summaryrefslogblamecommitdiffstats
path: root/vendor/github.com/golang/protobuf/proto/lib.go
blob: 1c225504a013c5da68f5b46caa5c110dd32db6cf (plain) (tree)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                                                            
// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2010 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.

/*
Package proto converts data structures to and from the wire format of
protocol buffers.  It works in concert with the Go source code generated
for .proto files by the protocol compiler.

A summary of the properties of the protocol buffer interface
for a protocol buffer variable v:

  - Names are turned from camel_case to CamelCase for export.
  - There are no methods on v to set fields; just treat
	them as structure fields.
  - There are getters that return a field's value if set,
	and return the field's default value if unset.
	The getters work even if the receiver is a nil message.
  - The zero value for a struct is its correct initialization state.
	All desired fields must be set before marshaling.
  - A Reset() method will restore a protobuf struct to its zero state.
  - Non-repeated fields are pointers to the values; nil means unset.
	That is, optional or required field int32 f becomes F *int32.
  - Repeated fields are slices.
  - Helper functions are available to aid the setting of fields.
	msg.Foo = proto.String("hello") // set field
  - Constants are defined to hold the default values of all fields that
	have them.  They have the form Default_StructName_FieldName.
	Because the getter methods handle defaulted values,
	direct use of these constants should be rare.
  - Enums are given type names and maps from names to values.
	Enum values are prefixed by the enclosing message's name, or by the
	enum's type name if it is a top-level enum. Enum types have a String
	method, and a Enum method to assist in message construction.
  - Nested messages, groups and enums have type names prefixed with the name of
	the surrounding message type.
  - Extensions are given descriptor names that start with E_,
	followed by an underscore-delimited list of the nested messages
	that contain it (if any) followed by the CamelCased name of the
	extension field itself.  HasExtension, ClearExtension, GetExtension
	and SetExtension are functions for manipulating extensions.
  - Oneof field sets are given a single field in their message,
	with distinguished wrapper types for each possible field value.
  - Marshal and Unmarshal are functions to encode and decode the wire format.

When the .proto file specifies `syntax="proto3"`, there are some differences:

  - Non-repeated fields of non-message type are values instead of pointers.
  - Enum types do not get an Enum method.

The simplest way to describe this is to see an example.
Given file test.proto, containing

	package example;

	enum FOO { X = 17; }

	message Test {
	  required string label = 1;
	  optional int32 type = 2 [default=77];
	  repeated int64 reps = 3;
	  optional group OptionalGroup = 4 {
	    required string RequiredField = 5;
	  }
	  oneof union {
	    int32 number = 6;
	    string name = 7;
	  }
	}

The resulting file, test.pb.go, is:

	package example

	import proto "github.com/golang/protobuf/proto"
	import math "math"

	type FOO int32
	const (
		FOO_X FOO = 17
	)
	var FOO_name = map[int32]string{
		17: "X",
	}
	var FOO_value = map[string]int32{
		"X": 17,
	}

	func (x FOO) Enum() *FOO {
		p := new(FOO)
		*p = x
		return p
	}
	func (x FOO) String() string {
		return proto.EnumName(FOO_name, int32(x))
	}
	func (x *FOO) UnmarshalJSON(data []byte) error {
		value, err := proto.UnmarshalJSONEnum(FOO_value, data)
		if err != nil {
			return err
		}
		*x = FOO(value)
		return nil
	}

	type Test struct {
		Label         *string             `protobuf:"bytes,1,req,name=label" json:"label,omitempty"`
		Type          *int32              `protobuf:"varint,2,opt,name=type,def=77" json:"type,omitempty"`
		Reps          []int64             `protobuf:"varint,3,rep,name=reps" json:"reps,omitempty"`
		Optionalgroup *Test_OptionalGroup `protobuf:"group,4,opt,name=OptionalGroup" json:"optionalgroup,omitempty"`
		// Types that are valid to be assigned to Union:
		//	*Test_Number
		//	*Test_Name
		Union            isTest_Union `protobuf_oneof:"union"`
		XXX_unrecognized []byte       `json:"-"`
	}
	func (m *Test) Reset()         { *m = Test{} }
	func (m *Test) String() string { return proto.CompactTextString(m) }
	func (*Test) ProtoMessage() {}

