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move input adapters outside of basic_json

pull/643/head
Théo DELRIEU 2017-07-01 20:01:28 +02:00
parent a332142194
commit 15625ca4a7
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GPG Key ID: CDC9DE164D97A180
3 changed files with 739 additions and 733 deletions
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556
src/json.hpp
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@ -1265,6 +1265,270 @@ struct static_const
template<typename T>
constexpr T static_const<T>::value;
////////////////////
// input adapters //
////////////////////
/// abstract input adapter interface
struct input_adapter
{
virtual int get_character() = 0;
virtual std::string read(size_t offset, size_t length) = 0;
virtual ~input_adapter() {}
};
/// a type to simplify interfaces
using input_adapter_t = std::shared_ptr<input_adapter>;
/// input adapter for cached stream input
template<std::size_t N>
class cached_input_stream_adapter : public input_adapter
{
public:
cached_input_stream_adapter(std::istream& i)
: is(i), start_position(is.tellg())
{
fill_buffer();
// skip byte order mark
if (fill_size >= 3 and buffer[0] == '\xEF' and buffer[1] == '\xBB' and buffer[2] == '\xBF')
{
buffer_pos += 3;
processed_chars += 3;
}
}
~cached_input_stream_adapter() override
{
// clear stream flags
is.clear();
// We initially read a lot of characters into the buffer, and we
// may not have processed all of them. Therefore, we need to
// "rewind" the stream after the last processed char.
is.seekg(start_position);
is.ignore(static_cast<std::streamsize>(processed_chars));
// clear stream flags
is.clear();
}
int get_character() override
{
// check if refilling is necessary and possible
if (buffer_pos == fill_size and not eof)
{
fill_buffer();
// check and remember that filling did not yield new input
if (fill_size == 0)
{
eof = true;
return std::char_traits<char>::eof();
}
// the buffer is ready
buffer_pos = 0;
}
++processed_chars;
assert(buffer_pos < buffer.size());
return buffer[buffer_pos++] & 0xFF;
}
std::string read(size_t offset, size_t length) override
{
// create buffer
std::string result(length, '\0');
// save stream position
const auto current_pos = is.tellg();
// save stream flags
const auto flags = is.rdstate();
// clear stream flags
is.clear();
// set stream position
is.seekg(static_cast<std::streamoff>(offset));
// read bytes
is.read(&result[0], static_cast<std::streamsize>(length));
// reset stream position
is.seekg(current_pos);
// reset stream flags
is.setstate(flags);
return result;
}
private:
void fill_buffer()
{
// fill
is.read(buffer.data(), static_cast<std::streamsize>(buffer.size()));
// store number of bytes in the buffer
fill_size = static_cast<size_t>(is.gcount());
}
/// the associated input stream
std::istream& is;
/// chars returned via get_character()
size_t processed_chars = 0;
/// chars processed in the current buffer
size_t buffer_pos = 0;
/// whether stream reached eof
bool eof = false;
/// how many chars have been copied to the buffer by last (re)fill
size_t fill_size = 0;
/// position of the stream when we started
const std::streampos start_position;
/// internal buffer
std::array<char, N> buffer{{}};
};
/// input adapter for buffer input
class input_buffer_adapter : public input_adapter
{
public:
input_buffer_adapter(const char* b, size_t l)
: input_adapter(), cursor(b), limit(b + l), start(b)
{
// skip byte order mark
if (l >= 3 and b[0] == '\xEF' and b[1] == '\xBB' and b[2] == '\xBF')
{
cursor += 3;
}
}
// delete because of pointer members
input_buffer_adapter(const input_buffer_adapter&) = delete;
input_buffer_adapter& operator=(input_buffer_adapter&) = delete;
int get_character() noexcept override
{
if (JSON_LIKELY(cursor < limit))
{
return *(cursor++) & 0xFF;
}
else
{
