/
flexbuffers.h
1538 lines (1362 loc) · 51.6 KB
/
flexbuffers.h
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/*
* Copyright 2017 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_FLEXBUFFERS_H_
#define FLATBUFFERS_FLEXBUFFERS_H_
#include <map>
// Used to select STL variant.
#include "flatbuffers/base.h"
// We use the basic binary writing functions from the regular FlatBuffers.
#include "flatbuffers/util.h"
#ifdef _MSC_VER
# include <intrin.h>
#endif
#if defined(_MSC_VER)
# pragma warning(push)
# pragma warning(disable : 4127) // C4127: conditional expression is constant
#endif
namespace flexbuffers {
class Reference;
class Map;
// These are used in the lower 2 bits of a type field to determine the size of
// the elements (and or size field) of the item pointed to (e.g. vector).
enum BitWidth {
BIT_WIDTH_8 = 0,
BIT_WIDTH_16 = 1,
BIT_WIDTH_32 = 2,
BIT_WIDTH_64 = 3,
};
// These are used as the upper 6 bits of a type field to indicate the actual
// type.
enum Type {
FBT_NULL = 0,
FBT_INT = 1,
FBT_UINT = 2,
FBT_FLOAT = 3,
// Types above stored inline, types below store an offset.
FBT_KEY = 4,
FBT_STRING = 5,
FBT_INDIRECT_INT = 6,
FBT_INDIRECT_UINT = 7,
FBT_INDIRECT_FLOAT = 8,
FBT_MAP = 9,
FBT_VECTOR = 10, // Untyped.
FBT_VECTOR_INT = 11, // Typed any size (stores no type table).
FBT_VECTOR_UINT = 12,
FBT_VECTOR_FLOAT = 13,
FBT_VECTOR_KEY = 14,
FBT_VECTOR_STRING = 15,
FBT_VECTOR_INT2 = 16, // Typed tuple (no type table, no size field).
FBT_VECTOR_UINT2 = 17,
FBT_VECTOR_FLOAT2 = 18,
FBT_VECTOR_INT3 = 19, // Typed triple (no type table, no size field).
FBT_VECTOR_UINT3 = 20,
FBT_VECTOR_FLOAT3 = 21,
FBT_VECTOR_INT4 = 22, // Typed quad (no type table, no size field).
FBT_VECTOR_UINT4 = 23,
FBT_VECTOR_FLOAT4 = 24,
FBT_BLOB = 25,
FBT_BOOL = 26,
FBT_VECTOR_BOOL =
36, // To Allow the same type of conversion of type to vector type
};
inline bool IsInline(Type t) { return t <= FBT_FLOAT || t == FBT_BOOL; }
inline bool IsTypedVectorElementType(Type t) {
return (t >= FBT_INT && t <= FBT_STRING) || t == FBT_BOOL;
}
inline bool IsTypedVector(Type t) {
return (t >= FBT_VECTOR_INT && t <= FBT_VECTOR_STRING) ||
t == FBT_VECTOR_BOOL;
}
inline bool IsFixedTypedVector(Type t) {
return t >= FBT_VECTOR_INT2 && t <= FBT_VECTOR_FLOAT4;
}
inline Type ToTypedVector(Type t, size_t fixed_len = 0) {
FLATBUFFERS_ASSERT(IsTypedVectorElementType(t));
switch (fixed_len) {
case 0: return static_cast<Type>(t - FBT_INT + FBT_VECTOR_INT);
case 2: return static_cast<Type>(t - FBT_INT + FBT_VECTOR_INT2);
case 3: return static_cast<Type>(t - FBT_INT + FBT_VECTOR_INT3);
case 4: return static_cast<Type>(t - FBT_INT + FBT_VECTOR_INT4);
default: FLATBUFFERS_ASSERT(0); return FBT_NULL;
}
}
inline Type ToTypedVectorElementType(Type t) {
FLATBUFFERS_ASSERT(IsTypedVector(t));
return static_cast<Type>(t - FBT_VECTOR_INT + FBT_INT);
}
inline Type ToFixedTypedVectorElementType(Type t, uint8_t *len) {
FLATBUFFERS_ASSERT(IsFixedTypedVector(t));
auto fixed_type = t - FBT_VECTOR_INT2;
*len = static_cast<uint8_t>(fixed_type / 3 +
2); // 3 types each, starting from length 2.
return static_cast<Type>(fixed_type % 3 + FBT_INT);
}
// TODO: implement proper support for 8/16bit floats, or decide not to
// support them.
typedef int16_t half;
typedef int8_t quarter;
// TODO: can we do this without conditionals using intrinsics or inline asm
// on some platforms? Given branch prediction the method below should be
// decently quick, but it is the most frequently executed function.
