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rocksdb/third-party/rapidjson/internal/pow10.h

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Add rapidjson to RocksDB Summary: This diff adds rapidjson (https://code.google.com/p/rapidjson/) to RocksDB repository. First step to adding JSON is to add a JSON parser :) I'm not sure if rapidjson is the right choice. I only considered folly as an alternative. Using folly JSON parser has serious downsides. I tried extracting folly::json from the folly library. However, it depends on folly::dynamic, which basically depends on everything else. I would prefer to avoid adding complete folly library as RocksDB dependency. Folly has a lot of its own dependencies (https://github.com/facebook/folly) and also looks like open source world has some trouble installing it (https://groups.google.com/forum/#!forum/facebook-folly -- 60% of the posts are compile errors). We can discuss this if you think otherwise. RapidJSON does not have any dependencies whatsoever. No boost, no STL. We don't need to compile it since it's all header files. The performance results are also impressive: https://code.google.com/p/rapidjson/wiki/Performance. However, I'll make sure to write code in a way that we can easily switch JSON implementations going forward. Quora thread has some alternatives: http://www.quora.com/What-is-the-best-C-JSON-library Test Plan: none Reviewers: dhruba, haobo, yhchiang, sdong, jamesgpearce Reviewed By: haobo CC: leveldb Differential Revision: https://reviews.facebook.net/D18729
2014-05-16 01:07:05 +02:00
#ifndef RAPIDJSON_POW10_
#define RAPIDJSON_POW10_
namespace rapidjson {
namespace internal {
//! Computes integer powers of 10 in double (10.0^n).
/*! This function uses lookup table for fast and accurate results.
\param n positive/negative exponent. Must <= 308.
\return 10.0^n
*/
inline double Pow10(int n) {
static const double e[] = { // 1e-308...1e308: 617 * 8 bytes = 4936 bytes
1e-308,1e-307,1e-306,1e-305,1e-304,1e-303,1e-302,1e-301,1e-300,
1e-299,1e-298,1e-297,1e-296,1e-295,1e-294,1e-293,1e-292,1e-291,1e-290,1e-289,1e-288,1e-287,1e-286,1e-285,1e-284,1e-283,1e-282,1e-281,1e-280,
1e-279,1e-278,1e-277,1e-276,1e-275,1e-274,1e-273,1e-272,1e-271,1e-270,1e-269,1e-268,1e-267,1e-266,1e-265,1e-264,1e-263,1e-262,1e-261,1e-260,
1e-259,1e-258,1e-257,1e-256,1e-255,1e-254,1e-253,1e-252,1e-251,1e-250,1e-249,1e-248,1e-247,1e-246,1e-245,1e-244,1e-243,1e-242,1e-241,1e-240,
1e-239,1e-238,1e-237,1e-236,1e-235,1e-234,1e-233,1e-232,1e-231,1e-230,1e-229,1e-228,1e-227,1e-226,1e-225,1e-224,1e-223,1e-222,1e-221,1e-220,
1e-219,1e-218,1e-217,1e-216,1e-215,1e-214,1e-213,1e-212,1e-211,1e-210,1e-209,1e-208,1e-207,1e-206,1e-205,1e-204,1e-203,1e-202,1e-201,1e-200,
1e-199,1e-198,1e-197,1e-196,1e-195,1e-194,1e-193,1e-192,1e-191,1e-190,1e-189,1e-188,1e-187,1e-186,1e-185,1e-184,1e-183,1e-182,1e-181,1e-180,
1e-179,1e-178,1e-177,1e-176,1e-175,1e-174,1e-173,1e-172,1e-171,1e-170,1e-169,1e-168,1e-167,1e-166,1e-165,1e-164,1e-163,1e-162,1e-161,1e-160,
1e-159,1e-158,1e-157,1e-156,1e-155,1e-154,1e-153,1e-152,1e-151,1e-150,1e-149,1e-148,1e-147,1e-146,1e-145,1e-144,1e-143,1e-142,1e-141,1e-140,
1e-139,1e-138,1e-137,1e-136,1e-135,1e-134,1e-133,1e-132,1e-131,1e-130,1e-129,1e-128,1e-127,1e-126,1e-125,1e-124,1e-123,1e-122,1e-121,1e-120,
