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fuchsia / third_party / github.com / google / flatbuffers / 88549130e1b1473238e1b7c35eb57c6b4a6692e1 / . / include / flatbuffers / 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 <algorithm>
#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 (except FBT_BOOL) 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,
// DEPRECATED, use FBT_VECTOR or FBT_VECTOR_KEY instead.
// Read test.cpp/FlexBuffersDeprecatedTest() for details on why.
FBT_VECTOR_STRING_DEPRECATED = 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
FBT_MAX_TYPE = 37
};
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_DEPRECATED) ||
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_ARM64EC)
// This is 64-bit Windows only, __movsb does not work on 32-bit Windows.
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_;
};
// Object that has a size, obtained either from size prefix, or elsewhere.
class Sized : public Object {
public:
// Size prefix.
Sized(const uint8_t *data, uint8_t byte_width)
: Object(data, byte_width), size_(read_size()) {}
// Manual size.
Sized(const uint8_t *data, uint8_t byte_width, size_t sz)
: Object(data, byte_width), size_(sz) {}
size_t size() const { return size_; }
// Access size stored in `byte_width_` bytes before data_ pointer.
size_t read_size() const {
return static_cast<size_t>(ReadUInt64(data_ - byte_width_, byte_width_));
}
protected:
size_t size_;
};
class String : public Sized {
public:
// Size prefix.
String(const uint8_t *data, uint8_t byte_width) : Sized(data, byte_width) {}
// Manual size.
String(const uint8_t *data, uint8_t byte_width, size_t sz)
: Sized(data, byte_width, sz) {}
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(), size()); }
static String EmptyString() {
static const char *empty_string = "";
return String(reinterpret_cast<const uint8_t *>(empty_string), 1, 0);
}
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_; }
friend Reference;
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() const { return type_; }
uint8_t size() const { 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_; }
};
inline void IndentString(std::string &s, int indent,
const char *indent_string) {
for (int i = 0; i < indent; i++) s += indent_string;
}
template<typename T>
void AppendToString(std::string &s, T &&v, bool keys_quoted, bool indented,
int cur_indent, const char *indent_string) {
s += "[";
s += indented ? "\n" : " ";
for (size_t i = 0; i < v.size(); i++) {
if (i) {
s += ",";
s += indented ? "\n" : " ";
}
if (indented) IndentString(s, cur_indent, indent_string);
v[i].ToString(true, keys_quoted, s, indented, cur_indent,
indent_string);
}
if (indented) {
s += "\n";
IndentString(s, cur_indent - 1, indent_string);
} else {
s += " ";
}
s += "]";
}
template<typename T>
void AppendToString(std::string &s, T &&v, bool keys_quoted) {
AppendToString(s, v, keys_quoted);
}
class Reference {
public:
Reference()
: data_(nullptr), parent_width_(0), byte_width_(0), type_(FBT_NULL) {}
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_(static_cast<uint8_t>(1 << (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 IsUntypedVector() const { return type_ == FBT_VECTOR; }
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: {
double d;
flatbuffers::StringToNumber(AsString().c_str(), &d);
return d;
}
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 || type_ == FBT_STRING) {
return reinterpret_cast<const char *>(Indirect());
} else {
return "";
}
}
// This function returns the empty string if you try to read something that
// is not a string or key.
String AsString() const {
if (type_ == FBT_STRING) {
return String(Indirect(), byte_width_);
} else if (type_ == FBT_KEY) {
auto key = Indirect();
return String(key, byte_width_,
strlen(reinterpret_cast<const char *>(key)));
} 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.
void ToString(bool strings_quoted, bool keys_quoted, std::string &s) const {
ToString(strings_quoted, keys_quoted, s, false, 0, "");
}
// This version additionally allow you to specify if you want indentation.
