aboutsummaryrefslogtreecommitdiff
path: root/NorthstarDedicatedTest/include/protobuf/map_entry_lite.h
blob: 61b89d2c78f7af2e4e1da38833aae738002d0a91 (plain)
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
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// 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.

#ifndef GOOGLE_PROTOBUF_MAP_ENTRY_LITE_H__
#define GOOGLE_PROTOBUF_MAP_ENTRY_LITE_H__

#include <assert.h>
#include <string>

#include <stubs/casts.h>
#include <parse_context.h>
#include <io/coded_stream.h>
#include <arena.h>
#include <arenastring.h>
#include <generated_message_util.h>
#include <map.h>
#include <map_type_handler.h>
#include <port.h>
#include <wire_format_lite.h>

#include <port_def.inc>
#ifdef SWIG
#error "You cannot SWIG proto headers"
#endif

namespace google {
namespace protobuf {
namespace internal {
template <typename Derived, typename Key, typename Value,
          WireFormatLite::FieldType kKeyFieldType,
          WireFormatLite::FieldType kValueFieldType>
class MapEntry;
template <typename Derived, typename Key, typename Value,
          WireFormatLite::FieldType kKeyFieldType,
          WireFormatLite::FieldType kValueFieldType>
class MapFieldLite;
}  // namespace internal
}  // namespace protobuf
}  // namespace google

namespace google {
namespace protobuf {
namespace internal {

// MoveHelper::Move is used to set *dest.  It copies *src, or moves it (in
// the C++11 sense), or swaps it. *src is left in a sane state for
// subsequent destruction, but shouldn't be used for anything.
template <bool is_enum, bool is_message, bool is_stringlike, typename T>
struct MoveHelper {  // primitives
  static void Move(T* src, T* dest) { *dest = *src; }
};

template <bool is_message, bool is_stringlike, typename T>
struct MoveHelper<true, is_message, is_stringlike, T> {  // enums
  static void Move(T* src, T* dest) { *dest = *src; }
  // T is an enum here, so allow conversions to and from int.
  static void Move(T* src, int* dest) { *dest = static_cast<int>(*src); }
  static void Move(int* src, T* dest) { *dest = static_cast<T>(*src); }
};

template <bool is_stringlike, typename T>
struct MoveHelper<false, true, is_stringlike, T> {  // messages
  static void Move(T* src, T* dest) { dest->Swap(src); }
};

template <typename T>
struct MoveHelper<false, false, true, T> {  // strings and similar
  static void Move(T* src, T* dest) {
    *dest = std::move(*src);
  }
};

// Functions for operating on a map entry.  Does not contain any representation
// (this class is not intended to be instantiated).
template <typename Key, typename Value, WireFormatLite::FieldType kKeyFieldType,
          WireFormatLite::FieldType kValueFieldType>
struct MapEntryFuncs {
  typedef MapTypeHandler<kKeyFieldType, Key> KeyTypeHandler;
  typedef MapTypeHandler<kValueFieldType, Value> ValueTypeHandler;
  static const int kKeyFieldNumber = 1;
  static const int kValueFieldNumber = 2;

  static uint8_t* InternalSerialize(int field_number, const Key& key,
                                    const Value& value, uint8_t* ptr,
                                    io::EpsCopyOutputStream* stream) {
    ptr = stream->EnsureSpace(ptr);
    ptr = WireFormatLite::WriteTagToArray(
        field_number, WireFormatLite::WIRETYPE_LENGTH_DELIMITED, ptr);
    ptr = io::CodedOutputStream::WriteVarint32ToArray(GetCachedSize(key, value),
                                                      ptr);

    ptr = KeyTypeHandler::Write(kKeyFieldNumber, key, ptr, stream);
    return ValueTypeHandler::Write(kValueFieldNumber, value, ptr, stream);
  }

  static size_t ByteSizeLong(const Key& key, const Value& value) {
    // Tags for key and value will both be one byte (field numbers 1 and 2).
    size_t inner_length =
        2 + KeyTypeHandler::ByteSize(key) + ValueTypeHandler::ByteSize(value);
    return inner_length + io::CodedOutputStream::VarintSize32(
                              static_cast<uint32_t>(inner_length));
  }

  static int GetCachedSize(const Key& key, const Value& value) {
    // Tags for key and value will both be one byte (field numbers 1 and 2).
    return 2 + KeyTypeHandler::GetCachedSize(key) +
           ValueTypeHandler::GetCachedSize(value);
  }
};