// We could do an (unaligned) 64-bit read if we ifdef out the platforms for
// which that doesn't work (or where we'd read into un-owned memory).
template<typename R, typename T1, typename T2, typename T4, typename T8>
R ReadSizedScalar(const uint8_t *data, uint8_t byte_width) {
return byte_width < 4
? (byte_width < 2
? static_cast<R>(flatbuffers::ReadScalar<T1>(data))
: static_cast<R>(flatbuffers::ReadScalar<T2>(data)))
: (byte_width < 8
? static_cast<R>(flatbuffers::ReadScalar<T4>(data))
: static_cast<R>(flatbuffers::ReadScalar<T8>(data)));
}
inline int64_t ReadInt64(const uint8_t *data, uint8_t byte_width) {
return ReadSizedScalar<int64_t, int8_t, int16_t, int32_t, int64_t>(
data, byte_width);
}
inline uint64_t ReadUInt64(const uint8_t *data, uint8_t byte_width) {
// This is the "hottest" function (all offset lookups use this), so worth
// optimizing if possible.
// TODO: GCC apparently replaces memcpy by a rep movsb, but only if count is a
// constant, which here it isn't. Test if memcpy is still faster than
// the conditionals in ReadSizedScalar. Can also use inline asm.
// clang-format off
#if defined(_MSC_VER) && (defined(_M_X64) || defined _M_IX86)
uint64_t u = 0;
__movsb(reinterpret_cast<uint8_t *>(&u),
reinterpret_cast<const uint8_t *>(data), byte_width);
return flatbuffers::EndianScalar(u);
#else
return ReadSizedScalar<uint64_t, uint8_t, uint16_t, uint32_t, uint64_t>(
data, byte_width);
#endif
// clang-format on
}
inline double ReadDouble(const uint8_t *data, uint8_t byte_width) {
return ReadSizedScalar<double, quarter, half, float, double>(data,
byte_width);
}
inline const uint8_t *Indirect(const uint8_t *offset, uint8_t byte_width) {
return offset - ReadUInt64(offset, byte_width);
}
template<typename T> const uint8_t *Indirect(const uint8_t *offset) {
return offset - flatbuffers::ReadScalar<T>(offset);
}
inline BitWidth WidthU(uint64_t u) {
#define FLATBUFFERS_GET_FIELD_BIT_WIDTH(value, width) \
{ \
if (!((u) & ~((1ULL << (width)) - 1ULL))) return BIT_WIDTH_##width; \
}
FLATBUFFERS_GET_FIELD_BIT_WIDTH(u, 8);
FLATBUFFERS_GET_FIELD_BIT_WIDTH(u, 16);
FLATBUFFERS_GET_FIELD_BIT_WIDTH(u, 32);
#undef FLATBUFFERS_GET_FIELD_BIT_WIDTH
return BIT_WIDTH_64;
}
inline BitWidth WidthI(int64_t i) {
auto u = static_cast<uint64_t>(i) << 1;
return WidthU(i >= 0 ? u : ~u);
}
inline BitWidth WidthF(double f) {
return static_cast<double>(static_cast<float>(f)) == f ? BIT_WIDTH_32
: BIT_WIDTH_64;
}
// Base class of all types below.
// Points into the data buffer and allows access to one type.
class Object {
public:
Object(const uint8_t *data, uint8_t byte_width)
: data_(data), byte_width_(byte_width) {}
protected:
const uint8_t *data_;
uint8_t byte_width_;
};
// Stores size in `byte_width_` bytes before data_ pointer.
