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AK: Fix userland parsing of rounded floating point numbers

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Parse JSON floating point literals properly,
No longer throwing a SyntaxError when the decimal portion
of the number exceeds the capacity of u32.

Added tests to AK/TestJSON and LibJS/builtins/JSON/JSON.parse
This commit is contained in:
serenitydev 2022-02-11 03:29:08 -05:00 • committed by Tim Flynn
parent af75503c17
commit 23c72c6728
3 changed files with 19 additions and 8 deletions
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14
AK/JsonParser.cpp
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@ -8,6 +8,7 @@
#include <AK/JsonArray.h> #include <AK/JsonArray.h>
#include <AK/JsonObject.h> #include <AK/JsonObject.h>
#include <AK/JsonParser.h> #include <AK/JsonParser.h>
#include <math.h>
namespace AK { namespace AK {
@ -251,17 +252,14 @@ ErrorOr<JsonValue> JsonParser::parse_number()
} }
StringView fraction_string(fraction_buffer.data(), fraction_buffer.size()); StringView fraction_string(fraction_buffer.data(), fraction_buffer.size());
auto fraction_string_uint = fraction_string.to_uint(); auto fraction_string_uint = fraction_string.to_uint<u64>();
if (!fraction_string_uint.has_value()) if (!fraction_string_uint.has_value())
return Error::from_string_literal("JsonParser: Error while parsing number"sv); return Error::from_string_literal("JsonParser: Error while parsing number"sv);
int fraction = fraction_string_uint.value(); auto fraction = static_cast<double>(fraction_string_uint.value());
fraction *= (whole < 0) ? -1 : 1; double sign = (whole < 0) ? -1 : 1;
auto divider = 1; auto divider = pow(10.0, static_cast<double>(fraction_buffer.size()));
for (size_t i = 0; i < fraction_buffer.size(); ++i) { value = JsonValue((double)whole + sign * (fraction / divider));
divider *= 10;
}
value = JsonValue((double)whole + ((double)fraction / divider));
} else { } else {
#endif #endif
auto to_unsigned_result = number_string.to_uint<u64>(); auto to_unsigned_result = number_string.to_uint<u64>();

6
Tests/AK/TestJSON.cpp
View file

@ -128,3 +128,9 @@ TEST_CASE(json_parse_empty_string)
auto value = JsonValue::from_string(""); auto value = JsonValue::from_string("");
EXPECT_EQ(value.value().is_null(), true); EXPECT_EQ(value.value().is_null(), true);
} }
TEST_CASE(json_parse_long_decimals)
{
auto value = JsonValue::from_string("1644452550.6489999294281");
EXPECT_EQ(value.value().as_double(), 1644452550.6489999294281);
}

7
Userland/Libraries/LibJS/Tests/builtins/JSON/JSON.parse.js
View file

@ -43,3 +43,10 @@ test("negative zero", () => {
expect(JSON.parse(-0)).toEqual(0); expect(JSON.parse(-0)).toEqual(0);
}); });
// The underlying parser resolves decimal numbers by storing the decimal portion in an integer
// This test handles a regression where the decimal portion was only using a u32 vs. u64
// and would fail to parse.
test("long decimal parse", () => {
expect(JSON.parse("1644452550.6489999294281")).toEqual(1644452550.6489999294281);
});