// MapEntryImpl is used to implement parsing and serialization of map entries.
// It uses Curious Recursive Template Pattern (CRTP) to provide the type of
// the eventual code to the template code.
template <typename Derived, typename Base, typename Key, typename Value,
          WireFormatLite::FieldType kKeyFieldType,
          WireFormatLite::FieldType kValueFieldType>
class MapEntryImpl : public Base {
 public:
  typedef MapEntryFuncs<Key, Value, kKeyFieldType, kValueFieldType> Funcs;

 protected:
  // Provide utilities to parse/serialize key/value.  Provide utilities to
  // manipulate internal stored type.
  typedef MapTypeHandler<kKeyFieldType, Key> KeyTypeHandler;
  typedef MapTypeHandler<kValueFieldType, Value> ValueTypeHandler;

  // Define internal memory layout. Strings and messages are stored as
  // pointers, while other types are stored as values.
  typedef typename KeyTypeHandler::TypeOnMemory KeyOnMemory;
  typedef typename ValueTypeHandler::TypeOnMemory ValueOnMemory;

  // Enum type cannot be used for MapTypeHandler::Read. Define a type
  // which will replace Enum with int.
  typedef typename KeyTypeHandler::MapEntryAccessorType KeyMapEntryAccessorType;
  typedef
      typename ValueTypeHandler::MapEntryAccessorType ValueMapEntryAccessorType;

  // Constants for field number.
  static const int kKeyFieldNumber = 1;
  static const int kValueFieldNumber = 2;

  // Constants for field tag.
  static const uint8_t kKeyTag =
      GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(kKeyFieldNumber, KeyTypeHandler::kWireType);
  static const uint8_t kValueTag = GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(
      kValueFieldNumber, ValueTypeHandler::kWireType);
  static const size_t kTagSize = 1;

 public:
  // Work-around for a compiler bug (see repeated_field.h).
  typedef void MapEntryHasMergeTypeTrait;
  typedef Derived EntryType;
  typedef Key EntryKeyType;
  typedef Value EntryValueType;
  static const WireFormatLite::FieldType kEntryKeyFieldType = kKeyFieldType;
  static const WireFormatLite::FieldType kEntryValueFieldType = kValueFieldType;

  constexpr MapEntryImpl()
      : key_(KeyTypeHandler::Constinit()),
        value_(ValueTypeHandler::Constinit()),
        _has_bits_{} {}

  explicit MapEntryImpl(Arena* arena)
      : Base(arena),
        key_(KeyTypeHandler::Constinit()),
        value_(ValueTypeHandler::Constinit()),
        _has_bits_{} {}

  ~MapEntryImpl() {
    if (Base::GetArenaForAllocation() != nullptr) return;
    KeyTypeHandler::DeleteNoArena(key_);
    ValueTypeHandler::DeleteNoArena(value_);
  }

  // accessors ======================================================

  virtual inline const KeyMapEntryAccessorType& key() const {
    return KeyTypeHandler::GetExternalReference(key_);
  }
  virtual inline const ValueMapEntryAccessorType& value() const {
    return ValueTypeHandler::DefaultIfNotInitialized(value_);
  }
  inline KeyMapEntryAccessorType* mutable_key() {
    set_has_key();
    return KeyTypeHandler::EnsureMutable(&key_, Base::GetArenaForAllocation());
  }
  inline ValueMapEntryAccessorType* mutable_value() {
    set_has_value();
    return ValueTypeHandler::EnsureMutable(&value_,
                                           Base::GetArenaForAllocation());
  }

