Initial commit of the FlatBuffers code.

Change-Id: I4c9f0f722490b374257adb3fec63e44ae93da920
Tested: using VS2010 / Xcode / gcc on Linux.

include/flatbuffers/flatbuffers.h

@@ -0,0 +1,685 @@
+/*
+ * Copyright 2014 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FLATBUFFERS_H_
+#define FLATBUFFERS_H_
+
+#include <assert.h>
+
+#include <cstdint>
+#include <cstring>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+#if __cplusplus <= 199711L && \
+    (!defined(_MSC_VER) || _MSC_VER < 1600) && \
+    (!defined(__GNUC__) || \
+      (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ < 40603))
+  #error A C++11 compatible compiler is required for FlatBuffers.
+  #error __cplusplus _MSC_VER __GNUC__  __GNUC_MINOR__  __GNUC_PATCHLEVEL__
+#endif
+
+// The wire format uses a little endian encoding (since that's efficient for
+// the common platforms).
+#if !defined(FLATBUFFERS_LITTLEENDIAN)
+  #if defined(__GNUC__) || defined(__clang__)
+    #ifdef __BIG_ENDIAN__
+      #define FLATBUFFERS_LITTLEENDIAN 0
+    #else
+      #define FLATBUFFERS_LITTLEENDIAN 1
+    #endif // __BIG_ENDIAN__
+  #elif defined(_MSC_VER)
+    #define FLATBUFFERS_LITTLEENDIAN 1
+  #else
+    #error Unable to determine endianness, define FLATBUFFERS_LITTLEENDIAN.
+  #endif
+#endif // !defined(FLATBUFFERS_LITTLEENDIAN)
+
+#define FLATBUFFERS_VERSION_MAJOR 1
+#define FLATBUFFERS_VERSION_MINOR 0
+#define FLATBUFFERS_VERSION_REVISION 0
+#define FLATBUFFERS_STRING_EXPAND(X) #X
+#define FLATBUFFERS_STRING(X) FLATBUFFERS_STRING_EXPAND(X)
+
+namespace flatbuffers {
+
+// Our default offset / size type, 32bit on purpose on 64bit systems.
+// Also, using a consistent offset type maintains compatibility of serialized
+// offset values between 32bit and 64bit systems.
+typedef uint32_t uoffset_t;
+
+// Signed offsets for references that can go in both directions.
+typedef int32_t soffset_t;
+
+// Offset/index used in v-tables, can be changed to uint8_t in
+// format forks to save a bit of space if desired.
+typedef uint16_t voffset_t;
+
+typedef uintmax_t largest_scalar_t;
+
+// Wrapper for uoffset_t to allow safe template specialization.
+template<typename T> struct Offset {
+  uoffset_t o;
+  Offset() : o(0) {}
+  explicit Offset(uoffset_t _o) : o(_o) {}
+  Offset<void> Union() const { return Offset<void>(o); }
+};
+
+inline void EndianCheck() {
+  int endiantest = 1;
+  // If this fails, see FLATBUFFERS_LITTLEENDIAN above.
+  assert(*reinterpret_cast<char *>(&endiantest) == FLATBUFFERS_LITTLEENDIAN);
+  (void)endiantest;
+}
+
+template<typename T> T EndianScalar(T t) {
+  #if FLATBUFFERS_LITTLEENDIAN
+    return t;
+  #else
+    // If you're on the few remaining big endian platforms, we make the bold
+    // assumption you're also on gcc/clang, and thus have bswap intrinsics:
+    if (sizeof(T) == 1) {   // Compile-time if-then's.
+      return t;
+    } else if (sizeof(T) == 2) {
+      auto r = __builtin_bswap16(*reinterpret_cast<uint16_t *>(&t));
+      return *reinterpret_cast<T *>(&r);
+    } else if (sizeof(T) == 4) {
+      auto r = __builtin_bswap32(*reinterpret_cast<uint32_t *>(&t));
+      return *reinterpret_cast<T *>(&r);
+    } else if (sizeof(T) == 8) {
+      auto r = __builtin_bswap64(*reinterpret_cast<uint64_t *>(&t));
+      return *reinterpret_cast<T *>(&r);
+    } else {
+      assert(0);
+    }
+  #endif
+}
+
+template<typename T> T ReadScalar(const void *p) {
+  return EndianScalar(*reinterpret_cast<const T *>(p));
+}
+
+template<typename T> void WriteScalar(void *p, T t) {
+  *reinterpret_cast<T *>(p) = EndianScalar(t);
+}
+
+template<typename T> size_t AlignOf() {
+  #ifdef _MSC_VER
+    return __alignof(T);
+  #else
+    return alignof(T);
+  #endif
+}
+
+// When we read serialized data from memory, in the case of most scalars,
+// we want to just read T, but in the case of Offset, we want to actually
+// perform the indirection and return a pointer.
