// Go support for Protocol Buffers - Google's data interchange format

//

// Copyright 2012 The Go Authors.  All rights reserved.

// https://github.com/golang/protobuf

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

//     * Neither the name of Google Inc. nor the names of its

// contributors may be used to endorse or promote products derived from

// this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// +build !purego,!appengine,!js

// This file contains the implementation of the proto field accesses using package unsafe.

package proto

import (

	"reflect"

	"sync/atomic"

	"unsafe"

)

const unsafeAllowed = true

// A field identifies a field in a struct, accessible from a pointer.

// In this implementation, a field is identified by its byte offset from the start of the struct.

type field uintptr

// toField returns a field equivalent to the given reflect field.

func toField(f *reflect.StructField) field {

	return field(f.Offset)

}

// invalidField is an invalid field identifier.

const invalidField = ^field(0)

// zeroField is a noop when calling pointer.offset.

const zeroField = field(0)

// IsValid reports whether the field identifier is valid.

func (f field) IsValid() bool {

	return f != invalidField

}

// The pointer type below is for the new table-driven encoder/decoder.

// The implementation here uses unsafe.Pointer to create a generic pointer.

// In pointer_reflect.go we use reflect instead of unsafe to implement

// the same (but slower) interface.

type pointer struct {

	p unsafe.Pointer

}

// size of pointer

var ptrSize = unsafe.Sizeof(uintptr(0))

// toPointer converts an interface of pointer type to a pointer

// that points to the same target.

func toPointer(i *Message) pointer {

	// Super-tricky - read pointer out of data word of interface value.

	// Saves ~25ns over the equivalent:

	// return valToPointer(reflect.ValueOf(*i))

	return pointer{p: (*[2]unsafe.Pointer)(unsafe.Pointer(i))[1]}

}

// toAddrPointer converts an interface to a pointer that points to

// the interface data.

	// Super-tricky - read or get the address of data word of interface value.

	if isptr {

		// The interface is of pointer type, thus it is a direct interface.

		// The data word is the pointer data itself. We take its address.

	}

}

// valToPointer converts v to a pointer. v must be of pointer type.

func valToPointer(v reflect.Value) pointer {

	return pointer{p: unsafe.Pointer(v.Pointer())}

}

// offset converts from a pointer to a structure to a pointer to

// one of its fields.

func (p pointer) offset(f field) pointer {

	// For safety, we should panic if !f.IsValid, however calling panic causes

	// this to no longer be inlineable, which is a serious performance cost.

	/*

		if !f.IsValid() {

			panic("invalid field")

		}

	*/

	return pointer{p: unsafe.Pointer(uintptr(p.p) + uintptr(f))}

}

func (p pointer) isNil() bool {

	return p.p == nil

}

func (p pointer) toInt64() *int64 {

	return (*int64)(p.p)

}

func (p pointer) toInt64Ptr() **int64 {

	return (**int64)(p.p)

}

func (p pointer) toInt64Slice() *[]int64 {

	return (*[]int64)(p.p)

}

func (p pointer) toInt32() *int32 {

	return (*int32)(p.p)

}

// See pointer_reflect.go for why toInt32Ptr/Slice doesn't exist.

/*

	func (p pointer) toInt32Ptr() **int32 {

		return (**int32)(p.p)

	}

	func (p pointer) toInt32Slice() *[]int32 {

		return (*[]int32)(p.p)

	}

*/

func (p pointer) getInt32Ptr() *int32 {

	return *(**int32)(p.p)

}

func (p pointer) setInt32Ptr(v int32) {

	*(**int32)(p.p) = &v

}

// getInt32Slice loads a []int32 from p.

// The value returned is aliased with the original slice.

// This behavior differs from the implementation in pointer_reflect.go.

func (p pointer) getInt32Slice() []int32 {

	return *(*[]int32)(p.p)

}

// setInt32Slice stores a []int32 to p.

// The value set is aliased with the input slice.

