json/include/nlohmann/detail/input/json_sax.hpp
2018-03-18 15:13:53 +01:00

606 lines
17 KiB
C++

#pragma once
#include <cstddef>
#include <string>
#include <vector>
#include <nlohmann/detail/input/parser.hpp>
#include <nlohmann/detail/exceptions.hpp>
namespace nlohmann
{
/*!
@brief SAX interface
*/
template<typename BasicJsonType>
struct json_sax
{
/// type for (signed) integers
using number_integer_t = typename BasicJsonType::number_integer_t;
/// type for unsigned integers
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
/// type for floating-point numbers
using number_float_t = typename BasicJsonType::number_float_t;
/// type for strings
using string_t = typename BasicJsonType::string_t;
/// constant to indicate that no size limit is given for array or object
static constexpr auto no_limit = std::size_t(-1);
/*!
@brief a null value was read
@return whether parsing should proceed
*/
virtual bool null() = 0;
/*!
@brief a boolean value was read
@param[in] val boolean value
@return whether parsing should proceed
*/
virtual bool boolean(bool val) = 0;
/*!
@brief an integer number was read
@param[in] val integer value
@return whether parsing should proceed
*/
virtual bool number_integer(number_integer_t val) = 0;
/*!
@brief an unsigned integer number was read
@param[in] val unsigned integer value
@return whether parsing should proceed
*/
virtual bool number_unsigned(number_unsigned_t val) = 0;
/*!
@brief an floating-point number was read
@param[in] val floating-point value
@param[in] s raw token value
@return whether parsing should proceed
*/
virtual bool number_float(number_float_t val, const string_t& s) = 0;
/*!
@brief a string was read
@param[in] val string value
@return whether parsing should proceed
*/
virtual bool string(string_t&& val) = 0;
/*!
@brief the beginning of an object was read
@param[in] elements number of object elements or no_limit if unknown
@return whether parsing should proceed
@note binary formats may report the number of elements
*/
virtual bool start_object(std::size_t elements = no_limit) = 0;
/*!
@brief an object key was read
@param[in] val object key
@return whether parsing should proceed
*/
virtual bool key(string_t&& val) = 0;
/*!
@brief the end of an object was read
@return whether parsing should proceed
*/
virtual bool end_object() = 0;
/*!
@brief the beginning of an array was read
@param[in] elements number of array elements or no_limit if unknown
@return whether parsing should proceed
@note binary formats may report the number of elements
*/
virtual bool start_array(std::size_t elements = no_limit) = 0;
/*!
@brief the end of an array was read
@return whether parsing should proceed
*/
virtual bool end_array() = 0;
/*!
@brief a binary value was read
@param[in] val byte vector
@return whether parsing should proceed
@note examples are CBOR type 2 strings, MessagePack bin, and maybe UBJSON
array<uint8t>
*/
virtual bool binary(const std::vector<uint8_t>& val) = 0;
/*!
@brief a parse error occurred
@param[in] position the position in the input where the error occurs
@param[in] last_token the last read token
@param[in] error_msg a detailed error message
@return whether parsing should proceed
*/
virtual bool parse_error(std::size_t position,
const std::string& last_token,
const detail::exception& ex) = 0;
virtual ~json_sax() = default;
};
namespace detail
{
template<typename BasicJsonType>
class json_sax_dom_parser : public json_sax<BasicJsonType>
{
public:
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using number_float_t = typename BasicJsonType::number_float_t;
using string_t = typename BasicJsonType::string_t;
json_sax_dom_parser(BasicJsonType& r, const bool allow_exceptions_ = true)
: root(r), allow_exceptions(allow_exceptions_)
{}
bool null() override
{
handle_value(nullptr);
return true;
}
bool boolean(bool val) override
{
handle_value(val);
return true;
}
bool number_integer(number_integer_t val) override
{
handle_value(val);
return true;
}
bool number_unsigned(number_unsigned_t val) override
{
handle_value(val);
return true;
}
bool number_float(number_float_t val, const string_t&) override
{
handle_value(val);
return true;
}
bool string(string_t&& val) override
{