1e-119,1e-118,1e-117,1e-116,1e-115,1e-114,1e-113,1e-112,1e-111,1e-110,1e-109,1e-108,1e-107,1e-106,1e-105,1e-104,1e-103,1e-102,1e-101,1e-100,
1e-99, 1e-98, 1e-97, 1e-96, 1e-95, 1e-94, 1e-93, 1e-92, 1e-91, 1e-90, 1e-89, 1e-88, 1e-87, 1e-86, 1e-85, 1e-84, 1e-83, 1e-82, 1e-81, 1e-80,
1e-79, 1e-78, 1e-77, 1e-76, 1e-75, 1e-74, 1e-73, 1e-72, 1e-71, 1e-70, 1e-69, 1e-68, 1e-67, 1e-66, 1e-65, 1e-64, 1e-63, 1e-62, 1e-61, 1e-60,
1e-59, 1e-58, 1e-57, 1e-56, 1e-55, 1e-54, 1e-53, 1e-52, 1e-51, 1e-50, 1e-49, 1e-48, 1e-47, 1e-46, 1e-45, 1e-44, 1e-43, 1e-42, 1e-41, 1e-40,
1e-39, 1e-38, 1e-37, 1e-36, 1e-35, 1e-34, 1e-33, 1e-32, 1e-31, 1e-30, 1e-29, 1e-28, 1e-27, 1e-26, 1e-25, 1e-24, 1e-23, 1e-22, 1e-21, 1e-20,
1e-19, 1e-18, 1e-17, 1e-16, 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10, 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1, 1e+0,
1e+1, 1e+2, 1e+3, 1e+4, 1e+5, 1e+6, 1e+7, 1e+8, 1e+9, 1e+10, 1e+11, 1e+12, 1e+13, 1e+14, 1e+15, 1e+16, 1e+17, 1e+18, 1e+19, 1e+20,
1e+21, 1e+22, 1e+23, 1e+24, 1e+25, 1e+26, 1e+27, 1e+28, 1e+29, 1e+30, 1e+31, 1e+32, 1e+33, 1e+34, 1e+35, 1e+36, 1e+37, 1e+38, 1e+39, 1e+40,
1e+41, 1e+42, 1e+43, 1e+44, 1e+45, 1e+46, 1e+47, 1e+48, 1e+49, 1e+50, 1e+51, 1e+52, 1e+53, 1e+54, 1e+55, 1e+56, 1e+57, 1e+58, 1e+59, 1e+60,
1e+61, 1e+62, 1e+63, 1e+64, 1e+65, 1e+66, 1e+67, 1e+68, 1e+69, 1e+70, 1e+71, 1e+72, 1e+73, 1e+74, 1e+75, 1e+76, 1e+77, 1e+78, 1e+79, 1e+80,
1e+81, 1e+82, 1e+83, 1e+84, 1e+85, 1e+86, 1e+87, 1e+88, 1e+89, 1e+90, 1e+91, 1e+92, 1e+93, 1e+94, 1e+95, 1e+96, 1e+97, 1e+98, 1e+99, 1e+100,
1e+101,1e+102,1e+103,1e+104,1e+105,1e+106,1e+107,1e+108,1e+109,1e+110,1e+111,1e+112,1e+113,1e+114,1e+115,1e+116,1e+117,1e+118,1e+119,1e+120,
1e+121,1e+122,1e+123,1e+124,1e+125,1e+126,1e+127,1e+128,1e+129,1e+130,1e+131,1e+132,1e+133,1e+134,1e+135,1e+136,1e+137,1e+138,1e+139,1e+140,
1e+141,1e+142,1e+143,1e+144,1e+145,1e+146,1e+147,1e+148,1e+149,1e+150,1e+151,1e+152,1e+153,1e+154,1e+155,1e+156,1e+157,1e+158,1e+159,1e+160,
1e+161,1e+162,1e+163,1e+164,1e+165,1e+166,1e+167,1e+168,1e+169,1e+170,1e+171,1e+172,1e+173,1e+174,1e+175,1e+176,1e+177,1e+178,1e+179,1e+180,
1e+181,1e+182,1e+183,1e+184,1e+185,1e+186,1e+187,1e+188,1e+189,1e+190,1e+191,1e+192,1e+193,1e+194,1e+195,1e+196,1e+197,1e+198,1e+199,1e+200,
1e+201,1e+202,1e+203,1e+204,1e+205,1e+206,1e+207,1e+208,1e+209,1e+210,1e+211,1e+212,1e+213,1e+214,1e+215,1e+216,1e+217,1e+218,1e+219,1e+220,
1e+221,1e+222,1e+223,1e+224,1e+225,1e+226,1e+227,1e+228,1e+229,1e+230,1e+231,1e+232,1e+233,1e+234,1e+235,1e+236,1e+237,1e+238,1e+239,1e+240,
1e+241,1e+242,1e+243,1e+244,1e+245,1e+246,1e+247,1e+248,1e+249,1e+250,1e+251,1e+252,1e+253,1e+254,1e+255,1e+256,1e+257,1e+258,1e+259,1e+260,
1e+261,1e+262,1e+263,1e+264,1e+265,1e+266,1e+267,1e+268,1e+269,1e+270,1e+271,1e+272,1e+273,1e+274,1e+275,1e+276,1e+277,1e+278,1e+279,1e+280,
1e+281,1e+282,1e+283,1e+284,1e+285,1e+286,1e+287,1e+288,1e+289,1e+290,1e+291,1e+292,1e+293,1e+294,1e+295,1e+296,1e+297,1e+298,1e+299,1e+300,
1e+301,1e+302,1e+303,1e+304,1e+305,1e+306,1e+307,1e+308
};
RAPIDJSON_ASSERT(n <= 308);
return n < -308 ? 0.0 : e[n + 308];
}
} // namespace internal
} // namespace rapidjson
#endif // RAPIDJSON_POW10_
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