class Sized : public Object {
public:
Sized(const uint8_t *data, uint8_t byte_width) : Object(data, byte_width) {}
size_t size() const {
return static_cast<size_t>(ReadUInt64(data_ - byte_width_, byte_width_));
}
};
class String : public Sized {
public:
String(const uint8_t *data, uint8_t byte_width) : Sized(data, byte_width) {}
size_t length() const { return size(); }
const char *c_str() const { return reinterpret_cast<const char *>(data_); }
std::string str() const { return std::string(c_str(), length()); }
static String EmptyString() {
static const uint8_t empty_string[] = { 0 /*len*/, 0 /*terminator*/ };
return String(empty_string + 1, 1);
}
bool IsTheEmptyString() const { return data_ == EmptyString().data_; }
};
class Blob : public Sized {
public:
Blob(const uint8_t *data_buf, uint8_t byte_width)
: Sized(data_buf, byte_width) {}
static Blob EmptyBlob() {
static const uint8_t empty_blob[] = { 0 /*len*/ };
return Blob(empty_blob + 1, 1);
}
bool IsTheEmptyBlob() const { return data_ == EmptyBlob().data_; }
const uint8_t *data() const { return data_; }
};
class Vector : public Sized {
public:
Vector(const uint8_t *data, uint8_t byte_width) : Sized(data, byte_width) {}
Reference operator[](size_t i) const;
static Vector EmptyVector() {
static const uint8_t empty_vector[] = { 0 /*len*/ };
return Vector(empty_vector + 1, 1);
}
bool IsTheEmptyVector() const { return data_ == EmptyVector().data_; }
};
class TypedVector : public Sized {
public:
TypedVector(const uint8_t *data, uint8_t byte_width, Type element_type)
: Sized(data, byte_width), type_(element_type) {}
Reference operator[](size_t i) const;
static TypedVector EmptyTypedVector() {
static const uint8_t empty_typed_vector[] = { 0 /*len*/ };
return TypedVector(empty_typed_vector + 1, 1, FBT_INT);
}
bool IsTheEmptyVector() const {
return data_ == TypedVector::EmptyTypedVector().data_;
}
Type ElementType() { return type_; }
private:
Type type_;
friend Map;
};
class FixedTypedVector : public Object {
public:
FixedTypedVector(const uint8_t *data, uint8_t byte_width, Type element_type,
uint8_t len)
: Object(data, byte_width), type_(element_type), len_(len) {}
Reference operator[](size_t i) const;
static FixedTypedVector EmptyFixedTypedVector() {
static const uint8_t fixed_empty_vector[] = { 0 /* unused */ };
return FixedTypedVector(fixed_empty_vector, 1, FBT_INT, 0);
}
bool IsTheEmptyFixedTypedVector() const {
return data_ == FixedTypedVector::EmptyFixedTypedVector().data_;
}
Type ElementType() { return type_; }
uint8_t size() { return len_; }
private:
Type type_;
uint8_t len_;
};
class Map : public Vector {
public:
Map(const uint8_t *data, uint8_t byte_width) : Vector(data, byte_width) {}
Reference operator[](const char *key) const;
Reference operator[](const std::string &key) const;
Vector Values() const { return Vector(data_, byte_width_); }
TypedVector Keys() const {
const size_t num_prefixed_fields = 3;
auto keys_offset = data_ - byte_width_ * num_prefixed_fields;
return TypedVector(Indirect(keys_offset, byte_width_),
static_cast<uint8_t>(
ReadUInt64(keys_offset + byte_width_, byte_width_)),
FBT_KEY);
}
static Map EmptyMap() {
static const uint8_t empty_map[] = {
0 /*keys_len*/, 0 /*keys_offset*/, 1 /*keys_width*/, 0 /*len*/
};
return Map(empty_map + 4, 1);
}
bool IsTheEmptyMap() const { return data_ == EmptyMap().data_; }
};
template<typename T>
void AppendToString(std::string &s, T &&v, bool keys_quoted) {
s += "[ ";
for (size_t i = 0; i < v.size(); i++) {
if (i) s += ", ";
v[i].ToString(true, keys_quoted, s);
}
s += " ]";
}
class Reference {
public:
Reference(const uint8_t *data, uint8_t parent_width, uint8_t byte_width,
Type type)
: data_(data),
parent_width_(parent_width),
byte_width_(byte_width),
type_(type) {}
Reference(const uint8_t *data, uint8_t parent_width, uint8_t packed_type)
: data_(data), parent_width_(parent_width) {
byte_width_ = 1U << static_cast<BitWidth>(packed_type & 3);
type_ = static_cast<Type>(packed_type >> 2);
}
Type GetType() const { return type_; }
bool IsNull() const { return type_ == FBT_NULL; }
bool IsBool() const { return type_ == FBT_BOOL; }
bool IsInt() const { return type_ == FBT_INT || type_ == FBT_INDIRECT_INT; }
bool IsUInt() const {
return type_ == FBT_UINT || type_ == FBT_INDIRECT_UINT;
}
bool IsIntOrUint() const { return IsInt() || IsUInt(); }
bool IsFloat() const {
return type_ == FBT_FLOAT || type_ == FBT_INDIRECT_FLOAT;
}
bool IsNumeric() const { return IsIntOrUint() || IsFloat(); }
bool IsString() const { return type_ == FBT_STRING; }
bool IsKey() const { return type_ == FBT_KEY; }
bool IsVector() const { return type_ == FBT_VECTOR || type_ == FBT_MAP; }
bool IsTypedVector() const { return flexbuffers::IsTypedVector(type_); }
bool IsFixedTypedVector() const { return flexbuffers::IsFixedTypedVector(type_); }
bool IsAnyVector() const { return (IsTypedVector() || IsFixedTypedVector() || IsVector());}
bool IsMap() const { return type_ == FBT_MAP; }
bool IsBlob() const { return type_ == FBT_BLOB; }
bool AsBool() const {
return (type_ == FBT_BOOL ? ReadUInt64(data_, parent_width_)
: AsUInt64()) != 0;
}
// Reads any type as a int64_t. Never fails, does most sensible conversion.