	type isTest_Union interface {
		isTest_Union()
	}

	type Test_Number struct {
		Number int32 `protobuf:"varint,6,opt,name=number"`
	}
	type Test_Name struct {
		Name string `protobuf:"bytes,7,opt,name=name"`
	}

	func (*Test_Number) isTest_Union() {}
	func (*Test_Name) isTest_Union()   {}

	func (m *Test) GetUnion() isTest_Union {
		if m != nil {
			return m.Union
		}
		return nil
	}
	const Default_Test_Type int32 = 77

	func (m *Test) GetLabel() string {
		if m != nil && m.Label != nil {
			return *m.Label
		}
		return ""
	}

	func (m *Test) GetType() int32 {
		if m != nil && m.Type != nil {
			return *m.Type
		}
		return Default_Test_Type
	}

	func (m *Test) GetOptionalgroup() *Test_OptionalGroup {
		if m != nil {
			return m.Optionalgroup
		}
		return nil
	}

	type Test_OptionalGroup struct {
		RequiredField *string `protobuf:"bytes,5,req" json:"RequiredField,omitempty"`
	}
	func (m *Test_OptionalGroup) Reset()         { *m = Test_OptionalGroup{} }
	func (m *Test_OptionalGroup) String() string { return proto.CompactTextString(m) }

	func (m *Test_OptionalGroup) GetRequiredField() string {
		if m != nil && m.RequiredField != nil {
			return *m.RequiredField
		}
		return ""
	}

	func (m *Test) GetNumber() int32 {
		if x, ok := m.GetUnion().(*Test_Number); ok {
			return x.Number
		}
		return 0
	}

	func (m *Test) GetName() string {
		if x, ok := m.GetUnion().(*Test_Name); ok {
			return x.Name
		}
		return ""
	}

	func init() {
		proto.RegisterEnum("example.FOO", FOO_name, FOO_value)
	}

To create and play with a Test object:

	package main

	import (
		"log"

		"github.com/golang/protobuf/proto"
		pb "./example.pb"
	)

	func main() {
		test := &pb.Test{
			Label: proto.String("hello"),
			Type:  proto.Int32(17),
			Reps:  []int64{1, 2, 3},
			Optionalgroup: &pb.Test_OptionalGroup{
				RequiredField: proto.String("good bye"),
			},
			Union: &pb.Test_Name{"fred"},
		}
		data, err := proto.Marshal(test)
		if err != nil {
			log.Fatal("marshaling error: ", err)
		}
		newTest := &pb.Test{}
		err = proto.Unmarshal(data, newTest)
		if err != nil {
			log.Fatal("unmarshaling error: ", err)
		}
		// Now test and newTest contain the same data.
		if test.GetLabel() != newTest.GetLabel() {
			log.Fatalf("data mismatch %q != %q", test.GetLabel(), newTest.GetLabel())
		}
		// Use a type switch to determine which oneof was set.
		switch u := test.Union.(type) {
		case *pb.Test_Number: // u.Number contains the number.
		case *pb.Test_Name: // u.Name contains the string.
		}
		// etc.
	}
*/
package proto

import (
	"encoding/json"
	"fmt"
	"log"
	"reflect"
	"sort"
	"strconv"
	"sync"
)

// Message is implemented by generated protocol buffer messages.
type Message interface {
	Reset()
	String() string
	ProtoMessage()
}

// Stats records allocation details about the protocol buffer encoders
// and decoders.  Useful for tuning the library itself.
type Stats struct {
	Emalloc uint64 // mallocs in encode
	Dmalloc uint64 // mallocs in decode
	Encode  uint64 // number of encodes
	Decode  uint64 // number of decodes
	Chit    uint64 // number of cache hits
	Cmiss   uint64 // number of cache misses
	Size    uint64 // number of sizes
}

// Set to true to enable stats collection.
const collectStats = false

var stats Stats

// GetStats returns a copy of the global Stats structure.
func GetStats() Stats { return stats }

// A Buffer is a buffer manager for marshaling and unmarshaling
// protocol buffers.  It may be reused between invocations to
// reduce memory usage.  It is not necessary to use a Buffer;
// the global functions Marshal and Unmarshal create a
// temporary Buffer and are fine for most applications.
type Buffer struct {
	buf   []byte // encode/decode byte stream
	index int    // read point

