diff options
Diffstat (limited to 'src/pkg/reflect/value.go')
| -rw-r--r-- | src/pkg/reflect/value.go | 1724 |
1 files changed, 0 insertions, 1724 deletions
diff --git a/src/pkg/reflect/value.go b/src/pkg/reflect/value.go deleted file mode 100644 index bfeb3267c..000000000 --- a/src/pkg/reflect/value.go +++ /dev/null @@ -1,1724 +0,0 @@ -// 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}) - } - // TODO(rsc): Check flagRO too. Decide what to do about asking for - // interface for a value obtained via an unexported field. - // If the field were of a known type, say chan int or *sync.Mutex, - // the caller could interfere with the data after getting the - // interface. But fmt.Print depends on being able to look. - // Now that reflect is more efficient the special cases in fmt - // might be less important. - return v.InternalMethod == 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 v.internal().Interface() -} - -func (iv internalValue) Interface() interface{} { - if iv.method { - panic("reflect.Value.Interface: cannot create interface value for method with bound receiver") - } - /* - if v.flag()&noExport != 0 { - panic("reflect.Value.Interface: cannot return value obtained from unexported struct field") - } - */ - - 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(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(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} -} - -// 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(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(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.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.Interface() - 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(ch iword, nb bool) (val iword, selected, received bool) -func chansend(ch iword, val iword, nb bool) bool - -func makechan(typ *runtime.Type, size uint32) (ch iword) -func makemap(t *runtime.Type) iword -func mapaccess(m iword, key iword) (val iword, ok bool) -func mapassign(m iword, key, val iword, ok bool) -func mapiterinit(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) |