return std::char_traits<char>::eof();
}
}
std::string read(size_t offset, size_t length) override
{
// avoid reading too many characters
const size_t max_length = static_cast<size_t>(limit - start);
return std::string(start + offset, (std::min)(length, max_length - offset));
}
private:
/// pointer to the current character
const char* cursor;
/// pointer past the last character
const char* limit;
/// pointer to the first character
const char* start;
};
struct input_adapter_factory
{
// native support
/// input adapter for input stream
static std::shared_ptr<input_adapter> create(std::istream& i)
{
return std::make_shared<cached_input_stream_adapter<16384>> (i);
}
/// input adapter for input stream
static std::shared_ptr<input_adapter> create(std::istream&& i)
{
return std::make_shared<cached_input_stream_adapter<16384>>(i);
}
/// input adapter for buffer
static std::shared_ptr<input_adapter> create(const char* b, size_t l)
{
return std::make_shared<input_buffer_adapter>(b, l);
}
// derived support
/// input adapter for string literal
template <typename CharT,
typename std::enable_if<
std::is_pointer<CharT>::value and
std::is_integral<
typename std::remove_pointer<CharT>::type>::value and
sizeof(typename std::remove_pointer<CharT>::type) == 1,
int>::type = 0>
static std::shared_ptr<input_adapter> create(CharT b)
{
return create(reinterpret_cast<const char*>(b),
std::strlen(reinterpret_cast<const char*>(b)));
}
/// input adapter for iterator range with contiguous storage
template <class IteratorType,
typename std::enable_if<
std::is_same<typename std::iterator_traits<
IteratorType>::iterator_category,
std::random_access_iterator_tag>::value,
int>::type = 0>
static std::shared_ptr<input_adapter> create(IteratorType first,
IteratorType last)
{
// assertion to check that the iterator range is indeed contiguous,
// see http://stackoverflow.com/a/35008842/266378 for more discussion
assert(std::accumulate(
first, last, std::pair<bool, int>(true, 0),
[&first](std::pair<bool, int> res, decltype(*first) val)
{
res.first &=
(val ==
*(std::next(std::addressof(*first), res.second++)));
return res;
})
.first);
// assertion to check that each element is 1 byte long
static_assert(
sizeof(typename std::iterator_traits<IteratorType>::value_type) == 1, "each element in the iterator range must have the size of 1 byte");
return create(reinterpret_cast<const char*>(&(*first)),
static_cast<size_t>(std::distance(first, last)));
}
/// input adapter for array
template <class T, std::size_t N>
static std::shared_ptr<input_adapter> create(T (&array)[N])
{
// delegate the call to the iterator-range overload
return create(std::begin(array), std::end(array));
}
/// input adapter for contiguous container
template <
class ContiguousContainer,
typename std::enable_if <
not std::is_pointer<ContiguousContainer>::value and
std::is_base_of<std::random_access_iterator_tag,
typename std::iterator_traits<decltype(std::begin(
std::declval<ContiguousContainer const>()))>::
iterator_category>::value,
int >::type = 0 >
static std::shared_ptr<input_adapter> create(const ContiguousContainer& c)
{
// delegate the call to the iterator-range overload
return create(std::begin(c), std::end(c));
}
};
} // namespace detail
@ -7822,7 +8086,7 @@ class basic_json
static basic_json parse(const CharT s,
const parser_callback_t cb = nullptr)
{
return parser(input_adapter::create(s), cb).parse(true);
return parser(detail::input_adapter_factory::create(s), cb).parse(true);
}
template<typename CharT, typename std::enable_if<
@ -7831,7 +8095,7 @@ class basic_json
sizeof(typename std::remove_pointer<CharT>::type) == 1, int>::type = 0>
static bool accept(const CharT s)
{
return parser(input_adapter::create(s)).accept(true);
return parser(detail::input_adapter_factory::create(s)).accept(true);
}
/*!