	// pools of basic types to amortize allocation.
	bools   []bool
	uint32s []uint32
	uint64s []uint64

	// extra pools, only used with pointer_reflect.go
	int32s   []int32
	int64s   []int64
	float32s []float32
	float64s []float64
}

// NewBuffer allocates a new Buffer and initializes its internal data to
// the contents of the argument slice.
func NewBuffer(e []byte) *Buffer {
	return &Buffer{buf: e}
}

// Reset resets the Buffer, ready for marshaling a new protocol buffer.
func (p *Buffer) Reset() {
	p.buf = p.buf[0:0] // for reading/writing
	p.index = 0        // for reading
}

// SetBuf replaces the internal buffer with the slice,
// ready for unmarshaling the contents of the slice.
func (p *Buffer) SetBuf(s []byte) {
	p.buf = s
	p.index = 0
}

// Bytes returns the contents of the Buffer.
func (p *Buffer) Bytes() []byte { return p.buf }

/*
 * Helper routines for simplifying the creation of optional fields of basic type.
 */

// Bool is a helper routine that allocates a new bool value
// to store v and returns a pointer to it.
func Bool(v bool) *bool {
	return &v
}

// Int32 is a helper routine that allocates a new int32 value
// to store v and returns a pointer to it.
func Int32(v int32) *int32 {
	return &v
}

// Int is a helper routine that allocates a new int32 value
// to store v and returns a pointer to it, but unlike Int32
// its argument value is an int.
func Int(v int) *int32 {
	p := new(int32)
	*p = int32(v)
	return p
}

// Int64 is a helper routine that allocates a new int64 value
// to store v and returns a pointer to it.
func Int64(v int64) *int64 {
	return &v
}

// Float32 is a helper routine that allocates a new float32 value
// to store v and returns a pointer to it.
func Float32(v float32) *float32 {
	return &v
}

// Float64 is a helper routine that allocates a new float64 value
// to store v and returns a pointer to it.
func Float64(v float64) *float64 {
	return &v
}

// Uint32 is a helper routine that allocates a new uint32 value
// to store v and returns a pointer to it.
func Uint32(v uint32) *uint32 {
	return &v
}

// Uint64 is a helper routine that allocates a new uint64 value
// to store v and returns a pointer to it.
func Uint64(v uint64) *uint64 {
	return &v
}

// String is a helper routine that allocates a new string value
// to store v and returns a pointer to it.
func String(v string) *string {
	return &v
}

// EnumName is a helper function to simplify printing protocol buffer enums
// by name.  Given an enum map and a value, it returns a useful string.
func EnumName(m map[int32]string, v int32) string {
	s, ok := m[v]
	if ok {
		return s
	}
	return strconv.Itoa(int(v))
}

// UnmarshalJSONEnum is a helper function to simplify recovering enum int values
// from their JSON-encoded representation. Given a map from the enum's symbolic
// names to its int values, and a byte buffer containing the JSON-encoded
// value, it returns an int32 that can be cast to the enum type by the caller.
//
// The function can deal with both JSON representations, numeric and symbolic.
func UnmarshalJSONEnum(m map[string]int32, data []byte, enumName string) (int32, error) {
	if data[0] == '"' {
		// New style: enums are strings.
		var repr string
		if err := json.Unmarshal(data, &repr); err != nil {
			return -1, err
		}
		val, ok := m[repr]
		if !ok {
			return 0, fmt.Errorf("unrecognized enum %s value %q", enumName, repr)
		}
		return val, nil
	}
	// Old style: enums are ints.
	var val int32
	if err := json.Unmarshal(data, &val); err != nil {
		return 0, fmt.Errorf("cannot unmarshal %#q into enum %s", data, enumName)
	}
	return val, nil
}

