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Increase precision of JSON::divisible_by #2330

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Merged
jviotti merged 1 commit into from
Apr 1, 2026
Merged

Increase precision of JSON::divisible_by #2330

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17 changes: 11 additions & 6 deletions src/core/json/json_value.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -543,8 +543,13 @@ auto JSON::operator-=(const JSON &substractive) -> JSON & {

const auto division{dividend_value / divisor_value};
Real integral = 0;
return !std::isinf(division) && !std::isnan(division) &&
std::modf(division, &integral) == 0.0;
if (!std::isinf(division) && !std::isnan(division) &&
std::modf(division, &integral) == 0.0) {
return true;
}

return Decimal::strict_from(dividend_value)
.divisible_by(Decimal::strict_from(divisor_value));
}

if (this->is_decimal() && divisor.is_decimal()) {
Expand All @@ -557,17 +562,17 @@ auto JSON::operator-=(const JSON &substractive) -> JSON & {
return this->to_decimal().divisible_by(divisor_decimal);
}

const Decimal divisor_decimal{divisor.to_real()};
return this->to_decimal().divisible_by(divisor_decimal);
return this->to_decimal().divisible_by(
Decimal::strict_from(divisor.to_real()));
}

if (this->is_integer()) {
const Decimal dividend_decimal{this->to_integer()};
return dividend_decimal.divisible_by(divisor.to_decimal());
}

const Decimal dividend_decimal{this->to_real()};
return dividend_decimal.divisible_by(divisor.to_decimal());
return Decimal::strict_from(this->to_real())
.divisible_by(divisor.to_decimal());
}

[[nodiscard]] auto
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11 changes: 11 additions & 0 deletions src/lang/numeric/decimal.cc
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Expand Up @@ -5,7 +5,9 @@

#include <array> // std::array
#include <cassert> // assert
#include <charconv> // std::to_chars
#include <cmath> // std::isfinite
#include <cstddef> // std::size_t
#include <cstring> // std::strlen
#include <iomanip> // std::setprecision
#include <limits> // std::numeric_limits
Expand Down Expand Up @@ -506,6 +508,15 @@ auto Decimal::negative_infinity() -> Decimal {
return result;
}

auto Decimal::strict_from(const double value) -> Decimal {
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@augmentcode augmentcode bot Apr 1, 2026

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Decimal::strict_from relies on assert(result.ec == std::errc{}) after std::to_chars; in non-assert builds a conversion failure could lead to constructing a Decimal from incomplete/invalid output. Consider defining/handling the failure mode (or documenting a strict precondition like “finite values only”) so callers don’t get UB/terminations unexpectedly.

Severity: medium

Other Locations
  • src/lang/numeric/include/sourcemeta/core/numeric_decimal.h:80

Fix This in Augment

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std::array<char, 64> buffer{};
const auto result{
std::to_chars(buffer.data(), buffer.data() + buffer.size(), value)};
assert(result.ec == std::errc{});
return Decimal{std::string_view{
buffer.data(), static_cast<std::size_t>(result.ptr - buffer.data())}};
}

auto Decimal::to_scientific_string() const -> std::string {
std::string result;

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4 changes: 4 additions & 0 deletions src/lang/numeric/include/sourcemeta/core/numeric_decimal.h
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Expand Up @@ -77,6 +77,10 @@ class SOURCEMETA_CORE_NUMERIC_EXPORT Decimal {
/// Create a signaling NaN value with an optional payload
[[nodiscard]] static auto snan(std::uint64_t payload = 0) -> Decimal;

/// Create a decimal from a double by converting through its shortest
/// round-trip string representation, avoiding IEEE 754 precision artifacts
[[nodiscard]] static auto strict_from(double value) -> Decimal;

/// Create a positive infinity value
[[nodiscard]] static auto infinity() -> Decimal;

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234 changes: 234 additions & 0 deletions test/json/json_decimal_test.cc
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Expand Up @@ -878,6 +878,240 @@ TEST(JSON_decimal, divisible_by_mixed_scale_decimal_real_divisible_true) {
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"1280.32"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_01_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"1280.325"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_1_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"100.3"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.1"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_1_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"100.35"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.1"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_001_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"25.123"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_001_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"25.1235"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.001"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_0001_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"99.9999"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.0001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_0001_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"99.99995"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.0001"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_01_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"1280.32"}};
const sourcemeta::core::JSON divisor{0.01};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_01_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"1280.325"}};
const sourcemeta::core::JSON divisor{0.01};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_1_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"100.3"}};
const sourcemeta::core::JSON divisor{0.1};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_1_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"100.35"}};
const sourcemeta::core::JSON divisor{0.1};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_001_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"25.123"}};
const sourcemeta::core::JSON divisor{0.001};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_001_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"25.1235"}};
const sourcemeta::core::JSON divisor{0.001};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_0001_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"99.9999"}};
const sourcemeta::core::JSON divisor{0.0001};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_real_0_0001_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"99.99995"}};
const sourcemeta::core::JSON divisor{0.0001};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{1280.32};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_01_false) {
const sourcemeta::core::JSON dividend{1280.325};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_1_true) {
const sourcemeta::core::JSON dividend{100.3};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.1"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_1_false) {
const sourcemeta::core::JSON dividend{100.35};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.1"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_001_true) {
const sourcemeta::core::JSON dividend{25.123};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_001_false) {
const sourcemeta::core::JSON dividend{25.1235};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.001"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_0001_true) {
const sourcemeta::core::JSON dividend{99.9999};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.0001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_real_decimal_0_0001_false) {
const sourcemeta::core::JSON dividend{99.99995};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.0001"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_integer_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{100};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_integer_decimal_0_1_true) {
const sourcemeta::core::JSON dividend{10};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.1"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_integer_decimal_0_001_true) {
const sourcemeta::core::JSON dividend{1};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_integer_decimal_0_0001_true) {
const sourcemeta::core::JSON dividend{1};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.0001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_negative_decimal_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"-1280.32"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_negative_decimal_real_0_01_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"-1280.32"}};
const sourcemeta::core::JSON divisor{0.01};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_negative_real_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{-1280.32};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_negative_integer_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{-100};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_3_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"0.9"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.3"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_3_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"1.0"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.3"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_7_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"2.1"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.7"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_decimal_decimal_0_7_false) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"2.0"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.7"}};
EXPECT_FALSE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_large_decimal_decimal_0_01_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"999999.99"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.01"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_large_decimal_real_0_01_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"999999.99"}};
const sourcemeta::core::JSON divisor{0.01};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, divisible_by_large_decimal_decimal_0_001_true) {
const sourcemeta::core::JSON dividend{sourcemeta::core::Decimal{"12345.678"}};
const sourcemeta::core::JSON divisor{sourcemeta::core::Decimal{"0.001"}};
EXPECT_TRUE(dividend.divisible_by(divisor));
}

TEST(JSON_decimal, fast_hash_positive) {
const sourcemeta::core::JSON document{sourcemeta::core::Decimal{"3.14"}};
EXPECT_EQ(document.fast_hash(), 8);
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