// Truncates floats, strings are attempted to be parsed for a number,
// vectors/maps return their size. Returns 0 if all else fails.
int64_t AsInt64() const {
if (type_ == FBT_INT) {
// A fast path for the common case.
return ReadInt64(data_, parent_width_);
} else
switch (type_) {
case FBT_INDIRECT_INT: return ReadInt64(Indirect(), byte_width_);
case FBT_UINT: return ReadUInt64(data_, parent_width_);
case FBT_INDIRECT_UINT: return ReadUInt64(Indirect(), byte_width_);
case FBT_FLOAT:
return static_cast<int64_t>(ReadDouble(data_, parent_width_));
case FBT_INDIRECT_FLOAT:
return static_cast<int64_t>(ReadDouble(Indirect(), byte_width_));
case FBT_NULL: return 0;
case FBT_STRING: return flatbuffers::StringToInt(AsString().c_str());
case FBT_VECTOR: return static_cast<int64_t>(AsVector().size());
case FBT_BOOL: return ReadInt64(data_, parent_width_);
default:
// Convert other things to int.
return 0;
}
}
// TODO: could specialize these to not use AsInt64() if that saves
// extension ops in generated code, and use a faster op than ReadInt64.
int32_t AsInt32() const { return static_cast<int32_t>(AsInt64()); }
int16_t AsInt16() const { return static_cast<int16_t>(AsInt64()); }
int8_t AsInt8() const { return static_cast<int8_t>(AsInt64()); }
uint64_t AsUInt64() const {
if (type_ == FBT_UINT) {
// A fast path for the common case.
return ReadUInt64(data_, parent_width_);
} else
switch (type_) {
case FBT_INDIRECT_UINT: return ReadUInt64(Indirect(), byte_width_);
case FBT_INT: return ReadInt64(data_, parent_width_);
case FBT_INDIRECT_INT: return ReadInt64(Indirect(), byte_width_);
case FBT_FLOAT:
return static_cast<uint64_t>(ReadDouble(data_, parent_width_));
case FBT_INDIRECT_FLOAT:
return static_cast<uint64_t>(ReadDouble(Indirect(), byte_width_));
case FBT_NULL: return 0;
case FBT_STRING: return flatbuffers::StringToUInt(AsString().c_str());
case FBT_VECTOR: return static_cast<uint64_t>(AsVector().size());
case FBT_BOOL: return ReadUInt64(data_, parent_width_);
default:
// Convert other things to uint.
return 0;
}
}
uint32_t AsUInt32() const { return static_cast<uint32_t>(AsUInt64()); }
uint16_t AsUInt16() const { return static_cast<uint16_t>(AsUInt64()); }
uint8_t AsUInt8() const { return static_cast<uint8_t>(AsUInt64()); }
double AsDouble() const {
if (type_ == FBT_FLOAT) {
// A fast path for the common case.
return ReadDouble(data_, parent_width_);
} else
switch (type_) {
case FBT_INDIRECT_FLOAT: return ReadDouble(Indirect(), byte_width_);
case FBT_INT:
return static_cast<double>(ReadInt64(data_, parent_width_));
case FBT_UINT:
return static_cast<double>(ReadUInt64(data_, parent_width_));
case FBT_INDIRECT_INT:
return static_cast<double>(ReadInt64(Indirect(), byte_width_));
case FBT_INDIRECT_UINT:
return static_cast<double>(ReadUInt64(Indirect(), byte_width_));
case FBT_NULL: return 0.0;
case FBT_STRING: return strtod(AsString().c_str(), nullptr);
case FBT_VECTOR: return static_cast<double>(AsVector().size());
case FBT_BOOL:
return static_cast<double>(ReadUInt64(data_, parent_width_));
default:
// Convert strings and other things to float.
return 0;
}
}
float AsFloat() const { return static_cast<float>(AsDouble()); }
const char *AsKey() const {
if (type_ == FBT_KEY) {
return reinterpret_cast<const char *>(Indirect());
} else {
return "";
}
}
// This function returns the empty string if you try to read a not-string.