+// The template specialization below does just that.
+// It is wrapped in a struct since function templates can't overload on the
+// return type like this.
+// The typedef is for the convenience of callers of this function
+// (avoiding the need for a trailing return decltype)
+template<typename T> struct IndirectHelper {
+  typedef T return_type;
+  static return_type Read(const uint8_t *p, uoffset_t i) {
+    return EndianScalar((reinterpret_cast<const T *>(p))[i]);
+  }
+};
+template<typename T> struct IndirectHelper<Offset<T>> {
+  typedef const T *return_type;
+  static return_type Read(const uint8_t *p, uoffset_t i) {
+    p += i * sizeof(uoffset_t);
+    return EndianScalar(reinterpret_cast<return_type>(
+        p + ReadScalar<uoffset_t>(p)));
+  }
+};
+template<typename T> struct IndirectHelper<const T *> {
+  typedef const T &return_type;
+  static return_type Read(const uint8_t *p, uoffset_t i) {
+    return *reinterpret_cast<const T *>(p + i * sizeof(T));
+  }
+};
+
+// This is used as a helper type for accessing vectors.
+// Vector::data() assumes the vector elements start after the length field.
+template<typename T> class Vector {
+ public:
+  uoffset_t Length() const { return EndianScalar(length_); }
+
+  typedef typename IndirectHelper<T>::return_type return_type;
+
+  return_type Get(uoffset_t i) const {
+    assert(i < Length());
+    return IndirectHelper<T>::Read(Data(), i);
+  }
+
+  const void *GetStructFromOffset(size_t o) const {
+    return reinterpret_cast<const void *>(Data() + o);
+  }
+
+ protected:
+  // This class is only used to access pre-existing data. Don't ever
+  // try to construct these manually.
+  Vector();
+
+  const uint8_t *Data() const {
+    return reinterpret_cast<const uint8_t *>(&length_ + 1);
+  }
+
+  uoffset_t length_;
+};
+
+struct String : public Vector<char> {
+  const char *c_str() const { return reinterpret_cast<const char *>(Data()); }
+};
+
+// This is a minimal replication of std::vector<uint8_t> functionality,
+// except growing from higher to lower addresses. i.e push_back() inserts data
+// in the lowest address in the vector.
+class vector_downward {
+ public:
+  explicit vector_downward(uoffset_t initial_size)
+    : reserved_(initial_size),
+      buf_(new uint8_t[reserved_]),
+      cur_(buf_ + reserved_) {
+    assert((initial_size & (sizeof(largest_scalar_t) - 1)) == 0);
+  }
+
+  ~vector_downward() { delete[] buf_; }
+
+  void clear() { cur_ = buf_ + reserved_; }
+
+  uoffset_t growth_policy(uoffset_t size) {
+    return (size / 2) & ~(sizeof(largest_scalar_t) - 1);
+  }
+
+  uint8_t *make_space(uoffset_t len) {
+    if (buf_ > cur_ - len) {
+      auto old_size = size();
+      reserved_ += std::max(len, growth_policy(reserved_));
+      auto new_buf = new uint8_t[reserved_];
+      auto new_cur = new_buf + reserved_ - old_size;
+      memcpy(new_cur, cur_, old_size);
+      cur_ = new_cur;
+      delete[] buf_;
+      buf_ = new_buf;
+    }
+    cur_ -= len;
+    // Beyond this, signed offsets may not have enough range:
+    // (FlatBuffers > 2GB not supported).
+    assert(size() < (1UL << (sizeof(soffset_t) * 8 - 1)) - 1);
+    return cur_;
+  }
+
+  uoffset_t size() const {
+    return static_cast<uoffset_t>(reserved_ - (cur_ - buf_));
+  }
+
+  uint8_t *data() const { return cur_; }
+
+  uint8_t *data_at(uoffset_t offset) { return buf_ + reserved_ - offset; }
+
+  // push() & fill() are most frequently called with small byte counts (<= 4),
+  // which is why we're using loops rather than calling memcpy/memset.
