A Jupyter kernel for C++ based on the cling
C++ interpreter and the xeus
native implementation of the Jupyter protocol, xeus.
In [1]:
#include <iostream>
std::cout << "some output" << std::endl;
In [2]:
std::cerr << "some error" << std::endl;
In [3]:
#include <stdexcept>
In [4]:
throw std::runtime_error("Unknown exception");
Omitting the ;
in the last statement of a cell results in an output being printed
In [5]:
int j = 5;
In [6]:
j
Out[6]:
In [7]:
double sqr(double a)
{
return a * a;
}
In [8]:
double a = 2.5;
double asqr = sqr(a);
asqr
Out[8]:
In [9]:
class Foo
{
public:
virtual ~Foo() {}
virtual void print(double value) const
{
std::cout << "Foo value = " << value << std::endl;
}
};
In [10]:
Foo bar;
bar.print(1.2);
In [11]:
class Bar : public Foo
{
public:
virtual ~Bar() {}
virtual void print(double value) const
{
std::cout << "Bar value = " << 2 * value << std::endl;
}
};
In [12]:
Foo* bar2 = new Bar;
bar2->print(1.2);
delete bar2;
In [13]:
#include <typeinfo>
template <class T>
class FooT
{
public:
explicit FooT(const T& t) : m_t(t) {}
void print() const
{
std::cout << typeid(T).name() << " m_t = " << m_t << std::endl;
}
private:
T m_t;
};
template <>
class FooT<int>
{
public:
explicit FooT(const int& t) : m_t(t) {}
void print() const
{
std::cout << "m_t = " << m_t << std::endl;
}
private:
int m_t;
};
In [14]:
FooT<double> foot1(1.2);
foot1.print();
In [15]:
FooT<int> foot2(4);
foot2.print();
In [16]:
class Foo11
{
public:
Foo11() { std::cout << "Foo11 default constructor" << std::endl; }
Foo11(const Foo11&) { std::cout << "Foo11 copy constructor" << std::endl; }
Foo11(Foo11&&) { std::cout << "Foo11 move constructor" << std::endl; }
};
In [17]:
Foo11 f1;
Foo11 f2(f1);
Foo11 f3(std::move(f1));
In [18]:
#include <vector>
std::vector<int> v = { 1, 2, 3};
auto iter = ++v.begin();
v
Out[18]:
In [19]:
*iter
Out[19]:
... and also lambda, universal references, decltype
, etc ...
In [21]:
?xt::xtensor
In [20]:
?std::vector
For a user-defined type T
, the rich rendering in the notebook and JupyterLab can be enabled by by implementing the function xeus::xjson mime_bundle_repr(const T& im)
, which returns the JSON mime bundle for that type.
More documentation on the rich display system of Jupyter and Xeus-cling is available at https://xeus-cling.readthedocs.io/en/latest/rich_display.html
In [22]:
#include <string>
#include <fstream>
#include "xtl/xbase64.hpp"
#include "xeus/xjson.hpp"
namespace im
{
struct image
{
inline image(const std::string& filename)
{
std::ifstream fin(filename, std::ios::binary);
m_buffer << fin.rdbuf();
}
std::stringstream m_buffer;
};
xeus::xjson mime_bundle_repr(const image& i)
{
auto bundle = xeus::xjson::object();
bundle["image/png"] = xtl::base64encode(i.m_buffer.str());
return bundle;
}
}
In [23]:
im::image marie("images/marie.png");
marie
Out[23]:
In [24]:
#include <string>
#include <fstream>
#include "xtl/xbase64.hpp"
#include "xeus/xjson.hpp"
namespace au
{
struct audio
{
inline audio(const std::string& filename)
{
std::ifstream fin(filename, std::ios::binary);
m_buffer << fin.rdbuf();
}
std::stringstream m_buffer;
};
xeus::xjson mime_bundle_repr(const audio& a)
{
auto bundle = xeus::xjson::object();
bundle["text/html"] =
std::string("<audio controls=\"controls\"><source src=\"data:audio/wav;base64,")
+ xtl::base64encode(a.m_buffer.str()) +
"\" type=\"audio/wav\" /></audio>";
return bundle;
}
}
In [25]:
au::audio drums("audio/audio.wav");
drums
Out[25]:
In [26]:
#include "xcpp/xdisplay.hpp"
In [27]:
xcpp::display(drums);
In [28]:
#include <string>
#include "xcpp/xdisplay.hpp"
namespace ht
{
struct html
{
inline html(const std::string& content)
{
m_content = content;
}
std::string m_content;
};
xeus::xjson mime_bundle_repr(const html& a)
{
auto bundle = xeus::xjson::object();
bundle["text/html"] = a.m_content;
return bundle;
}
}
// A red rectangle
ht::html rect(R"(
<div style='
width: 90px;
height: 50px;
line-height: 50px;
background-color: blue;
color: white;
text-align: center;'>
Original
</div>)");
In [29]:
xcpp::display(rect, "some_display_id");
In [30]:
// Update the rectangle to be blue
rect.m_content = R"(
<div style='
width: 90px;
height: 50px;
line-height: 50px;
background-color: red;
color: white;
text-align: center;'>
Updated
</div>)";
xcpp::display(rect, "some_display_id", true);
In [31]:
#include <chrono>
#include <iostream>
#include <thread>
#include "xcpp/xdisplay.hpp"
In [32]:
std::cout << "hello" << std::endl;
std::this_thread::sleep_for(std::chrono::seconds(1));
xcpp::clear_output(); // will flicker when replacing "hello" with "goodbye"
std::this_thread::sleep_for(std::chrono::seconds(1));
std::cout << "goodbye" << std::endl;
In [ ]:
std::cout << "hello" << std::endl;
std::this_thread::sleep_for(std::chrono::seconds(1));
xcpp::clear_output(true); // prevents flickering
std::this_thread::sleep_for(std::chrono::seconds(1));
std::cout << "goodbye" << std::endl;
Magics are special commands for the kernel that are not part of the C++ language.
They are defined with the symbol %
for a line magic and %%
for a cell magic.
More documentation for magics is available at https://xeus-cling.readthedocs.io/en/latest/magics.html.
In [ ]:
#include <algorithm>
#include <vector>
In [ ]:
std::vector<double> to_shuffle = {1, 2, 3, 4};
In [ ]:
%timeit std::random_shuffle(to_shuffle.begin(), to_shuffle.end());
In [ ]: