Compresses XML to a more compact representation.

xml_compression.cpp

template<typename Node>
class XMLCompressor
{
public:
	
	using map_t = std::map<std::string, std::string>;
	
	static map_t global_keywords;
	
	std::string operator()(Node* node, map_t& keywords = global_keywords)
	{
		std::string string;
		
		_compress(node, string, keywords);
		
		string.pop_back();
		
		return string;
	}
	
private:
	
	void _compress(Node* node, std::string& string, map_t& keywords)
	{
		if (! node) return;
		
		string += keywords.at(node->tag) + " ";
		
		for (const auto& attribute : node->attributes)
		{
			string += keywords.at(attribute.first) + " ";
			string += attribute.second + " ";
		}
		
		string += "0 ";
		
		if (! node->data.empty())
		{
			string += node->data + " ";
		}
		
		for (const auto& child : node->children)
		{
			_compress(child, string, keywords);
		}
		
		string += "0 ";
	}
};

template<typename Node>
typename XMLCompressor<Node>::map_t XMLCompressor<Node>::global_keywords = {
	{"family", "1"},
	{"person", "2"},
	{"first_name", "3"},
	{"last_name", "4"},
	{"state", "5"}
	
};


template<typename Node>
std::string compress(Node* root)
{
	XMLCompressor<Node> compress;
	
	return compress(root);
}

struct XMLNode
{
	using attributes_t = std::map<std::string, std::string>;
	
	using children_t = std::vector<XMLNode*>;
	
	XMLNode(const std::string& tag_,
			const std::string& data_,
			const attributes_t& attributes_ = attributes_t(),
			const children_t& children_ = children_t())
	: tag(tag_)
	, data(data_)
	, attributes(attributes_)
	, children(children_)
	{ }
	
	std::string tag;
	
	std::string data;
	
	attributes_t attributes;
	
	std::vector<XMLNode*> children;
};

template<typename Node>
void delete_xml_tree(Node* node)
{
	for (auto& child : node->children)
	{
		delete_xml_tree(child);
	}
	
	delete node;
}

int main(int argc, char* argv[])
{
	XMLNode* root = new XMLNode("family",
								"",
								{
									{"last_name", "McDowell"},
									{"state", "CA"}
								},
								{
									new XMLNode("person",
												"Some Message",
											 {{"first_name", "Gayle"}})
								});
	
	print::ln(compress(root));
	
	delete_xml_tree(root);
}