handle_value(val);
return true;
}
bool start_object(std::size_t len) override
{
ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
{
JSON_THROW(out_of_range::create(408,
"excessive object size: " + std::to_string(len)));
}
return true;
}
bool key(string_t&& val) override
{
// add null at given key and store the reference for later
object_element = &(ref_stack.back()->m_value.object->operator[](val));
return true;
}
bool end_object() override
{
ref_stack.pop_back();
return true;
}
bool start_array(std::size_t len) override
{
ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
{
JSON_THROW(out_of_range::create(408,
"excessive array size: " + std::to_string(len)));
}
return true;
}
bool end_array() override
{
ref_stack.pop_back();
return true;
}
bool binary(const std::vector<uint8_t>&) override
{
return true;
}
bool parse_error(std::size_t, const std::string&,
const detail::exception& ex) override
{
errored = true;
if (allow_exceptions)
{
// determine the proper exception type from the id
switch ((ex.id / 100) % 100)
{
case 1:
JSON_THROW(*reinterpret_cast<const detail::parse_error*>(&ex));
case 2:
JSON_THROW(*reinterpret_cast<const detail::invalid_iterator*>(&ex)); // LCOV_EXCL_LINE
case 3:
JSON_THROW(*reinterpret_cast<const detail::type_error*>(&ex)); // LCOV_EXCL_LINE
case 4:
JSON_THROW(*reinterpret_cast<const detail::out_of_range*>(&ex));
case 5:
JSON_THROW(*reinterpret_cast<const detail::other_error*>(&ex)); // LCOV_EXCL_LINE
default:
assert(false); // LCOV_EXCL_LINE
}
}
return false;
}
bool is_errored() const
{
return errored;
}
private:
/*!
@invariant If the ref stack is empty, then the passed value will be the new
root.
@invariant If the ref stack contains a value, then it is an array or an
object to which we can add elements
*/
template<typename Value>
BasicJsonType* handle_value(Value&& v)
{
if (ref_stack.empty())
{
root = BasicJsonType(std::forward<Value>(v));
return &root;
}
else
{
switch (ref_stack.back()->m_type)
{
case value_t::array:
{
ref_stack.back()->m_value.array->push_back(BasicJsonType(std::forward<Value>(v)));
return &(ref_stack.back()->m_value.array->back());
}
case value_t::object:
{
assert(object_element);
*object_element = BasicJsonType(std::forward<Value>(v));
return object_element;
}
default:
assert(false); // LCOV_EXCL_LINE
}
}
}
/// the parsed JSON value
BasicJsonType& root;
/// stack to model hierarchy of values
std::vector<BasicJsonType*> ref_stack;
/// helper to hold the reference for the next object element
BasicJsonType* object_element = nullptr;
/// whether a syntax error occurred
bool errored = false;
/// whether to throw exceptions in case of errors
const bool allow_exceptions = true;
};
template<typename BasicJsonType>
class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
{
public:
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using number_float_t = typename BasicJsonType::number_float_t;
using string_t = typename BasicJsonType::string_t;
using parser_callback_t = typename BasicJsonType::parser_callback_t;
using parse_event_t = typename BasicJsonType::parse_event_t;
json_sax_dom_callback_parser(BasicJsonType& r,
const parser_callback_t cb = nullptr,
const bool allow_exceptions_ = true)
: root(r), callback(cb), allow_exceptions(allow_exceptions_)
{
keep_stack.push_back(true);
}
bool null() override
{
handle_value(nullptr);
return true;
}
bool boolean(bool val) override
{
handle_value(val);
return true;
}
bool number_integer(number_integer_t val) override
{
handle_value(val);
return true;
}
bool number_unsigned(number_unsigned_t val) override
{
handle_value(val);
return true;
}
bool number_float(number_float_t val, const string_t&) override
{
handle_value(val);
return true;
}
bool string(string_t&& val) override
{
handle_value(val);
return true;
}
bool start_object(std::size_t len) override
{
const bool keep = callback(ref_stack.size() + 1, parse_event_t::object_start, discarded);
keep_stack.push_back(keep);
ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
{
JSON_THROW(out_of_range::create(408,
"excessive object size: " + std::to_string(len)));
}
return true;
}
bool key(string_t&& val) override
{
BasicJsonType k = BasicJsonType(std::forward < string_t&& > (val));