// This behavior differs from the implementation in pointer_reflect.go.

func (p pointer) setInt32Slice(v []int32) {

	*(*[]int32)(p.p) = v

}

// TODO: Can we get rid of appendInt32Slice and use setInt32Slice instead?

func (p pointer) appendInt32Slice(v int32) {

	s := (*[]int32)(p.p)

	*s = append(*s, v)

}

func (p pointer) toUint64() *uint64 {

	return (*uint64)(p.p)

}

func (p pointer) toUint64Ptr() **uint64 {

	return (**uint64)(p.p)

}

func (p pointer) toUint64Slice() *[]uint64 {

	return (*[]uint64)(p.p)

}

func (p pointer) toUint32() *uint32 {

	return (*uint32)(p.p)

}

func (p pointer) toUint32Ptr() **uint32 {

	return (**uint32)(p.p)

}

func (p pointer) toUint32Slice() *[]uint32 {

	return (*[]uint32)(p.p)

}

func (p pointer) toBool() *bool {

	return (*bool)(p.p)

}

func (p pointer) toBoolPtr() **bool {

	return (**bool)(p.p)

}

func (p pointer) toBoolSlice() *[]bool {

	return (*[]bool)(p.p)

}

func (p pointer) toFloat64() *float64 {

	return (*float64)(p.p)

}

func (p pointer) toFloat64Ptr() **float64 {

	return (**float64)(p.p)

}

func (p pointer) toFloat64Slice() *[]float64 {

	return (*[]float64)(p.p)

}

func (p pointer) toFloat32() *float32 {

	return (*float32)(p.p)

}

func (p pointer) toFloat32Ptr() **float32 {

	return (**float32)(p.p)

}

func (p pointer) toFloat32Slice() *[]float32 {

	return (*[]float32)(p.p)

}

func (p pointer) toString() *string {

	return (*string)(p.p)

}

func (p pointer) toStringPtr() **string {

	return (**string)(p.p)

}

func (p pointer) toStringSlice() *[]string {

	return (*[]string)(p.p)

}

func (p pointer) toBytes() *[]byte {

	return (*[]byte)(p.p)

}

func (p pointer) toBytesSlice() *[][]byte {

	return (*[][]byte)(p.p)

}

func (p pointer) toExtensions() *XXX_InternalExtensions {

	return (*XXX_InternalExtensions)(p.p)

}

func (p pointer) toOldExtensions() *map[int32]Extension {

	return (*map[int32]Extension)(p.p)

}

// getPointerSlice loads []*T from p as a []pointer.

// The value returned is aliased with the original slice.

// This behavior differs from the implementation in pointer_reflect.go.

func (p pointer) getPointerSlice() []pointer {

	// Super-tricky - p should point to a []*T where T is a

	// message type. We load it as []pointer.

	return *(*[]pointer)(p.p)

}

// setPointerSlice stores []pointer into p as a []*T.

// The value set is aliased with the input slice.

// This behavior differs from the implementation in pointer_reflect.go.

func (p pointer) setPointerSlice(v []pointer) {

	// Super-tricky - p should point to a []*T where T is a

	// message type. We store it as []pointer.

	*(*[]pointer)(p.p) = v

}

// getPointer loads the pointer at p and returns it.

func (p pointer) getPointer() pointer {

	return pointer{p: *(*unsafe.Pointer)(p.p)}

}

// setPointer stores the pointer q at p.

func (p pointer) setPointer(q pointer) {

	*(*unsafe.Pointer)(p.p) = q.p

}

// append q to the slice pointed to by p.

func (p pointer) appendPointer(q pointer) {

	s := (*[]unsafe.Pointer)(p.p)

	*s = append(*s, q.p)

}

// getInterfacePointer returns a pointer that points to the

// interface data of the interface pointed by p.

func (p pointer) getInterfacePointer() pointer {

	// Super-tricky - read pointer out of data word of interface value.

	return pointer{p: (*(*[2]unsafe.Pointer)(p.p))[1]}

}

// asPointerTo returns a reflect.Value that is a pointer to an

// object of type t stored at p.

func (p pointer) asPointerTo(t reflect.Type) reflect.Value {

	return reflect.NewAt(t, p.p)

}

func atomicLoadUnmarshalInfo(p **unmarshalInfo) *unmarshalInfo {

	return (*unmarshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))

}

func atomicStoreUnmarshalInfo(p **unmarshalInfo, v *unmarshalInfo) {

	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))

}

func atomicLoadMarshalInfo(p **marshalInfo) *marshalInfo {

	return (*marshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))

}

func atomicStoreMarshalInfo(p **marshalInfo, v *marshalInfo) {

	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))

}

func atomicLoadMergeInfo(p **mergeInfo) *mergeInfo {

	return (*mergeInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))

}

func atomicStoreMergeInfo(p **mergeInfo, v *mergeInfo) {

	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))

}

func atomicLoadDiscardInfo(p **discardInfo) *discardInfo {

	return (*discardInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))

}

func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) {

	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))

}