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🔨 simplified binary write

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Also added some comments and improved the documentation.
This commit is contained in:
Niels Lohmann 2017-07-08 20:31:13 +02:00
parent b3ac36db93
commit b38ecb5ca9
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GPG Key ID: 7F3CEA63AE251B69
1 changed files with 26 additions and 26 deletions
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52
src/json.hpp
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@ -9897,22 +9897,23 @@ class basic_json
/*
@brief read a number from the input
@tparam T the type of the number
@tparam NumberType the type of the number
@return number of type @a T
@return number of type @a NumberType
@note This function needs to respect the system's endianess, because
bytes in CBOR and MessagePack are stored in network order (big
endian) and therefore need reordering on little endian systems.
@throw parse_error.110 if input has less than `sizeof(T)` bytes
@throw parse_error.110 if input has less than `sizeof(NumberType)`
bytes
*/
template<typename T>
T get_number()
template<typename NumberType>
NumberType get_number()
{
// step 1: read input into array with system's byte order
std::array<uint8_t, sizeof(T)> vec;
for (size_t i = 0; i < sizeof(T); ++i)
std::array<uint8_t, sizeof(NumberType)> vec;
for (size_t i = 0; i < sizeof(NumberType); ++i)
{
get();
check_eof();
@ -9920,7 +9921,7 @@ class basic_json
// reverse byte order prior to conversion if necessary
if (is_little_endian)
{
vec[sizeof(T) - i - 1] = static_cast<uint8_t>(current);
vec[sizeof(NumberType) - i - 1] = static_cast<uint8_t>(current);
}
else
{
@ -9929,8 +9930,8 @@ class basic_json
}
// step 2: convert array into number of type T and return
T result;
std::memcpy(&result, vec.data(), sizeof(T));
NumberType result;
std::memcpy(&result, vec.data(), sizeof(NumberType));
return result;
}
@ -9939,6 +9940,10 @@ class basic_json
@param[in] len number of bytes to read
@note We can not reserve @a len bytes for the result, because @a len
may be too large. Usually, @ref check_eof() detects the end of
the input before we run out of string memory.
@return string created by reading @a len bytes
@throw parse_error.110 if input has less than @a len bytes
@ -10658,33 +10663,28 @@ class basic_json
/*
@brief write a number to output input
@param[in] n number of type @a T
@tparam T the type of the number
@param[in] n number of type @a NumberType
@tparam NumberType the type of the number
@note This function needs to respect the system's endianess, because
bytes in CBOR and MessagePack are stored in network order (big
endian) and therefore need reordering on little endian systems.
*/
template<typename T>
void write_number(T n)
template<typename NumberType>
void write_number(NumberType n)
{
// step 1: write number to array of length T
std::array<uint8_t, sizeof(T)> vec;
std::memcpy(vec.data(), &n, sizeof(T));
// step 1: write number to array of length NumberType
std::array<uint8_t, sizeof(NumberType)> vec;
std::memcpy(vec.data(), &n, sizeof(NumberType));
// step 2: write array to output (with possible reordering)
for (size_t i = 0; i < sizeof(T); ++i)
if (is_little_endian)
{
// reverse byte order prior to conversion if necessary
if (is_little_endian)
{
oa->write_character(vec[sizeof(T) - i - 1]);
}
else
{
oa->write_character(vec[i]); // LCOV_EXCL_LINE
}
std::reverse(vec.begin(), vec.end());
}
oa->write_characters(vec.data(), sizeof(NumberType));
}
private: