[857] | 1 | // (C) Copyright Jonathan Turkanis 2003.
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| 2 | // Distributed under the Boost Software License, Version 1.0. (See accompanying
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| 3 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
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| 4 |
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| 5 | // See http://www.boost.org/libs/iostreams for documentation.
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| 6 |
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| 7 | // Contains the definitions of the class templates symmetric_filter,
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| 8 | // which models DualUseFilter based on a model of the Symmetric Filter.
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| 9 |
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| 10 | //
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| 11 | // Roughly, a Symmetric Filter is a class type with the following interface:
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| 12 | //
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| 13 | // struct symmetric_filter {
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| 14 | // typedef xxx char_type;
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| 15 | //
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| 16 | // bool filter( const char*& begin_in, const char* end_in,
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| 17 | // char*& begin_out, char* end_out, bool flush )
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| 18 | // {
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| 19 | // // Consume as many characters as possible from the interval
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| 20 | // // [begin_in, end_in), without exhausting the output range
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| 21 | // // [begin_out, end_out). If flush is true, write as mush output
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| 22 | // // as possible.
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| 23 | // // A return value of true indicates that filter should be called
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| 24 | // // again. More precisely, if flush is false, a return value of
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| 25 | // // false indicates that the natural end of stream has been reached
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| 26 | // // and that all filtered data has been forwarded; if flush is
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| 27 | // // true, a return value of false indicates that all filtered data
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| 28 | // // has been forwarded.
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| 29 | // }
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| 30 | // void close() { /* Reset filter's state. */ }
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| 31 | // };
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| 32 | //
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| 33 | // Symmetric Filter filters need not be CopyConstructable.
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| 34 | //
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| 35 |
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| 36 | #ifndef BOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED
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| 37 | #define BOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED
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| 38 |
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| 39 | #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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| 40 | # pragma once
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| 41 | #endif
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| 42 |
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| 43 | #include <cassert>
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| 44 | #include <memory> // allocator, auto_ptr.
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| 45 | #include <boost/config.hpp> // BOOST_DEDUCED_TYPENAME.
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| 46 | #include <boost/iostreams/char_traits.hpp>
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| 47 | #include <boost/iostreams/constants.hpp> // buffer size.
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| 48 | #include <boost/iostreams/detail/buffer.hpp>
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| 49 | #include <boost/iostreams/detail/char_traits.hpp>
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| 50 | #include <boost/iostreams/detail/closer.hpp>
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| 51 | #include <boost/iostreams/detail/config/limits.hpp>
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| 52 | #include <boost/iostreams/detail/template_params.hpp>
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| 53 | #include <boost/iostreams/traits.hpp>
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| 54 | #include <boost/iostreams/operations.hpp> // read, write.
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| 55 | #include <boost/iostreams/pipeline.hpp>
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| 56 | #include <boost/preprocessor/iteration/local.hpp>
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| 57 | #include <boost/preprocessor/punctuation/comma_if.hpp>
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| 58 | #include <boost/preprocessor/repetition/enum_binary_params.hpp>
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| 59 | #include <boost/preprocessor/repetition/enum_params.hpp>
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| 60 | #include <boost/shared_ptr.hpp>
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| 61 |
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| 62 | // Must come last.
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| 63 | #include <boost/iostreams/detail/config/disable_warnings.hpp> // MSVC.
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| 64 |
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| 65 | namespace boost { namespace iostreams {
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| 66 |
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| 67 | template< typename SymmetricFilter,
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| 68 | typename Alloc =
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| 69 | std::allocator<
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| 70 | BOOST_DEDUCED_TYPENAME char_type_of<SymmetricFilter>::type
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| 71 | > >
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| 72 | class symmetric_filter {
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| 73 | public:
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| 74 | typedef typename char_type_of<SymmetricFilter>::type char_type;
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| 75 | typedef std::basic_string<char_type> string_type;
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| 76 | struct category
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| 77 | : dual_use,
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| 78 | filter_tag,
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| 79 | multichar_tag,
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| 80 | closable_tag
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| 81 | { };
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| 82 |
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| 83 | // Expands to a sequence of ctors which forward to impl.
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| 84 | #define BOOST_PP_LOCAL_MACRO(n) \
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| 85 | BOOST_IOSTREAMS_TEMPLATE_PARAMS(n, T) \
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| 86 | explicit symmetric_filter( \
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| 87 | int buffer_size BOOST_PP_COMMA_IF(n) \
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| 88 | BOOST_PP_ENUM_BINARY_PARAMS(n, const T, &t) ) \
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| 89 | : pimpl_(new impl(buffer_size BOOST_PP_COMMA_IF(n) \
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| 90 | BOOST_PP_ENUM_PARAMS(n, t))) \
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| 91 | { } \
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| 92 | /**/
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| 93 | #define BOOST_PP_LOCAL_LIMITS (0, BOOST_IOSTREAMS_MAX_FORWARDING_ARITY)
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| 94 | #include BOOST_PP_LOCAL_ITERATE()
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| 95 | #undef BOOST_PP_LOCAL_MACRO
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| 96 |
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| 97 | template<typename Source>
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| 98 | std::streamsize read(Source& src, char_type* s, std::streamsize n)
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| 99 | {
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| 100 | using namespace std;
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| 101 | if (!(state() & f_read))
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| 102 | begin_read();
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| 103 |
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| 104 | buffer_type& buf = pimpl_->buf_;
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| 105 | int status = (state() & f_eof) != 0 ? f_eof : f_good;
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| 106 | char_type *next_s = s,
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| 107 | *end_s = s + n;
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| 108 | while (true)
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| 109 | {
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| 110 | // Invoke filter if there are unconsumed characters in buffer or if
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| 111 | // filter must be flushed.
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| 112 | bool flush = status == f_eof;
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| 113 | if (buf.ptr() != buf.eptr() || flush) {
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| 114 | const char_type* next = buf.ptr();
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| 115 | bool done =
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| 116 | !filter().filter(next, buf.eptr(), next_s, end_s, flush);
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| 117 | buf.ptr() = buf.data() + (next - buf.data());
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| 118 | if (done)
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| 119 | return detail::check_eof(static_cast<streamsize>(next_s - s));
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| 120 | }
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| 121 |
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| 122 | // If no more characters are available without blocking, or
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| 123 | // if read request has been satisfied, return.
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| 124 | if ( status == f_would_block && buf.ptr() == buf.eptr() ||
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| 125 | next_s == end_s )
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| 126 | {
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| 127 | return static_cast<streamsize>(next_s - s);
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| 128 | }
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| 129 |
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| 130 | // Fill buffer.
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| 131 | if (status == f_good)
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| 132 | status = fill(src);
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| 133 | }
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| 134 | }
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| 135 |
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| 136 | template<typename Sink>
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| 137 | std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
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| 138 | {
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| 139 | if (!(state() & f_write))
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| 140 | begin_write();
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| 141 |
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| 142 | buffer_type& buf = pimpl_->buf_;
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| 143 | const char_type *next_s, *end_s;
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| 144 | for (next_s = s, end_s = s + n; next_s != end_s; ) {
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| 145 | if (buf.ptr() == buf.eptr() && !flush(snk))
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| 146 | break;
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| 147 | filter().filter(next_s, end_s, buf.ptr(), buf.eptr(), false);
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| 148 | }
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| 149 | return static_cast<std::streamsize>(next_s - s);
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| 150 | }
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| 151 |
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| 152 | // Give detail::closer<> permission to call close().
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| 153 | typedef symmetric_filter<SymmetricFilter, Alloc> self;
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| 154 | friend struct detail::closer<self>;
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| 155 |
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| 156 | template<typename Sink>
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| 157 | void close(Sink& snk, BOOST_IOS::openmode which)
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| 158 | {
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| 159 | using namespace std;
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| 160 | if ((state() & f_read) && (which & BOOST_IOS::in))
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| 161 | close();
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| 162 | if ((state() & f_write) && (which & BOOST_IOS::out)) {
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| 163 |
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| 164 | // Repeatedly invoke filter() with no input.
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| 165 | detail::closer<self> closer(*this);
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| 166 | buffer_type& buf = pimpl_->buf_;
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| 167 | char dummy;
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| 168 | const char* end = &dummy;
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| 169 | bool again = true;
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| 170 | while (again) {
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| 171 | if (buf.ptr() != buf.eptr())
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| 172 | again = filter().filter(end, end, buf.ptr(), buf.eptr(), true);
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| 173 | flush(snk);
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| 174 | }
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| 175 | }
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| 176 | }
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| 177 | SymmetricFilter& filter() { return *pimpl_; }
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| 178 | string_type unconsumed_input() const;
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| 179 |
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| 180 | // Give impl access to buffer_type on Tru64
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| 181 | #if !BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042))
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| 182 | private:
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| 183 | #endif
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| 184 | typedef detail::buffer<char_type, Alloc> buffer_type;
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| 185 | private:
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| 186 | buffer_type& buf() { return pimpl_->buf_; }
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| 187 | const buffer_type& buf() const { return pimpl_->buf_; }
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| 188 | int& state() { return pimpl_->state_; }
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| 189 | void begin_read();
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| 190 | void begin_write();
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| 191 |
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| 192 | template<typename Source>
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| 193 | int fill(Source& src)
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| 194 | {
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| 195 | std::streamsize amt = iostreams::read(src, buf().data(), buf().size());
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| 196 | if (amt == -1) {
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| 197 | state() |= f_eof;
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| 198 | return f_eof;
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| 199 | }
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| 200 | buf().set(0, amt);
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| 201 | return amt == buf().size() ? f_good : f_would_block;
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| 202 | }
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| 203 |
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| 204 | // Attempts to write the contents of the buffer the given Sink.