  // implements MessageLite =========================================

  // MapEntryImpl is for implementation only and this function isn't called
  // anywhere. Just provide a fake implementation here for MessageLite.
  std::string GetTypeName() const override { return ""; }

  void CheckTypeAndMergeFrom(const MessageLite& other) override {
    MergeFromInternal(*::google::protobuf::internal::DownCast<const Derived*>(&other));
  }

  const char* _InternalParse(const char* ptr, ParseContext* ctx) final {
    while (!ctx->Done(&ptr)) {
      uint32_t tag;
      ptr = ReadTag(ptr, &tag);
      GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
      if (tag == kKeyTag) {
        set_has_key();
        KeyMapEntryAccessorType* key = mutable_key();
        ptr = KeyTypeHandler::Read(ptr, ctx, key);
        if (!Derived::ValidateKey(key)) return nullptr;
      } else if (tag == kValueTag) {
        set_has_value();
        ValueMapEntryAccessorType* value = mutable_value();
        ptr = ValueTypeHandler::Read(ptr, ctx, value);
        if (!Derived::ValidateValue(value)) return nullptr;
      } else {
        if (tag == 0 || WireFormatLite::GetTagWireType(tag) ==
                            WireFormatLite::WIRETYPE_END_GROUP) {
          ctx->SetLastTag(tag);
          return ptr;
        }
        ptr = UnknownFieldParse(tag, static_cast<std::string*>(nullptr), ptr,
                                ctx);
      }
      GOOGLE_PROTOBUF_PARSER_ASSERT(ptr);
    }
    return ptr;
  }

  size_t ByteSizeLong() const override {
    size_t size = 0;
    size += kTagSize + static_cast<size_t>(KeyTypeHandler::ByteSize(key()));
    size += kTagSize + static_cast<size_t>(ValueTypeHandler::ByteSize(value()));
    return size;
  }

  ::uint8_t* _InternalSerialize(
      ::uint8_t* ptr, io::EpsCopyOutputStream* stream) const override {
    ptr = KeyTypeHandler::Write(kKeyFieldNumber, key(), ptr, stream);
    return ValueTypeHandler::Write(kValueFieldNumber, value(), ptr, stream);
  }

  // Don't override SerializeWithCachedSizesToArray.  Use MessageLite's.

  int GetCachedSize() const override {
    int size = 0;
    size += has_key() ? static_cast<int>(kTagSize) +
                            KeyTypeHandler::GetCachedSize(key())
                      : 0;
    size += has_value() ? static_cast<int>(kTagSize) +
                              ValueTypeHandler::GetCachedSize(value())
                        : 0;
    return size;
  }

  bool IsInitialized() const override {
    return ValueTypeHandler::IsInitialized(value_);
  }

  Base* New(Arena* arena) const override {
    Derived* entry = Arena::CreateMessage<Derived>(arena);
    return entry;
  }

 protected:
  // We can't declare this function directly here as it would hide the other
  // overload (const Message&).
  void MergeFromInternal(const MapEntryImpl& from) {
    if (from._has_bits_[0]) {
      if (from.has_key()) {
        KeyTypeHandler::EnsureMutable(&key_, Base::GetArenaForAllocation());
        KeyTypeHandler::Merge(from.key(), &key_, Base::GetArenaForAllocation());
        set_has_key();
      }
      if (from.has_value()) {
        ValueTypeHandler::EnsureMutable(&value_, Base::GetArenaForAllocation());
        ValueTypeHandler::Merge(from.value(), &value_,
                                Base::GetArenaForAllocation());
        set_has_value();
      }
    }
  }

 public:
  void Clear() override {
    KeyTypeHandler::Clear(&key_, Base::GetArenaForAllocation());
    ValueTypeHandler::Clear(&value_, Base::GetArenaForAllocation());
    clear_has_key();
    clear_has_value();
  }

  // Parsing using MergePartialFromCodedStream, above, is not as
  // efficient as it could be.  This helper class provides a speedier way.
  template <typename MapField, typename Map>
  class Parser {
   public:
    explicit Parser(MapField* mf) : mf_(mf), map_(mf->MutableMap()) {}
    ~Parser() {
      if (entry_ != nullptr && entry_->GetArenaForAllocation() == nullptr)
        delete entry_;
    }

