read_until.ipp

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//
// read_until.ipp
// ~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_READ_UNTIL_IPP
#define ASIO_READ_UNTIL_IPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/push_options.hpp"

#include "asio/detail/push_options.hpp"
#include <algorithm>
#include <limits>
#include <string>
#include <utility>
#include "asio/detail/pop_options.hpp"

#include "asio/buffer.hpp"
#include "asio/detail/bind_handler.hpp"
#include "asio/detail/const_buffers_iterator.hpp"
#include "asio/detail/handler_alloc_helpers.hpp"
#include "asio/detail/handler_invoke_helpers.hpp"
#include "asio/detail/throw_error.hpp"

namespace asio {

template <typename SyncReadStream, typename Allocator>
inline std::size_t read_until(SyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, char delim)
{
  asio::error_code ec;
  std::size_t bytes_transferred = read_until(s, b, delim, ec);
  asio::detail::throw_error(ec);
  return bytes_transferred;
}

template <typename SyncReadStream, typename Allocator>
std::size_t read_until(SyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, char delim,
    asio::error_code& ec)
{
  std::size_t next_search_start = 0;
  for (;;)
  {
    // Determine the range of the data to be searched.
    typedef typename asio::basic_streambuf<
      Allocator>::const_buffers_type const_buffers_type;
    typedef asio::detail::const_buffers_iterator<
      const_buffers_type> iterator;
    const_buffers_type buffers = b.data();
    iterator begin(buffers, next_search_start);
    iterator end(buffers, (std::numeric_limits<std::size_t>::max)());

    // Look for a match.
    iterator iter = std::find(begin, end, delim);
    if (iter != end)
    {
      // Found a match. We're done.
      ec = asio::error_code();
      return iter.position() + 1;
    }
    else
    {
      // No match. Next search can start with the new data.
      next_search_start = end.position();
    }

    // Check if buffer is full.
    if (b.size() == b.max_size())
    {
      ec = error::not_found;
      return 0;
    }

    // Need more data.
    std::size_t bytes_available =
      std::min<std::size_t>(512, b.max_size() - b.size());
    b.commit(s.read_some(b.prepare(bytes_available), ec));
    if (ec)
      return 0;
  }
}

template <typename SyncReadStream, typename Allocator>
inline std::size_t read_until(SyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, const std::string& delim)
{
  asio::error_code ec;
  std::size_t bytes_transferred = read_until(s, b, delim, ec);
  asio::detail::throw_error(ec);
  return bytes_transferred;
}

namespace detail
{
  // Algorithm that finds a subsequence of equal values in a sequence. Returns
  // (iterator,true) if a full match was found, in which case the iterator
  // points to the beginning of the match. Returns (iterator,false) if a
  // partial match was found at the end of the first sequence, in which case
  // the iterator points to the beginning of the partial match. Returns
  // (last1,false) if no full or partial match was found.
  template <typename Iterator1, typename Iterator2>
  std::pair<Iterator1, bool> partial_search(
      Iterator1 first1, Iterator1 last1, Iterator2 first2, Iterator2 last2)
  {
    for (Iterator1 iter1 = first1; iter1 != last1; ++iter1)
    {
      Iterator1 test_iter1 = iter1;
      Iterator2 test_iter2 = first2;
      for (;; ++test_iter1, ++test_iter2)
      {
        if (test_iter2 == last2)
          return std::make_pair(iter1, true);
        if (test_iter1 == last1)
        {
          if (test_iter2 != first2)
            return std::make_pair(iter1, false);
          else
            break;
        }
        if (*test_iter1 != *test_iter2)
          break;
      }
    }
    return std::make_pair(last1, false);
  }
} // namespace detail

template <typename SyncReadStream, typename Allocator>
std::size_t read_until(SyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, const std::string& delim,
    asio::error_code& ec)
{
  std::size_t next_search_start = 0;
  for (;;)
  {
    // Determine the range of the data to be searched.
    typedef typename asio::basic_streambuf<
      Allocator>::const_buffers_type const_buffers_type;
    typedef asio::detail::const_buffers_iterator<
      const_buffers_type> iterator;
    const_buffers_type buffers = b.data();
    iterator begin(buffers, next_search_start);
    iterator end(buffers, (std::numeric_limits<std::size_t>::max)());

    // Look for a match.
    std::pair<iterator, bool> result = asio::detail::partial_search(
        begin, end, delim.begin(), delim.end());
    if (result.first != end)
    {
      if (result.second)
      {
        // Full match. We're done.
        ec = asio::error_code();
        return result.first.position() + delim.length();
      }
      else
      {
        // Partial match. Next search needs to start from beginning of match.
        next_search_start = result.first.position();
      }
    }
    else
    {
      // No match. Next search can start with the new data.
      next_search_start = end.position();
    }

    // Check if buffer is full.
    if (b.size() == b.max_size())
    {
      ec = error::not_found;
      return 0;
    }