// DebugPrint dumps the encoded data in b in a debugging format with a header
// including the string s. Used in testing but made available for general debugging.
func (p *Buffer) DebugPrint(s string, b []byte) {
	var u uint64

	obuf := p.buf
	index := p.index
	p.buf = b
	p.index = 0
	depth := 0

	fmt.Printf("\n--- %s ---\n", s)

out:
	for {
		for i := 0; i < depth; i++ {
			fmt.Print("  ")
		}

		index := p.index
		if index == len(p.buf) {
			break
		}

		op, err := p.DecodeVarint()
		if err != nil {
			fmt.Printf("%3d: fetching op err %v\n", index, err)
			break out
		}
		tag := op >> 3
		wire := op & 7

		switch wire {
		default:
			fmt.Printf("%3d: t=%3d unknown wire=%d\n",
				index, tag, wire)
			break out

		case WireBytes:
			var r []byte

			r, err = p.DecodeRawBytes(false)
			if err != nil {
				break out
			}
			fmt.Printf("%3d: t=%3d bytes [%d]", index, tag, len(r))
			if len(r) <= 6 {
				for i := 0; i < len(r); i++ {
					fmt.Printf(" %.2x", r[i])
				}
			} else {
				for i := 0; i < 3; i++ {
					fmt.Printf(" %.2x", r[i])
				}
				fmt.Printf(" ..")
				for i := len(r) - 3; i < len(r); i++ {
					fmt.Printf(" %.2x", r[i])
				}
			}
			fmt.Printf("\n")

		case WireFixed32:
			u, err = p.DecodeFixed32()
			if err != nil {
				fmt.Printf("%3d: t=%3d fix32 err %v\n", index, tag, err)
				break out
			}
			fmt.Printf("%3d: t=%3d fix32 %d\n", index, tag, u)

		case WireFixed64:
			u, err = p.DecodeFixed64()
			if err != nil {
				fmt.Printf("%3d: t=%3d fix64 err %v\n", index, tag, err)
				break out
			}
			fmt.Printf("%3d: t=%3d fix64 %d\n", index, tag, u)

		case WireVarint:
			u, err = p.DecodeVarint()
			if err != nil {
				fmt.Printf("%3d: t=%3d varint err %v\n", index, tag, err)
				break out
			}
			fmt.Printf("%3d: t=%3d varint %d\n", index, tag, u)

		case WireStartGroup:
			fmt.Printf("%3d: t=%3d start\n", index, tag)
			depth++

		case WireEndGroup:
			depth--
			fmt.Printf("%3d: t=%3d end\n", index, tag)
		}
	}

	if depth != 0 {
		fmt.Printf("%3d: start-end not balanced %d\n", p.index, depth)
	}
	fmt.Printf("\n")

	p.buf = obuf
	p.index = index
}

// SetDefaults sets unset protocol buffer fields to their default values.
// It only modifies fields that are both unset and have defined defaults.
// It recursively sets default values in any non-nil sub-messages.
func SetDefaults(pb Message) {
	setDefaults(reflect.ValueOf(pb), true, false)
}

// v is a pointer to a struct.
func setDefaults(v reflect.Value, recur, zeros bool) {
	v = v.Elem()

	defaultMu.RLock()
	dm, ok := defaults[v.Type()]
	defaultMu.RUnlock()
	if !ok {
		dm = buildDefaultMessage(v.Type())
		defaultMu.Lock()
		defaults[v.Type()] = dm
		defaultMu.Unlock()
	}

