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Optimize parsing JSON number. (#1406)

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xiehan
2023-10-26 17:33:14 +08:00
committed by GitHub
parent 10a6b26c0e
commit 815867e056
1 changed files with 85 additions and 15 deletions
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100
src/util/json_parser.c
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@@ -270,6 +270,71 @@ static int __parse_json_string(const char *cursor, const char **end,
return 0;
}
static double __power_of_10[309] = {
1.0e0, 1.0e1, 1.0e2, 1.0e3, 1.0e4,
1.0e5, 1.0e6, 1.0e7, 1.0e8, 1.0e9,
1.0e10, 1.0e11, 1.0e12, 1.0e13, 1.0e14,
1.0e15, 1.0e16, 1.0e17, 1.0e18, 1.0e19,
1.0e20, 1.0e21, 1.0e22, 1.0e23, 1.0e24,
1.0e25, 1.0e26, 1.0e27, 1.0e28, 1.0e29,
1.0e30, 1.0e31, 1.0e32, 1.0e33, 1.0e34,
1.0e35, 1.0e36, 1.0e37, 1.0e38, 1.0e39,
1.0e40, 1.0e41, 1.0e42, 1.0e43, 1.0e44,
1.0e45, 1.0e46, 1.0e47, 1.0e48, 1.0e49,
1.0e50, 1.0e51, 1.0e52, 1.0e53, 1.0e54,
1.0e55, 1.0e56, 1.0e57, 1.0e58, 1.0e59,
1.0e60, 1.0e61, 1.0e62, 1.0e63, 1.0e64,
1.0e65, 1.0e66, 1.0e67, 1.0e68, 1.0e69,
1.0e70, 1.0e71, 1.0e72, 1.0e73, 1.0e74,
1.0e75, 1.0e76, 1.0e77, 1.0e78, 1.0e79,
1.0e80, 1.0e81, 1.0e82, 1.0e83, 1.0e84,
1.0e85, 1.0e86, 1.0e87, 1.0e88, 1.0e89,
1.0e90, 1.0e91, 1.0e92, 1.0e93, 1.0e94,
1.0e95, 1.0e96, 1.0e97, 1.0e98, 1.0e99,
1.0e100, 1.0e101, 1.0e102, 1.0e103, 1.0e104,
1.0e105, 1.0e106, 1.0e107, 1.0e108, 1.0e109,
1.0e110, 1.0e111, 1.0e112, 1.0e113, 1.0e114,
1.0e115, 1.0e116, 1.0e117, 1.0e118, 1.0e119,
1.0e120, 1.0e121, 1.0e122, 1.0e123, 1.0e124,
1.0e125, 1.0e126, 1.0e127, 1.0e128, 1.0e129,
1.0e130, 1.0e131, 1.0e132, 1.0e133, 1.0e134,
1.0e135, 1.0e136, 1.0e137, 1.0e138, 1.0e139,
1.0e140, 1.0e141, 1.0e142, 1.0e143, 1.0e144,
1.0e145, 1.0e146, 1.0e147, 1.0e148, 1.0e149,
1.0e150, 1.0e151, 1.0e152, 1.0e153, 1.0e154,
1.0e155, 1.0e156, 1.0e157, 1.0e158, 1.0e159,
1.0e160, 1.0e161, 1.0e162, 1.0e163, 1.0e164,
1.0e165, 1.0e166, 1.0e167, 1.0e168, 1.0e169,
1.0e170, 1.0e171, 1.0e172, 1.0e173, 1.0e174,
1.0e175, 1.0e176, 1.0e177, 1.0e178, 1.0e179,
1.0e180, 1.0e181, 1.0e182, 1.0e183, 1.0e184,
1.0e185, 1.0e186, 1.0e187, 1.0e188, 1.0e189,
1.0e190, 1.0e191, 1.0e192, 1.0e193, 1.0e194,
1.0e195, 1.0e196, 1.0e197, 1.0e198, 1.0e199,
1.0e200, 1.0e201, 1.0e202, 1.0e203, 1.0e204,
1.0e205, 1.0e206, 1.0e207, 1.0e208, 1.0e209,
1.0e210, 1.0e211, 1.0e212, 1.0e213, 1.0e214,
1.0e215, 1.0e216, 1.0e217, 1.0e218, 1.0e219,
1.0e220, 1.0e221, 1.0e222, 1.0e223, 1.0e224,
1.0e225, 1.0e226, 1.0e227, 1.0e228, 1.0e229,
1.0e230, 1.0e231, 1.0e232, 1.0e233, 1.0e234,
1.0e235, 1.0e236, 1.0e237, 1.0e238, 1.0e239,
1.0e240, 1.0e241, 1.0e242, 1.0e243, 1.0e244,
1.0e245, 1.0e246, 1.0e247, 1.0e248, 1.0e249,
1.0e250, 1.0e251, 1.0e252, 1.0e253, 1.0e254,
1.0e255, 1.0e256, 1.0e257, 1.0e258, 1.0e259,
1.0e260, 1.0e261, 1.0e262, 1.0e263, 1.0e264,
1.0e265, 1.0e266, 1.0e267, 1.0e268, 1.0e269,
1.0e270, 1.0e271, 1.0e272, 1.0e273, 1.0e274,
1.0e275, 1.0e276, 1.0e277, 1.0e278, 1.0e279,
1.0e280, 1.0e281, 1.0e282, 1.0e283, 1.0e284,
1.0e285, 1.0e286, 1.0e287, 1.0e288, 1.0e289,
1.0e290, 1.0e291, 1.0e292, 1.0e293, 1.0e294,
1.0e295, 1.0e296, 1.0e297, 1.0e298, 1.0e299,
1.0e300, 1.0e301, 1.0e302, 1.0e303, 1.0e304,
1.0e305, 1.0e306, 1.0e307, 1.0e308
};
static double __evaluate_json_number(const char *integer,
const char *fraction,
int exp)
@@ -287,16 +352,17 @@ static double __evaluate_json_number(const char *integer,
{
figures++;
mant = *integer - '0';
while (isdigit(*++integer))
while (isdigit(*++integer) && figures < 18)
{
if (figures < 18)
{
figures++;
mant *= 10;
mant += *integer - '0';
}
else
exp++;
figures++;
mant *= 10;
mant += *integer - '0';
}
while (isdigit(*integer))
{
exp++;
integer++;
}
}
else
@@ -321,15 +387,19 @@ static double __evaluate_json_number(const char *integer,
num = mant;
if (exp != 0 && figures != 0)
{
if (exp > 0)
num *= pow(10, exp);
else if (exp >= -308)
num /= pow(10, -exp);
else
if (exp > 309 - figures)
num = INFINITY;
else if (exp > 0)
num *= __power_of_10[exp];
else if (exp > -309)
num /= __power_of_10[-exp];
else if (exp > -324 - figures)
{
num /= pow(10, -exp - 308);
num /= __power_of_10[-exp - 308];
num /= 1.0e308;
}
else
num = 0.0;
}
return sign ? -num : num;