String AsString() const {
if (type_ == FBT_STRING) {
return String(Indirect(), byte_width_);
} else {
return String::EmptyString();
}
}
// Unlike AsString(), this will convert any type to a std::string.
std::string ToString() const {
std::string s;
ToString(false, false, s);
return s;
}
// Convert any type to a JSON-like string. strings_quoted determines if
// string values at the top level receive "" quotes (inside other values
// they always do). keys_quoted determines if keys are quoted, at any level.
// TODO(wvo): add further options to have indentation/newlines.
void ToString(bool strings_quoted, bool keys_quoted, std::string &s) const {
if (type_ == FBT_STRING) {
String str(Indirect(), byte_width_);
if (strings_quoted) {
flatbuffers::EscapeString(str.c_str(), str.length(), &s, true, false);
} else {
s.append(str.c_str(), str.length());
}
} else if (IsKey()) {
auto str = AsKey();
if (keys_quoted) {
flatbuffers::EscapeString(str, strlen(str), &s, true, false);
} else {
s += str;
}
} else if (IsInt()) {
s += flatbuffers::NumToString(AsInt64());
} else if (IsUInt()) {
s += flatbuffers::NumToString(AsUInt64());
} else if (IsFloat()) {
s += flatbuffers::NumToString(AsDouble());
} else if (IsNull()) {
s += "null";
} else if (IsBool()) {
s += AsBool() ? "true" : "false";
} else if (IsMap()) {
s += "{ ";
auto m = AsMap();
auto keys = m.Keys();
auto vals = m.Values();
for (size_t i = 0; i < keys.size(); i++) {
keys[i].ToString(true, keys_quoted, s);
s += ": ";
vals[i].ToString(true, keys_quoted, s);
if (i < keys.size() - 1) s += ", ";
}
s += " }";
} else if (IsVector()) {
AppendToString<Vector>(s, AsVector(), keys_quoted);
} else if (IsTypedVector()) {
AppendToString<TypedVector>(s, AsTypedVector(), keys_quoted);
} else if (IsFixedTypedVector()) {
AppendToString<FixedTypedVector>(s, AsFixedTypedVector(), keys_quoted);
} else if (IsBlob()) {
auto blob = AsBlob();
flatbuffers::EscapeString(reinterpret_cast<const char*>(blob.data()), blob.size(), &s, true, false);
} else {
s += "(?)";
}
}
// This function returns the empty blob if you try to read a not-blob.
// Strings can be viewed as blobs too.
Blob AsBlob() const {
if (type_ == FBT_BLOB || type_ == FBT_STRING) {
return Blob(Indirect(), byte_width_);
} else {
return Blob::EmptyBlob();
}
}
// This function returns the empty vector if you try to read a not-vector.
// Maps can be viewed as vectors too.
Vector AsVector() const {
if (type_ == FBT_VECTOR || type_ == FBT_MAP) {
return Vector(Indirect(), byte_width_);
} else {
return Vector::EmptyVector();
}
}
TypedVector AsTypedVector() const {
if (IsTypedVector()) {
return TypedVector(Indirect(), byte_width_,
ToTypedVectorElementType(type_));
} else {
return TypedVector::EmptyTypedVector();
}
}
FixedTypedVector AsFixedTypedVector() const {
if (IsFixedTypedVector()) {
uint8_t len = 0;
auto vtype = ToFixedTypedVectorElementType(type_, &len);
return FixedTypedVector(Indirect(), byte_width_, vtype, len);
} else {
return FixedTypedVector::EmptyFixedTypedVector();
}
}
Map AsMap() const {
if (type_ == FBT_MAP) {
return Map(Indirect(), byte_width_);
} else {
return Map::EmptyMap();
}
}
template<typename T> T As() const;
// Experimental: Mutation functions.
// These allow scalars in an already created buffer to be updated in-place.
// Since by default scalars are stored in the smallest possible space,
// the new value may not fit, in which case these functions return false.