    // This does what the typical MergePartialFromCodedStream() is expected to
    // do, with the additional side-effect that if successful (i.e., if true is
    // going to be its return value) it inserts the key-value pair into map_.
    bool MergePartialFromCodedStream(io::CodedInputStream* input) {
      // Look for the expected thing: a key and then a value.  If it fails,
      // invoke the enclosing class's MergePartialFromCodedStream, or return
      // false if that would be pointless.
      if (input->ExpectTag(kKeyTag)) {
        if (!KeyTypeHandler::Read(input, &key_)) {
          return false;
        }
        // Peek at the next byte to see if it is kValueTag.  If not, bail out.
        const void* data;
        int size;
        input->GetDirectBufferPointerInline(&data, &size);
        // We could use memcmp here, but we don't bother. The tag is one byte.
        static_assert(kTagSize == 1, "tag size must be 1");
        if (size > 0 && *reinterpret_cast<const char*>(data) == kValueTag) {
          typename Map::size_type map_size = map_->size();
          value_ptr_ = &(*map_)[key_];
          if (PROTOBUF_PREDICT_TRUE(map_size != map_->size())) {
            // We created a new key-value pair.  Fill in the value.
            typedef
                typename MapIf<ValueTypeHandler::kIsEnum, int*, Value*>::type T;
            input->Skip(kTagSize);  // Skip kValueTag.
            if (!ValueTypeHandler::Read(input,
                                        reinterpret_cast<T>(value_ptr_))) {
              map_->erase(key_);  // Failure! Undo insertion.
              return false;
            }
            if (input->ExpectAtEnd()) return true;
            return ReadBeyondKeyValuePair(input);
          }
        }
      } else {
        key_ = Key();
      }

      NewEntry();
      *entry_->mutable_key() = key_;
      const bool result = entry_->MergePartialFromCodedStream(input);
      if (result) UseKeyAndValueFromEntry();
      return result;
    }

    const char* _InternalParse(const char* ptr, ParseContext* ctx) {
      if (PROTOBUF_PREDICT_TRUE(!ctx->Done(&ptr) && *ptr == kKeyTag)) {
        ptr = KeyTypeHandler::Read(ptr + 1, ctx, &key_);
        if (PROTOBUF_PREDICT_FALSE(!ptr || !Derived::ValidateKey(&key_))) {
          return nullptr;
        }
        if (PROTOBUF_PREDICT_TRUE(!ctx->Done(&ptr) && *ptr == kValueTag)) {
          typename Map::size_type map_size = map_->size();
          value_ptr_ = &(*map_)[key_];
          if (PROTOBUF_PREDICT_TRUE(map_size != map_->size())) {
            using T =
                typename MapIf<ValueTypeHandler::kIsEnum, int*, Value*>::type;
            ptr = ValueTypeHandler::Read(ptr + 1, ctx,
                                         reinterpret_cast<T>(value_ptr_));
            if (PROTOBUF_PREDICT_FALSE(!ptr ||
                                       !Derived::ValidateValue(value_ptr_))) {
              map_->erase(key_);  // Failure! Undo insertion.
              return nullptr;
            }
            if (PROTOBUF_PREDICT_TRUE(ctx->Done(&ptr))) return ptr;
            if (!ptr) return nullptr;
            NewEntry();
            ValueMover::Move(value_ptr_, entry_->mutable_value());
            map_->erase(key_);
            goto move_key;
          }
        } else {
          if (!ptr) return nullptr;
        }
        NewEntry();
      move_key:
        KeyMover::Move(&key_, entry_->mutable_key());
      } else {
        if (!ptr) return nullptr;
        NewEntry();
      }
      ptr = entry_->_InternalParse(ptr, ctx);
      if (ptr) UseKeyAndValueFromEntry();
      return ptr;
    }

    template <typename UnknownType>
    const char* ParseWithEnumValidation(const char* ptr, ParseContext* ctx,
                                        bool (*is_valid)(int),
                                        uint32_t field_num,
                                        InternalMetadata* metadata) {
      auto entry = NewEntry();
      ptr = entry->_InternalParse(ptr, ctx);
      if (!ptr) return nullptr;
      if (is_valid(entry->value())) {
        UseKeyAndValueFromEntry();
      } else {
        WriteLengthDelimited(field_num, entry->SerializeAsString(),
                             metadata->mutable_unknown_fields<UnknownType>());
      }
      return ptr;
    }