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| 205 | // Returns true if at least on character was written.
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| 206 | template<typename Sink>
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| 207 | bool flush(Sink& snk)
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| 208 | {
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| 209 | typedef typename iostreams::category_of<Sink>::type category;
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| 210 | typedef is_convertible<category, output> can_write;
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| 211 | return flush(snk, can_write());
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| 212 | }
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| 213 |
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| 214 | template<typename Sink>
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| 215 | bool flush(Sink& snk, mpl::true_)
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| 216 | {
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| 217 | using std::streamsize;
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| 218 | typedef char_traits<char_type> traits_type;
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| 219 | streamsize amt =
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| 220 | static_cast<streamsize>(buf().ptr() - buf().data());
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| 221 | streamsize result =
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| 222 | boost::iostreams::write(snk, buf().data(), amt);
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| 223 | if (result < amt && result > 0)
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| 224 | traits_type::move(buf().data(), buf().data() + result, amt - result);
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| 225 | buf().set(amt - result, buf().size());
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| 226 | return result != 0;
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| 227 | }
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| 228 |
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| 229 | template<typename Sink>
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| 230 | bool flush(Sink& snk, mpl::false_) { return true;}
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| 231 |
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| 232 | void close();
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| 233 |
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| 234 | enum flag_type {
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| 235 | f_read = 1,
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| 236 | f_write = f_read << 1,
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| 237 | f_eof = f_write << 1,
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| 238 | f_good,
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| 239 | f_would_block
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| 240 | };
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| 241 |
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| 242 | struct impl : SymmetricFilter {
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| 243 |
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| 244 | // Expands to a sequence of ctors which forward to SymmetricFilter.
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| 245 | #define BOOST_PP_LOCAL_MACRO(n) \
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| 246 | BOOST_IOSTREAMS_TEMPLATE_PARAMS(n, T) \
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| 247 | impl( int buffer_size BOOST_PP_COMMA_IF(n) \
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| 248 | BOOST_PP_ENUM_BINARY_PARAMS(n, const T, &t) ) \
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| 249 | : SymmetricFilter(BOOST_PP_ENUM_PARAMS(n, t)), \
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| 250 | buf_(buffer_size), state_(0) \
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| 251 | { } \
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| 252 | /**/
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| 253 | #define BOOST_PP_LOCAL_LIMITS (0, BOOST_IOSTREAMS_MAX_FORWARDING_ARITY)
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| 254 | #include BOOST_PP_LOCAL_ITERATE()
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| 255 | #undef BOOST_PP_LOCAL_MACRO
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| 256 |
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| 257 | buffer_type buf_;
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| 258 | int state_;
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| 259 | };
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| 260 |
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| 261 | shared_ptr<impl> pimpl_;
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| 262 | };
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| 263 | BOOST_IOSTREAMS_PIPABLE(symmetric_filter, 2)
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| 264 |
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| 265 | //------------------Implementation of symmetric_filter----------------//
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| 266 |
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| 267 | template<typename SymmetricFilter, typename Alloc>
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| 268 | void symmetric_filter<SymmetricFilter, Alloc>::begin_read()
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| 269 | {
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| 270 | assert(!(state() & f_write));
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| 271 | state() |= f_read;
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| 272 | buf().set(0, 0);
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| 273 | }
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| 274 |
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| 275 | template<typename SymmetricFilter, typename Alloc>
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| 276 | void symmetric_filter<SymmetricFilter, Alloc>::begin_write()
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| 277 | {
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| 278 | assert(!(state() & f_read));
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| 279 | state() |= f_write;
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| 280 | buf().set(0, buf().size());
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| 281 | }
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| 282 |
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| 283 | template<typename SymmetricFilter, typename Alloc>
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| 284 | void symmetric_filter<SymmetricFilter, Alloc>::close()
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| 285 | {
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| 286 | state() = 0;
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| 287 | buf().set(0, 0);
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| 288 | filter().close();
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| 289 | }
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| 290 |
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| 291 | template<typename SymmetricFilter, typename Alloc>
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| 292 | typename symmetric_filter<SymmetricFilter, Alloc>::string_type
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| 293 | symmetric_filter<SymmetricFilter, Alloc>::unconsumed_input() const
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| 294 | { return string_type(buf().ptr(), buf().eptr()); }
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| 295 |
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| 296 | //----------------------------------------------------------------------------//
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| 297 |
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| 298 | } } // End namespaces iostreams, boost.
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| 299 |
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| 300 | #include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC.
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| 301 |
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| 302 | #endif // #ifndef BOOST_IOSTREAMS_SYMMETRIC_FILTER_HPP_INCLUDED
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