{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<img src=\"./images/xeus-cling.svg\" style=\"width: 50%;\"  alt=\"Jupyter Logo\">\n",
    "\n",
    "<center>A Jupyter kernel for C++ based on the C++ interpreter cling and the native implementation of the Jupyter protocol xeus.</center>\n",
    "\n",
    "<div style=\"background: #f1f1f1;\n",
    "            border: 1px solid grey;\n",
    "            margin: 16px 0 8px 0;\n",
    "            text-align: center;\n",
    "            padding: 8px; \">\n",
    "    This live demo is powered by\n",
    "    <div style=\"margin-left: auto; margin-right: auto; display: flex; max-width: 600px\">\n",
    "        <div style=\"margin: 20px;\"><img src=\"./images/binder-logo.png\" style=\"height: 40px;\" alt=\"Binder Logo\"></div>\n",
    "        <div style=\"margin: 20px;\"><img src=\"./images/jupyter-logo.png\" style=\"height: 40px;\"  alt=\"Jupyter Logo\"></div>\n",
    "        <div style=\"margin: 20px;\"><img src=\"./images/cling-logo.png\" style=\"height: 40px;\"  alt=\"Cling Logo\"></div>\n",
    "    </div>\n",
    "</div>\n",
    "<div style=\"background: #ffeded;\n",
    "            border: 1px solid grey;\n",
    "            margin: 8px 0 8px 0;\n",
    "            text-align: center;\n",
    "            padding: 8px;\">\n",
    "    <i class=\"fa-warning fa\" \n",
    "       style=\"font-size: 40px;\n",
    "              line-height: 40px;\n",
    "              margin: 8px;\n",
    "              color: #444;\">\n",
    "    </i>\n",
    "    <div>\n",
    "    This live demo may not be runnable from behind certain corporate proxies that block the websocket protocol.\n",
    "    </div>\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Introduction\n",
    "\n",
    "`xtensor` is a C++ library meant for numerical analysis with multi-dimensional array expressions.\n",
    "\n",
    "`xtensor` provides\n",
    "\n",
    " - an extensible expression system enabling **lazy broadcasting**.\n",
    " - an API following the idioms of the **C++ standard library**.\n",
    " - tools to manipulate array expressions and build upon `xtensor`.\n",
    "\n",
    "The implementation of the containers of `xtensor` is inspired by [NumPy](http://www.numpy.org), the Python array programming library. **Adaptors** for existing data structures to be plugged into our expression system can easily be written. In fact, `xtensor` can be used to **process `numpy` data structures inplace** using Python's [buffer protocol](https://docs.python.org/3/c-api/buffer.html).\n",
    "\n",
    "`xtensor` requires a modern C++ compiler supporting C++14. The following C+ compilers are supported:\n",
    "\n",
    " - On Windows platforms, Visual C++ 2015 Update 2, or more recent\n",
    " - On Unix platforms, gcc 4.9 or a recent version of Clang"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Usage\n",
    "\n",
    "<div style=\"background: #efffed;\n",
    "            border: 1px solid grey;\n",
    "            margin: 8px 0 8px 0;\n",
    "            text-align: center;\n",
    "            padding: 8px; \">\n",
    "    <i class=\"fa-play fa\" \n",
    "       style=\"font-size: 40px;\n",
    "              line-height: 40px;\n",
    "              margin: 8px;\n",
    "              color: #444;\">\n",
    "    </i>\n",
    "    <div>\n",
    "    To run the selected code cell, hit <pre style=\"background: #efffed\">Shift + Enter</pre>\n",
    "    </div>\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "## Output and error streams\n",
    "\n",
    "`std::cout` and `std::cerr` are correctly redirected"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "#include <iostream>\n",
    "\n",
    "std::cout << \"some output\" << std::endl;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "std::cerr << \"some error\" << std::endl;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "#include <stdexcept>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "throw std::runtime_error(\"BAAAD\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Omitting the `;` in the last statement of a cell gives an output"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "int i = 4"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "int j = 5;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "j"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Interpreting the C++ programming language\n",
    "\n",
    "`cling` has a broad support of the features of C++. You can define functions, classes, templates, etc ..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Functions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "double sqr(double a)\n",
    "{\n",
    "    return a * a;\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "double a = 2.5;\n",
