#include <iostream>
#include <string>
#include <unordered_map>
#include <list>
#include <memory>

using namespace std;

// Pure Element

class Element {
public:
  virtual string write() const = 0;
  virtual ~Element();
};

Element::~Element() {}

// Text Element

class TextElement : public Element {
  string text;
public:
  TextElement(const string&);
  string write() const;
  operator shared_ptr<Element>() const;
};

TextElement::TextElement(const string& text) : text(text) {}

string TextElement::write() const {
  return text;
}

TextElement::operator shared_ptr<Element>() const {
  return make_shared<TextElement>(*this);
}

// Attribute List

class AttributeList : public Element, public unordered_map<string,string> {
public:
  using unordered_map::unordered_map;
  string write() const;
};

string AttributeList::write() const {
  string buf;
  for(const auto& it : *this) {
    buf += " " + it.first + "=\"" + it.second + "\"";
  }
  return buf;
}

// Html

class Html : public Element, public list<shared_ptr<Element>> {
public:
  using list::list;
  string write() const;
};

string Html::write() const {
  string buf;
  for(const auto& it : *this) {
    buf += it->write();
  }
  return buf;
}

// Tag

class Tag : public Element {
public:
  string tag;
  AttributeList attr;
  Html body;
  Tag(const string&, const Html&);
  Tag(const string&, const AttributeList&, const Html&);
  string write() const;
  operator shared_ptr<Element>() const;
};

Tag::Tag(const string& tag, const Html& body) : tag(tag), body(body) {}

Tag::Tag(const string& tag, const AttributeList& attr, const Html& body) :
  tag(tag), attr(attr), body(body) {}

string Tag::write() const {
  return string("<") + tag + attr.write() + ">" + body.write() + "</" + tag + ">";
}

Tag::operator shared_ptr<Element>() const {
  return make_shared<Tag>(*this);
}

// Tests

void speed_test(const Html& html) {
  for(int i = 0; i < 1000000; i++) {
    html.write();
  }
}

int main() {
  Html html {Tag("html", {
	Tag("head", {Tag("title", {TextElement("Hello, world!")})}),
	  Tag("body", {{"style", "background-color: salmon"}}, {
	      Tag("p", {{"style", "font-family: serif"}}, {
		  TextElement("Hello, "), Tag("i", {TextElement("world")}),
		    TextElement("!")})})})};

  speed_test(html);
}