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// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
// (C) Copyright 2005-2007 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_LINE_FILTER_HPP_INCLUDED
#define BOOST_IOSTREAMS_LINE_FILTER_HPP_INCLUDED
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
#include <algorithm> // min.
#include <boost/assert.hpp>
#include <memory> // allocator.
#include <string>
#include <boost/config.hpp> // BOOST_STATIC_CONSTANT.
#include <boost/iostreams/categories.hpp>
#include <boost/iostreams/checked_operations.hpp>
#include <boost/iostreams/detail/ios.hpp> // openmode, streamsize.
#include <boost/iostreams/read.hpp> // check_eof
#include <boost/iostreams/pipeline.hpp>
#include <boost/iostreams/write.hpp>
// Must come last.
#include <boost/iostreams/detail/config/disable_warnings.hpp> // VC7.1 C4244.
namespace boost { namespace iostreams {
//
// Template name: line_filter.
// Template paramters:
// Ch - The character type.
// Alloc - The allocator type.
// Description: Filter which processes data one line at a time.
//
template< typename Ch,
typename Alloc =
#if BOOST_WORKAROUND(__GNUC__, < 3)
typename std::basic_string<Ch>::allocator_type
#else
std::allocator<Ch>
#endif
>
class basic_line_filter {
private:
typedef typename std::basic_string<Ch>::traits_type string_traits;
public:
typedef Ch char_type;
typedef char_traits<char_type> traits_type;
typedef std::basic_string<
Ch,
string_traits,
Alloc
> string_type;
struct category
: dual_use,
filter_tag,
multichar_tag,
closable_tag
{ };
protected:
basic_line_filter(bool suppress_newlines = false)
: pos_(string_type::npos),
flags_(suppress_newlines ? f_suppress : 0)
{ }
public:
virtual ~basic_line_filter() { }
template<typename Source>
std::streamsize read(Source& src, char_type* s, std::streamsize n)
{
using namespace std;
BOOST_ASSERT(!(flags_ & f_write));
flags_ |= f_read;
// Handle unfinished business.
std::streamsize result = 0;
if (!cur_line_.empty() && (result = read_line(s, n)) == n)
return n;
typename traits_type::int_type status = traits_type::good();
while (result < n && !traits_type::is_eof(status)) {
// Call next_line() to retrieve a line of filtered text, and
// read_line() to copy it into buffer s.
if (traits_type::would_block(status = next_line(src)))
return result;
result += read_line(s + result, n - result);
}
return detail::check_eof(result);
}
template<typename Sink>
std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
{
using namespace std;
BOOST_ASSERT(!(flags_ & f_read));
flags_ |= f_write;
// Handle unfinished business.
if (pos_ != string_type::npos && !write_line(snk))
return 0;
const char_type *cur = s, *next;
while (true) {
// Search for the next full line in [cur, s + n), filter it
// and write it to snk.
typename string_type::size_type rest = n - (cur - s);
if ((next = traits_type::find(cur, rest, traits_type::newline()))) {
cur_line_.append(cur, next - cur);
cur = next + 1;
if (!write_line(snk))
return static_cast<std::streamsize>(cur - s);
} else {
cur_line_.append(cur, rest);
return n;
}
}
}
template<typename Sink>
void close(Sink& snk, BOOST_IOS::openmode which)
{
if ((flags_ & f_read) && which == BOOST_IOS::in)
close_impl();
if ((flags_ & f_write) && which == BOOST_IOS::out) {
try {
if (!cur_line_.empty())
write_line(snk);
} catch (...) {
try {
close_impl();
} catch (...) { }
throw;
}
close_impl();
}
}
private:
virtual string_type do_filter(const string_type& line) = 0;
// Copies filtered characters fron the current line into
// the given buffer.
std::streamsize read_line(char_type* s, std::streamsize n)
{
using namespace std;
std::streamsize result =
(std::min) (n, static_cast<std::streamsize>(cur_line_.size()));
traits_type::copy(s, cur_line_.data(), result);
cur_line_.erase(0, result);
return result;
}
// Attempts to retrieve a line of text from the given source; returns
// an int_type as a good/eof/would_block status code.
template<typename Source>
typename traits_type::int_type next_line(Source& src)
{
using namespace std;
typename traits_type::int_type c;
while ( traits_type::is_good(c = iostreams::get(src)) &&
c != traits_type::newline() )
{
cur_line_ += traits_type::to_int_type(c);
}
if (!traits_type::would_block(c)) {
if (!cur_line_.empty() || c == traits_type::newline())
cur_line_ = do_filter(cur_line_);
if (c == traits_type::newline() && (flags_ & f_suppress) == 0)
cur_line_ += c;
}
return c; // status indicator.
}
// Filters the current line and attemps to write it to the given sink.
// Returns true for success.
template<typename Sink>
bool write_line(Sink& snk)
{
string_type line = do_filter(cur_line_);
if ((flags_ & f_suppress) == 0)
line += traits_type::newline();
std::streamsize amt = static_cast<std::streamsize>(line.size());
bool result = iostreams::write_if(snk, line.data(), amt) == amt;
if (result)
clear();
return result;
}
void close_impl()
{
clear();
flags_ &= f_suppress;
}
void clear()
{
cur_line_.erase();
pos_ = string_type::npos;
}
enum flag_type {
f_read = 1,
f_write = f_read << 1,
f_suppress = f_write << 1
};
string_type cur_line_;
typename string_type::size_type pos_;
int flags_;
};
BOOST_IOSTREAMS_PIPABLE(basic_line_filter, 2)
typedef basic_line_filter<char> line_filter;
typedef basic_line_filter<wchar_t> wline_filter;
} } // End namespaces iostreams, boost.
#include <boost/iostreams/detail/config/enable_warnings.hpp>
#endif // #ifndef BOOST_IOSTREAMS_LINE_FILTER_HPP_INCLUDED
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