+  void push(const uint8_t *bytes, size_t size) {
+    auto dest = make_space(size);
+    for (size_t i = 0; i < size; i++) dest[i] = bytes[i];
+  }
+
+  void fill(size_t zero_pad_bytes) {
+    auto dest = make_space(zero_pad_bytes);
+    for (size_t i = 0; i < zero_pad_bytes; i++) dest[i] = 0;
+  }
+
+  void pop(size_t bytes_to_remove) { cur_ += bytes_to_remove; }
+
+ private:
+  uoffset_t reserved_;
+  uint8_t *buf_;
+  uint8_t *cur_;  // Points at location between empty (below) and used (above).
+};
+
+// Converts a Field ID to a virtual table offset.
+inline voffset_t FieldIndexToOffset(voffset_t field_id) {
+  // Should correspond to what EndTable() below builds up.
+  const int fixed_fields = 2;  // Vtable size and Object Size.
+  return (field_id + fixed_fields) * sizeof(voffset_t);
+}
+
+// Computes how many bytes you'd have to pad to be able to write an
+// "scalar_size" scalar if the buffer had grown to "buf_size" (downwards in
+// memory).
+inline size_t PaddingBytes(size_t buf_size, size_t scalar_size) {
+  return ((~buf_size) + 1) & (scalar_size - 1);
+}
+
+// Helper class to hold data needed in creation of a flat buffer.
+// To serialize data, you typically call one of the Create*() functions in
+// the generated code, which in turn call a sequence of StartTable/PushElement/
+// AddElement/EndTable, or the builtin CreateString/CreateVector functions.
+// Do this is depth-first order to build up a tree to the root.
+// Finish() wraps up the buffer ready for transport.
+class FlatBufferBuilder {
+ public:
+  explicit FlatBufferBuilder(uoffset_t initial_size = 1024)
+    : buf_(initial_size), minalign_(1), force_defaults_(false) {
+    offsetbuf_.reserve(16);  // Avoid first few reallocs.
+    vtables_.reserve(16);
+    EndianCheck();
+    flatbuffer_version_string =
+	    "FlatBuffers "
+	    FLATBUFFERS_STRING(FLATBUFFERS_VERSION_MAJOR) "."
+	    FLATBUFFERS_STRING(FLATBUFFERS_VERSION_MINOR) "."
+	    FLATBUFFERS_STRING(FLATBUFFERS_VERSION_REVISION);
+  }
+
+  // Reset all the state in this FlatBufferBuilder so it can be reused
+  // to construct another buffer.
+  void Clear() {
+    buf_.clear();
+    offsetbuf_.clear();
+    vtables_.clear();
+  }
+
+  // The current size of the serialized buffer, counting from the end.
+  uoffset_t GetSize() const { return buf_.size(); }
+
+  // Get the serialized buffer (after you call Finish()).
+  uint8_t *GetBufferPointer() const { return buf_.data(); }
+
+  const char *GetVersionString() { return flatbuffer_version_string; }
+
+  void ForceDefaults(bool fd) { force_defaults_ = fd; }
+
+  void Pad(size_t num_bytes) { buf_.fill(num_bytes); }
+
+  void Align(size_t elem_size) {
+    if (elem_size > minalign_) minalign_ = elem_size;
+    buf_.fill(PaddingBytes(buf_.size(), elem_size));
+  }
+
+  void PushBytes(const uint8_t *bytes, size_t size) {
+    buf_.push(bytes, size);
+  }
+
+  void PopBytes(size_t amount) { buf_.pop(amount); }
+
+  template<typename T> void AssertScalarT() {
+    // The code assumes power of 2 sizes and endian-swap-ability.
+    static_assert(std::is_scalar<T>::value
+        // The Offset<T> type is essentially a scalar but fails is_scalar.
+        || sizeof(T) == sizeof(Offset<void>),
+           "T must be a scalar type");
+  }
+
+  // Write a single aligned scalar to the buffer
+  template<typename T> uoffset_t PushElement(T element) {
+    AssertScalarT<T>();
+    T litle_endian_element = EndianScalar(element);
+    Align(sizeof(T));
+    PushBytes(reinterpret_cast<uint8_t *>(&litle_endian_element), sizeof(T));
+    return GetSize();
+  }
+
+  template<typename T> uoffset_t PushElement(Offset<T> off) {
+    // Special case for offsets: see ReferTo below.
+    return PushElement(ReferTo(off.o));
+  }
+
+  // When writing fields, we track where they are, so we can create correct
+  // vtables later.
+  void TrackField(voffset_t field, uoffset_t off) {
+    FieldLoc fl = { off, field };
+    offsetbuf_.push_back(fl);
+  }
+
+  // Like PushElement, but additionally tracks the field this represents.
