boost/iostreams/filter/aggregate.hpp
// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
// (C) Copyright 2003-2007 Jonathan Turkanis
// 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.)
// See http://www.boost.org/libs/iostreams for documentation.
#ifndef BOOST_IOSTREAMS_AGGREGATE_FILTER_HPP_INCLUDED
#define BOOST_IOSTREAMS_AGGREGATE_FILTER_HPP_INCLUDED
#if defined(_MSC_VER)
# pragma once
#endif
#include <algorithm> // copy, min.
#include <boost/assert.hpp>
#include <iterator> // back_inserter
#include <vector>
#include <boost/iostreams/constants.hpp> // default_device_buffer_size
#include <boost/iostreams/categories.hpp>
#include <boost/iostreams/detail/char_traits.hpp>
#include <boost/iostreams/detail/ios.hpp> // openmode, streamsize.
#include <boost/iostreams/pipeline.hpp>
#include <boost/iostreams/read.hpp> // check_eof
#include <boost/iostreams/write.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/type_traits/is_convertible.hpp>
// Must come last.
#include <boost/iostreams/detail/config/disable_warnings.hpp> // MSVC.
namespace boost { namespace iostreams {
//
// Template name: aggregate_filter.
// Template parameters:
// Ch - The character type.
// Alloc - The allocator type.
// Description: Utility for defining DualUseFilters which filter an
// entire stream at once. To use, override the protected virtual
// member do_filter.
// Note: This filter should not be copied while it is in use.
//
template<typename Ch, typename Alloc = std::allocator<Ch> >
class aggregate_filter {
public:
typedef Ch char_type;
struct category
: dual_use,
filter_tag,
multichar_tag,
closable_tag
{ };
aggregate_filter() : ptr_(0), state_(0) { }
virtual ~aggregate_filter() { }
template<typename Source>
std::streamsize read(Source& src, char_type* s, std::streamsize n)
{
using namespace std;
BOOST_ASSERT(!(state_ & f_write));
state_ |= f_read;
if (!(state_ & f_eof))
do_read(src);
std::streamsize amt =
(std::min)(n, static_cast<std::streamsize>(data_.size() - ptr_));
if (amt) {
BOOST_IOSTREAMS_CHAR_TRAITS(char_type)::copy(s, &data_[ptr_], amt);
ptr_ += amt;
}
return detail::check_eof(amt);
}
template<typename Sink>
std::streamsize write(Sink&, const char_type* s, std::streamsize n)
{
BOOST_ASSERT(!(state_ & f_read));
state_ |= f_write;
data_.insert(data_.end(), s, s + n);
return n;
}
template<typename Sink>
void close(Sink& sink, BOOST_IOS::openmode which)
{
if ((state_ & f_read) != 0 && which == BOOST_IOS::in)
close_impl();
if ((state_ & f_write) != 0 && which == BOOST_IOS::out) {
try {
vector_type filtered;
do_filter(data_, filtered);
do_write(
sink, &filtered[0],
static_cast<std::streamsize>(filtered.size())
);
} catch (...) {
close_impl();
throw;
}
close_impl();
}
}
protected:
typedef std::vector<Ch, Alloc> vector_type;
typedef typename vector_type::size_type size_type;
private:
virtual void do_filter(const vector_type& src, vector_type& dest) = 0;
virtual void do_close() { }
template<typename Source>
void do_read(Source& src)
{
using std::streamsize;
vector_type data;
while (true) {
const std::streamsize size = default_device_buffer_size;
Ch buf[size];
std::streamsize amt;
if ((amt = boost::iostreams::read(src, buf, size)) == -1)
break;
data.insert(data.end(), buf, buf + amt);
}
do_filter(data, data_);
state_ |= f_eof;
}
template<typename Sink>
void do_write(Sink& sink, const char_type* s, std::streamsize n)
{
typedef typename iostreams::category_of<Sink>::type category;
typedef is_convertible<category, output> can_write;
do_write(sink, s, n, can_write());
}
template<typename Sink>
void do_write(Sink& sink, const char_type* s, std::streamsize n, mpl::true_)
{ iostreams::write(sink, s, n); }
template<typename Sink>
void do_write(Sink&, const char_type*, std::streamsize, mpl::false_) { }
void close_impl()
{
data_.clear();
ptr_ = 0;
state_ = 0;
do_close();
}
enum flag_type {
f_read = 1,
f_write = f_read << 1,
f_eof = f_write << 1
};
// Note: typically will not be copied while vector contains data.
vector_type data_;
size_type ptr_;
int state_;
};
BOOST_IOSTREAMS_PIPABLE(aggregate_filter, 1)
} } // End namespaces iostreams, boost.
#include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC.
#endif // #ifndef BOOST_IOSTREAMS_AGGREGATE_FILTER_HPP_INCLUDED