@ -7865,12 +8129,12 @@ class basic_json
static basic_json parse(std::istream& i,
const parser_callback_t cb = nullptr)
{
return parser(input_adapter::create(i), cb).parse(true);
return parser(detail::input_adapter_factory::create(i), cb).parse(true);
}
static bool accept(std::istream& i)
{
return parser(input_adapter::create(i)).accept(true);
return parser(detail::input_adapter_factory::create(i)).accept(true);
}
/*!
@ -7879,12 +8143,12 @@ class basic_json
static basic_json parse(std::istream&& i,
const parser_callback_t cb = nullptr)
{
return parser(input_adapter::create(i), cb).parse(true);
return parser(detail::input_adapter_factory::create(i), cb).parse(true);
}
static bool accept(std::istream&& i)
{
return parser(input_adapter::create(i)).accept(true);
return parser(detail::input_adapter_factory::create(i)).accept(true);
}
/*!
@ -7939,7 +8203,7 @@ class basic_json
static basic_json parse(IteratorType first, IteratorType last,
const parser_callback_t cb = nullptr)
{
return parser(input_adapter::create(first, last), cb).parse(true);
return parser(detail::input_adapter_factory::create(first, last), cb).parse(true);
}
template<class IteratorType, typename std::enable_if<
@ -7948,7 +8212,7 @@ class basic_json
typename std::iterator_traits<IteratorType>::iterator_category>::value, int>::type = 0>
static bool accept(IteratorType first, IteratorType last)
{
return parser(input_adapter::create(first, last)).accept(true);
return parser(detail::input_adapter_factory::create(first, last)).accept(true);
}
/*!
@ -8030,7 +8294,7 @@ class basic_json
JSON_DEPRECATED
friend std::istream& operator<<(basic_json& j, std::istream& i)
{
j = parser(input_adapter::create(i)).parse(false);
j = parser(detail::input_adapter_factory::create(i)).parse(false);
return i;
}
@ -8061,7 +8325,7 @@ class basic_json
*/
friend std::istream& operator>>(std::istream& i, basic_json& j)
{
j = parser(input_adapter::create(i)).parse(false);
j = parser(detail::input_adapter_factory::create(i)).parse(false);
return i;
}
@ -9100,263 +9364,6 @@ class basic_json
private:
////////////////////
// input adapters //
////////////////////
/// abstract input adapter interface
class input_adapter
{
public:
virtual int get_character() = 0;
virtual std::string read(size_t offset, size_t length) = 0;
virtual ~input_adapter() {}
// native support
/// input adapter for input stream
static std::shared_ptr<input_adapter> create(std::istream& i)
{
return std::make_shared<cached_input_stream_adapter<16384>> (i);
}
/// input adapter for input stream
static std::shared_ptr<input_adapter> create(std::istream&& i)
{
return std::make_shared<cached_input_stream_adapter<16384>>(i);
}
/// input adapter for buffer
static std::shared_ptr<input_adapter> create(const char* b, size_t l)
{
return std::make_shared<input_buffer_adapter>(b, l);
}
// derived support
/// input adapter for string literal
template<typename CharT, typename std::enable_if<
std::is_pointer<CharT>::value and
std::is_integral<typename std::remove_pointer<CharT>::type>::value and
sizeof(typename std::remove_pointer<CharT>::type) == 1, int>::type = 0>
static std::shared_ptr<input_adapter> create(CharT b)
{
return create(reinterpret_cast<const char*>(b),
std::strlen(reinterpret_cast<const char*>(b)));
}
/// input adapter for iterator range with contiguous storage
template<class IteratorType, typename std::enable_if<
std::is_same<typename std::iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value
, int>::type
= 0>
static std::shared_ptr<input_adapter> create(IteratorType first, IteratorType last)
{
// assertion to check that the iterator range is indeed contiguous,
// see http://stackoverflow.com/a/35008842/266378 for more discussion
assert(std::accumulate(first, last, std::pair<bool, int>(true, 0),
