63 lines
3.7 KiB
C++
63 lines
3.7 KiB
C++
// Tencent is pleased to support the open source community by making RapidJSON available.
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//
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// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
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//
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// Licensed under the MIT License (the "License"); you may not use this file except
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// in compliance with the License. You may obtain a copy of the License at
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//
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// http://opensource.org/licenses/MIT
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//
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// Unless required by applicable law or agreed to in writing, software distributed
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// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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// CONDITIONS OF ANY KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations under the License.
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#ifndef RAPIDJSON_POW10_
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#define RAPIDJSON_POW10_
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#include "../rapidjson.h"
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RAPIDJSON_NAMESPACE_BEGIN
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namespace internal {
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//! Computes integer powers of 10 in double (10.0^n).
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/*! This function uses lookup table for fast and accurate results.
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\param n non-negative exponent. Must <= 308.
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\return 10.0^n
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*/
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inline double Pow10(int n) {
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static const double e[] = {
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// 1e-0...1e308: 309 * 8 bytes = 2472 bytes
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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1e+308
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};
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RAPIDJSON_ASSERT(n >= 0 && n <= 308);
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return e[n];
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}
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} // namespace internal
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RAPIDJSON_NAMESPACE_END
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#endif // RAPIDJSON_POW10_
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