	for _, sf := range dm.scalars {
		f := v.Field(sf.index)
		if !f.IsNil() {
			// field already set
			continue
		}
		dv := sf.value
		if dv == nil && !zeros {
			// no explicit default, and don't want to set zeros
			continue
		}
		fptr := f.Addr().Interface() // **T
		// TODO: Consider batching the allocations we do here.
		switch sf.kind {
		case reflect.Bool:
			b := new(bool)
			if dv != nil {
				*b = dv.(bool)
			}
			*(fptr.(**bool)) = b
		case reflect.Float32:
			f := new(float32)
			if dv != nil {
				*f = dv.(float32)
			}
			*(fptr.(**float32)) = f
		case reflect.Float64:
			f := new(float64)
			if dv != nil {
				*f = dv.(float64)
			}
			*(fptr.(**float64)) = f
		case reflect.Int32:
			// might be an enum
			if ft := f.Type(); ft != int32PtrType {
				// enum
				f.Set(reflect.New(ft.Elem()))
				if dv != nil {
					f.Elem().SetInt(int64(dv.(int32)))
				}
			} else {
				// int32 field
				i := new(int32)
				if dv != nil {
					*i = dv.(int32)
				}
				*(fptr.(**int32)) = i
			}
		case reflect.Int64:
			i := new(int64)
			if dv != nil {
				*i = dv.(int64)
			}
			*(fptr.(**int64)) = i
		case reflect.String:
			s := new(string)
			if dv != nil {
				*s = dv.(string)
			}
			*(fptr.(**string)) = s
		case reflect.Uint8:
			// exceptional case: []byte
			var b []byte
			if dv != nil {
				db := dv.([]byte)
				b = make([]byte, len(db))
				copy(b, db)
			} else {
				b = []byte{}
			}
			*(fptr.(*[]byte)) = b
		case reflect.Uint32:
			u := new(uint32)
			if dv != nil {
				*u = dv.(uint32)
			}
			*(fptr.(**uint32)) = u
		case reflect.Uint64:
			u := new(uint64)
			if dv != nil {
				*u = dv.(uint64)
			}
			*(fptr.(**uint64)) = u
		default:
			log.Printf("proto: can't set default for field %v (sf.kind=%v)", f, sf.kind)
		}
	}

	for _, ni := range dm.nested {
		f := v.Field(ni)
		// f is *T or []*T or map[T]*T
		switch f.Kind() {
		case reflect.Ptr:
			if f.IsNil() {
				continue
			}
			setDefaults(f, recur, zeros)

		case reflect.Slice:
			for i := 0; i < f.Len(); i++ {
				e := f.Index(i)
				if e.IsNil() {
					continue
				}
				setDefaults(e, recur, zeros)
			}

		case reflect.Map:
			for _, k := range f.MapKeys() {
				e := f.MapIndex(k)
				if e.IsNil() {
					continue
				}
				setDefaults(e, recur, zeros)
			}
		}
	}
}

var (
	// defaults maps a protocol buffer struct type to a slice of the fields,
	// with its scalar fields set to their proto-declared non-zero default values.
	defaultMu sync.RWMutex
	defaults  = make(map[reflect.Type]defaultMessage)

	int32PtrType = reflect.TypeOf((*int32)(nil))
)

// defaultMessage represents information about the default values of a message.
type defaultMessage struct {
	scalars []scalarField
	nested  []int // struct field index of nested messages
}

type scalarField struct {
	index int          // struct field index
	kind  reflect.Kind // element type (the T in *T or []T)
	value interface{}  // the proto-declared default value, or nil
}

// t is a struct type.
func buildDefaultMessage(t reflect.Type) (dm defaultMessage) {
	sprop := GetProperties(t)
	for _, prop := range sprop.Prop {
		fi, ok := sprop.decoderTags.get(prop.Tag)
		if !ok {
			// XXX_unrecognized
			continue
		}
		ft := t.Field(fi).Type

		sf, nested, err := fieldDefault(ft, prop)
		switch {
		case err != nil:
			log.Print(err)
		case nested:
			dm.nested = append(dm.nested, fi)
		case sf != nil:
			sf.index = fi
			dm.scalars = append(dm.scalars, *sf)
		}
	}

	return dm
}

// fieldDefault returns the scalarField for field type ft.
// sf will be nil if the field can not have a default.
// nestedMessage will be true if this is a nested message.
// Note that sf.index is not set on return.
func fieldDefault(ft reflect.Type, prop *Properties) (sf *scalarField, nestedMessage bool, err error) {
	var canHaveDefault bool
	switch ft.Kind() {
	case reflect.Ptr:
		if ft.Elem().Kind() == reflect.Struct {
			nestedMessage = true
		} else {
			canHaveDefault = true // proto2 scalar field
		}

	case reflect.Slice:
		switch ft.Elem().Kind() {
		case reflect.Ptr:
			nestedMessage = true // repeated message
		case reflect.Uint8:
			canHaveDefault = true // bytes field
		}

	case reflect.Map:
		if ft.Elem().Kind() == reflect.Ptr {
			nestedMessage = true // map with message values
		}
	}

	if !canHaveDefault {
		if nestedMessage {
			return nil, true, nil
		}
		return nil, false, nil
	}

