65 lines
2.3 KiB
C++
65 lines
2.3 KiB
C++
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// fig18_01.cpp
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// Creating a generator coroutine with co_yield.
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#include <fmt/format.h>
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#include <iostream>
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#include <sstream>
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#include <thread>
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#include <tl/generator.hpp>
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// get current thread's ID as a string
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std::string id() {
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std::ostringstream out;
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out << std::this_thread::get_id();
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return out.str();
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}
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// coroutine that repeatedly yields the next Fibonacci value in sequence
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tl::generator<int> fibonacciGenerator(int limit) {
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std::cout << fmt::format(
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"Thread {}: fibonacciGenerator started executing\n", id());
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int value1{0}; // Fibonacci(0)
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int value2{1}; // Fibonacci(1)
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for (int i{0}; i < limit; ++i) {
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co_yield value1; // yield current value of value1
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// update value1 and value2 for next iteration
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int temp{value1 + value2};
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value1 = value2;
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value2 = temp;
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}
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std::cout << fmt::format(
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"Thread {}: fibonacciGenerator finished executing\n", id());
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}
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int main() {
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std::cout << fmt::format("Thread {}: main begins\n", id());
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// display first 10 Fibonacci values
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for (int i{0}; auto value : fibonacciGenerator(10)) {
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std::cout << fmt::format("Fibonacci({}) is {}\n", i++, value);
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}
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std::cout << fmt::format("Thread {}: main ends\n", id());
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}
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/**************************************************************************
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* (C) Copyright 1992-2021 by Deitel & Associates, Inc. and *
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* Pearson Education, Inc. All Rights Reserved. *
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* *
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* DISCLAIMER: The authors and publisher of this book have used their *
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* best efforts in preparing the book. These efforts include the *
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* development, research, and testing of the theories and programs *
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* to determine their effectiveness. The authors and publisher make *
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* no warranty of any kind, expressed or implied, with regard to these *
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* programs or to the documentation contained in these books. The authors *
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* and publisher shall not be liable in any event for incidental or *
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* consequential damages in connection with, or arising out of, the *
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* furnishing, performance, or use of these programs. *
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**************************************************************************/
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