premiere-libtorrent/include/libtorrent/lazy_entry.hpp

/*

Copyright (c) 2003, Arvid Norberg
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/

#ifndef TORRENT_LAZY_ENTRY_HPP_INCLUDED
#define TORRENT_LAZY_ENTRY_HPP_INCLUDED

#include <utility>
#include <vector>
#include "libtorrent/assert.hpp"
#include "libtorrent/size_type.hpp"
#include <iosfwd>

namespace libtorrent
{
	struct lazy_entry;

	char const* parse_int(char const* start, char const* end, char delimiter, boost::int64_t& val);
	// return 0 = success
	int lazy_bdecode(char const* start, char const* end, lazy_entry& ret, int depth_limit = 1000);

	struct lazy_entry
	{
		enum entry_type_t
		{
			none_t, dict_t, list_t, string_t, int_t
		};

		lazy_entry() : m_type(none_t), m_begin(0), m_end(0)
		{ m_data.start = 0; }

		entry_type_t type() const { return m_type; }

		// start points to the first decimal digit
		// length is the number of digits
		void construct_int(char const* start, int length)
		{
			TORRENT_ASSERT(m_type == none_t);
			m_type = int_t;
			m_data.start = start;
			m_size = length;
			m_begin = start - 1; // include 'i'
			m_end = start + length + 1; // include 'e'
		}

		size_type int_value() const;

		// string functions
		// ================

		void construct_string(char const* start, int length);

		// the string is not null-terminated!
		char const* string_ptr() const
		{
			TORRENT_ASSERT(m_type == string_t);
			return m_data.start;
		}

		// this will return a null terminated string
		// it will write to the source buffer!
		char const* string_cstr() const
		{
			TORRENT_ASSERT(m_type == string_t);
			const_cast<char*>(m_data.start)[m_size] = 0;
			return m_data.start;
		}

		std::string string_value() const
		{
			TORRENT_ASSERT(m_type == string_t);
			return std::string(m_data.start, m_size);
		}

		int string_length() const
		{ return m_size; }

		// dictionary functions
		// ====================

		void construct_dict(char const* begin)
		{
			TORRENT_ASSERT(m_type == none_t);
			m_type = dict_t;
			m_size = 0;
			m_capacity = 0;
			m_begin = begin;
		}

		lazy_entry* dict_append(char const* name);
		lazy_entry* dict_find(char const* name);
		lazy_entry const* dict_find(char const* name) const
		{ return const_cast<lazy_entry*>(this)->dict_find(name); }

		std::string dict_find_string_value(char const* name) const;
		size_type dict_find_int_value(char const* name, size_type default_val = 0) const;
		lazy_entry const* dict_find_dict(char const* name) const;
		lazy_entry const* dict_find_list(char const* name) const;
		lazy_entry const* dict_find_string(char const* name) const;

		std::pair<std::string, lazy_entry const*> dict_at(int i) const
		{
			TORRENT_ASSERT(m_type == dict_t);
			TORRENT_ASSERT(i < m_size);
			std::pair<char const*, lazy_entry> const& e = m_data.dict[i];
			return std::make_pair(std::string(e.first, e.second.m_begin - e.first), &e.second);
		}

		int dict_size() const
		{
			TORRENT_ASSERT(m_type == dict_t);
			return m_size;
		}

		// list functions
		// ==============

		void construct_list(char const* begin)
		{
			TORRENT_ASSERT(m_type == none_t);
			m_type = list_t;
			m_size = 0;
			m_capacity = 0;
			m_begin = begin;
		}

		lazy_entry* list_append();
		lazy_entry* list_at(int i)
		{
			TORRENT_ASSERT(m_type == list_t);
			TORRENT_ASSERT(i < m_size);
			return &m_data.list[i];
		}
		lazy_entry const* list_at(int i) const
		{ return const_cast<lazy_entry*>(this)->list_at(i); }

		std::string list_string_value_at(int i) const;
		size_type list_int_value_at(int i, size_type default_val = 0) const;

		int list_size() const
		{
			TORRENT_ASSERT(m_type == list_t);
			return m_size;
		}

		// end points one byte passed last byte
		void set_end(char const* end)
		{
			TORRENT_ASSERT(end > m_begin);
			m_end = end;
		}
		
		void clear();

		// releases ownership of any memory allocated
		void release()
		{
			m_data.start = 0;
			m_size = 0;
			m_capacity = 0;
			m_type = none_t;
		}

		~lazy_entry()
		{ clear(); }

		// returns pointers into the source buffer where
		// this entry has its bencoded data
		std::pair<char const*, int> data_section() const;

		void swap(lazy_entry& e)
		{
			using std::swap;
			swap(m_type, e.m_type);
			swap(m_data.start, e.m_data.start);
			swap(m_size, e.m_size);
			swap(m_capacity, e.m_capacity);
			swap(m_begin, e.m_begin);
			swap(m_end, e.m_end);
		}

	private:

		entry_type_t m_type;
		union data_t
		{
			std::pair<char const*, lazy_entry>* dict;
			lazy_entry* list;
			char const* start;
		} m_data;
		int m_size; // if list or dictionary, the number of items
		int m_capacity; // if list or dictionary, allocated number of items
		// used for dictionaries and lists to record the range
		// in the original buffer they are based on
		char const* m_begin;
		char const* m_end;
	};

	std::ostream& operator<<(std::ostream& os, lazy_entry const& e);

};


#endif