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Fix Mutate() methods of Array<scalar/struct> (override 5508) (#5526) 

* Draft with Array specialization (#5508)

* Array specialization + SFINAE to fold copy-paste (#5508)

* Add implicit specialization of Array<scalar> and Array<struct> (#5508)

- Tag dispatching is used for implicit specialization
- Array<scalar> and Array<struct> have different iterators and accessors
- Array<scalar> and Array<struct> have different Mutate() methods

* Add implicit specialization of Array<scalar> and Array<struct> (#5508)

- Tag dispatching is used for implicit specialization
- Array<scalar> and Array<struct> have different iterators and accessors
- Array<scalar> and Array<struct> have different Mutate() methods
This commit is contained in:
Vladimir Glavnyy 2019-09-23 23:31:51 +07:00 committed by Wouter van Oortmerssen
parent e365c502ff
commit cbdf82e2fb
4 changed files with 94 additions and 42 deletions
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10
include/flatbuffers/base.h
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@ -330,22 +330,20 @@ template<typename T> T EndianSwap(T t) {
if (sizeof(T) == 1) { // Compile-time if-then's.
return t;
} else if (sizeof(T) == 2) {
union { T t; uint16_t i; } u;
u.t = t;
union { T t; uint16_t i; } u = { t };
u.i = FLATBUFFERS_BYTESWAP16(u.i);
return u.t;
} else if (sizeof(T) == 4) {
union { T t; uint32_t i; } u;
u.t = t;
union { T t; uint32_t i; } u = { t };
u.i = FLATBUFFERS_BYTESWAP32(u.i);
return u.t;
} else if (sizeof(T) == 8) {
union { T t; uint64_t i; } u;
u.t = t;
union { T t; uint64_t i; } u = { t };
u.i = FLATBUFFERS_BYTESWAP64(u.i);
return u.t;
} else {
FLATBUFFERS_ASSERT(0);
return t;
}
}

70
include/flatbuffers/flatbuffers.h
View File

@ -402,18 +402,23 @@ template<typename T> static inline size_t VectorLength(const Vector<T> *v) {
// This is used as a helper type for accessing arrays.
template<typename T, uint16_t length> class Array {
public:
typedef VectorIterator<T, typename IndirectHelper<T>::return_type>
const_iterator;
typedef VectorReverseIterator<const_iterator> const_reverse_iterator;
typedef
typename flatbuffers::integral_constant<bool, flatbuffers::is_scalar<T>::value>
scalar_tag;
typedef
typename flatbuffers::conditional<scalar_tag::value, T, const T *>::type
IndirectHelperType;
typedef typename IndirectHelper<T>::return_type return_type;
public:
typedef typename IndirectHelper<IndirectHelperType>::return_type return_type;
typedef VectorIterator<T, return_type> const_iterator;
typedef VectorReverseIterator<const_iterator> const_reverse_iterator;
FLATBUFFERS_CONSTEXPR uint16_t size() const { return length; }
return_type Get(uoffset_t i) const {
FLATBUFFERS_ASSERT(i < size());
return IndirectHelper<T>::Read(Data(), i);
return IndirectHelper<IndirectHelperType>::Read(Data(), i);
}
return_type operator[](uoffset_t i) const { return Get(i); }
@ -432,22 +437,22 @@ template<typename T, uint16_t length> class Array {
const_reverse_iterator crbegin() const { return rbegin(); }
const_reverse_iterator crend() const { return rend(); }
// Change elements if you have a non-const pointer to this object.
void Mutate(uoffset_t i, const T &val) {
FLATBUFFERS_ASSERT(i < size());
WriteScalar(data() + i, val);
}
// Get a mutable pointer to elements inside this array.
// @note This method should be only used to mutate arrays of structs followed
// by a @p Mutate operation. For primitive types use @p Mutate directly.
// This method used to mutate arrays of structs followed by a @p Mutate
// operation. For primitive types use @p Mutate directly.
// @warning Assignments and reads to/from the dereferenced pointer are not
// automatically converted to the correct endianness.
T *GetMutablePointer(uoffset_t i) const {
typename flatbuffers::conditional<scalar_tag::value, void, T *>::type
GetMutablePointer(uoffset_t i) const {
FLATBUFFERS_ASSERT(i < size());
return const_cast<T *>(&data()[i]);
}
// Change elements if you have a non-const pointer to this object.
void Mutate(uoffset_t i, const T &val) {
MutateImpl(scalar_tag(), i, val);
}
// The raw data in little endian format. Use with care.
const uint8_t *Data() const { return data_; }
@ -458,6 +463,17 @@ template<typename T, uint16_t length> class Array {
T *data() { return reinterpret_cast<T *>(Data()); }
protected:
void MutateImpl(flatbuffers::integral_constant<bool, true>, uoffset_t i,
const T &val) {
FLATBUFFERS_ASSERT(i < size());
WriteScalar(data() + i, val);
}
void MutateImpl(flatbuffers::integral_constant<bool, false>, uoffset_t i,
const T &val) {
*(GetMutablePointer(i)) = val;
}
// This class is only used to access pre-existing data. Don't ever
// try to construct these manually.
// 'constexpr' allows us to use 'size()' at compile time.
@ -475,6 +491,30 @@ template<typename T, uint16_t length> class Array {
// This class is a pointer. Copying will therefore create an invalid object.
// Private and unimplemented copy constructor.
Array(const Array &);
Array &operator=(const Array &);
};
// Specialization for Array[struct] with access using Offset<void> pointer.
// This specialization used by idl_gen_text.cpp.
template<typename T, uint16_t length> class Array<Offset<T>, length> {
static_assert(flatbuffers::is_same<T, void>::value, "unexpected type T");
public:
const uint8_t *Data() const { return data_; }
// Make idl_gen_text.cpp::PrintContainer happy.
const void *operator[](uoffset_t) const {
FLATBUFFERS_ASSERT(false);
return nullptr;
}
private:
// This class is only used to access pre-existing data.
Array();
Array(const Array &);
Array &operator=(const Array &);
uint8_t data_[1];
};
// Lexicographically compare two strings (possibly containing nulls), and

