json/include/nlohmann/detail/output/primitive_serializer.hpp
2018-06-02 00:16:08 -05:00

415 lines
16 KiB
C++

#pragma once
#include <algorithm> // reverse, remove, fill, find, none_of
#include <array> // array
#include <cassert> // assert
#include <ciso646> // and, or
#include <clocale> // localeconv, lconv
#include <cmath> // labs, isfinite, isnan, signbit
#include <cstddef> // size_t, ptrdiff_t
#include <cstdint> // uint8_t
#include <cstdio> // snprintf
#include <limits> // numeric_limits
#include <string> // string
#include <type_traits> // is_same
#include <nlohmann/detail/exceptions.hpp>
#include <nlohmann/detail/conversions/to_chars.hpp>
#include <nlohmann/detail/macro_scope.hpp>
#include <nlohmann/detail/meta.hpp>
#include <nlohmann/detail/output/output_adapters.hpp>
#include <nlohmann/detail/value_t.hpp>
namespace nlohmann
{
namespace detail
{
///////////////////
// serialization //
///////////////////
template<typename BasicJsonType>
class primitive_serializer
{
using string_t = typename BasicJsonType::string_t;
using number_float_t = typename BasicJsonType::number_float_t;
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
static constexpr uint8_t UTF8_ACCEPT = 0;
static constexpr uint8_t UTF8_REJECT = 1;
using output_adapter_protocol_t = output_adapter_protocol<char>;
public:
/*!
@param[in] s output stream to serialize to
@param[in] ichar indentation character to use
*/
primitive_serializer()
: loc(std::localeconv()),
thousands_sep(loc->thousands_sep == nullptr ? '\0' : * (loc->thousands_sep)),
decimal_point(loc->decimal_point == nullptr ? '\0' : * (loc->decimal_point))
{}
// delete because of pointer members
primitive_serializer(const primitive_serializer&) = delete;
primitive_serializer& operator=(const primitive_serializer&) = delete;
/*!
@brief dump escaped string
Escape a string by replacing certain special characters by a sequence of an
escape character (backslash) and another character and other control
characters by a sequence of "\u" followed by a four-digit hex
representation. The escaped string is written to output stream @a o.
@param[in] s the string to escape
@param[in] ensure_ascii whether to escape non-ASCII characters with
\uXXXX sequences
@complexity Linear in the length of string @a s.
*/
void dump_escaped(output_adapter_protocol_t& o, const string_t& s, const bool ensure_ascii)
{
uint32_t codepoint;
uint8_t state = UTF8_ACCEPT;
std::size_t bytes = 0; // number of bytes written to string_buffer
for (std::size_t i = 0; i < s.size(); ++i)
{
const auto byte = static_cast<uint8_t>(s[i]);
switch (decode(state, codepoint, byte))
{
case UTF8_ACCEPT: // decode found a new code point
{
switch (codepoint)
{
case 0x08: // backspace
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'b';
break;
}
case 0x09: // horizontal tab
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 't';
break;
}
case 0x0A: // newline
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'n';
break;
}
case 0x0C: // formfeed
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'f';
break;
}
case 0x0D: // carriage return
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = 'r';
break;
}
case 0x22: // quotation mark
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = '\"';
break;
}
case 0x5C: // reverse solidus
{
string_buffer[bytes++] = '\\';
string_buffer[bytes++] = '\\';
break;
}
default:
{
// escape control characters (0x00..0x1F) or, if
// ensure_ascii parameter is used, non-ASCII characters
if ((codepoint <= 0x1F) or (ensure_ascii and (codepoint >= 0x7F)))
{
if (codepoint <= 0xFFFF)
{
std::snprintf(string_buffer.data() + bytes, 7, "\\u%04x",
static_cast<uint16_t>(codepoint));
bytes += 6;
}
else
{
std::snprintf(string_buffer.data() + bytes, 13, "\\u%04x\\u%04x",
static_cast<uint16_t>(0xD7C0 + (codepoint >> 10)),
static_cast<uint16_t>(0xDC00 + (codepoint & 0x3FF)));
bytes += 12;
}
}
else
{
// copy byte to buffer (all previous bytes
// been copied have in default case above)
string_buffer[bytes++] = s[i];
}
break;
}
}
// write buffer and reset index; there must be 13 bytes
// left, as this is the maximal number of bytes to be
// written ("\uxxxx\uxxxx\0") for one code point
if (string_buffer.size() - bytes < 13)
{
o.write_characters(string_buffer.data(), bytes);
bytes = 0;
}
break;
}
case UTF8_REJECT: // decode found invalid UTF-8 byte
{
std::string sn(3, '\0');
snprintf(&sn[0], sn.size(), "%.2X", byte);
JSON_THROW(type_error::create(316, "invalid UTF-8 byte at index " + std::to_string(i) + ": 0x" + sn));
}
default: // decode found yet incomplete multi-byte code point
{
if (not ensure_ascii)
{
// code point will not be escaped - copy byte to buffer
string_buffer[bytes++] = s[i];
}
break;
}
}
}
if (JSON_LIKELY(state == UTF8_ACCEPT))
{
// write buffer
if (bytes > 0)
{
o.write_characters(string_buffer.data(), bytes);
}
}
else
{
// we finish reading, but do not accept: string was incomplete
std::string sn(3, '\0');
snprintf(&sn[0], sn.size(), "%.2X", static_cast<uint8_t>(s.back()));
JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + sn));
}
}
/*!
@brief dump an integer
Dump a given integer to output stream @a o. Works internally with
@a number_buffer.
@param[in] x integer number (signed or unsigned) to dump
@tparam NumberType either @a number_integer_t or @a number_unsigned_t
*/
template<typename NumberType, detail::enable_if_t<
std::is_same<NumberType, number_unsigned_t>::value or
std::is_same<NumberType, number_integer_t>::value,
int> = 0>
void dump_integer(output_adapter_protocol_t& o, NumberType x)
{
// special case for "0"
if (x == 0)
{
o.write_character('0');
return;
}
const bool is_negative = (x <= 0) and (x != 0); // see issue #755
std::size_t i = 0;
while (x != 0)
{
// spare 1 byte for '\0'
assert(i < number_buffer.size() - 1);
const auto digit = std::labs(static_cast<long>(x % 10));
number_buffer[i++] = static_cast<char>('0' + digit);
x /= 10;
}
if (is_negative)
{
// make sure there is capacity for the '-'
assert(i < number_buffer.size() - 2);
number_buffer[i++] = '-';
}
std::reverse(number_buffer.begin(), number_buffer.begin() + i);
o.write_characters(number_buffer.data(), i);
}
/*!
@brief dump a floating-point number
Dump a given floating-point number to output stream @a o. Works internally
with @a number_buffer.
@param[in] x floating-point number to dump
*/
void dump_float(output_adapter_protocol_t& o, number_float_t x)
{
// NaN / inf
if (not std::isfinite(x))
{
o.write_characters("null", 4);
return;
}
// If number_float_t is an IEEE-754 single or double precision number,
// use the Grisu2 algorithm to produce short numbers which are
// guaranteed to round-trip, using strtof and strtod, resp.
//
// NB: The test below works if <long double> == <double>.
static constexpr bool is_ieee_single_or_double
= (std::numeric_limits<number_float_t>::is_iec559 and std::numeric_limits<number_float_t>::digits == 24 and std::numeric_limits<number_float_t>::max_exponent == 128) or
(std::numeric_limits<number_float_t>::is_iec559 and std::numeric_limits<number_float_t>::digits == 53 and std::numeric_limits<number_float_t>::max_exponent == 1024);
dump_float(o, x, std::integral_constant<bool, is_ieee_single_or_double>());
}
private:
void dump_float(output_adapter_protocol_t& o, number_float_t x, std::true_type /*is_ieee_single_or_double*/)
{
char* begin = number_buffer.data();
char* end = ::nlohmann::detail::to_chars(begin, begin + number_buffer.size(), x);
o.write_characters(begin, static_cast<size_t>(end - begin));
}
void dump_float(output_adapter_protocol_t& o, number_float_t x, std::false_type /*is_ieee_single_or_double*/)
{
// get number of digits for a float -> text -> float round-trip
static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
// the actual conversion
std::ptrdiff_t len = snprintf(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
// negative value indicates an error
assert(len > 0);
// check if buffer was large enough
assert(static_cast<std::size_t>(len) < number_buffer.size());
// erase thousands separator
if (thousands_sep != '\0')
{
const auto end = std::remove(number_buffer.begin(),
number_buffer.begin() + len, thousands_sep);
std::fill(end, number_buffer.end(), '\0');
assert((end - number_buffer.begin()) <= len);
len = (end - number_buffer.begin());
}
// convert decimal point to '.'
if (decimal_point != '\0' and decimal_point != '.')
{
const auto dec_pos = std::find(number_buffer.begin(), number_buffer.end(), decimal_point);
if (dec_pos != number_buffer.end())
{
*dec_pos = '.';
}
}
o.write_characters(number_buffer.data(), static_cast<std::size_t>(len));
// determine if need to append ".0"
const bool value_is_int_like =
std::none_of(number_buffer.begin(), number_buffer.begin() + len + 1,
[](char c)
{
return (c == '.' or c == 'e');
});
if (value_is_int_like)
{
o.write_characters(".0", 2);
}
}
/*!
@brief check whether a string is UTF-8 encoded
The function checks each byte of a string whether it is UTF-8 encoded. The
result of the check is stored in the @a state parameter. The function must
be called initially with state 0 (accept). State 1 means the string must
be rejected, because the current byte is not allowed. If the string is
completely processed, but the state is non-zero, the string ended
prematurely; that is, the last byte indicated more bytes should have
followed.
@param[in,out] state the state of the decoding
@param[in,out] codep codepoint (valid only if resulting state is UTF8_ACCEPT)
@param[in] byte next byte to decode
@return new state
@note The function has been edited: a std::array is used.
@copyright Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
@sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
*/
static uint8_t decode(uint8_t& state, uint32_t& codep, const uint8_t byte) noexcept
{
static const std::array<uint8_t, 400> utf8d =
{
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
}
};
const uint8_t type = utf8d[byte];
codep = (state != UTF8_ACCEPT)
? (byte & 0x3fu) | (codep << 6)
: static_cast<uint32_t>(0xff >> type) & (byte);
state = utf8d[256u + state * 16u + type];
return state;
}
private:
/// a (hopefully) large enough character buffer
std::array<char, 64> number_buffer{{}};
/// the locale
const std::lconv* loc = nullptr;
/// the locale's thousand separator character
const char thousands_sep = '\0';
/// the locale's decimal point character
const char decimal_point = '\0';
/// string buffer
std::array<char, 512> string_buffer{{}};
};
}
}