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+// Copyright 2008 Google Inc.
+// All Rights Reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: wan@google.com (Zhanyong Wan)
+// Author: vladl@google.com (Vlad Losev)
+
+// This provides interface PrimeTable that determines whether a number is a
+// prime and determines a next prime number. This interface is used
+// in Google Test samples demonstrating use of parameterized tests.
+
+#ifndef GTEST_SAMPLES_PRIME_TABLES_H_
+#define GTEST_SAMPLES_PRIME_TABLES_H_
+
+#include <algorithm>
+
+// The prime table interface.
+class PrimeTable {
+ public:
+  virtual ~PrimeTable() {}
+
+  // Returns true iff n is a prime number.
+  virtual bool IsPrime(int n) const = 0;
+
+  // Returns the smallest prime number greater than p; or returns -1
+  // if the next prime is beyond the capacity of the table.
+  virtual int GetNextPrime(int p) const = 0;
+};
+
+// Implementation #1 calculates the primes on-the-fly.
+class OnTheFlyPrimeTable : public PrimeTable {
+ public:
+  virtual bool IsPrime(int n) const {
+    if (n <= 1) return false;
+
+    for (int i = 2; i*i <= n; i++) {
+      // n is divisible by an integer other than 1 and itself.
+      if ((n % i) == 0) return false;
+    }
+
+    return true;
+  }
+
+  virtual int GetNextPrime(int p) const {
+    for (int n = p + 1; n > 0; n++) {
+      if (IsPrime(n)) return n;
+    }
+
+    return -1;
+  }
+};
+
+// Implementation #2 pre-calculates the primes and stores the result
+// in an array.
+class PreCalculatedPrimeTable : public PrimeTable {
+ public:
+  // 'max' specifies the maximum number the prime table holds.
+  explicit PreCalculatedPrimeTable(int max)
+      : is_prime_size_(max + 1), is_prime_(new bool[max + 1]) {
+    CalculatePrimesUpTo(max);
+  }
+  virtual ~PreCalculatedPrimeTable() { delete[] is_prime_; }
+
+  virtual bool IsPrime(int n) const {
+    return 0 <= n && n < is_prime_size_ && is_prime_[n];
+  }
+
+  virtual int GetNextPrime(int p) const {
+    for (int n = p + 1; n < is_prime_size_; n++) {
+      if (is_prime_[n]) return n;
+    }
+
+    return -1;
+  }
+
+ private:
+  void CalculatePrimesUpTo(int max) {
+    ::std::fill(is_prime_, is_prime_ + is_prime_size_, true);
+    is_prime_[0] = is_prime_[1] = false;
+
+    for (int i = 2; i <= max; i++) {
+      if (!is_prime_[i]) continue;
+
+      // Marks all multiples of i (except i itself) as non-prime.
+      for (int j = 2*i; j <= max; j += i) {
+        is_prime_[j] = false;
+      }
+    }
+  }
+
+  const int is_prime_size_;
+  bool* const is_prime_;
+};
+
+#endif  // GTEST_SAMPLES_PRIME_TABLES_H_