void ToString(bool strings_quoted, bool keys_quoted, std::string &s,
bool indented, int cur_indent, const char *indent_string) 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 += "{";
s += indented ? "\n" : " ";
auto m = AsMap();
auto keys = m.Keys();
auto vals = m.Values();
for (size_t i = 0; i < keys.size(); i++) {
bool kq = keys_quoted;
if (!kq) {
// FlexBuffers keys may contain arbitrary characters, only allow
// unquoted if it looks like an "identifier":
const char *p = keys[i].AsKey();
if (!flatbuffers::is_alpha(*p) && *p != '_') {
kq = true;
} else {
while (*++p) {
if (!flatbuffers::is_alnum(*p) && *p != '_') {
kq = true;
break;
}
}
}
}
if (indented) IndentString(s, cur_indent + 1, indent_string);
keys[i].ToString(true, kq, s);
s += ": ";
vals[i].ToString(true, keys_quoted, s, indented, cur_indent + 1, indent_string);
if (i < keys.size() - 1) {
s += ",";
if (!indented) s += " ";
}
if (indented) s += "\n";
}
if (!indented) s += " ";
if (indented) IndentString(s, cur_indent, indent_string);
s += "}";
} else if (IsVector()) {
AppendToString<Vector>(s, AsVector(), keys_quoted, indented,
cur_indent + 1, indent_string);
} else if (IsTypedVector()) {
AppendToString<TypedVector>(s, AsTypedVector(), keys_quoted, indented,
cur_indent + 1, indent_string);
} else if (IsFixedTypedVector()) {
AppendToString<FixedTypedVector>(s, AsFixedTypedVector(), keys_quoted,
indented, cur_indent + 1, indent_string);
} 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()) {
auto tv =
TypedVector(Indirect(), byte_width_, ToTypedVectorElementType(type_));
if (tv.type_ == FBT_STRING) {
// These can't be accessed as strings, since we don't know the bit-width
// of the size field, see the declaration of
// FBT_VECTOR_STRING_DEPRECATED above for details.
// We change the type here to be keys, which are a subtype of strings,
// and will ignore the size field. This will truncate strings with
// embedded nulls.
tv.type_ = FBT_KEY;
}
return tv;
} 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;
}
friend class Verifier;
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;
default: FLATBUFFERS_ASSERT(false); return Reference();
}
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(buffer.data(), 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),
has_duplicate_keys_(false),
flags_(flags),
force_min_bit_width_(BIT_WIDTH_8),
key_pool(KeyOffsetCompare(buf_)),
string_pool(StringOffsetCompare(buf_)) {
buf_.clear();
}
#ifdef FLATBUFFERS_DEFAULT_DECLARATION
Builder(Builder &&) = default;
Builder &operator=(Builder &&) = default;
#endif
/// @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);
}
void String(const char *key, const flexbuffers::String &str) {
Key(key);
String(str);
}
size_t Blob(const void *data, size_t len) {
return CreateBlob(data, len, 0, FBT_BLOB);
}
size_t Blob(const std::vector<uint8_t> &v) {
return CreateBlob(v.data(), v.size(), 0, FBT_BLOB);
}
void Blob(const char *key, const void *data, size_t len) {
Key(key);
Blob(data, len);
}
void Blob(const char *key, const std::vector<uint8_t> &v) {
Key(key);
Blob(v);
}
// TODO(wvo): support all the FlexBuffer types (like flexbuffers::String),
// e.g. Vector etc. Also in overloaded versions.
// Also some FlatBuffers types?
size_t StartVector() { return stack_.size(); }
size_t StartVector(const char *key) {
Key(key);
return stack_.size();
}
size_t StartMap() { return stack_.size(); }
size_t StartMap(const char *key) {
Key(key);
return stack_.size();
}
// TODO(wvo): allow this to specify an alignment greater than the natural
// alignment.
size_t EndVector(size_t start, bool typed, bool fixed) {
auto vec = CreateVector(start, stack_.size() - start, 1, typed, fixed);
// Remove temp elements and return vector.
stack_.resize(start);
stack_.push_back(vec);
return static_cast<size_t>(vec.u_);
}
size_t EndMap(size_t start) {
// We should have interleaved keys and values on the stack.
auto len = MapElementCount(start);
// Make sure keys are all strings:
for (auto key = start; key < stack_.size(); key += 2) {
FLATBUFFERS_ASSERT(stack_[key].type_ == FBT_KEY);
}
// Now sort values, so later we can do a binary search lookup.
// We want to sort 2 array elements at a time.
struct TwoValue {
Value key;
Value val;
};
// TODO(wvo): strict aliasing?
// TODO(wvo): allow the caller to indicate the data is already sorted
// for maximum efficiency? With an assert to check sortedness to make sure
// we're not breaking binary search.
// Or, we can track if the map is sorted as keys are added which would be
// be quite cheap (cheaper than checking it here), so we can skip this
// step automatically when appliccable, and encourage people to write in
// sorted fashion.
// std::sort is typically already a lot faster on sorted data though.
auto dict = reinterpret_cast<TwoValue *>(stack_.data() + start);
std::sort(
dict, dict + len, [&](const TwoValue &a, const TwoValue &b) -> bool {
auto as = reinterpret_cast<const char *>(buf_.data() + a.key.u_);
auto bs = reinterpret_cast<const char *>(buf_.data() + b.key.u_);
auto comp = strcmp(as, bs);
// We want to disallow duplicate keys, since this results in a
// map where values cannot be found.