    MapEntryImpl* NewEntry() { return entry_ = mf_->NewEntry(); }

    const Key& key() const { return key_; }
    const Value& value() const { return *value_ptr_; }

    const Key& entry_key() const { return entry_->key(); }
    const Value& entry_value() const { return entry_->value(); }

   private:
    void UseKeyAndValueFromEntry() {
      // Update key_ in case we need it later (because key() is called).
      // This is potentially inefficient, especially if the key is
      // expensive to copy (e.g., a long string), but this is a cold
      // path, so it's not a big deal.
      key_ = entry_->key();
      value_ptr_ = &(*map_)[key_];
      ValueMover::Move(entry_->mutable_value(), value_ptr_);
    }

    // After reading a key and value successfully, and inserting that data
    // into map_, we are not at the end of the input.  This is unusual, but
    // allowed by the spec.
    bool ReadBeyondKeyValuePair(io::CodedInputStream* input) PROTOBUF_COLD {
      NewEntry();
      ValueMover::Move(value_ptr_, entry_->mutable_value());
      map_->erase(key_);
      KeyMover::Move(&key_, entry_->mutable_key());
      const bool result = entry_->MergePartialFromCodedStream(input);
      if (result) UseKeyAndValueFromEntry();
      return result;
    }

    typedef MoveHelper<KeyTypeHandler::kIsEnum, KeyTypeHandler::kIsMessage,
                       KeyTypeHandler::kWireType ==
                           WireFormatLite::WIRETYPE_LENGTH_DELIMITED,
                       Key>
        KeyMover;
    typedef MoveHelper<ValueTypeHandler::kIsEnum, ValueTypeHandler::kIsMessage,
                       ValueTypeHandler::kWireType ==
                           WireFormatLite::WIRETYPE_LENGTH_DELIMITED,
                       Value>
        ValueMover;

    MapField* const mf_;
    Map* const map_;
    Key key_;
    Value* value_ptr_;
    MapEntryImpl* entry_ = nullptr;
  };

 protected:
  void set_has_key() { _has_bits_[0] |= 0x00000001u; }
  bool has_key() const { return (_has_bits_[0] & 0x00000001u) != 0; }
  void clear_has_key() { _has_bits_[0] &= ~0x00000001u; }
  void set_has_value() { _has_bits_[0] |= 0x00000002u; }
  bool has_value() const { return (_has_bits_[0] & 0x00000002u) != 0; }
  void clear_has_value() { _has_bits_[0] &= ~0x00000002u; }

 public:
  inline Arena* GetArena() const { return Base::GetArena(); }

 public:  // Needed for constructing tables
  KeyOnMemory key_;
  ValueOnMemory value_;
  uint32_t _has_bits_[1];

 private:
  friend class ::PROTOBUF_NAMESPACE_ID::Arena;
  typedef void InternalArenaConstructable_;
  typedef void DestructorSkippable_;
  template <typename C, typename K, typename V, WireFormatLite::FieldType,
            WireFormatLite::FieldType>
  friend class internal::MapEntry;
  template <typename C, typename K, typename V, WireFormatLite::FieldType,
            WireFormatLite::FieldType>
  friend class internal::MapFieldLite;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MapEntryImpl);
};

template <typename T, typename Key, typename Value,
          WireFormatLite::FieldType kKeyFieldType,
          WireFormatLite::FieldType kValueFieldType>
class MapEntryLite : public MapEntryImpl<T, MessageLite, Key, Value,
                                         kKeyFieldType, kValueFieldType> {
 public:
  typedef MapEntryImpl<T, MessageLite, Key, Value, kKeyFieldType,
                       kValueFieldType>
      SuperType;
  constexpr MapEntryLite() {}
  explicit MapEntryLite(Arena* arena) : SuperType(arena) {}
  ~MapEntryLite() {
    MessageLite::_internal_metadata_.template Delete<std::string>();
  }
  void MergeFrom(const MapEntryLite& other) { MergeFromInternal(other); }

 private:
  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MapEntryLite);
};
// The completely unprincipled and unwieldy use of template parameters in
// the map code necessitates wrappers to make the code a little bit more
// manageable.
template <typename Derived>
struct DeconstructMapEntry;

template <typename T, typename K, typename V, WireFormatLite::FieldType key,
          WireFormatLite::FieldType value>
struct DeconstructMapEntry<MapEntryLite<T, K, V, key, value> > {
  typedef K Key;
  typedef V Value;
  static const WireFormatLite::FieldType kKeyFieldType = key;
  static const WireFormatLite::FieldType kValueFieldType = value;
};