[&first](std::pair<bool, int> res, decltype(*first) val)
{
res.first &= (val == *(std::next(std::addressof(*first), res.second++)));
return res;
}).first);
// assertion to check that each element is 1 byte long
static_assert(sizeof(typename std::iterator_traits<IteratorType>::value_type) == 1,
"each element in the iterator range must have the size of 1 byte");
const auto len = static_cast<size_t>(std::distance(first, last));
if (JSON_LIKELY(len > 0))
{
// there is at least one element: use the address of first
return create(reinterpret_cast<const char*>(&(*first)), len);
}
else
{
// the address of first cannot be used - use nullptr
return create(nullptr, len);
}
}
/// input adapter for array
template<class T, std::size_t N>
static std::shared_ptr<input_adapter> create(T (&array)[N])
{
// delegate the call to the iterator-range overload
return create(std::begin(array), std::end(array));
}
/// input adapter for contiguous container
template<class ContiguousContainer, typename std::enable_if<
not std::is_pointer<ContiguousContainer>::value and
std::is_base_of<
std::random_access_iterator_tag,
typename std::iterator_traits<decltype(std::begin(std::declval<ContiguousContainer const>()))>::iterator_category>::value
, int>::type = 0>
static std::shared_ptr<input_adapter> create(const ContiguousContainer& c)
{
// delegate the call to the iterator-range overload
return create(std::begin(c), std::end(c));
}
};
/// a type to simplify interfaces
using input_adapter_t = std::shared_ptr<input_adapter>;
/// input adapter for cached stream input
template<std::size_t N>
class cached_input_stream_adapter : public input_adapter
{
public:
cached_input_stream_adapter(std::istream& i)
: is(i), start_position(is.tellg())
{
fill_buffer();
// skip byte order mark
if (fill_size >= 3 and buffer[0] == '\xEF' and buffer[1] == '\xBB' and buffer[2] == '\xBF')
{
buffer_pos += 3;
processed_chars += 3;
}
}
~cached_input_stream_adapter() override
{
// clear stream flags
is.clear();
// We initially read a lot of characters into the buffer, and we
// may not have processed all of them. Therefore, we need to
// "rewind" the stream after the last processed char.
is.seekg(start_position);
is.ignore(static_cast<std::streamsize>(processed_chars));
// clear stream flags
is.clear();
}
int get_character() override
{
// check if refilling is necessary and possible
if (buffer_pos == fill_size and not eof)
{
fill_buffer();
// check and remember that filling did not yield new input
if (fill_size == 0)
{
eof = true;
return std::char_traits<char>::eof();
}
// the buffer is ready
buffer_pos = 0;
}
++processed_chars;
assert(buffer_pos < buffer.size());
return buffer[buffer_pos++] & 0xFF;
}
std::string read(size_t offset, size_t length) override
{
// create buffer
std::string result(length, '\0');
// save stream position
const auto current_pos = is.tellg();
// save stream flags
const auto flags = is.rdstate();
// clear stream flags
is.clear();
// set stream position
is.seekg(static_cast<std::streamoff>(offset));
// read bytes
is.read(&result[0], static_cast<std::streamsize>(length));
// reset stream position
is.seekg(current_pos);
// reset stream flags
is.setstate(flags);
return result;
}
private:
void fill_buffer()
{
// fill
is.read(buffer.data(), static_cast<std::streamsize>(buffer.size()));
// store number of bytes in the buffer
fill_size = static_cast<size_t>(is.gcount());
}
/// the associated input stream
std::istream& is;
/// chars returned via get_character()
size_t processed_chars = 0;
/// chars processed in the current buffer
size_t buffer_pos = 0;
/// whether stream reached eof
bool eof = false;
/// how many chars have been copied to the buffer by last (re)fill
size_t fill_size = 0;
/// position of the stream when we started
const std::streampos start_position;