// To avoid this, you can construct the values you intend to mutate using
// Builder::ForceMinimumBitWidth.
bool MutateInt(int64_t i) {
if (type_ == FBT_INT) {
return Mutate(data_, i, parent_width_, WidthI(i));
} else if (type_ == FBT_INDIRECT_INT) {
return Mutate(Indirect(), i, byte_width_, WidthI(i));
} else if (type_ == FBT_UINT) {
auto u = static_cast<uint64_t>(i);
return Mutate(data_, u, parent_width_, WidthU(u));
} else if (type_ == FBT_INDIRECT_UINT) {
auto u = static_cast<uint64_t>(i);
return Mutate(Indirect(), u, byte_width_, WidthU(u));
} else {
return false;
}
}
bool MutateBool(bool b) {
return type_ == FBT_BOOL && Mutate(data_, b, parent_width_, BIT_WIDTH_8);
}
bool MutateUInt(uint64_t u) {
if (type_ == FBT_UINT) {
return Mutate(data_, u, parent_width_, WidthU(u));
} else if (type_ == FBT_INDIRECT_UINT) {
return Mutate(Indirect(), u, byte_width_, WidthU(u));
} else if (type_ == FBT_INT) {
auto i = static_cast<int64_t>(u);
return Mutate(data_, i, parent_width_, WidthI(i));
} else if (type_ == FBT_INDIRECT_INT) {
auto i = static_cast<int64_t>(u);
return Mutate(Indirect(), i, byte_width_, WidthI(i));
} else {
return false;
}
}
bool MutateFloat(float f) {
if (type_ == FBT_FLOAT) {
return MutateF(data_, f, parent_width_, BIT_WIDTH_32);
} else if (type_ == FBT_INDIRECT_FLOAT) {
return MutateF(Indirect(), f, byte_width_, BIT_WIDTH_32);
} else {
return false;
}
}
bool MutateFloat(double d) {
if (type_ == FBT_FLOAT) {
return MutateF(data_, d, parent_width_, WidthF(d));
} else if (type_ == FBT_INDIRECT_FLOAT) {
return MutateF(Indirect(), d, byte_width_, WidthF(d));
} else {
return false;
}
}
bool MutateString(const char *str, size_t len) {
auto s = AsString();
if (s.IsTheEmptyString()) return false;
// This is very strict, could allow shorter strings, but that creates
// garbage.
if (s.length() != len) return false;
memcpy(const_cast<char *>(s.c_str()), str, len);
return true;
}
bool MutateString(const char *str) { return MutateString(str, strlen(str)); }
bool MutateString(const std::string &str) {
return MutateString(str.data(), str.length());
}
private:
const uint8_t *Indirect() const {
return flexbuffers::Indirect(data_, parent_width_);
}
template<typename T>
bool Mutate(const uint8_t *dest, T t, size_t byte_width,
BitWidth value_width) {
auto fits = static_cast<size_t>(static_cast<size_t>(1U) << value_width) <=
byte_width;
if (fits) {
t = flatbuffers::EndianScalar(t);
memcpy(const_cast<uint8_t *>(dest), &t, byte_width);
}
return fits;
}
template<typename T>
bool MutateF(const uint8_t *dest, T t, size_t byte_width,
BitWidth value_width) {
if (byte_width == sizeof(double))
return Mutate(dest, static_cast<double>(t), byte_width, value_width);
if (byte_width == sizeof(float))
return Mutate(dest, static_cast<float>(t), byte_width, value_width);
FLATBUFFERS_ASSERT(false);
return false;
}
const uint8_t *data_;
uint8_t parent_width_;
uint8_t byte_width_;
Type type_;
};
// Template specialization for As().
template<> inline bool Reference::As<bool>() const { return AsBool(); }
template<> inline int8_t Reference::As<int8_t>() const { return AsInt8(); }
template<> inline int16_t Reference::As<int16_t>() const { return AsInt16(); }
template<> inline int32_t Reference::As<int32_t>() const { return AsInt32(); }
template<> inline int64_t Reference::As<int64_t>() const { return AsInt64(); }
template<> inline uint8_t Reference::As<uint8_t>() const { return AsUInt8(); }
template<> inline uint16_t Reference::As<uint16_t>() const { return AsUInt16(); }
template<> inline uint32_t Reference::As<uint32_t>() const { return AsUInt32(); }
template<> inline uint64_t Reference::As<uint64_t>() const { return AsUInt64(); }
template<> inline double Reference::As<double>() const { return AsDouble(); }
template<> inline float Reference::As<float>() const { return AsFloat(); }
template<> inline String Reference::As<String>() const { return AsString(); }
template<> inline std::string Reference::As<std::string>() const {
return AsString().str();
}
template<> inline Blob Reference::As<Blob>() const { return AsBlob(); }
template<> inline Vector Reference::As<Vector>() const { return AsVector(); }
template<> inline TypedVector Reference::As<TypedVector>() const {
return AsTypedVector();
}
template<> inline FixedTypedVector Reference::As<FixedTypedVector>() const {
return AsFixedTypedVector();
}
template<> inline Map Reference::As<Map>() const { return AsMap(); }
inline uint8_t PackedType(BitWidth bit_width, Type type) {
return static_cast<uint8_t>(bit_width | (type << 2));
}
inline uint8_t NullPackedType() { return PackedType(BIT_WIDTH_8, FBT_NULL); }
// Vector accessors.