// But we can't assert here (since we don't want to fail on
// random JSON input) or have an error mechanism.
// Instead, we set has_duplicate_keys_ in the builder to
// signal this.
// TODO: Have to check for pointer equality, as some sort
// implementation apparently call this function with the same
// element?? Why?
if (!comp && &a != &b) has_duplicate_keys_ = true;
return comp < 0;
});
// First create a vector out of all keys.
// TODO(wvo): if kBuilderFlagShareKeyVectors is true, see if we can share
// the first vector.
auto keys = CreateVector(start, len, 2, true, false);
auto vec = CreateVector(start + 1, len, 2, false, false, &keys);
// Remove temp elements and return map.
stack_.resize(start);
stack_.push_back(vec);
return static_cast<size_t>(vec.u_);
}
// Call this after EndMap to see if the map had any duplicate keys.
// Any map with such keys won't be able to retrieve all values.
bool HasDuplicateKeys() const { return has_duplicate_keys_; }
template<typename F> size_t Vector(F f) {
auto start = StartVector();
f();
return EndVector(start, false, false);
}
template<typename F, typename T> size_t Vector(F f, T &state) {
auto start = StartVector();
f(state);
return EndVector(start, false, false);
}
template<typename F> size_t Vector(const char *key, F f) {
auto start = StartVector(key);
f();
return EndVector(start, false, false);
}
template<typename F, typename T>
size_t Vector(const char *key, F f, T &state) {
auto start = StartVector(key);
f(state);
return EndVector(start, false, false);
}
template<typename T> void Vector(const T *elems, size_t len) {
if (flatbuffers::is_scalar<T>::value) {
// This path should be a lot quicker and use less space.
ScalarVector(elems, len, false);
} else {
auto start = StartVector();
for (size_t i = 0; i < len; i++) Add(elems[i]);
EndVector(start, false, false);
}
}
template<typename T>
void Vector(const char *key, const T *elems, size_t len) {
Key(key);
Vector(elems, len);
}
template<typename T> void Vector(const std::vector<T> &vec) {
Vector(vec.data(), vec.size());
}
template<typename F> size_t TypedVector(F f) {
auto start = StartVector();
f();
return EndVector(start, true, false);
}
template<typename F, typename T> size_t TypedVector(F f, T &state) {
auto start = StartVector();
f(state);
return EndVector(start, true, false);
}
template<typename F> size_t TypedVector(const char *key, F f) {
auto start = StartVector(key);
f();
return EndVector(start, true, false);
}
template<typename F, typename T>
size_t TypedVector(const char *key, F f, T &state) {
auto start = StartVector(key);
f(state);
return EndVector(start, true, false);
}
template<typename T> size_t FixedTypedVector(const T *elems, size_t len) {
// We only support a few fixed vector lengths. Anything bigger use a
// regular typed vector.
FLATBUFFERS_ASSERT(len >= 2 && len <= 4);
// And only scalar values.
static_assert(flatbuffers::is_scalar<T>::value, "Unrelated types");
return ScalarVector(elems, len, true);
}
template<typename T>
size_t FixedTypedVector(const char *key, const T *elems, size_t len) {
Key(key);
return FixedTypedVector(elems, len);
}
template<typename F> size_t Map(F f) {
auto start = StartMap();
f();
return EndMap(start);
}
template<typename F, typename T> size_t Map(F f, T &state) {
auto start = StartMap();
f(state);
return EndMap(start);
}
template<typename F> size_t Map(const char *key, F f) {
auto start = StartMap(key);
f();
return EndMap(start);
}
template<typename F, typename T> size_t Map(const char *key, F f, T &state) {
auto start = StartMap(key);
f(state);
return EndMap(start);
}
template<typename T> void Map(const std::map<std::string, T> &map) {
auto start = StartMap();
for (auto it = map.begin(); it != map.end(); ++it)
Add(it->first.c_str(), it->second);
EndMap(start);
}
size_t MapElementCount(size_t start) {
// Make sure it is an even number:
auto len = stack_.size() - start;
FLATBUFFERS_ASSERT(!(len & 1));
len /= 2;
return len;
}
// If you wish to share a value explicitly (a value not shared automatically
// through one of the BUILDER_FLAG_SHARE_* flags) you can do so with these
// functions. Or if you wish to turn those flags off for performance reasons
// and still do some explicit sharing. For example:
// builder.IndirectDouble(M_PI);
// auto id = builder.LastValue(); // Remember where we stored it.
