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pointer_reflect.go 
357 строк · 10.3 Кб
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// Go support for Protocol Buffers - Google's data interchange format
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//
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// Copyright 2012 The Go Authors.  All rights reserved.
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// https://github.com/golang/protobuf
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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//     * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//     * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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//     * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// +build purego appengine js
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// This file contains an implementation of proto field accesses using package reflect.
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// It is slower than the code in pointer_unsafe.go but it avoids package unsafe and can
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// be used on App Engine.
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package proto
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import (
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	"reflect"
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	"sync"
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)
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const unsafeAllowed = false
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// A field identifies a field in a struct, accessible from a pointer.
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// In this implementation, a field is identified by the sequence of field indices
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// passed to reflect's FieldByIndex.
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type field []int
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// toField returns a field equivalent to the given reflect field.
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func toField(f *reflect.StructField) field {
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	return f.Index
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}
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// invalidField is an invalid field identifier.
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var invalidField = field(nil)
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// zeroField is a noop when calling pointer.offset.
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var zeroField = field([]int{})
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// IsValid reports whether the field identifier is valid.
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func (f field) IsValid() bool { return f != nil }
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// The pointer type is for the table-driven decoder.
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// The implementation here uses a reflect.Value of pointer type to
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// create a generic pointer. In pointer_unsafe.go we use unsafe
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// instead of reflect to implement the same (but faster) interface.
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type pointer struct {
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	v reflect.Value
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}
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// toPointer converts an interface of pointer type to a pointer
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// that points to the same target.
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func toPointer(i *Message) pointer {
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	return pointer{v: reflect.ValueOf(*i)}
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}
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// toAddrPointer converts an interface to a pointer that points to
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// the interface data.
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func toAddrPointer(i *interface{}, isptr bool) pointer {
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	v := reflect.ValueOf(*i)
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	u := reflect.New(v.Type())
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	u.Elem().Set(v)
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	return pointer{v: u}
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}
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// valToPointer converts v to a pointer.  v must be of pointer type.
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func valToPointer(v reflect.Value) pointer {
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	return pointer{v: v}
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}
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// offset converts from a pointer to a structure to a pointer to
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// one of its fields.
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func (p pointer) offset(f field) pointer {
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	return pointer{v: p.v.Elem().FieldByIndex(f).Addr()}
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}
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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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// grow updates the slice s in place to make it one element longer.
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// s must be addressable.
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// Returns the (addressable) new element.
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func grow(s reflect.Value) reflect.Value {
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	n, m := s.Len(), s.Cap()
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	if n < m {
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		s.SetLen(n + 1)
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	} else {
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		s.Set(reflect.Append(s, reflect.Zero(s.Type().Elem())))
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	}
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	return s.Index(n)
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}
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func (p pointer) toInt64() *int64 {
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	return p.v.Interface().(*int64)
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}
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func (p pointer) toInt64Ptr() **int64 {
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	return p.v.Interface().(**int64)
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}
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func (p pointer) toInt64Slice() *[]int64 {
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	return p.v.Interface().(*[]int64)
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}
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var int32ptr = reflect.TypeOf((*int32)(nil))
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func (p pointer) toInt32() *int32 {
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	return p.v.Convert(int32ptr).Interface().(*int32)
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}
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// The toInt32Ptr/Slice methods don't work because of enums.
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// Instead, we must use set/get methods for the int32ptr/slice case.
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/*
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	func (p pointer) toInt32Ptr() **int32 {
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		return p.v.Interface().(**int32)
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}
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	func (p pointer) toInt32Slice() *[]int32 {
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		return p.v.Interface().(*[]int32)
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}
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*/
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func (p pointer) getInt32Ptr() *int32 {
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	if p.v.Type().Elem().Elem() == reflect.TypeOf(int32(0)) {
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		// raw int32 type
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		return p.v.Elem().Interface().(*int32)
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	}
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	// an enum
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	return p.v.Elem().Convert(int32PtrType).Interface().(*int32)
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}
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func (p pointer) setInt32Ptr(v int32) {
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	// Allocate value in a *int32. Possibly convert that to a *enum.
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	// Then assign it to a **int32 or **enum.
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	// Note: we can convert *int32 to *enum, but we can't convert
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	// **int32 to **enum!
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	p.v.Elem().Set(reflect.ValueOf(&v).Convert(p.v.Type().Elem()))
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}
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// getInt32Slice copies []int32 from p as a new slice.
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// This behavior differs from the implementation in pointer_unsafe.go.
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func (p pointer) getInt32Slice() []int32 {
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	if p.v.Type().Elem().Elem() == reflect.TypeOf(int32(0)) {
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		// raw int32 type
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		return p.v.Elem().Interface().([]int32)
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	}
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	// an enum
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	// Allocate a []int32, then assign []enum's values into it.
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	// Note: we can't convert []enum to []int32.
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	slice := p.v.Elem()
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	s := make([]int32, slice.Len())
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	for i := 0; i < slice.Len(); i++ {
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		s[i] = int32(slice.Index(i).Int())
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	}
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	return s
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}
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// setInt32Slice copies []int32 into p as a new slice.
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// This behavior differs from the implementation in pointer_unsafe.go.
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func (p pointer) setInt32Slice(v []int32) {
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	if p.v.Type().Elem().Elem() == reflect.TypeOf(int32(0)) {
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		// raw int32 type
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		p.v.Elem().Set(reflect.ValueOf(v))
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		return
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	}
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	// an enum
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	// Allocate a []enum, then assign []int32's values into it.