/// internal buffer
std::array<char, N> buffer{{}};
};
/// input adapter for buffer input
class input_buffer_adapter : public input_adapter
{
public:
input_buffer_adapter(const char* b, size_t l)
: input_adapter(), cursor(b), limit(b + l), start(b)
{
// skip byte order mark
if (l >= 3 and b[0] == '\xEF' and b[1] == '\xBB' and b[2] == '\xBF')
{
cursor += 3;
}
}
// delete because of pointer members
input_buffer_adapter(const input_buffer_adapter&) = delete;
input_buffer_adapter& operator=(input_buffer_adapter&) = delete;
int get_character() noexcept override
{
if (JSON_LIKELY(cursor < limit))
{
return *(cursor++) & 0xFF;
}
else
{
return std::char_traits<char>::eof();
}
}
std::string read(size_t offset, size_t length) override
{
// avoid reading too many characters
const size_t max_length = static_cast<size_t>(limit - start);
return std::string(start + offset, (std::min)(length, max_length - offset));
}
private:
/// pointer to the current character
const char* cursor;
/// pointer past the last character
const char* limit;
/// pointer to the first character
const char* start;
};
//////////////////////////////////////////
// binary serialization/deserialization //
//////////////////////////////////////////
@ -9364,7 +9371,6 @@ class basic_json
/// @name binary serialization/deserialization support
/// @{
private:
/*!
@brief deserialization of CBOR and MessagePack values
*/
@ -9376,7 +9382,7 @@ class basic_json
@param[in] adapter input adapter to read from
*/
explicit binary_reader(input_adapter_t adapter)
explicit binary_reader(detail::input_adapter_t adapter)
: ia(adapter), is_little_endian(little_endianess())
{
assert(ia);
@ -10489,7 +10495,7 @@ class basic_json
private:
/// input adapter
input_adapter_t ia = nullptr;
detail::input_adapter_t ia = nullptr;
/// the current character
int current = std::char_traits<char>::eof();
@ -11299,7 +11305,7 @@ class basic_json
static basic_json from_cbor(const std::vector<uint8_t>& v,
const size_t start_index = 0)
{
binary_reader br(input_adapter::create(v.begin() + static_cast<difference_type>(start_index), v.end()));
binary_reader br(detail::input_adapter_factory::create(v.begin() + static_cast<difference_type>(start_index), v.end()));
return br.parse_cbor();
}
@ -11374,7 +11380,7 @@ class basic_json
static basic_json from_msgpack(const std::vector<uint8_t>& v,
const size_t start_index = 0)
{
binary_reader br(input_adapter::create(v.begin() + static_cast<difference_type>(start_index), v.end()));
binary_reader br(detail::input_adapter_factory::create(v.begin() + static_cast<difference_type>(start_index), v.end()));
return br.parse_msgpack();
}
@ -11460,7 +11466,7 @@ class basic_json
}
}
explicit lexer(input_adapter_t adapter)
explicit lexer(detail::input_adapter_t adapter)
: ia(adapter), decimal_point_char(get_decimal_point())
{}
@ -12864,7 +12870,7 @@ scan_number_done:
private:
/// input adapter
input_adapter_t ia = nullptr;
detail::input_adapter_t ia = nullptr;
/// the current character
int current = std::char_traits<char>::eof();
@ -12903,7 +12909,7 @@ scan_number_done:
{
public:
/// a parser reading from an input adapter
explicit parser(input_adapter_t adapter,
explicit parser(detail::input_adapter_t adapter,
const parser_callback_t cb = nullptr)
: callback(cb), m_lexer(adapter)
{}

2
test/src/unit-class_lexer.cpp
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@ -36,7 +36,7 @@ using nlohmann::json;
json::lexer::token_type scan_string(const char* s);
json::lexer::token_type scan_string(const char* s)
{
return json::lexer(json::input_adapter::create(s)).scan();
return json::lexer(nlohmann::detail::input_adapter_factory::create(s)).scan();
}
TEST_CASE("lexer class")

914
test/src/unit-class_parser.cpp
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