// .. more code goes here ..
// builder.ReuseValue(id); // Refers to same double by offset.
// LastValue works regardless of whether the value has a key or not.
// Works on any data type.
struct Value;
Value LastValue() { return stack_.back(); }
void ReuseValue(Value v) { stack_.push_back(v); }
void ReuseValue(const char *key, Value v) {
Key(key);
ReuseValue(v);
}
// Undo the last element serialized. Call once for a value and once for a
// key.
void Undo() {
stack_.pop_back();
}
// Overloaded Add that tries to call the correct function above.
void Add(int8_t i) { Int(i); }
void Add(int16_t i) { Int(i); }
void Add(int32_t i) { Int(i); }
void Add(int64_t i) { Int(i); }
void Add(uint8_t u) { UInt(u); }
void Add(uint16_t u) { UInt(u); }
void Add(uint32_t u) { UInt(u); }
void Add(uint64_t u) { UInt(u); }
void Add(float f) { Float(f); }
void Add(double d) { Double(d); }
void Add(bool b) { Bool(b); }
void Add(const char *str) { String(str); }
void Add(const std::string &str) { String(str); }
void Add(const flexbuffers::String &str) { String(str); }
template<typename T> void Add(const std::vector<T> &vec) { Vector(vec); }
template<typename T> void Add(const char *key, const T &t) {
Key(key);
Add(t);
}
template<typename T> void Add(const std::map<std::string, T> &map) {
Map(map);
}
template<typename T> void operator+=(const T &t) { Add(t); }
// This function is useful in combination with the Mutate* functions above.
// It forces elements of vectors and maps to have a minimum size, such that
// they can later be updated without failing.
// Call with no arguments to reset.
void ForceMinimumBitWidth(BitWidth bw = BIT_WIDTH_8) {
force_min_bit_width_ = bw;
}
void Finish() {
// If you hit this assert, you likely have objects that were never included
// in a parent. You need to have exactly one root to finish a buffer.
// Check your Start/End calls are matched, and all objects are inside
// some other object.
FLATBUFFERS_ASSERT(stack_.size() == 1);
// Write root value.
auto byte_width = Align(stack_[0].ElemWidth(buf_.size(), 0));
WriteAny(stack_[0], byte_width);
// Write root type.
Write(stack_[0].StoredPackedType(), 1);
// Write root size. Normally determined by parent, but root has no parent :)
Write(byte_width, 1);
finished_ = true;
}
private:
void Finished() const {
// If you get this assert, you're attempting to get access a buffer
// which hasn't been finished yet. Be sure to call
// Builder::Finish with your root object.
FLATBUFFERS_ASSERT(finished_);
}
// Align to prepare for writing a scalar with a certain size.
uint8_t Align(BitWidth alignment) {
auto byte_width = 1U << alignment;
buf_.insert(buf_.end(), flatbuffers::PaddingBytes(buf_.size(), byte_width),
0);
return static_cast<uint8_t>(byte_width);
}
void WriteBytes(const void *val, size_t size) {
buf_.insert(buf_.end(), reinterpret_cast<const uint8_t *>(val),
reinterpret_cast<const uint8_t *>(val) + size);
}
template<typename T> void Write(T val, size_t byte_width) {
FLATBUFFERS_ASSERT(sizeof(T) >= byte_width);
val = flatbuffers::EndianScalar(val);
WriteBytes(&val, byte_width);
}
void WriteDouble(double f, uint8_t byte_width) {
switch (byte_width) {
case 8: Write(f, byte_width); break;
case 4: Write(static_cast<float>(f), byte_width); break;
// case 2: Write(static_cast<half>(f), byte_width); break;
// case 1: Write(static_cast<quarter>(f), byte_width); break;
default: FLATBUFFERS_ASSERT(0);
}
}
void WriteOffset(uint64_t o, uint8_t byte_width) {
auto reloff = buf_.size() - o;
FLATBUFFERS_ASSERT(byte_width == 8 || reloff < 1ULL << (byte_width * 8));
Write(reloff, byte_width);
}
template<typename T> void PushIndirect(T val, Type type, BitWidth bit_width) {
auto byte_width = Align(bit_width);
auto iloc = buf_.size();
Write(val, byte_width);
stack_.push_back(Value(static_cast<uint64_t>(iloc), type, bit_width));
}
static BitWidth WidthB(size_t byte_width) {
switch (byte_width) {
case 1: return BIT_WIDTH_8;
case 2: return BIT_WIDTH_16;
case 4: return BIT_WIDTH_32;
case 8: return BIT_WIDTH_64;
default: FLATBUFFERS_ASSERT(false); return BIT_WIDTH_64;
}
}
template<typename T> static Type GetScalarType() {
static_assert(flatbuffers::is_scalar<T>::value, "Unrelated types");
return flatbuffers::is_floating_point<T>::value ? FBT_FLOAT
: flatbuffers::is_same<T, bool>::value
? FBT_BOOL
: (flatbuffers::is_unsigned<T>::value ? FBT_UINT : FBT_INT);
}
public:
// This was really intended to be private, except for LastValue/ReuseValue.