16
include/flatbuffers/stl_emulation.h
View File

@ -139,7 +139,11 @@ inline void vector_emplace_back(std::vector<T> *vector, V &&data) {
template <typename T> using is_floating_point = std::is_floating_point<T>;
template <typename T> using is_unsigned = std::is_unsigned<T>;
template <typename T> using make_unsigned = std::make_unsigned<T>;
#else
template<bool B, class T, class F>
using conditional = std::conditional<B, T, F>;
template<class T, T v>
using integral_constant = std::integral_constant<T, v>;
#else
// Map C++ TR1 templates defined by stlport.
template <typename T> using is_scalar = std::tr1::is_scalar<T>;
template <typename T, typename U> using is_same = std::tr1::is_same<T,U>;
@ -157,7 +161,11 @@ inline void vector_emplace_back(std::vector<T> *vector, V &&data) {
template<> struct make_unsigned<long> { using type = unsigned long; };
template<>
struct make_unsigned<long long> { using type = unsigned long long; };
#endif // !FLATBUFFERS_CPP98_STL
template<bool B, class T, class F>
using conditional = std::tr1::conditional<B, T, F>;
template<class T, T v>
using integral_constant = std::tr1::integral_constant<T, v>;
#endif // !FLATBUFFERS_CPP98_STL
#else
// MSVC 2010 doesn't support C++11 aliases.
template <typename T> struct is_scalar : public std::is_scalar<T> {};
@ -166,6 +174,10 @@ inline void vector_emplace_back(std::vector<T> *vector, V &&data) {
public std::is_floating_point<T> {};
template <typename T> struct is_unsigned : public std::is_unsigned<T> {};
template <typename T> struct make_unsigned : public std::make_unsigned<T> {};
template<bool B, class T, class F>
struct conditional : public std::conditional<B, T, F> {};
template<class T, T v>
struct integral_constant : public std::integral_constant<T, v> {};
#endif // defined(FLATBUFFERS_TEMPLATES_ALIASES)
#ifndef FLATBUFFERS_CPP98_STL

