shared-buffer/example/shared_buffer_example.cpp at develop · connectivecpp/shared-buffer · GitHub

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/** @file

* @brief Example code demonstrating use of @c chops::shared_buffer.

* See @c threaded_wait_shared_demo.cpp for multithreaded example.

* @author Thurman Gillespy

* 3/22/19

* Minor changes 4/3/2025 by Cliff Green (change repeat to iota, append now has endian flag).

* Distributed under the Boost Software License, Version 1.0.

* (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

* Sample make file:

* g++ -std=c++17 -I ~/Projects/utility-rack/include/ \

* -I ~/Projects/boost_1_69_0/ \

* shared_buffer_demo.cpp

#include <iostream>

#include <cstdlib> // EXIT_SUCCESS

#include <cstddef> // std::byte

#include <cstdint> // std::uint16_t

#include <string>

#include <cstring> // std::strlen

#include <ranges> // std::views::iota

#include "serialize/extract_append.hpp"

#include "buffer/shared_buffer.hpp"

// tasty utility lambda function

constexpr auto printLn = [] () { std::cout << std::endl; };

// utility functions for casting @c wait_queue.data()

template <class C>

const char* cast_to_char_ptr (const C& buf) {

return static_cast<const char*> (static_cast<const void*> (buf.data()));

}

template <class C>

const std::uint16_t* cast_to_uint16_ptr (const C& buf) {

return static_cast<const std::uint16_t*> (static_cast<const void*> (buf.data()));

}

int main() {

// create empty shared buffer1

chops::mutable_shared_buffer buf1;

std::cout << "buffer1 contains " << buf1.size() << " bytes" << std::endl;

// c-string to add to buffer1

constexpr char str1[] = "A cat in the hat.";

const char* strptr = str1;

// add one char at a time

for (int i : std::views::iota(0u, std::strlen(strptr) + 1)) {

buf1.append(static_cast<std::byte> (*strptr++));

}

// what str1 and the loop replaces

// buf1.append(static_cast<std::byte>('A');

// buf1.append((static_cast<std::byte>(' ');

// buf1.append((static_cast<std::byte>('c');

// etc.

std::cout << "buffer1 contains (including trailing nul char) " << buf1.size() << " bytes" << std::endl;

// print the output, one char at a time

const char* byte = cast_to_char_ptr (buf1); // data starts here

for (unsigned int i = 0; i < buf1.size(); ++i) {

std::cout << *byte++;

}

printLn();

// append a string with one call to append

buf1.clear(); // empty the buffer

std::cout << "buffer1 contains " << buf1.size() << " bytes" << std::endl;

const std::string str = "Green eggs and ham.";

// convert str to C-string, add to buffer1

buf1.append(str.c_str(), str.size() + 1);

std::cout << "buffer1 contains " << buf1.size() << " bytes" << std::endl;

// print c-string

std::cout << cast_to_char_ptr (buf1) << std::endl;

// write some short ints to a buffer

constexpr int NUM_INTS = 15;

chops::mutable_shared_buffer buf2(NUM_INTS * sizeof(std::uint16_t));

std::cout << "buffer2 contains " << buf2.size() << " bytes and ";

std::cout << (buf2.size()/sizeof(std::uint16_t)) << " short integers\n";

// input some numbers

const std::uint16_t* data = cast_to_uint16_ptr (buf2);// data starts here

// create number, convert to 'network' (big endian) byte order, place into buf2

std::uint16_t count = 1;

auto x = buf2.data();

for (int i : std::views::iota(0, NUM_INTS)) {

auto sz = chops::append_val <std::endian::big, std::uint16_t> (x, count++ * 5);

x += sz;

}

// print them out

// read 2 bytes, convert back to native endian order, print

x = buf2.data();

for (int i : std::views::iota(0, NUM_INTS)) {

std::cout << chops::extract_val<std::endian::native, std::uint16_t>(x) << " ";

x+=2;

}

printLn();

// swap the buffers, print result

buf2.swap(buf1);

std::cout << "buffer2 contents after swap" << std::endl;

std::cout << cast_to_char_ptr (buf2) << std::endl;

std::cout << "buffer1 contents after swap" << std::endl;

x = buf1.data();

for (int i : std::views::iota(0, NUM_INTS)) {

std::cout << chops::extract_val<std::endian::native, std::uint16_t>(x) << " ";

x+=2;

}

printLn();

return EXIT_SUCCESS;

}

shared-buffer/example/shared_buffer_example.cpp at develop · connectivecpp/shared-buffer · GitHub

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