struct Value {
union {
int64_t i_;
uint64_t u_;
double f_;
};
Type type_;
// For scalars: of itself, for vector: of its elements, for string: length.
BitWidth min_bit_width_;
Value() : i_(0), type_(FBT_NULL), min_bit_width_(BIT_WIDTH_8) {}
Value(bool b)
: u_(static_cast<uint64_t>(b)),
type_(FBT_BOOL),
min_bit_width_(BIT_WIDTH_8) {}
Value(int64_t i, Type t, BitWidth bw)
: i_(i), type_(t), min_bit_width_(bw) {}
Value(uint64_t u, Type t, BitWidth bw)
: u_(u), type_(t), min_bit_width_(bw) {}
Value(float f)
: f_(static_cast<double>(f)),
type_(FBT_FLOAT),
min_bit_width_(BIT_WIDTH_32) {}
Value(double f) : f_(f), type_(FBT_FLOAT), min_bit_width_(WidthF(f)) {}
uint8_t StoredPackedType(BitWidth parent_bit_width_ = BIT_WIDTH_8) const {
return PackedType(StoredWidth(parent_bit_width_), type_);
}
BitWidth ElemWidth(size_t buf_size, size_t elem_index) const {
if (IsInline(type_)) {
return min_bit_width_;
} else {
// We have an absolute offset, but want to store a relative offset
// elem_index elements beyond the current buffer end. Since whether
// the relative offset fits in a certain byte_width depends on
// the size of the elements before it (and their alignment), we have
// to test for each size in turn.
for (size_t byte_width = 1;
byte_width <= sizeof(flatbuffers::largest_scalar_t);
byte_width *= 2) {
// Where are we going to write this offset?
auto offset_loc = buf_size +
flatbuffers::PaddingBytes(buf_size, byte_width) +
elem_index * byte_width;
// Compute relative offset.
auto offset = offset_loc - u_;
// Does it fit?
auto bit_width = WidthU(offset);
if (static_cast<size_t>(static_cast<size_t>(1U) << bit_width) ==
byte_width)
return bit_width;
}
FLATBUFFERS_ASSERT(false); // Must match one of the sizes above.
return BIT_WIDTH_64;
}
}
BitWidth StoredWidth(BitWidth parent_bit_width_ = BIT_WIDTH_8) const {
if (IsInline(type_)) {
return (std::max)(min_bit_width_, parent_bit_width_);
} else {
return min_bit_width_;
}
}
};
private:
void WriteAny(const Value &val, uint8_t byte_width) {
switch (val.type_) {
case FBT_NULL:
case FBT_INT: Write(val.i_, byte_width); break;
case FBT_BOOL:
case FBT_UINT: Write(val.u_, byte_width); break;
case FBT_FLOAT: WriteDouble(val.f_, byte_width); break;
default: WriteOffset(val.u_, byte_width); break;
}
}
size_t CreateBlob(const void *data, size_t len, size_t trailing, Type type) {
auto bit_width = WidthU(len);
auto byte_width = Align(bit_width);
Write<uint64_t>(len, byte_width);
auto sloc = buf_.size();
WriteBytes(data, len + trailing);
stack_.push_back(Value(static_cast<uint64_t>(sloc), type, bit_width));
return sloc;
}
template<typename T>
size_t ScalarVector(const T *elems, size_t len, bool fixed) {
auto vector_type = GetScalarType<T>();
auto byte_width = sizeof(T);
auto bit_width = WidthB(byte_width);
// If you get this assert, you're trying to write a vector with a size
// field that is bigger than the scalars you're trying to write (e.g. a
// byte vector > 255 elements). For such types, write a "blob" instead.
// TODO: instead of asserting, could write vector with larger elements
// instead, though that would be wasteful.