+  template<typename T> void AddElement(voffset_t field, T e, T def) {
+    // We don't serialize values equal to the default.
+    if (e == def && !force_defaults_) return;
+    auto off = PushElement(e);
+    TrackField(field, off);
+  }
+
+  template<typename T> void AddOffset(voffset_t field, Offset<T> off) {
+    if (!off.o) return;  // An offset of 0 means NULL, don't store.
+    AddElement(field, ReferTo(off.o), static_cast<uoffset_t>(0));
+  }
+
+  template<typename T> void AddStruct(voffset_t field, const T *structptr) {
+    if (!structptr) return;  // Default, don't store.
+    Align(AlignOf<T>());
+    PushBytes(reinterpret_cast<const uint8_t *>(structptr), sizeof(T));
+    TrackField(field, GetSize());
+  }
+
+  void AddStructOffset(voffset_t field, uoffset_t off) {
+    TrackField(field, off);
+  }
+
+  // Offsets initially are relative to the end of the buffer (downwards).
+  // This function converts them to be relative to the current location
+  // in the buffer (when stored here), pointing upwards.
+  uoffset_t ReferTo(uoffset_t off) {
+    Align(sizeof(uoffset_t));  // To ensure GetSize() below is correct.
+    assert(off <= GetSize());  // Must refer to something already in buffer.
+    return GetSize() - off + sizeof(uoffset_t);
+  }
+
+  void NotNested() {
+    // If you hit this, you're trying to construct an object when another
+    // hasn't finished yet.
+    assert(!offsetbuf_.size());
+  }
+
+  // From generated code (or from the parser), we call StartTable/EndTable
+  // with a sequence of AddElement calls in between.
+  uoffset_t StartTable() {
+    NotNested();
+    return GetSize();
+  }
+
+  // This finishes one serialized object by generating the vtable if it's a
+  // table, comparing it against existing vtables, and writing the
+  // resulting vtable offset.
+  uoffset_t EndTable(uoffset_t start, voffset_t numfields) {
+    // Write the vtable offset, which is the start of any Table.
+    // We fill it's value later.
+    auto vtableoffsetloc = PushElement<uoffset_t>(0);
+    // Write a vtable, which consists entirely of voffset_t elements.
+    // It starts with the number of offsets, followed by a type id, followed
+    // by the offsets themselves. In reverse:
+    buf_.fill(numfields * sizeof(voffset_t));
+    auto table_object_size = vtableoffsetloc - start;
+    assert(table_object_size < 0x10000);  // Vtable use 16bit offsets.
+    PushElement<voffset_t>(table_object_size);
+    PushElement<voffset_t>(FieldIndexToOffset(numfields));
+    // Write the offsets into the table
+    for (auto field_location = offsetbuf_.begin();
+              field_location != offsetbuf_.end();
+            ++field_location) {
+      auto pos = (vtableoffsetloc - field_location->off);
+      // If this asserts, it means you've set a field twice.
+      assert(!ReadScalar<voffset_t>(buf_.data() + field_location->id));
+      WriteScalar<voffset_t>(buf_.data() + field_location->id, pos);
+    }
+    offsetbuf_.clear();
+    auto vt1 = reinterpret_cast<voffset_t *>(buf_.data());
+    auto vt1_size = *vt1;
+    auto vt_use = GetSize();
+    // See if we already have generated a vtable with this exact same
+    // layout before. If so, make it point to the old one, remove this one.
+    for (auto it = vtables_.begin(); it != vtables_.end(); ++it) {
+      if (memcmp(buf_.data_at(*it), vt1, vt1_size)) continue;
+      vt_use = *it;
+      buf_.pop(GetSize() - vtableoffsetloc);
+      break;
+    }
+    // If this is a new vtable, remember it.
+    if (vt_use == GetSize()) {
+      vtables_.push_back(vt_use);
+    }
+    // Fill the vtable offset we created above.
+    // The offset points from the beginning of the object to where the
+    // vtable is stored.
+    // Offsets default direction is downward in memory for future format
+    // flexibility (storing all vtables at the start of the file).
+    WriteScalar(buf_.data_at(vtableoffsetloc),
+                static_cast<soffset_t>(vt_use) -
+                  static_cast<soffset_t>(vtableoffsetloc));
+    return vtableoffsetloc;
+  }
+
+  uoffset_t StartStruct(size_t alignment) {
+    Align(alignment);
+    return GetSize();
+  }
+
+  uoffset_t EndStruct() { return GetSize(); }
+
+  void ClearOffsets() { offsetbuf_.clear(); }
+
+  // Aligns such that when "len" bytes are written, an object can be written
+  // after it with "alignment" without padding.