    // Need more data.
    std::size_t bytes_available =
      std::min<std::size_t>(512, b.max_size() - b.size());
    b.commit(s.read_some(b.prepare(bytes_available), ec));
    if (ec)
      return 0;
  }
}

template <typename SyncReadStream, typename Allocator>
inline std::size_t read_until(SyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, const boost::regex& expr)
{
  asio::error_code ec;
  std::size_t bytes_transferred = read_until(s, b, expr, ec);
  asio::detail::throw_error(ec);
  return bytes_transferred;
}

template <typename SyncReadStream, typename Allocator>
std::size_t read_until(SyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
    asio::error_code& ec)
{
  std::size_t next_search_start = 0;
  for (;;)
  {
    // Determine the range of the data to be searched.
    typedef typename asio::basic_streambuf<
      Allocator>::const_buffers_type const_buffers_type;
    typedef asio::detail::const_buffers_iterator<
      const_buffers_type> iterator;
    const_buffers_type buffers = b.data();
    iterator begin(buffers, next_search_start);
    iterator end(buffers, (std::numeric_limits<std::size_t>::max)());

    // Look for a match.
    boost::match_results<iterator> match_results;
    if (boost::regex_search(begin, end, match_results, expr,
          boost::match_default | boost::match_partial))
    {
      if (match_results[0].matched)
      {
        // Full match. We're done.
        ec = asio::error_code();
        return match_results[0].second.position();
      }
      else
      {
        // Partial match. Next search needs to start from beginning of match.
        next_search_start = match_results[0].first.position();
      }
    }
    else
    {
      // No match. Next search can start with the new data.
      next_search_start = end.position();
    }

    // Check if buffer is full.
    if (b.size() == b.max_size())
    {
      ec = error::not_found;
      return 0;
    }

    // Need more data.
    std::size_t bytes_available =
      std::min<std::size_t>(512, b.max_size() - b.size());
    b.commit(s.read_some(b.prepare(bytes_available), ec));
    if (ec)
      return 0;
  }
}

namespace detail
{
  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
  class read_until_delim_handler
  {
  public:
    read_until_delim_handler(AsyncReadStream& stream,
        asio::basic_streambuf<Allocator>& streambuf, char delim,
        std::size_t next_search_start, ReadHandler handler)
      : stream_(stream),
        streambuf_(streambuf),
        delim_(delim),
        next_search_start_(next_search_start),
        handler_(handler)
    {
    }

    void operator()(const asio::error_code& ec,
        std::size_t bytes_transferred)
    {
      // Check for errors.
      if (ec)
      {
        std::size_t bytes = 0;
        handler_(ec, bytes);
        return;
      }

      // Commit received data to streambuf's get area.
      streambuf_.commit(bytes_transferred);

      // Determine the range of the data to be searched.
      typedef typename asio::basic_streambuf<
        Allocator>::const_buffers_type const_buffers_type;
      typedef asio::detail::const_buffers_iterator<
        const_buffers_type> iterator;
      const_buffers_type buffers = streambuf_.data();
      iterator begin(buffers, next_search_start_);
      iterator end(buffers, (std::numeric_limits<std::size_t>::max)());

      // Look for a match.
      iterator iter = std::find(begin, end, delim_);
      if (iter != end)
      {
        // Found a match. We're done.
        std::size_t bytes = iter.position() + 1;
        handler_(ec, bytes);
        return;
      }

      // No match. Check if buffer is full.
      if (streambuf_.size() == streambuf_.max_size())
      {
        std::size_t bytes = 0;
        asio::error_code ec(error::not_found);
        handler_(ec, bytes);
        return;
      }

      // Next search can start with the new data.
      next_search_start_ = end.position();

      // Start a new asynchronous read operation to obtain more data.
      std::size_t bytes_available =
        std::min<std::size_t>(512, streambuf_.max_size() - streambuf_.size());
      stream_.async_read_some(streambuf_.prepare(bytes_available), *this);
    }

  //private:
    AsyncReadStream& stream_;
    asio::basic_streambuf<Allocator>& streambuf_;
    char delim_;
    std::size_t next_search_start_;
    ReadHandler handler_;
  };

  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
  inline void* asio_handler_allocate(std::size_t size,
      read_until_delim_handler<AsyncReadStream,
        Allocator, ReadHandler>* this_handler)
  {
    return asio_handler_alloc_helpers::allocate(
        size, &this_handler->handler_);
  }

  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
  inline void asio_handler_deallocate(void* pointer, std::size_t size,
      read_until_delim_handler<AsyncReadStream,
        Allocator, ReadHandler>* this_handler)
  {
    asio_handler_alloc_helpers::deallocate(
        pointer, size, &this_handler->handler_);
  }

  template <typename Function, typename AsyncReadStream, typename Allocator,
      typename ReadHandler>
  inline void asio_handler_invoke(const Function& function,
      read_until_delim_handler<AsyncReadStream,
        Allocator, ReadHandler>* this_handler)
  {
    asio_handler_invoke_helpers::invoke(
        function, &this_handler->handler_);
  }
} // namespace detail

template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
void async_read_until(AsyncReadStream& s,
    asio::basic_streambuf<Allocator>& b, char delim, ReadHandler handler)
{
  // Determine the range of the data to be searched.
  typedef typename asio::basic_streambuf<
    Allocator>::const_buffers_type const_buffers_type;
  typedef asio::detail::const_buffers_iterator<
    const_buffers_type> iterator;
  const_buffers_type buffers = b.data();
  iterator begin(buffers, 0);
  iterator end(buffers, (std::numeric_limits<std::size_t>::max)());

  // Look for a match.
  iterator iter = std::find(begin, end, delim);