// Helpers for deterministic serialization =============================

// This struct can be used with any generic sorting algorithm.  If the Key
// type is relatively small and easy to copy then copying Keys into an
// array of SortItems can be beneficial.  Then all the data the sorting
// algorithm needs to touch is in that one array.
template <typename Key, typename PtrToKeyValuePair>
struct SortItem {
  SortItem() {}
  explicit SortItem(PtrToKeyValuePair p) : first(p->first), second(p) {}

  Key first;
  PtrToKeyValuePair second;
};

template <typename T>
struct CompareByFirstField {
  bool operator()(const T& a, const T& b) const { return a.first < b.first; }
};

template <typename T>
struct CompareByDerefFirst {
  bool operator()(const T& a, const T& b) const { return a->first < b->first; }
};

// Helper for table driven serialization

template <WireFormatLite::FieldType FieldType>
struct FromHelper {
  template <typename T>
  static const T& From(const T& x) {
    return x;
  }
};

template <>
struct FromHelper<WireFormatLite::TYPE_STRING> {
  static ArenaStringPtr From(const std::string& x) {
    ArenaStringPtr res;
    TaggedPtr<std::string> ptr;
    ptr.Set(const_cast<std::string*>(&x));
    res.UnsafeSetTaggedPointer(ptr);
    return res;
  }
};
template <>
struct FromHelper<WireFormatLite::TYPE_BYTES> {
  static ArenaStringPtr From(const std::string& x) {
    ArenaStringPtr res;
    TaggedPtr<std::string> ptr;
    ptr.Set(const_cast<std::string*>(&x));
    res.UnsafeSetTaggedPointer(ptr);
    return res;
  }
};
template <>
struct FromHelper<WireFormatLite::TYPE_MESSAGE> {
  template <typename T>
  static T* From(const T& x) {
    return const_cast<T*>(&x);
  }
};

template <typename MapEntryType>
struct MapEntryHelper;

template <typename T, typename Key, typename Value,
          WireFormatLite::FieldType kKeyFieldType,
          WireFormatLite::FieldType kValueFieldType>
struct MapEntryHelper<
    MapEntryLite<T, Key, Value, kKeyFieldType, kValueFieldType> > {
  // Provide utilities to parse/serialize key/value.  Provide utilities to
  // manipulate internal stored type.
  typedef MapTypeHandler<kKeyFieldType, Key> KeyTypeHandler;
  typedef MapTypeHandler<kValueFieldType, Value> ValueTypeHandler;

  // Define internal memory layout. Strings and messages are stored as
  // pointers, while other types are stored as values.
  typedef typename KeyTypeHandler::TypeOnMemory KeyOnMemory;
  typedef typename ValueTypeHandler::TypeOnMemory ValueOnMemory;

  explicit MapEntryHelper(const MapPair<Key, Value>& map_pair)
      : _has_bits_(3),
        _cached_size_(2 + KeyTypeHandler::GetCachedSize(map_pair.first) +
                      ValueTypeHandler::GetCachedSize(map_pair.second)),
        key_(FromHelper<kKeyFieldType>::From(map_pair.first)),
        value_(FromHelper<kValueFieldType>::From(map_pair.second)) {}

  // Purposely not following the style guide naming. These are the names
  // the proto compiler would generate given the map entry descriptor.
  // The proto compiler generates the offsets in this struct as if this was
  // a regular message. This way the table driven code barely notices it's
  // dealing with a map field.
  uint32_t _has_bits_;     // NOLINT
  uint32_t _cached_size_;  // NOLINT
  KeyOnMemory key_;      // NOLINT
  ValueOnMemory value_;  // NOLINT
};

}  // namespace internal
}  // namespace protobuf
}  // namespace google

#include <port_undef.inc>

#endif  // GOOGLE_PROTOBUF_MAP_ENTRY_LITE_H__