FLATBUFFERS_ASSERT(WidthU(len) <= bit_width);
Align(bit_width);
if (!fixed) Write<uint64_t>(len, byte_width);
auto vloc = buf_.size();
for (size_t i = 0; i < len; i++) Write(elems[i], byte_width);
stack_.push_back(Value(static_cast<uint64_t>(vloc),
ToTypedVector(vector_type, fixed ? len : 0),
bit_width));
return vloc;
}
Value CreateVector(size_t start, size_t vec_len, size_t step, bool typed,
bool fixed, const Value *keys = nullptr) {
FLATBUFFERS_ASSERT(
!fixed ||
typed); // typed=false, fixed=true combination is not supported.
// Figure out smallest bit width we can store this vector with.
auto bit_width = (std::max)(force_min_bit_width_, WidthU(vec_len));
auto prefix_elems = 1;
if (keys) {
// If this vector is part of a map, we will pre-fix an offset to the keys
// to this vector.
bit_width = (std::max)(bit_width, keys->ElemWidth(buf_.size(), 0));
prefix_elems += 2;
}
Type vector_type = FBT_KEY;
// Check bit widths and types for all elements.
for (size_t i = start; i < stack_.size(); i += step) {
auto elem_width =
stack_[i].ElemWidth(buf_.size(), i - start + prefix_elems);
bit_width = (std::max)(bit_width, elem_width);
if (typed) {
if (i == start) {
vector_type = stack_[i].type_;
} else {
// If you get this assert, you are writing a typed vector with
// elements that are not all the same type.
FLATBUFFERS_ASSERT(vector_type == stack_[i].type_);
}
}
}
// If you get this assert, your typed types are not one of:
// Int / UInt / Float / Key.
FLATBUFFERS_ASSERT(!typed || IsTypedVectorElementType(vector_type));
auto byte_width = Align(bit_width);
// Write vector. First the keys width/offset if available, and size.
if (keys) {
WriteOffset(keys->u_, byte_width);
Write<uint64_t>(1ULL << keys->min_bit_width_, byte_width);
}
if (!fixed) Write<uint64_t>(vec_len, byte_width);
// Then the actual data.
auto vloc = buf_.size();
for (size_t i = start; i < stack_.size(); i += step) {
WriteAny(stack_[i], byte_width);
}
// Then the types.
if (!typed) {
for (size_t i = start; i < stack_.size(); i += step) {
buf_.push_back(stack_[i].StoredPackedType(bit_width));
}
}
return Value(static_cast<uint64_t>(vloc),
keys ? FBT_MAP
: (typed ? ToTypedVector(vector_type, fixed ? vec_len : 0)
: FBT_VECTOR),
bit_width);
}
// You shouldn't really be copying instances of this class.
Builder(const Builder &);
Builder &operator=(const Builder &);
std::vector<uint8_t> buf_;
std::vector<Value> stack_;
bool finished_;
bool has_duplicate_keys_;
BuilderFlag flags_;
BitWidth force_min_bit_width_;
struct KeyOffsetCompare {
explicit KeyOffsetCompare(const std::vector<uint8_t> &buf) : buf_(&buf) {}
bool operator()(size_t a, size_t b) const {
auto stra = reinterpret_cast<const char *>(buf_->data() + a);
auto strb = reinterpret_cast<const char *>(buf_->data() + b);
return strcmp(stra, strb) < 0;
}
const std::vector<uint8_t> *buf_;
};
typedef std::pair<size_t, size_t> StringOffset;
struct StringOffsetCompare {
explicit StringOffsetCompare(const std::vector<uint8_t> &buf)
: buf_(&buf) {}
bool operator()(const StringOffset &a, const StringOffset &b) const {
auto stra = buf_->data() + a.first;
auto strb = buf_->data() + b.first;
auto cr = memcmp(stra, strb, (std::min)(a.second, b.second) + 1);
return cr < 0 || (cr == 0 && a.second < b.second);
}
const std::vector<uint8_t> *buf_;
};
typedef std::set<size_t, KeyOffsetCompare> KeyOffsetMap;
typedef std::set<StringOffset, StringOffsetCompare> StringOffsetMap;
KeyOffsetMap key_pool;
StringOffsetMap string_pool;
friend class Verifier;
};
// Helper class to verify the integrity of a FlexBuffer
class Verifier FLATBUFFERS_FINAL_CLASS {
public:
Verifier(const uint8_t *buf, size_t buf_len,
// Supplying this vector likely results in faster verification
// of larger buffers with many shared keys/strings, but
// comes at the cost of using additional memory the same size of
// the buffer being verified, so it is by default off.