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	// Note: we can't convert []enum to []int32.
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	slice := reflect.MakeSlice(p.v.Type().Elem(), len(v), cap(v))
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	for i, x := range v {
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		slice.Index(i).SetInt(int64(x))
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	}
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	p.v.Elem().Set(slice)
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}
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func (p pointer) appendInt32Slice(v int32) {
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	grow(p.v.Elem()).SetInt(int64(v))
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}
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func (p pointer) toUint64() *uint64 {
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	return p.v.Interface().(*uint64)
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}
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func (p pointer) toUint64Ptr() **uint64 {
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	return p.v.Interface().(**uint64)
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}
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func (p pointer) toUint64Slice() *[]uint64 {
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	return p.v.Interface().(*[]uint64)
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}
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func (p pointer) toUint32() *uint32 {
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	return p.v.Interface().(*uint32)
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}
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func (p pointer) toUint32Ptr() **uint32 {
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	return p.v.Interface().(**uint32)
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}
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func (p pointer) toUint32Slice() *[]uint32 {
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	return p.v.Interface().(*[]uint32)
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}
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func (p pointer) toBool() *bool {
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	return p.v.Interface().(*bool)
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}
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func (p pointer) toBoolPtr() **bool {
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	return p.v.Interface().(**bool)
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}
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func (p pointer) toBoolSlice() *[]bool {
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	return p.v.Interface().(*[]bool)
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}
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func (p pointer) toFloat64() *float64 {
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	return p.v.Interface().(*float64)
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}
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func (p pointer) toFloat64Ptr() **float64 {
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	return p.v.Interface().(**float64)
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}
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func (p pointer) toFloat64Slice() *[]float64 {
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	return p.v.Interface().(*[]float64)
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}
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func (p pointer) toFloat32() *float32 {
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	return p.v.Interface().(*float32)
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}
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func (p pointer) toFloat32Ptr() **float32 {
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	return p.v.Interface().(**float32)
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}
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func (p pointer) toFloat32Slice() *[]float32 {
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	return p.v.Interface().(*[]float32)
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}
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func (p pointer) toString() *string {
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	return p.v.Interface().(*string)
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}
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func (p pointer) toStringPtr() **string {
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	return p.v.Interface().(**string)
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}
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func (p pointer) toStringSlice() *[]string {
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	return p.v.Interface().(*[]string)
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}
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func (p pointer) toBytes() *[]byte {
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	return p.v.Interface().(*[]byte)
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}
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func (p pointer) toBytesSlice() *[][]byte {
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	return p.v.Interface().(*[][]byte)
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}
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func (p pointer) toExtensions() *XXX_InternalExtensions {
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	return p.v.Interface().(*XXX_InternalExtensions)
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}
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func (p pointer) toOldExtensions() *map[int32]Extension {
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	return p.v.Interface().(*map[int32]Extension)
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}
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func (p pointer) getPointer() pointer {
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	return pointer{v: p.v.Elem()}
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}
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func (p pointer) setPointer(q pointer) {
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	p.v.Elem().Set(q.v)
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}
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func (p pointer) appendPointer(q pointer) {
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	grow(p.v.Elem()).Set(q.v)
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}
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// getPointerSlice 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) getPointerSlice() []pointer {
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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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// setPointerSlice copies []pointer into p as a new []*T.
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// This behavior differs from the implementation in pointer_unsafe.go.
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func (p pointer) setPointerSlice(v []pointer) {
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	if v == nil {
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		p.v.Elem().Set(reflect.New(p.v.Elem().Type()).Elem())
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		return
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	}
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	s := reflect.MakeSlice(p.v.Elem().Type(), 0, len(v))
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	for _, p := range v {
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		s = reflect.Append(s, p.v)
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	}
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	p.v.Elem().Set(s)
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}
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// getInterfacePointer returns a pointer that points to the
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// interface data of the interface pointed by p.
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func (p pointer) getInterfacePointer() pointer {
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	if p.v.Elem().IsNil() {
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		return pointer{v: p.v.Elem()}
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	}
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	return pointer{v: p.v.Elem().Elem().Elem().Field(0).Addr()} // *interface -> interface -> *struct -> struct
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}
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func (p pointer) asPointerTo(t reflect.Type) reflect.Value {
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	// TODO: check that p.v.Type().Elem() == t?
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	return p.v
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}
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func atomicLoadUnmarshalInfo(p **unmarshalInfo) *unmarshalInfo {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	return *p
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}
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func atomicStoreUnmarshalInfo(p **unmarshalInfo, v *unmarshalInfo) {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	*p = v
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}
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func atomicLoadMarshalInfo(p **marshalInfo) *marshalInfo {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	return *p
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}
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func atomicStoreMarshalInfo(p **marshalInfo, v *marshalInfo) {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	*p = v
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}
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func atomicLoadMergeInfo(p **mergeInfo) *mergeInfo {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	return *p
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}
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func atomicStoreMergeInfo(p **mergeInfo, v *mergeInfo) {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	*p = v
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}
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func atomicLoadDiscardInfo(p **discardInfo) *discardInfo {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	return *p
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}
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func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) {
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	atomicLock.Lock()
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	defer atomicLock.Unlock()
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	*p = v
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}
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var atomicLock sync.Mutex
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