+  void PreAlign(size_t len, size_t alignment) {
+    buf_.fill(PaddingBytes(GetSize() + len, alignment));
+  }
+  template<typename T> void PreAlign(size_t len) {
+    AssertScalarT<T>();
+    PreAlign(len, sizeof(T));
+  }
+
+  // Functions to store strings, which are allowed to contain any binary data.
+  Offset<String> CreateString(const char *str, size_t len) {
+    NotNested();
+    PreAlign<uoffset_t>(len + 1);  // Always 0-terminated.
+    buf_.fill(1);
+    PushBytes(reinterpret_cast<const uint8_t *>(str), len);
+    PushElement(static_cast<uoffset_t>(len));
+    return Offset<String>(GetSize());
+  }
+
+  Offset<String> CreateString(const char *str) {
+    return CreateString(str, strlen(str));
+  }
+
+  Offset<String> CreateString(const std::string &str) {
+    return CreateString(str.c_str(), str.length());
+  }
+
+  uoffset_t EndVector(size_t len) {
+    return PushElement(static_cast<uoffset_t>(len));
+  }
+
+  void StartVector(size_t len, size_t elemsize) {
+    PreAlign<uoffset_t>(len * elemsize);
+    PreAlign(len * elemsize, elemsize);  // Just in case elemsize > uoffset_t.
+  }
+
+  uint8_t *ReserveElements(size_t len, size_t elemsize) {
+    return buf_.make_space(len * elemsize);
+  }
+
+  template<typename T> Offset<Vector<T>> CreateVector(const T *v, size_t len) {
+    NotNested();
+    StartVector(len, sizeof(T));
+    auto i = len;
+    do {
+      PushElement(v[--i]);
+    } while (i);
+    return Offset<Vector<T>>(EndVector(len));
+  }
+
+  template<typename T> Offset<Vector<T>> CreateVector(const std::vector<T> &v){
+    return CreateVector(&v[0], v.size());
+  }
+
+  template<typename T> Offset<Vector<const T *>> CreateVectorOfStructs(
+                                                      const T *v, size_t len) {
+    NotNested();
+    StartVector(len, AlignOf<T>());
+    PushBytes(reinterpret_cast<const uint8_t *>(v), sizeof(T) * len);
+    return Offset<Vector<const T *>>(EndVector(len));
+  }
+
+  template<typename T> Offset<Vector<const T *>> CreateVectorOfStructs(
+                                                     const std::vector<T> &v) {
+    return CreateVector(&v[0], v.size());
+  }
+
+  // Finish serializing a buffer by writing the root offset.
+  template<typename T> void Finish(Offset<T> root) {
+    // This will cause the whole buffer to be aligned.
+    PreAlign(sizeof(uoffset_t), minalign_);
+    PushElement(ReferTo(root.o));  // Location of root.
+  }
+
+ private:
+  struct FieldLoc {
+    uoffset_t off;
+    voffset_t id;
+  };
+
+  vector_downward buf_;
+
+  // Accumulating offsets of table members while it is being built.
+  std::vector<FieldLoc> offsetbuf_;
+
+  std::vector<uoffset_t> vtables_;  // todo: Could make this into a map?
+
+  size_t minalign_;
+
+  bool force_defaults_;  // Serialize values equal to their defaults anyway.
+
+  // String which identifies the current version of FlatBuffers.
+  // flatbuffer_version_string is used by Google developers to identify which
+  // applications uploaded to Google Play are using this library.  This allows
+  // the development team at Google to determine the popularity of the library.
+  // How it works: Applications that are uploaded to the Google Play Store are
+  // scanned for this version string.  We track which applications are using it
+  // to measure popularity.  You are free to remove it (of course) but we would
+  // appreciate if you left it in.
+  const char *flatbuffer_version_string;
+};
+
+// Helper to get a typed pointer to the root object contained in the buffer.
+template<typename T> const T *GetRoot(const void *buf) {
+  EndianCheck();
+  return reinterpret_cast<const T *>(reinterpret_cast<const uint8_t *>(buf) +
+    EndianScalar(*reinterpret_cast<const uoffset_t *>(buf)));
+}
+
+// "structs_" are flat structures that do not have an offset table, thus
+// always have all members present and do not support forwards/backwards
+// compatible extensions.