// Note: if you try to access outside of bounds, you get a Null value back
// instead. Normally this would be an assert, but since this is "dynamically
// typed" data, you may not want that (someone sends you a 2d vector and you
// wanted 3d).
// The Null converts seamlessly into a default value for any other type.
// TODO(wvo): Could introduce an #ifdef that makes this into an assert?
inline Reference Vector::operator[](size_t i) const {
auto len = size();
if (i >= len) return Reference(nullptr, 1, NullPackedType());
auto packed_type = (data_ + len * byte_width_)[i];
auto elem = data_ + i * byte_width_;
return Reference(elem, byte_width_, packed_type);
}
inline Reference TypedVector::operator[](size_t i) const {
auto len = size();
if (i >= len) return Reference(nullptr, 1, NullPackedType());
auto elem = data_ + i * byte_width_;
return Reference(elem, byte_width_, 1, type_);
}
inline Reference FixedTypedVector::operator[](size_t i) const {
if (i >= len_) return Reference(nullptr, 1, NullPackedType());
auto elem = data_ + i * byte_width_;
return Reference(elem, byte_width_, 1, type_);
}
template<typename T> int KeyCompare(const void *key, const void *elem) {
auto str_elem = reinterpret_cast<const char *>(
Indirect<T>(reinterpret_cast<const uint8_t *>(elem)));
auto skey = reinterpret_cast<const char *>(key);
return strcmp(skey, str_elem);
}
inline Reference Map::operator[](const char *key) const {
auto keys = Keys();
// We can't pass keys.byte_width_ to the comparison function, so we have
// to pick the right one ahead of time.
int (*comp)(const void *, const void *) = nullptr;
switch (keys.byte_width_) {
case 1: comp = KeyCompare<uint8_t>; break;
case 2: comp = KeyCompare<uint16_t>; break;
case 4: comp = KeyCompare<uint32_t>; break;
case 8: comp = KeyCompare<uint64_t>; break;
}
auto res = std::bsearch(key, keys.data_, keys.size(), keys.byte_width_, comp);
if (!res) return Reference(nullptr, 1, NullPackedType());
auto i = (reinterpret_cast<uint8_t *>(res) - keys.data_) / keys.byte_width_;
return (*static_cast<const Vector *>(this))[i];
}
inline Reference Map::operator[](const std::string &key) const {
return (*this)[key.c_str()];
}
inline Reference GetRoot(const uint8_t *buffer, size_t size) {
// See Finish() below for the serialization counterpart of this.
// The root starts at the end of the buffer, so we parse backwards from there.
auto end = buffer + size;
auto byte_width = *--end;
auto packed_type = *--end;
end -= byte_width; // The root data item.
return Reference(end, byte_width, packed_type);
}
inline Reference GetRoot(const std::vector<uint8_t> &buffer) {
return GetRoot(flatbuffers::vector_data(buffer), buffer.size());
}
// Flags that configure how the Builder behaves.
// The "Share" flags determine if the Builder automatically tries to pool
// this type. Pooling can reduce the size of serialized data if there are
// multiple maps of the same kind, at the expense of slightly slower
// serialization (the cost of lookups) and more memory use (std::set).
// By default this is on for keys, but off for strings.
// Turn keys off if you have e.g. only one map.
// Turn strings on if you expect many non-unique string values.
// Additionally, sharing key vectors can save space if you have maps with
// identical field populations.
enum BuilderFlag {
BUILDER_FLAG_NONE = 0,
BUILDER_FLAG_SHARE_KEYS = 1,
BUILDER_FLAG_SHARE_STRINGS = 2,
BUILDER_FLAG_SHARE_KEYS_AND_STRINGS = 3,
BUILDER_FLAG_SHARE_KEY_VECTORS = 4,
BUILDER_FLAG_SHARE_ALL = 7,
};
class Builder FLATBUFFERS_FINAL_CLASS {
public:
Builder(size_t initial_size = 256,
BuilderFlag flags = BUILDER_FLAG_SHARE_KEYS)
: buf_(initial_size),
finished_(false),
flags_(flags),
force_min_bit_width_(BIT_WIDTH_8),
key_pool(KeyOffsetCompare(buf_)),
string_pool(StringOffsetCompare(buf_)) {
buf_.clear();
}
/// @brief Get the serialized buffer (after you call `Finish()`).