	// We now know that ft is a pointer or slice.
	sf = &scalarField{kind: ft.Elem().Kind()}

	// scalar fields without defaults
	if !prop.HasDefault {
		return sf, false, nil
	}

	// a scalar field: either *T or []byte
	switch ft.Elem().Kind() {
	case reflect.Bool:
		x, err := strconv.ParseBool(prop.Default)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default bool %q: %v", prop.Default, err)
		}
		sf.value = x
	case reflect.Float32:
		x, err := strconv.ParseFloat(prop.Default, 32)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default float32 %q: %v", prop.Default, err)
		}
		sf.value = float32(x)
	case reflect.Float64:
		x, err := strconv.ParseFloat(prop.Default, 64)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default float64 %q: %v", prop.Default, err)
		}
		sf.value = x
	case reflect.Int32:
		x, err := strconv.ParseInt(prop.Default, 10, 32)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default int32 %q: %v", prop.Default, err)
		}
		sf.value = int32(x)
	case reflect.Int64:
		x, err := strconv.ParseInt(prop.Default, 10, 64)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default int64 %q: %v", prop.Default, err)
		}
		sf.value = x
	case reflect.String:
		sf.value = prop.Default
	case reflect.Uint8:
		// []byte (not *uint8)
		sf.value = []byte(prop.Default)
	case reflect.Uint32:
		x, err := strconv.ParseUint(prop.Default, 10, 32)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default uint32 %q: %v", prop.Default, err)
		}
		sf.value = uint32(x)
	case reflect.Uint64:
		x, err := strconv.ParseUint(prop.Default, 10, 64)
		if err != nil {
			return nil, false, fmt.Errorf("proto: bad default uint64 %q: %v", prop.Default, err)
		}
		sf.value = x
	default:
		return nil, false, fmt.Errorf("proto: unhandled def kind %v", ft.Elem().Kind())
	}

	return sf, false, nil
}

// Map fields may have key types of non-float scalars, strings and enums.
// The easiest way to sort them in some deterministic order is to use fmt.
// If this turns out to be inefficient we can always consider other options,
// such as doing a Schwartzian transform.

func mapKeys(vs []reflect.Value) sort.Interface {
	s := mapKeySorter{
		vs: vs,
		// default Less function: textual comparison
		less: func(a, b reflect.Value) bool {
			return fmt.Sprint(a.Interface()) < fmt.Sprint(b.Interface())
		},
	}

	// Type specialization per https://developers.google.com/protocol-buffers/docs/proto#maps;
	// numeric keys are sorted numerically.
	if len(vs) == 0 {
		return s
	}
	switch vs[0].Kind() {
	case reflect.Int32, reflect.Int64:
		s.less = func(a, b reflect.Value) bool { return a.Int() < b.Int() }
	case reflect.Uint32, reflect.Uint64:
		s.less = func(a, b reflect.Value) bool { return a.Uint() < b.Uint() }
	}

	return s
}

type mapKeySorter struct {
	vs   []reflect.Value
	less func(a, b reflect.Value) bool
}

func (s mapKeySorter) Len() int      { return len(s.vs) }
func (s mapKeySorter) Swap(i, j int) { s.vs[i], s.vs[j] = s.vs[j], s.vs[i] }
func (s mapKeySorter) Less(i, j int) bool {
	return s.less(s.vs[i], s.vs[j])
}

// isProto3Zero reports whether v is a zero proto3 value.
func isProto3Zero(v reflect.Value) bool {
	switch v.Kind() {
	case reflect.Bool:
		return !v.Bool()
	case reflect.Int32, reflect.Int64:
		return v.Int() == 0
	case reflect.Uint32, reflect.Uint64:
		return v.Uint() == 0
	case reflect.Float32, reflect.Float64:
		return v.Float() == 0
	case reflect.String:
		return v.String() == ""
	}
	return false
}

// ProtoPackageIsVersion2 is referenced from generated protocol buffer files
// to assert that that code is compatible with this version of the proto package.
const ProtoPackageIsVersion2 = true

// ProtoPackageIsVersion1 is referenced from generated protocol buffer files
// to assert that that code is compatible with this version of the proto package.
const ProtoPackageIsVersion1 = true