// 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 an implementation of proto field accesses using package reflect.

// It is slower than the code in pointer_unsafe.go but it avoids package unsafe and can

// be used on App Engine.

package proto

import (

	"reflect"

	"sync"

)

const unsafeAllowed = false

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

// In this implementation, a field is identified by the sequence of field indices

// passed to reflect's FieldByIndex.

type field []int

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

func toField(f *reflect.StructField) field {

	return f.Index

}

// invalidField is an invalid field identifier.

var invalidField = field(nil)

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

var zeroField = field([]int{})

// IsValid reports whether the field identifier is valid.

func (f field) IsValid() bool { return f != nil }

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

// The implementation here uses a reflect.Value of pointer type to

// create a generic pointer. In pointer_unsafe.go we use unsafe

// instead of reflect to implement the same (but faster) interface.

type pointer struct {

	v reflect.Value

}

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

// that points to the same target.

func toPointer(i *Message) pointer {

	return pointer{v: reflect.ValueOf(*i)}

}

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

// the interface data.

func toAddrPointer(i *interface{}, isptr bool) pointer {

	v := reflect.ValueOf(*i)

	u := reflect.New(v.Type())

	u.Elem().Set(v)

	return pointer{v: u}

}

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

func valToPointer(v reflect.Value) pointer {

	return pointer{v: v}

}

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

// one of its fields.

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

	return pointer{v: p.v.Elem().FieldByIndex(f).Addr()}

}

func (p pointer) isNil() bool {

	return p.v.IsNil()

}

// grow updates the slice s in place to make it one element longer.

// s must be addressable.

// Returns the (addressable) new element.

func grow(s reflect.Value) reflect.Value {

	n, m := s.Len(), s.Cap()

	if n < m {

		s.SetLen(n + 1)

	} else {

		s.Set(reflect.Append(s, reflect.Zero(s.Type().Elem())))

	}

	return s.Index(n)

}

func (p pointer) toInt64() *int64 {

	return p.v.Interface().(*int64)

}

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

	return p.v.Interface().(**int64)

}

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

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

}

var int32ptr = reflect.TypeOf((*int32)(nil))

func (p pointer) toInt32() *int32 {

	return p.v.Convert(int32ptr).Interface().(*int32)

}

// The toInt32Ptr/Slice methods don't work because of enums.

// Instead, we must use set/get methods for the int32ptr/slice case.

/*

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

		return p.v.Interface().(**int32)

}

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

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

}

*/

func (p pointer) getInt32Ptr() *int32 {

	if p.v.Type().Elem().Elem() == reflect.TypeOf(int32(0)) {

		// raw int32 type

		return p.v.Elem().Interface().(*int32)

	}

	// an enum

	return p.v.Elem().Convert(int32PtrType).Interface().(*int32)

}

func (p pointer) setInt32Ptr(v int32) {

	// Allocate value in a *int32. Possibly convert that to a *enum.

	// Then assign it to a **int32 or **enum.

	// Note: we can convert *int32 to *enum, but we can't convert

	// **int32 to **enum!

	p.v.Elem().Set(reflect.ValueOf(&v).Convert(p.v.Type().Elem()))

}

// getInt32Slice copies []int32 from p as a new slice.

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

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

	if p.v.Type().Elem().Elem() == reflect.TypeOf(int32(0)) {

		// raw int32 type

		return p.v.Elem().Interface().([]int32)

	}

	// an enum

	// Allocate a []int32, then assign []enum's values into it.

	// Note: we can't convert []enum to []int32.

	slice := p.v.Elem()

	s := make([]int32, slice.Len())

	for i := 0; i < slice.Len(); i++ {

		s[i] = int32(slice.Index(i).Int())

	}

	return s

}

// setInt32Slice copies []int32 into p as a new slice.

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

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

	if p.v.Type().Elem().Elem() == reflect.TypeOf(int32(0)) {

		// raw int32 type

		p.v.Elem().Set(reflect.ValueOf(v))

		return

	}

	// an enum

	// Allocate a []enum, then assign []int32's values into it.

