) |
| } |
| |
| // MakeChan creates a new channel with the specified type and buffer size. |
| func MakeChan(typ Type, buffer int) Value { |
| if typ.Kind() != Chan { |
| panic("reflect: MakeChan of non-chan type") |
| } |
| if buffer < 0 { |
| panic("MakeChan: negative buffer size") |
| } |
| if typ.ChanDir() != BothDir { |
| panic("MakeChan: unidirectional channel type") |
| } |
| ch := makechan(typ.runtimeType(), uint32(buffer)) |
| return valueFromIword(0, typ, ch) |
| } |
| |
| // MakeMap creates a new map of the specified type. |
| func MakeMap(typ Type) Value { |
| if typ.Kind() != Map { |
| panic("reflect: MakeMap of non-map type") |
| } |
| m := makemap(typ.runtimeType()) |
| return valueFromIword(0, typ, m) |
| } |
| |
| // Indirect returns the value that v points to. |
| // If v is a nil pointer, Indirect returns a nil Value. |
| // If v is not a pointer, Indirect returns v. |
| func Indirect(v Value) Value { |
| if v.Kind() != Ptr { |
| return v |
| } |
| return v.Elem() |
| } |
| |
| // ValueOf returns a new Value initialized to the concrete value |
| // stored in the interface i. ValueOf(nil) returns the zero Value. |
| func ValueOf(i interface{}) Value { |
| if i == nil { |
| return Value{} |
| } |
| // 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) |
| } |
| |
| // Zero returns a Value representing a zero value for the specified type. |
| // The result is different from the zero value of the Value struct, |
| // which represents no value at all. |
| // For example, Zero(TypeOf(42)) returns a Value with Kind Int and value 0. |
| func Zero(typ Type) Value { |
| if typ == nil { |
| panic("reflect: Zero(nil)") |
| } |
| if typ.Size() <= ptrSize { |
| return valueFromIword(0, typ, 0) |
| } |
| return valueFromAddr(0, typ, unsafe.New(typ)) |
| } |
| |
| // New returns a Value representing a pointer to a new zero value |
| // for the specified type. That is, the returned Value's Type is PtrTo(t). |
| func New(typ Type) Value { |
| if typ == nil { |
| panic("reflect: New(nil)") |
| } |
| ptr := unsafe.New(typ) |
| return valueFromIword(0, PtrTo(typ), iword(ptr)) |
| } |
| |
| // 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()) |
| } |
| |
| dst1 := dst.(*commonType) |
| if directlyAssignable(dst1, iv.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{})) |
| } |
| x := iv.valueInterface(false) |
| if dst.NumMethod() == 0 { |
| *(*interface{})(addr) = x |
| } else { |
| ifaceE2I(dst1.runtimeType(), x, addr) |
| } |
| iv.addr = addr |
| iv.word = iword(addr) |
| iv.typ = dst1 |
| return iv |
| } |
| |
| // Failed. |
| panic(what + ": value of type " + iv.typ.String() + " is not assignable to type " + dst.String()) |
| } |
| |
| // implemented in ../pkg/runtime |
| func chancap(ch iword) int32 |
| func chanclose(ch iword) |
| func chanlen(ch iword) int32 |
| func chanrecv(t *runtime.Type, ch iword, nb bool) (val iword, selected, received bool) |
| 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 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 |
| func mapiterkey(it *byte) (key iword, ok bool) |
| func mapiternext(it *byte) |
| func maplen(m iword) int32 |
| |
| func call(fn, arg unsafe.Pointer, n uint32) |
| func ifaceE2I(t *runtime.Type, src interface{}, dst unsafe.Pointer) |