1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/webrtc/trunk/testing/gtest/samples/prime_tables.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,123 @@
1.4 +// Copyright 2008 Google Inc.
1.5 +// All Rights Reserved.
1.6 +//
1.7 +// Redistribution and use in source and binary forms, with or without
1.8 +// modification, are permitted provided that the following conditions are
1.9 +// met:
1.10 +//
1.11 +// * Redistributions of source code must retain the above copyright
1.12 +// notice, this list of conditions and the following disclaimer.
1.13 +// * Redistributions in binary form must reproduce the above
1.14 +// copyright notice, this list of conditions and the following disclaimer
1.15 +// in the documentation and/or other materials provided with the
1.16 +// distribution.
1.17 +// * Neither the name of Google Inc. nor the names of its
1.18 +// contributors may be used to endorse or promote products derived from
1.19 +// this software without specific prior written permission.
1.20 +//
1.21 +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.22 +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.23 +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
1.24 +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
1.25 +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
1.26 +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
1.27 +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
1.28 +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
1.29 +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
1.30 +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
1.31 +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.32 +//
1.33 +// Author: wan@google.com (Zhanyong Wan)
1.34 +// Author: vladl@google.com (Vlad Losev)
1.35 +
1.36 +// This provides interface PrimeTable that determines whether a number is a
1.37 +// prime and determines a next prime number. This interface is used
1.38 +// in Google Test samples demonstrating use of parameterized tests.
1.39 +
1.40 +#ifndef GTEST_SAMPLES_PRIME_TABLES_H_
1.41 +#define GTEST_SAMPLES_PRIME_TABLES_H_
1.42 +
1.43 +#include <algorithm>
1.44 +
1.45 +// The prime table interface.
1.46 +class PrimeTable {
1.47 + public:
1.48 + virtual ~PrimeTable() {}
1.49 +
1.50 + // Returns true iff n is a prime number.
1.51 + virtual bool IsPrime(int n) const = 0;
1.52 +
1.53 + // Returns the smallest prime number greater than p; or returns -1
1.54 + // if the next prime is beyond the capacity of the table.
1.55 + virtual int GetNextPrime(int p) const = 0;
1.56 +};
1.57 +
1.58 +// Implementation #1 calculates the primes on-the-fly.
1.59 +class OnTheFlyPrimeTable : public PrimeTable {
1.60 + public:
1.61 + virtual bool IsPrime(int n) const {
1.62 + if (n <= 1) return false;
1.63 +
1.64 + for (int i = 2; i*i <= n; i++) {
1.65 + // n is divisible by an integer other than 1 and itself.
1.66 + if ((n % i) == 0) return false;
1.67 + }
1.68 +
1.69 + return true;
1.70 + }
1.71 +
1.72 + virtual int GetNextPrime(int p) const {
1.73 + for (int n = p + 1; n > 0; n++) {
1.74 + if (IsPrime(n)) return n;
1.75 + }
1.76 +
1.77 + return -1;
1.78 + }
1.79 +};
1.80 +
1.81 +// Implementation #2 pre-calculates the primes and stores the result
1.82 +// in an array.
1.83 +class PreCalculatedPrimeTable : public PrimeTable {
1.84 + public:
1.85 + // 'max' specifies the maximum number the prime table holds.
1.86 + explicit PreCalculatedPrimeTable(int max)
1.87 + : is_prime_size_(max + 1), is_prime_(new bool[max + 1]) {
1.88 + CalculatePrimesUpTo(max);
1.89 + }
1.90 + virtual ~PreCalculatedPrimeTable() { delete[] is_prime_; }
1.91 +
1.92 + virtual bool IsPrime(int n) const {
1.93 + return 0 <= n && n < is_prime_size_ && is_prime_[n];
1.94 + }
1.95 +
1.96 + virtual int GetNextPrime(int p) const {
1.97 + for (int n = p + 1; n < is_prime_size_; n++) {
1.98 + if (is_prime_[n]) return n;
1.99 + }
1.100 +
1.101 + return -1;
1.102 + }
1.103 +
1.104 + private:
1.105 + void CalculatePrimesUpTo(int max) {
1.106 + ::std::fill(is_prime_, is_prime_ + is_prime_size_, true);
1.107 + is_prime_[0] = is_prime_[1] = false;
1.108 +
1.109 + for (int i = 2; i <= max; i++) {
1.110 + if (!is_prime_[i]) continue;
1.111 +
1.112 + // Marks all multiples of i (except i itself) as non-prime.
1.113 + for (int j = 2*i; j <= max; j += i) {
1.114 + is_prime_[j] = false;
1.115 + }
1.116 + }
1.117 + }
1.118 +
1.119 + const int is_prime_size_;
1.120 + bool* const is_prime_;
1.121 +
1.122 + // Disables compiler warning "assignment operator could not be generated."
1.123 + void operator=(const PreCalculatedPrimeTable& rhs);
1.124 +};
1.125 +
1.126 +#endif // GTEST_SAMPLES_PRIME_TABLES_H_
