179 lines
6.3 KiB
Go
179 lines
6.3 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build purego appengine
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package impl
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import (
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"fmt"
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"reflect"
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"sync"
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)
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const UnsafeEnabled = false
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// Pointer is an opaque pointer type.
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type Pointer interface{}
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// offset represents the offset to a struct field, accessible from a pointer.
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// The offset is the field index into a struct.
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type offset struct {
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index int
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export exporter
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}
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// offsetOf returns a field offset for the struct field.
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func offsetOf(f reflect.StructField, x exporter) offset {
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if len(f.Index) != 1 {
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panic("embedded structs are not supported")
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}
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if f.PkgPath == "" {
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return offset{index: f.Index[0]} // field is already exported
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}
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if x == nil {
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panic("exporter must be provided for unexported field")
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}
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return offset{index: f.Index[0], export: x}
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}
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// IsValid reports whether the offset is valid.
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func (f offset) IsValid() bool { return f.index >= 0 }
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// invalidOffset is an invalid field offset.
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var invalidOffset = offset{index: -1}
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// zeroOffset is a noop when calling pointer.Apply.
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var zeroOffset = offset{index: 0}
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// pointer is an abstract representation of a pointer to a struct or field.
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type pointer struct{ v reflect.Value }
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// pointerOf returns p as a pointer.
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func pointerOf(p Pointer) pointer {
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return pointerOfIface(p)
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}
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// pointerOfValue returns v as a pointer.
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func pointerOfValue(v reflect.Value) pointer {
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return pointer{v: v}
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}
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// pointerOfIface returns the pointer portion of an interface.
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func pointerOfIface(v interface{}) pointer {
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return pointer{v: reflect.ValueOf(v)}
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}
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// IsNil reports whether the pointer is nil.
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func (p pointer) IsNil() bool {
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return p.v.IsNil()
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}
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// Apply adds an offset to the pointer to derive a new pointer
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// to a specified field. The current pointer must be pointing at a struct.
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func (p pointer) Apply(f offset) pointer {
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if f.export != nil {
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if v := reflect.ValueOf(f.export(p.v.Interface(), f.index)); v.IsValid() {
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return pointer{v: v}
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}
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}
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return pointer{v: p.v.Elem().Field(f.index).Addr()}
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}
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// AsValueOf treats p as a pointer to an object of type t and returns the value.
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// It is equivalent to reflect.ValueOf(p.AsIfaceOf(t))
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func (p pointer) AsValueOf(t reflect.Type) reflect.Value {
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if got := p.v.Type().Elem(); got != t {
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panic(fmt.Sprintf("invalid type: got %v, want %v", got, t))
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}
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return p.v
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}
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// AsIfaceOf treats p as a pointer to an object of type t and returns the value.
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// It is equivalent to p.AsValueOf(t).Interface()
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func (p pointer) AsIfaceOf(t reflect.Type) interface{} {
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return p.AsValueOf(t).Interface()
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}
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func (p pointer) Bool() *bool { return p.v.Interface().(*bool) }
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func (p pointer) BoolPtr() **bool { return p.v.Interface().(**bool) }
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func (p pointer) BoolSlice() *[]bool { return p.v.Interface().(*[]bool) }
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func (p pointer) Int32() *int32 { return p.v.Interface().(*int32) }
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func (p pointer) Int32Ptr() **int32 { return p.v.Interface().(**int32) }
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func (p pointer) Int32Slice() *[]int32 { return p.v.Interface().(*[]int32) }
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func (p pointer) Int64() *int64 { return p.v.Interface().(*int64) }
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func (p pointer) Int64Ptr() **int64 { return p.v.Interface().(**int64) }
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func (p pointer) Int64Slice() *[]int64 { return p.v.Interface().(*[]int64) }
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func (p pointer) Uint32() *uint32 { return p.v.Interface().(*uint32) }
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func (p pointer) Uint32Ptr() **uint32 { return p.v.Interface().(**uint32) }
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func (p pointer) Uint32Slice() *[]uint32 { return p.v.Interface().(*[]uint32) }
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func (p pointer) Uint64() *uint64 { return p.v.Interface().(*uint64) }
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func (p pointer) Uint64Ptr() **uint64 { return p.v.Interface().(**uint64) }
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func (p pointer) Uint64Slice() *[]uint64 { return p.v.Interface().(*[]uint64) }
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func (p pointer) Float32() *float32 { return p.v.Interface().(*float32) }
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func (p pointer) Float32Ptr() **float32 { return p.v.Interface().(**float32) }
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func (p pointer) Float32Slice() *[]float32 { return p.v.Interface().(*[]float32) }
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func (p pointer) Float64() *float64 { return p.v.Interface().(*float64) }
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func (p pointer) Float64Ptr() **float64 { return p.v.Interface().(**float64) }
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func (p pointer) Float64Slice() *[]float64 { return p.v.Interface().(*[]float64) }
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func (p pointer) String() *string { return p.v.Interface().(*string) }
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func (p pointer) StringPtr() **string { return p.v.Interface().(**string) }
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func (p pointer) StringSlice() *[]string { return p.v.Interface().(*[]string) }
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func (p pointer) Bytes() *[]byte { return p.v.Interface().(*[]byte) }
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func (p pointer) BytesPtr() **[]byte { return p.v.Interface().(**[]byte) }
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func (p pointer) BytesSlice() *[][]byte { return p.v.Interface().(*[][]byte) }
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func (p pointer) WeakFields() *weakFields { return (*weakFields)(p.v.Interface().(*WeakFields)) }
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func (p pointer) Extensions() *map[int32]ExtensionField {
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return p.v.Interface().(*map[int32]ExtensionField)
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}
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func (p pointer) Elem() pointer {
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return pointer{v: p.v.Elem()}
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}
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// PointerSlice copies []*T from p as a new []pointer.
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// This behavior differs from the implementation in pointer_unsafe.go.
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func (p pointer) PointerSlice() []pointer {
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// TODO: reconsider this
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if p.v.IsNil() {
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return nil
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}
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n := p.v.Elem().Len()
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s := make([]pointer, n)
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for i := 0; i < n; i++ {
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s[i] = pointer{v: p.v.Elem().Index(i)}
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}
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return s
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}
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// AppendPointerSlice appends v to p, which must be a []*T.
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func (p pointer) AppendPointerSlice(v pointer) {
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sp := p.v.Elem()
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sp.Set(reflect.Append(sp, v.v))
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}
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// SetPointer sets *p to v.
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func (p pointer) SetPointer(v pointer) {
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p.v.Elem().Set(v.v)
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}
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func (Export) MessageStateOf(p Pointer) *messageState { panic("not supported") }
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func (ms *messageState) pointer() pointer { panic("not supported") }
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func (ms *messageState) messageInfo() *MessageInfo { panic("not supported") }
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func (ms *messageState) LoadMessageInfo() *MessageInfo { panic("not supported") }
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func (ms *messageState) StoreMessageInfo(mi *MessageInfo) { panic("not supported") }
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type atomicNilMessage struct {
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once sync.Once
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m messageReflectWrapper
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}
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func (m *atomicNilMessage) Init(mi *MessageInfo) *messageReflectWrapper {
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m.once.Do(func() {
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m.m.p = pointerOfIface(reflect.Zero(mi.GoReflectType).Interface())
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m.m.mi = mi
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})
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return &m.m
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}
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