const bool keep = callback(ref_stack.size(), parse_event_t::key, k);
// add null at given key and store the reference for later
object_element = &(ref_stack.back()->m_value.object->operator[](val));
return true;
}
bool end_object() override
{
const bool keep = callback(ref_stack.size() - 1, parse_event_t::object_end, *ref_stack.back());
if (not keep)
{
*ref_stack.back() = discarded;
}
ref_stack.pop_back();
keep_stack.pop_back();
return true;
}
bool start_array(std::size_t len) override
{
const bool keep = callback(ref_stack.size() + 1, parse_event_t::array_start, discarded);
keep_stack.push_back(keep);
ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
{
JSON_THROW(out_of_range::create(408,
"excessive array size: " + std::to_string(len)));
}
return true;
}
bool end_array() override
{
const bool keep = callback(ref_stack.size() - 1, parse_event_t::array_end, *ref_stack.back());
if (not keep)
{
*ref_stack.back() = discarded;
}
ref_stack.pop_back();
keep_stack.pop_back();
return true;
}
bool binary(const std::vector<uint8_t>&) override
{
return true;
}
bool parse_error(std::size_t, const std::string&,
const detail::exception& ex) override
{
errored = true;
if (allow_exceptions)
{
// determine the proper exception type from the id
switch ((ex.id / 100) % 100)
{
case 1:
JSON_THROW(*reinterpret_cast<const detail::parse_error*>(&ex));
case 2:
JSON_THROW(*reinterpret_cast<const detail::invalid_iterator*>(&ex)); // LCOV_EXCL_LINE
case 3:
JSON_THROW(*reinterpret_cast<const detail::type_error*>(&ex)); // LCOV_EXCL_LINE
case 4:
JSON_THROW(*reinterpret_cast<const detail::out_of_range*>(&ex));
case 5:
JSON_THROW(*reinterpret_cast<const detail::other_error*>(&ex)); // LCOV_EXCL_LINE
default:
assert(false); // LCOV_EXCL_LINE
}
}
return false;
}
bool is_errored() const
{
return errored;
}
private:
/*!
@invariant If the ref stack is empty, then the passed value will be the new
root.
@invariant If the ref stack contains a value, then it is an array or an
object to which we can add elements
*/
template<typename Value>
BasicJsonType* handle_value(Value&& v)
{
if (ref_stack.empty())
{
root = BasicJsonType(std::forward<Value>(v));
return &root;
}
else
{
switch (ref_stack.back()->m_type)
{
case value_t::array:
{
ref_stack.back()->m_value.array->push_back(BasicJsonType(std::forward<Value>(v)));
return &(ref_stack.back()->m_value.array->back());
}
case value_t::object:
{
assert(object_element);
*object_element = BasicJsonType(std::forward<Value>(v));
return object_element;
}
default:
assert(false); // LCOV_EXCL_LINE
}
}
}
/// the parsed JSON value
BasicJsonType& root;
/// stack to model hierarchy of values
std::vector<BasicJsonType*> ref_stack;
/// stack to manage which values to keep
std::vector<bool> keep_stack;
/// helper to hold the reference for the next object element
BasicJsonType* object_element = nullptr;
/// whether a syntax error occurred
bool errored = false;
/// callback function
const parser_callback_t callback = nullptr;
/// whether to throw exceptions in case of errors
const bool allow_exceptions = true;
/// a discarded value for the callback
BasicJsonType discarded = BasicJsonType::value_t::discarded;
};
template<typename BasicJsonType>
class json_sax_acceptor : public json_sax<BasicJsonType>
{
public:
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using number_float_t = typename BasicJsonType::number_float_t;
using string_t = typename BasicJsonType::string_t;
bool null() override
{
return true;
}
bool boolean(bool) override
{
return true;
}
bool number_integer(number_integer_t) override
{
return true;
}
bool number_unsigned(number_unsigned_t) override
{
return true;
}
bool number_float(number_float_t, const string_t&) override
{
return true;
}
bool string(string_t&&) override
{
return true;
}
bool start_object(std::size_t) override
{
return true;
}
bool key(string_t&&) override
{
return true;
}
bool end_object() override
{
return true;
}
bool start_array(std::size_t) override
{
return true;
}
bool end_array() override
{
return true;
}
bool binary(const std::vector<uint8_t>&) override
{
return true;
}
bool parse_error(std::size_t, const std::string&, const detail::exception&) override
{
return false;
}
};
}
}