std::vector<uint8_t> *reuse_tracker = nullptr,
bool _check_alignment = true, size_t max_depth = 64)
: buf_(buf),
size_(buf_len),
depth_(0),
max_depth_(max_depth),
num_vectors_(0),
max_vectors_(buf_len),
check_alignment_(_check_alignment),
reuse_tracker_(reuse_tracker) {
FLATBUFFERS_ASSERT(static_cast<int32_t>(size_) < FLATBUFFERS_MAX_BUFFER_SIZE);
if (reuse_tracker_) {
reuse_tracker_->clear();
reuse_tracker_->resize(size_, PackedType(BIT_WIDTH_8, FBT_NULL));
}
}
private:
// Central location where any verification failures register.
bool Check(bool ok) const {
// clang-format off
#ifdef FLATBUFFERS_DEBUG_VERIFICATION_FAILURE
FLATBUFFERS_ASSERT(ok);
#endif
// clang-format on
return ok;
}
// Verify any range within the buffer.
bool VerifyFrom(size_t elem, size_t elem_len) const {
return Check(elem_len < size_ && elem <= size_ - elem_len);
}
bool VerifyBefore(size_t elem, size_t elem_len) const {
return Check(elem_len <= elem);
}
bool VerifyFromPointer(const uint8_t *p, size_t len) {
auto o = static_cast<size_t>(p - buf_);
return VerifyFrom(o, len);
}
bool VerifyBeforePointer(const uint8_t *p, size_t len) {
auto o = static_cast<size_t>(p - buf_);
return VerifyBefore(o, len);
}
bool VerifyByteWidth(size_t width) {
return Check(width == 1 || width == 2 || width == 4 || width == 8);
}
bool VerifyType(int type) { return Check(type >= 0 && type < FBT_MAX_TYPE); }
bool VerifyOffset(uint64_t off, const uint8_t *p) {
return Check(off <= static_cast<uint64_t>(size_)) &&
off <= static_cast<uint64_t>(p - buf_);
}
bool VerifyAlignment(const uint8_t *p, size_t size) const {
auto o = static_cast<size_t>(p - buf_);
return Check((o & (size - 1)) == 0 || !check_alignment_);
}
// Macro, since we want to escape from parent function & use lazy args.
#define FLEX_CHECK_VERIFIED(P, PACKED_TYPE) \
if (reuse_tracker_) { \
auto packed_type = PACKED_TYPE; \
auto existing = (*reuse_tracker_)[P - buf_]; \
if (existing == packed_type) return true; \
/* Fail verification if already set with different type! */ \
if (!Check(existing == 0)) return false; \
(*reuse_tracker_)[P - buf_] = packed_type; \
}
bool VerifyVector(Reference r, const uint8_t *p, Type elem_type) {
// Any kind of nesting goes thru this function, so guard against that
// here, both with simple nesting checks, and the reuse tracker if on.
depth_++;
num_vectors_++;
if (!Check(depth_ <= max_depth_ && num_vectors_ <= max_vectors_))
return false;
auto size_byte_width = r.byte_width_;
if (!VerifyBeforePointer(p, size_byte_width)) return false;
FLEX_CHECK_VERIFIED(p - size_byte_width,
PackedType(Builder::WidthB(size_byte_width), r.type_));
auto sized = Sized(p, size_byte_width);
auto num_elems = sized.size();
auto elem_byte_width = r.type_ == FBT_STRING || r.type_ == FBT_BLOB
? uint8_t(1)
: r.byte_width_;
auto max_elems = SIZE_MAX / elem_byte_width;
if (!Check(num_elems < max_elems))
return false; // Protect against byte_size overflowing.
auto byte_size = num_elems * elem_byte_width;
if (!VerifyFromPointer(p, byte_size)) return false;
if (elem_type == FBT_NULL) {
// Verify type bytes after the vector.
if (!VerifyFromPointer(p + byte_size, num_elems)) return false;
auto v = Vector(p, size_byte_width);
for (size_t i = 0; i < num_elems; i++)
if (!VerifyRef(v[i])) return false;
} else if (elem_type == FBT_KEY) {
auto v = TypedVector(p, elem_byte_width, FBT_KEY);
for (size_t i = 0; i < num_elems; i++)
if (!VerifyRef(v[i])) return false;
} else {
FLATBUFFERS_ASSERT(IsInline(elem_type));
}
depth_--;
return true;
}
bool VerifyKeys(const uint8_t *p, uint8_t byte_width) {
// The vector part of the map has already been verified.
