Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

fix: minimize the precision loss when dumping double to string #712

Merged
merged 7 commits into from
Jan 29, 2024
Merged

fix: minimize the precision loss when dumping double to string #712

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
6130f2e
fix: minimize the precision loss when dumping double to string
junekhan Oct 25, 2023
8bb7cf1
fix: abandon one-time macro
junekhan Jan 21, 2024
543fa7a
fix: replace hard-coded buffer size, replace `sprintf` with `snprintf`
junekhan Jan 22, 2024
f1894c5
fix: replace `DECIMAL_DIG` with `DBL_DECIMAL_DIG`
junekhan Jan 23, 2024
75d7811
Update json.h changed to C++11 DECIMAL_DIGIT
gittiver Jan 23, 2024
69b17cc
added cfloat include
gittiver Jan 23, 2024
5ba4b39
fix: identify float and double as different numeral types, and approa…
junekhan Jan 24, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
49 changes: 38 additions & 11 deletions include/crow/json.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
#include <memory>
#include <vector>
#include <cmath>
#include <cfloat>

#include "crow/utility.h"
#include "crow/settings.h"
Expand Down Expand Up @@ -105,7 +106,8 @@ namespace crow
Signed_integer,
Unsigned_integer,
Floating_point,
Null
Null,
Double_precision_floating_point
};

class rvalue;
Expand Down Expand Up @@ -781,6 +783,7 @@ namespace crow
switch (r.nt())
{
case num_type::Floating_point: os << r.d(); break;
case num_type::Double_precision_floating_point: os << r.d(); break;
case num_type::Signed_integer: os << r.i(); break;
case num_type::Unsigned_integer: os << r.u(); break;
case num_type::Null: throw std::runtime_error("Number with num_type Null");
Expand Down Expand Up @@ -1318,7 +1321,9 @@ namespace crow
ui(value) {}
constexpr number(std::int64_t value) noexcept:
si(value) {}
constexpr number(double value) noexcept:
explicit constexpr number(double value) noexcept:
d(value) {}
explicit constexpr number(float value) noexcept:
d(value) {}
} num; ///< Value if type is a number.
std::string s; ///< Value if type is a string.
Expand Down Expand Up @@ -1357,7 +1362,7 @@ namespace crow
wvalue(float value):
returnable("application/json"), t_(type::Number), nt(num_type::Floating_point), num(static_cast<double>(value)) {}
wvalue(double value):
returnable("application/json"), t_(type::Number), nt(num_type::Floating_point), num(static_cast<double>(value)) {}
returnable("application/json"), t_(type::Number), nt(num_type::Double_precision_floating_point), num(static_cast<double>(value)) {}

wvalue(char const* value):
returnable("application/json"), t_(type::String), s(value) {}
Expand Down Expand Up @@ -1408,7 +1413,7 @@ namespace crow
return;
case type::Number:
nt = r.nt();
if (nt == num_type::Floating_point)
if (nt == num_type::Floating_point || nt == num_type::Double_precision_floating_point)
num.d = r.d();
else if (nt == num_type::Signed_integer)
num.si = r.i();
Expand Down Expand Up @@ -1444,7 +1449,7 @@ namespace crow
return;
case type::Number:
nt = r.nt;
if (nt == num_type::Floating_point)
if (nt == num_type::Floating_point || nt == num_type::Double_precision_floating_point)
num.d = r.num.d;
else if (nt == num_type::Signed_integer)
num.si = r.num.si;
Expand Down Expand Up @@ -1514,7 +1519,7 @@ namespace crow
return *this;
}

wvalue& operator=(double value)
wvalue& operator=(float value)
{
reset();
t_ = type::Number;
Expand All @@ -1523,6 +1528,15 @@ namespace crow
return *this;
}

wvalue& operator=(double value)
{
reset();
t_ = type::Number;
num.d = value;
nt = num_type::Double_precision_floating_point;
return *this;
}

wvalue& operator=(unsigned short value)
{
reset();
Expand Down Expand Up @@ -1835,7 +1849,7 @@ namespace crow
case type::True: out += "true"; break;
case type::Number:
{
if (v.nt == num_type::Floating_point)
if (v.nt == num_type::Floating_point || v.nt == num_type::Double_precision_floating_point)
{
if (isnan(v.num.d) || isinf(v.num.d))
{
Expand All @@ -1850,11 +1864,22 @@ namespace crow
zero
} f_state;
char outbuf[128];
if (v.nt == num_type::Double_precision_floating_point)
{
#ifdef _MSC_VER
sprintf_s(outbuf, sizeof(outbuf), "%f", v.num.d);
sprintf_s(outbuf, sizeof(outbuf), "%.*g", DECIMAL_DIG, v.num.d);
#else
snprintf(outbuf, sizeof(outbuf), "%f", v.num.d);
snprintf(outbuf, sizeof(outbuf), "%.*g", DECIMAL_DIG, v.num.d);
#endif
}
else
{
#ifdef _MSC_VER
sprintf_s(outbuf, sizeof(outbuf), "%f", v.num.d);
#else
snprintf(outbuf, sizeof(outbuf), "%f", v.num.d);
#endif
}
char *p = &outbuf[0], *o = nullptr; // o is the position of the first trailing 0
f_state = start;
while (*p != '\0')
Expand Down Expand Up @@ -1968,14 +1993,16 @@ namespace crow
{
int64_t get(int64_t fallback)
{
if (ref.t() != type::Number || ref.nt == num_type::Floating_point)
if (ref.t() != type::Number || ref.nt == num_type::Floating_point ||
ref.nt == num_type::Double_precision_floating_point)
return fallback;
return ref.num.si;
}

double get(double fallback)
{
if (ref.t() != type::Number || ref.nt != num_type::Floating_point)
if (ref.t() != type::Number || ref.nt != num_type::Floating_point ||
ref.nt == num_type::Double_precision_floating_point)
return fallback;
return ref.num.d;
}
Expand Down
2 changes: 1 addition & 1 deletion include/crow/middlewares/session.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,7 @@ namespace crow
{
case type::Number:
{
if (rv.nt() == num_type::Floating_point)
if (rv.nt() == num_type::Floating_point || rv.nt() == num_type::Double_precision_floating_point)
return multi_value{rv.d()};
else if (rv.nt() == num_type::Unsigned_integer)
return multi_value{int64_t(rv.u())};
Expand Down
6 changes: 4 additions & 2 deletions tests/unittest.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1038,11 +1038,13 @@ TEST_CASE("json::wvalue::wvalue(float)")

TEST_CASE("json::wvalue::wvalue(double)")
{
double d = 4.2;
double d = 0.036303908355795146;
json::wvalue value = d;

CHECK(value.t() == json::type::Number);
CHECK(value.dump() == "4.2");
auto dumped_value = value.dump();
CROW_LOG_DEBUG << dumped_value;
CHECK(std::abs(utility::lexical_cast<double>(dumped_value) - d) < numeric_limits<double>::epsilon());
} // json::wvalue::wvalue(double)

TEST_CASE("json::wvalue::wvalue(char const*)")
Expand Down
Loading