// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
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// (C) Copyright 2005-2007 Jonathan Turkanis
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
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// See http://www.boost.org/libs/iostreams for documentation.
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#ifndef BOOST_IOSTREAMS_LINE_FILTER_HPP_INCLUDED
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#define BOOST_IOSTREAMS_LINE_FILTER_HPP_INCLUDED
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#if defined(_MSC_VER)
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# pragma once
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#endif
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#include <algorithm> // min.
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#include <boost/assert.hpp>
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#include <memory> // allocator.
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#include <string>
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#include <boost/config.hpp> // BOOST_STATIC_CONSTANT.
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#include <boost/iostreams/categories.hpp>
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#include <boost/iostreams/checked_operations.hpp>
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#include <boost/iostreams/detail/ios.hpp> // openmode, streamsize.
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#include <boost/iostreams/read.hpp> // check_eof
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#include <boost/iostreams/pipeline.hpp>
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#include <boost/iostreams/write.hpp>
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// Must come last.
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#include <boost/iostreams/detail/config/disable_warnings.hpp> // VC7.1 C4244.
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namespace boost { namespace iostreams {
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//
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// Template name: line_filter.
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// Template parameters:
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// Ch - The character type.
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// Alloc - The allocator type.
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// Description: Filter which processes data one line at a time.
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//
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template< typename Ch,
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typename Alloc = std::allocator<Ch> >
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class basic_line_filter {
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private:
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typedef typename std::basic_string<Ch>::traits_type string_traits;
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public:
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typedef Ch char_type;
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typedef char_traits<char_type> traits_type;
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typedef std::basic_string<
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Ch,
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string_traits,
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Alloc
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> string_type;
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struct category
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: dual_use,
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filter_tag,
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multichar_tag,
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closable_tag
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{ };
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protected:
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basic_line_filter(bool suppress_newlines = false)
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: pos_(string_type::npos),
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flags_(suppress_newlines ? f_suppress : 0)
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{ }
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public:
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virtual ~basic_line_filter() { }
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template<typename Source>
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std::streamsize read(Source& src, char_type* s, std::streamsize n)
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{
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using namespace std;
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BOOST_ASSERT(!(flags_ & f_write));
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flags_ |= f_read;
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// Handle unfinished business.
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std::streamsize result = 0;
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if (!cur_line_.empty() && (result = read_line(s, n)) == n)
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return n;
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typename traits_type::int_type status = traits_type::good();
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while (result < n && !traits_type::is_eof(status)) {
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// Call next_line() to retrieve a line of filtered text, and
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// read_line() to copy it into buffer s.
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if (traits_type::would_block(status = next_line(src)))
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return result;
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result += read_line(s + result, n - result);
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}
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return detail::check_eof(result);
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}
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template<typename Sink>
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std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
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{
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using namespace std;
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BOOST_ASSERT(!(flags_ & f_read));
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flags_ |= f_write;
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// Handle unfinished business.
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if (pos_ != string_type::npos && !write_line(snk))
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return 0;
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const char_type *cur = s, *next;
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while (true) {
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// Search for the next full line in [cur, s + n), filter it
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// and write it to snk.
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typename string_type::size_type rest = n - (cur - s);
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if ((next = traits_type::find(cur, rest, traits_type::newline()))) {
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cur_line_.append(cur, next - cur);
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cur = next + 1;
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if (!write_line(snk))
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return static_cast<std::streamsize>(cur - s);
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} else {
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cur_line_.append(cur, rest);
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return n;
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}
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}
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}
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template<typename Sink>
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void close(Sink& snk, BOOST_IOS::openmode which)
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{
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if ((flags_ & f_read) && which == BOOST_IOS::in)
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close_impl();
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if ((flags_ & f_write) && which == BOOST_IOS::out) {
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try {
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if (!cur_line_.empty())
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write_line(snk);
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} catch (...) {
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try {
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close_impl();
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} catch (...) { }
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throw;
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}
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close_impl();
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}
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}
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private:
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virtual string_type do_filter(const string_type& line) = 0;
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// Copies filtered characters fron the current line into
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// the given buffer.
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std::streamsize read_line(char_type* s, std::streamsize n)
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{
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using namespace std;
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std::streamsize result =
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(std::min) (n, static_cast<std::streamsize>(cur_line_.size()));
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traits_type::copy(s, cur_line_.data(), result);
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cur_line_.erase(0, result);
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return result;
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}
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// Attempts to retrieve a line of text from the given source; returns
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// an int_type as a good/eof/would_block status code.
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template<typename Source>
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typename traits_type::int_type next_line(Source& src)
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{
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using namespace std;
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typename traits_type::int_type c;
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while ( traits_type::is_good(c = iostreams::get(src)) &&
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c != traits_type::newline() )
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{
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cur_line_ += traits_type::to_int_type(c);
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}
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if (!traits_type::would_block(c)) {
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if (!cur_line_.empty() || c == traits_type::newline())
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cur_line_ = do_filter(cur_line_);
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if (c == traits_type::newline() && (flags_ & f_suppress) == 0)
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cur_line_ += c;
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}
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return c; // status indicator.
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}
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// Filters the current line and attemps to write it to the given sink.
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// Returns true for success.
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template<typename Sink>
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bool write_line(Sink& snk)
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{
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string_type line = do_filter(cur_line_);
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if ((flags_ & f_suppress) == 0)
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line += traits_type::newline();
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std::streamsize amt = static_cast<std::streamsize>(line.size());
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bool result = iostreams::write_if(snk, line.data(), amt) == amt;
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if (result)
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clear();
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return result;
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}
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void close_impl()
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{
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clear();
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flags_ &= f_suppress;
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}
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void clear()
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{
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cur_line_.erase();
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pos_ = string_type::npos;
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}
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enum flag_type {
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f_read = 1,
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f_write = f_read << 1,
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f_suppress = f_write << 1
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};
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string_type cur_line_;
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typename string_type::size_type pos_;
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int flags_;
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};
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BOOST_IOSTREAMS_PIPABLE(basic_line_filter, 2)
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typedef basic_line_filter<char> line_filter;
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typedef basic_line_filter<wchar_t> wline_filter;
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} } // End namespaces iostreams, boost.
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#include <boost/iostreams/detail/config/enable_warnings.hpp>
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#endif // #ifndef BOOST_IOSTREAMS_LINE_FILTER_HPP_INCLUDED
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