const size_t num_prefixed_fields = 3;
if (!VerifyBeforePointer(p, byte_width * num_prefixed_fields)) return false;
p -= byte_width * num_prefixed_fields;
auto off = ReadUInt64(p, byte_width);
if (!VerifyOffset(off, p)) return false;
auto key_byte_with =
static_cast<uint8_t>(ReadUInt64(p + byte_width, byte_width));
if (!VerifyByteWidth(key_byte_with)) return false;
return VerifyVector(Reference(p, byte_width, key_byte_with, FBT_VECTOR_KEY),
p - off, FBT_KEY);
}
bool VerifyKey(const uint8_t *p) {
FLEX_CHECK_VERIFIED(p, PackedType(BIT_WIDTH_8, FBT_KEY));
while (p < buf_ + size_)
if (*p++) return true;
return false;
}
#undef FLEX_CHECK_VERIFIED
bool VerifyTerminator(const String &s) {
return VerifyFromPointer(reinterpret_cast<const uint8_t *>(s.c_str()),
s.size() + 1);
}
bool VerifyRef(Reference r) {
// r.parent_width_ and r.data_ already verified.
if (!VerifyByteWidth(r.byte_width_) || !VerifyType(r.type_)) {
return false;
}
if (IsInline(r.type_)) {
// Inline scalars, don't require further verification.
return true;
}
// All remaining types are an offset.
auto off = ReadUInt64(r.data_, r.parent_width_);
if (!VerifyOffset(off, r.data_)) return false;
auto p = r.Indirect();
if (!VerifyAlignment(p, r.byte_width_)) return false;
switch (r.type_) {
case FBT_INDIRECT_INT:
case FBT_INDIRECT_UINT:
case FBT_INDIRECT_FLOAT: return VerifyFromPointer(p, r.byte_width_);
case FBT_KEY: return VerifyKey(p);
case FBT_MAP:
return VerifyVector(r, p, FBT_NULL) && VerifyKeys(p, r.byte_width_);
case FBT_VECTOR: return VerifyVector(r, p, FBT_NULL);
case FBT_VECTOR_INT: return VerifyVector(r, p, FBT_INT);
case FBT_VECTOR_BOOL:
case FBT_VECTOR_UINT: return VerifyVector(r, p, FBT_UINT);
case FBT_VECTOR_FLOAT: return VerifyVector(r, p, FBT_FLOAT);
case FBT_VECTOR_KEY: return VerifyVector(r, p, FBT_KEY);
case FBT_VECTOR_STRING_DEPRECATED:
// Use of FBT_KEY here intentional, see elsewhere.
return VerifyVector(r, p, FBT_KEY);
case FBT_BLOB: return VerifyVector(r, p, FBT_UINT);
case FBT_STRING:
return VerifyVector(r, p, FBT_UINT) &&
VerifyTerminator(String(p, r.byte_width_));
case FBT_VECTOR_INT2:
case FBT_VECTOR_UINT2:
case FBT_VECTOR_FLOAT2:
case FBT_VECTOR_INT3:
case FBT_VECTOR_UINT3:
case FBT_VECTOR_FLOAT3:
case FBT_VECTOR_INT4:
case FBT_VECTOR_UINT4:
case FBT_VECTOR_FLOAT4: {
uint8_t len = 0;
auto vtype = ToFixedTypedVectorElementType(r.type_, &len);
if (!VerifyType(vtype)) return false;
return VerifyFromPointer(p, static_cast<size_t>(r.byte_width_) * len);
}
default: return false;
}
}
public:
bool VerifyBuffer() {
if (!Check(size_ >= 3)) return false;
auto end = buf_ + size_;
auto byte_width = *--end;
auto packed_type = *--end;
return VerifyByteWidth(byte_width) && Check(end - buf_ >= byte_width) &&
VerifyRef(Reference(end - byte_width, byte_width, packed_type));
}
private:
const uint8_t *buf_;
size_t size_;
size_t depth_;
const size_t max_depth_;
size_t num_vectors_;
const size_t max_vectors_;
bool check_alignment_;
std::vector<uint8_t> *reuse_tracker_;
};
// Utility function that constructs the Verifier for you, see above for
// parameters.
inline bool VerifyBuffer(const uint8_t *buf, size_t buf_len,
std::vector<uint8_t> *reuse_tracker = nullptr) {
Verifier verifier(buf, buf_len, reuse_tracker);
return verifier.VerifyBuffer();
}
} // namespace flexbuffers
#if defined(_MSC_VER)
# pragma warning(pop)
#endif
#endif // FLATBUFFERS_FLEXBUFFERS_H_