/// @return Returns a vector owned by this class.
const std::vector<uint8_t> &GetBuffer() const {
Finished();
return buf_;
}
// Size of the buffer. Does not include unfinished values.
size_t GetSize() const { return buf_.size(); }
// Reset all state so we can re-use the buffer.
void Clear() {
buf_.clear();
stack_.clear();
finished_ = false;
// flags_ remains as-is;
force_min_bit_width_ = BIT_WIDTH_8;
key_pool.clear();
string_pool.clear();
}
// All value constructing functions below have two versions: one that
// takes a key (for placement inside a map) and one that doesn't (for inside
// vectors and elsewhere).
void Null() { stack_.push_back(Value()); }
void Null(const char *key) {
Key(key);
Null();
}
void Int(int64_t i) { stack_.push_back(Value(i, FBT_INT, WidthI(i))); }
void Int(const char *key, int64_t i) {
Key(key);
Int(i);
}
void UInt(uint64_t u) { stack_.push_back(Value(u, FBT_UINT, WidthU(u))); }
void UInt(const char *key, uint64_t u) {
Key(key);
UInt(u);
}
void Float(float f) { stack_.push_back(Value(f)); }
void Float(const char *key, float f) {
Key(key);
Float(f);
}
void Double(double f) { stack_.push_back(Value(f)); }
void Double(const char *key, double d) {
Key(key);
Double(d);
}
void Bool(bool b) { stack_.push_back(Value(b)); }
void Bool(const char *key, bool b) {
Key(key);
Bool(b);
}
void IndirectInt(int64_t i) { PushIndirect(i, FBT_INDIRECT_INT, WidthI(i)); }
void IndirectInt(const char *key, int64_t i) {
Key(key);
IndirectInt(i);
}
void IndirectUInt(uint64_t u) {
PushIndirect(u, FBT_INDIRECT_UINT, WidthU(u));
}
void IndirectUInt(const char *key, uint64_t u) {
Key(key);
IndirectUInt(u);
}
void IndirectFloat(float f) {
PushIndirect(f, FBT_INDIRECT_FLOAT, BIT_WIDTH_32);
}
void IndirectFloat(const char *key, float f) {
Key(key);
IndirectFloat(f);
}
void IndirectDouble(double f) {
PushIndirect(f, FBT_INDIRECT_FLOAT, WidthF(f));
}
void IndirectDouble(const char *key, double d) {
Key(key);
IndirectDouble(d);
}
size_t Key(const char *str, size_t len) {
auto sloc = buf_.size();
WriteBytes(str, len + 1);
if (flags_ & BUILDER_FLAG_SHARE_KEYS) {
auto it = key_pool.find(sloc);
if (it != key_pool.end()) {
// Already in the buffer. Remove key we just serialized, and use
// existing offset instead.
buf_.resize(sloc);
sloc = *it;
} else {
key_pool.insert(sloc);
}
}
stack_.push_back(Value(static_cast<uint64_t>(sloc), FBT_KEY, BIT_WIDTH_8));
return sloc;
}
size_t Key(const char *str) { return Key(str, strlen(str)); }
size_t Key(const std::string &str) { return Key(str.c_str(), str.size()); }
size_t String(const char *str, size_t len) {
auto reset_to = buf_.size();
auto sloc = CreateBlob(str, len, 1, FBT_STRING);
if (flags_ & BUILDER_FLAG_SHARE_STRINGS) {
StringOffset so(sloc, len);
auto it = string_pool.find(so);
if (it != string_pool.end()) {
// Already in the buffer. Remove string we just serialized, and use
// existing offset instead.
buf_.resize(reset_to);
sloc = it->first;
stack_.back().u_ = sloc;
} else {
string_pool.insert(so);
}
}
return sloc;
}
size_t String(const char *str) { return String(str, strlen(str)); }
size_t String(const std::string &str) {
return String(str.c_str(), str.size());
}
void String(const flexbuffers::String &str) {
String(str.c_str(), str.length());
}
void String(const char *key, const char *str) {
Key(key);
String(str);
}
void String(const char *key, const std::string &str) {
Key(key);
String(str);