    "double asqr = sqr(a);\n",
    "asqr"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Classes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class Foo\n",
    "{\n",
    "public:\n",
    "\n",
    "    virtual ~Foo() {}\n",
    "    \n",
    "    virtual void print(double value) const\n",
    "    {\n",
    "        std::cout << \"Foo value = \" << value << std::endl;\n",
    "    }\n",
    "};"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "Foo bar;\n",
    "bar.print(1.2);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Polymorphism"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class Bar : public Foo\n",
    "{\n",
    "public:\n",
    "\n",
    "    virtual ~Bar() {}\n",
    "    \n",
    "    virtual void print(double value) const\n",
    "    {\n",
    "        std::cout << \"Bar value = \" << 2 * value << std::endl;\n",
    "    }\n",
    "};"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "Foo* bar2 = new Bar;\n",
    "bar2->print(1.2);\n",
    "delete bar2;"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Templates"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "#include <typeinfo>\n",
    "\n",
    "template <class T>\n",
    "class FooT\n",
    "{\n",
    "public:\n",
    "    \n",
    "    explicit FooT(const T& t) : m_t(t) {}\n",
    "    \n",
    "    void print() const\n",
    "    {\n",
    "        std::cout << typeid(T).name() << \" m_t = \" << m_t << std::endl;\n",
    "    }\n",
    "    \n",
    "private:\n",
    "    \n",
    "    T m_t;\n",
    "};\n",
    "\n",
    "template <>\n",
    "class FooT<int>\n",
    "{\n",
    "public:\n",
    "    \n",
    "    explicit FooT(const int& t) : m_t(t) {}\n",
    "    \n",
    "    void print() const\n",
    "    {\n",
    "        std::cout << \"m_t = \" << m_t << std::endl;\n",
    "    }\n",
    "    \n",
    "private:\n",
    "    \n",
    "    int m_t;\n",
    "};"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "FooT<double> foot1(1.2);\n",
    "foot1.print();"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "FooT<int> foot2(4);\n",
    "foot2.print();"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## C++11 / C++14 support"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class Foo11\n",
    "{\n",
    "public:\n",
    "    \n",
    "    Foo11() { std::cout << \"Foo11 default constructor\" << std::endl; }\n",
    "    Foo11(const Foo11&) { std::cout << \"Foo11 copy constructor\" << std::endl; }\n",
    "    Foo11(Foo11&&) { std::cout << \"Foo11 move constructor\" << std::endl; }\n",
    "};"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "Foo11 f1;\n",
    "Foo11 f2(f1);\n",
    "Foo11 f3(std::move(f1));"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "#include <vector>\n",
    "\n",
    "std::vector<int> v = { 1, 2, 3};\n",
    "auto iter = ++v.begin();\n",
    "v"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "*iter"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "... and also lambda, universal references, `decltype`, etc ..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Documentation and completion"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "?std::vector"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "## Using the `display_data` mechanism"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "#include <string>\n",
    "#include <fstream>\n",
    "\n",
    "#include \"xtl/xbase64.hpp\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "std::ifstream fin(\"images/marie.png\", std::ios::binary);\n",
    "std::stringstream buffer;\n",
    "buffer << fin.rdbuf();"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "xeus::xjson mime;\n",
    "mime[\"image/png\"] = xtl::base64encode(buffer.str());"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "xeus::get_interpreter().display_data(\n",
    "    std::move(mime),\n",
    "    xeus::xjson::object(),\n",
    "    xeus::xjson::object());"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "std::ifstream fwav(\"audio/audio.wav\", std::ios::binary);\n",
    "std::stringstream wav_buffer;\n",
    "wav_buffer << fwav.rdbuf();\n",
    "xeus::xjson audio_mime;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "audio_mime[\"text/html\"] =\n",
    "    std::string(\"<audio controls=\\\"controls\\\"><source src=\\\"data:audio/wav;base64,\")\n",
    "    + xtl::base64encode(wav_buffer.str()) +\n",
    "    \"\\\" type=\\\"audio/wav\\\" /></audio>\";"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "xeus::get_interpreter().display_data(\n",
    "    std::move(audio_mime),\n",
    "    xeus::xjson::object(),\n",
    "    xeus::xjson::object());"
   ]
  }
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