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Alternative handling of integer types relying on strto[u]ll

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This commit is contained in:
Alex Astashyn 2016-12-04 13:23:39 -05:00
parent c75efedc6e
commit e41a956782
2 changed files with 88 additions and 4 deletions
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46
src/json.hpp
View file

@ -9073,6 +9073,8 @@ basic_json_parser_66:
note: in floating-point case strtod may parse
past the token's end - this is not an error.
any leading blanks are not handled.
*/
struct strtonum
{
@ -9232,6 +9234,45 @@ basic_json_parser_66:
return ok;
}
#if 1 // parsing with strto[u]ll - easier to understand but slightly slower
signed long long parse_integral(
char** endptr,
/*is_signed*/std::true_type) const
{
return std::strtoll(m_start, endptr, 10);
}
unsigned long long parse_integral(
char** endptr,
/*is_signed*/std::false_type) const
{
return std::strtoull(m_start, endptr, 10);
}
template<typename T>
bool parse(T& value, /*is_integral=*/std::true_type) const
{
char* endptr = nullptr;
errno = 0; // these are thread-local
const auto x = parse_integral(&endptr, std::is_signed<T>());
static_assert(std::is_signed<T>() // called right overload?
== std::is_signed<decltype(x)>(), "");
value = static_cast<T>(x);
return x == static_cast<decltype(x)>(value) // x fits into destination T
and (x != 0 or is_integral()) // strto[u]ll did nto fail
and errno == 0 // strto[u]ll did not overflow
and m_start < m_end // token was not empty
and endptr == m_end // parsed entire token exactly
and (x < 0) == (*m_start == '-'); // input was sign-compatible
}
#else // parsing integral types manually
template<typename T>
bool parse(T& value, /*is_integral=*/std::true_type) const
{
@ -9240,7 +9281,7 @@ basic_json_parser_66:
if (beg == end)
{
return false;
return false; // empty token
}
const bool is_negative = (*beg == '-');
@ -9261,7 +9302,7 @@ basic_json_parser_66:
bool valid = beg < end // must have some digits;
and ( T(-1) < 0 // type must be signed
or !is_negative); // if value is negative
or !is_negative); // ...if value is negative
while (beg < end and valid)
{
@ -9288,6 +9329,7 @@ basic_json_parser_66:
// into positives is for edge cases, e.g. -2^63
return valid && (is_negative == (value < 0));
}
#endif
};
/*!

46
src/json.hpp.re2c
View file

@ -8222,6 +8222,8 @@ class basic_json
note: in floating-point case strtod may parse
past the token's end - this is not an error.
any leading blanks are not handled.
*/
struct strtonum
{
@ -8381,6 +8383,45 @@ class basic_json
return ok;
}
#if 1 // parsing with strto[u]ll - easier to understand but slightly slower
signed long long parse_integral(
char** endptr,
/*is_signed*/std::true_type) const
{
return std::strtoll(m_start, endptr, 10);
}
unsigned long long parse_integral(
char** endptr,
/*is_signed*/std::false_type) const
{
return std::strtoull(m_start, endptr, 10);
}
template<typename T>
bool parse(T& value, /*is_integral=*/std::true_type) const
{
char* endptr = nullptr;
errno = 0; // these are thread-local
const auto x = parse_integral(&endptr, std::is_signed<T>());
static_assert(std::is_signed<T>() // called right overload?
== std::is_signed<decltype(x)>(), "");
value = static_cast<T>(x);
return x == static_cast<decltype(x)>(value) // x fits into destination T
and (x != 0 or is_integral()) // strto[u]ll did nto fail
and errno == 0 // strto[u]ll did not overflow
and m_start < m_end // token was not empty
and endptr == m_end // parsed entire token exactly
and (x < 0) == (*m_start == '-'); // input was sign-compatible
}
#else // parsing integral types manually
template<typename T>
bool parse(T& value, /*is_integral=*/std::true_type) const
{
@ -8389,7 +8430,7 @@ class basic_json
if (beg == end)
{
return false;
return false; // empty token
}
const bool is_negative = (*beg == '-');
@ -8410,7 +8451,7 @@ class basic_json
bool valid = beg < end // must have some digits;
and ( T(-1) < 0 // type must be signed
or !is_negative); // if value is negative
or !is_negative); // ...if value is negative
while (beg < end and valid)
{
@ -8437,6 +8478,7 @@ class basic_json
// into positives is for edge cases, e.g. -2^63
return valid && (is_negative == (value < 0));
}
#endif
};
/*!