+
+class Struct {
+ public:
+  template<typename T> T GetField(uoffset_t o) const {
+    return ReadScalar<T>(&data_[o]);
+  }
+
+  template<typename T> T GetPointer(uoffset_t o) const {
+    auto p = &data_[o];
+    return reinterpret_cast<T>(p + ReadScalar<uoffset_t>(p));
+  }
+
+  template<typename T> T GetStruct(uoffset_t o) const {
+    return reinterpret_cast<T>(&data_[o]);
+  }
+
+ private:
+  uint8_t data_[1];
+};
+
+// "tables" use an offset table (possibly shared) that allows fields to be
+// omitted and added at will, but uses an extra indirection to read.
+class Table {
+ public:
+  // This gets the field offset for any of the functions below it, or 0
+  // if the field was not present.
+  voffset_t GetOptionalFieldOffset(voffset_t field) const {
+    // The vtable offset is always at the start.
+    auto vtable = &data_ - ReadScalar<soffset_t>(&data_);
+    // The first element is the size of the vtable (fields + type id + itself).
+    auto vtsize = ReadScalar<voffset_t>(vtable);
+    // If the field we're accessing is outside the vtable, we're reading older
+    // data, so it's the same as if the offset was 0 (not present).
+    return field < vtsize ? ReadScalar<voffset_t>(vtable + field) : 0;
+  }
+
+  template<typename T> T GetField(voffset_t field, T defaultval) const {
+    auto field_offset = GetOptionalFieldOffset(field);
+    return field_offset ? ReadScalar<T>(&data_[field_offset]) : defaultval;
+  }
+
+  template<typename P> P GetPointer(voffset_t field) const {
+    auto field_offset = GetOptionalFieldOffset(field);
+    auto p = &data_[field_offset];
+    return field_offset
+      ? reinterpret_cast<P>(p + ReadScalar<uoffset_t>(p))
+      : nullptr;
+  }
+
+  template<typename P> P GetStruct(voffset_t field) const {
+    auto field_offset = GetOptionalFieldOffset(field);
+    return field_offset ? reinterpret_cast<P>(&data_[field_offset]) : nullptr;
+  }
+
+  template<typename T> void SetField(voffset_t field, T val) {
+    auto field_offset = GetOptionalFieldOffset(field);
+    // If this asserts, you're trying to set a field that's not there
+    // (or should we return a bool instead?).
+    // check if it exists first using CheckField()
+    assert(field_offset);
+    WriteScalar(&data_[field_offset], val);
+  }
+
+  bool CheckField(voffset_t field) const {
+    return GetOptionalFieldOffset(field) != 0;
+  }
+
+ private:
+  // private constructor & copy constructor: you obtain instances of this
+  // class by pointing to existing data only
+  Table() {};
+  Table(const Table &other) {};
+
+  uint8_t data_[1];
+};
+
+// Utility function for reverse lookups on the EnumNames*() functions
+// (in the generated C++ code)
+// names must be NULL terminated.
+inline size_t LookupEnum(const char **names, const char *name) {
+  for (const char **p = names; *p; p++)
+    if (!strcmp(*p, name))
+      return p - names;
+  return -1;
+}
+
+// These macros allow us to layout a struct with a guarantee that they'll end
+// up looking the same on different compilers and platforms.
+// It does this by disallowing the compiler to do any padding, and then
+// does padding itself by inserting extra padding fields that make every
+// element aligned to its own size.
+// Additionally, it manually sets the alignment of the struct as a whole,
+// which is typically its largest element, or a custom size set in the schema
+// by the force_align attribute.
+// These are used in the generated code only.
+
+#if defined(_MSC_VER)
+  #define MANUALLY_ALIGNED_STRUCT(alignment) \
+    __pragma(pack(1)); \
+    struct __declspec(align(alignment))
+  #define STRUCT_END(name, size) \
+    __pragma(pack()); \
+    static_assert(sizeof(name) == size, "compiler breaks packing rules");
+#elif defined(__GNUC__) || defined(__clang__)
+  #define MANUALLY_ALIGNED_STRUCT(alignment) \
+    _Pragma("pack(1)"); \
+    struct __attribute__((aligned(alignment)))
+  #define STRUCT_END(name, size) \
+    _Pragma("pack()"); \
+    static_assert(sizeof(name) == size, "compiler breaks packing rules");
+#else
+  #error Unknown compiler, please define structure alignment macros
+#endif
+
+}  // namespace flatbuffers
+
+#endif  // FLATBUFFERS_H_