	// Note: we can't convert []enum to []int32.

	slice := reflect.MakeSlice(p.v.Type().Elem(), len(v), cap(v))

	for i, x := range v {

		slice.Index(i).SetInt(int64(x))

	}

	p.v.Elem().Set(slice)

}

func (p pointer) appendInt32Slice(v int32) {

	grow(p.v.Elem()).SetInt(int64(v))

}

func (p pointer) toUint64() *uint64 {

	return p.v.Interface().(*uint64)

}

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

	return p.v.Interface().(**uint64)

}

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

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

}

func (p pointer) toUint32() *uint32 {

	return p.v.Interface().(*uint32)

}

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

	return p.v.Interface().(**uint32)

}

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

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

}

func (p pointer) toBool() *bool {

	return p.v.Interface().(*bool)

}

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

	return p.v.Interface().(**bool)

}

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

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

}

func (p pointer) toFloat64() *float64 {

	return p.v.Interface().(*float64)

}

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

	return p.v.Interface().(**float64)

}

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

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

}

func (p pointer) toFloat32() *float32 {

	return p.v.Interface().(*float32)

}

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

	return p.v.Interface().(**float32)

}

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

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

}

func (p pointer) toString() *string {

	return p.v.Interface().(*string)

}

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

	return p.v.Interface().(**string)

}

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

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

}

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

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

}

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

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

}

func (p pointer) toExtensions() *XXX_InternalExtensions {

	return p.v.Interface().(*XXX_InternalExtensions)

}

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

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

}

func (p pointer) getPointer() pointer {

	return pointer{v: p.v.Elem()}

}

func (p pointer) setPointer(q pointer) {

	p.v.Elem().Set(q.v)

}

func (p pointer) appendPointer(q pointer) {

	grow(p.v.Elem()).Set(q.v)

}

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

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

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

	if p.v.IsNil() {

		return nil

	}

	n := p.v.Elem().Len()

	s := make([]pointer, n)

	for i := 0; i < n; i++ {

		s[i] = pointer{v: p.v.Elem().Index(i)}

	}

	return s

}

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

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

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

	if v == nil {

		p.v.Elem().Set(reflect.New(p.v.Elem().Type()).Elem())

		return

	}

	s := reflect.MakeSlice(p.v.Elem().Type(), 0, len(v))

	for _, p := range v {

		s = reflect.Append(s, p.v)

	}

	p.v.Elem().Set(s)

}

// getInterfacePointer returns a pointer that points to the

// interface data of the interface pointed by p.

func (p pointer) getInterfacePointer() pointer {

	if p.v.Elem().IsNil() {

		return pointer{v: p.v.Elem()}

	}

	return pointer{v: p.v.Elem().Elem().Elem().Field(0).Addr()} // *interface -> interface -> *struct -> struct

}

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

	// TODO: check that p.v.Type().Elem() == t?

	return p.v

}

func atomicLoadUnmarshalInfo(p **unmarshalInfo) *unmarshalInfo {

	atomicLock.Lock()

	defer atomicLock.Unlock()

	return *p

}

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

	atomicLock.Lock()

	defer atomicLock.Unlock()

	*p = v

}

func atomicLoadMarshalInfo(p **marshalInfo) *marshalInfo {

	atomicLock.Lock()

	defer atomicLock.Unlock()

	return *p

}

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

	atomicLock.Lock()

	defer atomicLock.Unlock()

	*p = v

}

func atomicLoadMergeInfo(p **mergeInfo) *mergeInfo {

	atomicLock.Lock()

	defer atomicLock.Unlock()

	return *p

}

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

	atomicLock.Lock()

	defer atomicLock.Unlock()

	*p = v

}

func atomicLoadDiscardInfo(p **discardInfo) *discardInfo {

	atomicLock.Lock()

	defer atomicLock.Unlock()

	return *p

}

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

	atomicLock.Lock()

	defer atomicLock.Unlock()

	*p = v

}

var atomicLock sync.Mutex