40
tests/test.cpp
View File

@ -2895,35 +2895,37 @@ void FixedLengthArrayTest() {
TEST_EQ(mArStruct->b()->size(), 15);
TEST_EQ(mArStruct->b()->Get(aStruct.b()->size() - 1), -14);
TEST_EQ(mArStruct->c(), 12);
TEST_NOTNULL(mArStruct->d()->Get(0).a());
TEST_EQ(mArStruct->d()->Get(0).a()->Get(0), 1);
TEST_EQ(mArStruct->d()->Get(0).a()->Get(1), 2);
TEST_NOTNULL(mArStruct->d()->Get(1).a());
TEST_EQ(mArStruct->d()->Get(1).a()->Get(0), 3);
TEST_EQ(mArStruct->d()->Get(1).a()->Get(1), 4);
TEST_NOTNULL(mArStruct->d()->Get(0));
TEST_NOTNULL(mArStruct->d()->Get(0)->a());
TEST_EQ(mArStruct->d()->Get(0)->a()->Get(0), 1);
TEST_EQ(mArStruct->d()->Get(0)->a()->Get(1), 2);
TEST_NOTNULL(mArStruct->d()->Get(1));
TEST_NOTNULL(mArStruct->d()->Get(1)->a());
TEST_EQ(mArStruct->d()->Get(1)->a()->Get(0), 3);
TEST_EQ(mArStruct->d()->Get(1)->a()->Get(1), 4);
TEST_NOTNULL(mArStruct->mutable_d()->GetMutablePointer(1));
TEST_NOTNULL(mArStruct->mutable_d()->GetMutablePointer(1)->mutable_a());
mArStruct->mutable_d()->GetMutablePointer(1)->mutable_a()->Mutate(1, 5);
TEST_EQ(mArStruct->d()->Get(1).a()->Get(1), 5);
TEST_EQ(mArStruct->d()->Get(0).b() == MyGame::Example::TestEnum::B, true);
TEST_NOTNULL(mArStruct->d()->Get(0).c());
TEST_EQ(mArStruct->d()->Get(0).c()->Get(0) == MyGame::Example::TestEnum::C,
TEST_EQ(mArStruct->d()->Get(1)->a()->Get(1), 5);
TEST_EQ(mArStruct->d()->Get(0)->b() == MyGame::Example::TestEnum::B, true);
TEST_NOTNULL(mArStruct->d()->Get(0)->c());
TEST_EQ(mArStruct->d()->Get(0)->c()->Get(0) == MyGame::Example::TestEnum::C,
true);
TEST_EQ(mArStruct->d()->Get(0).c()->Get(1) == MyGame::Example::TestEnum::A,
TEST_EQ(mArStruct->d()->Get(0)->c()->Get(1) == MyGame::Example::TestEnum::A,
true);
TEST_EQ(mArStruct->d()->Get(0).d()->Get(0),
TEST_EQ(mArStruct->d()->Get(0)->d()->Get(0),
flatbuffers::numeric_limits<int64_t>::max());
TEST_EQ(mArStruct->d()->Get(0).d()->Get(1),
TEST_EQ(mArStruct->d()->Get(0)->d()->Get(1),
flatbuffers::numeric_limits<int64_t>::min());
TEST_EQ(mArStruct->d()->Get(1).b() == MyGame::Example::TestEnum::C, true);
TEST_NOTNULL(mArStruct->d()->Get(1).c());
TEST_EQ(mArStruct->d()->Get(1).c()->Get(0) == MyGame::Example::TestEnum::C,
TEST_EQ(mArStruct->d()->Get(1)->b() == MyGame::Example::TestEnum::C, true);
TEST_NOTNULL(mArStruct->d()->Get(1)->c());
TEST_EQ(mArStruct->d()->Get(1)->c()->Get(0) == MyGame::Example::TestEnum::C,
true);
TEST_EQ(mArStruct->d()->Get(1).c()->Get(1) == MyGame::Example::TestEnum::A,
TEST_EQ(mArStruct->d()->Get(1)->c()->Get(1) == MyGame::Example::TestEnum::A,
true);
TEST_EQ(mArStruct->d()->Get(1).d()->Get(0),
TEST_EQ(mArStruct->d()->Get(1)->d()->Get(0),
flatbuffers::numeric_limits<int64_t>::min());
TEST_EQ(mArStruct->d()->Get(1).d()->Get(1),
TEST_EQ(mArStruct->d()->Get(1)->d()->Get(1),
flatbuffers::numeric_limits<int64_t>::max());
for (int i = 0; i < mArStruct->b()->size() - 1; i++)
TEST_EQ(mArStruct->b()->Get(i), i + 1);