boost/spirit/home/karma/detail/output_iterator.hpp
// Copyright (c) 2001-2011 Hartmut Kaiser // // 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) #if !defined(BOOST_SPIRIT_KARMA_OUTPUT_ITERATOR_MAY_26_2007_0506PM) #define BOOST_SPIRIT_KARMA_OUTPUT_ITERATOR_MAY_26_2007_0506PM #if defined(_MSC_VER) #pragma once #endif #include <iterator> #include <vector> #include <algorithm> #include <boost/config.hpp> #include <boost/noncopyable.hpp> #include <boost/mpl/if.hpp> #include <boost/spirit/home/karma/generator.hpp> #include <boost/spirit/home/support/iterators/ostream_iterator.hpp> #include <boost/spirit/home/support/unused.hpp> #if defined(BOOST_MSVC) && defined(BOOST_SPIRIT_UNICODE) #include <boost/spirit/home/support/char_encoding/unicode.hpp> #endif namespace boost { namespace spirit { namespace karma { namespace detail { /////////////////////////////////////////////////////////////////////////// // This class is used to keep track of the current position in the output. /////////////////////////////////////////////////////////////////////////// class position_sink { public: position_sink() : count(0), line(1), column(1) {} void tidy() { count = 0; line = 1; column = 1; } template <typename T> void output(T const& value) { ++count; if (value == '\n') { ++line; column = 1; } else { ++column; } } std::size_t get_count() const { return count; } std::size_t get_line() const { return line; } std::size_t get_column() const { return column; } private: std::size_t count; std::size_t line; std::size_t column; }; /////////////////////////////////////////////////////////////////////////// struct position_policy { position_policy() {} position_policy(position_policy const& rhs) : track_position_data(rhs.track_position_data) {} template <typename T> void output(T const& value) { // track position in the output track_position_data.output(value); } // return the current count in the output std::size_t get_out_count() const { return track_position_data.get_count(); } // return the current line in the output std::size_t get_line() const { return track_position_data.get_line(); } // return the current column in the output std::size_t get_column() const { return track_position_data.get_column(); } private: position_sink track_position_data; // for position tracking }; struct no_position_policy { no_position_policy() {} no_position_policy(no_position_policy const&) {} template <typename T> void output(T const& /*value*/) {} }; /////////////////////////////////////////////////////////////////////////// // This class is used to count the number of characters streamed into the // output. /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator> class counting_sink : boost::noncopyable { public: counting_sink(OutputIterator& sink_, std::size_t count_ = 0 , bool enabled = true) : count(count_), initial_count(count), prev_count(0), sink(sink_) { prev_count = sink.chain_counting(enabled ? this : NULL); } ~counting_sink() { if (prev_count) // propagate count prev_count->update_count(count-initial_count); sink.chain_counting(prev_count); } void output() { ++count; } std::size_t get_count() const { return count; } // propagate count from embedded counters void update_count(std::size_t c) { count += c; } private: std::size_t count; std::size_t initial_count; counting_sink* prev_count; // previous counter in chain OutputIterator& sink; }; /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator> struct counting_policy { public: counting_policy() : count(NULL) {} counting_policy(counting_policy const& rhs) : count(rhs.count) {} // functions related to counting counting_sink<OutputIterator>* chain_counting( counting_sink<OutputIterator>* count_data) { counting_sink<OutputIterator>* prev_count = count; count = count_data; return prev_count; } template <typename T> void output(T const&) { // count characters, if appropriate if (NULL != count) count->output(); } private: counting_sink<OutputIterator>* count; // for counting }; struct no_counting_policy { no_counting_policy() {} no_counting_policy(no_counting_policy const&) {} template <typename T> void output(T const& /*value*/) {} }; /////////////////////////////////////////////////////////////////////////// // The following classes are used to intercept the output into a buffer // allowing to do things like alignment, character escaping etc. /////////////////////////////////////////////////////////////////////////// class buffer_sink : boost::noncopyable { // wchar_t is only 16-bits on Windows. If BOOST_SPIRIT_UNICODE is // defined, the character type is 32-bits wide so we need to make // sure the buffer is at least that wide. #if defined(BOOST_MSVC) && defined(BOOST_SPIRIT_UNICODE) typedef spirit::char_encoding::unicode::char_type buffer_char_type; #else typedef wchar_t buffer_char_type; #endif public: buffer_sink() : width(0) {} ~buffer_sink() { tidy(); } void enable(std::size_t width_) { tidy(); // release existing buffer width = (width_ == std::size_t(-1)) ? 0 : width_; buffer.reserve(width); } void tidy() { buffer.clear(); width = 0; } template <typename T> void output(T const& value) { BOOST_STATIC_ASSERT(sizeof(T) <= sizeof(buffer_char_type)); buffer.push_back(value); } template <typename OutputIterator_> bool copy(OutputIterator_& sink, std::size_t maxwidth) const { #if defined(BOOST_MSVC) #pragma warning(push) #pragma warning(disable: 4267) #endif typename std::basic_string<buffer_char_type>::const_iterator end = buffer.begin() + (std::min)(buffer.size(), maxwidth); #if defined(BOOST_MSVC) #pragma warning(pop) #endif std::copy(buffer.begin(), end, sink); return true; } template <typename RestIterator> bool copy_rest(RestIterator& sink, std::size_t start_at) const { #if defined(BOOST_MSVC) #pragma warning(push) #pragma warning(disable: 4267) #endif typename std::basic_string<buffer_char_type>::const_iterator begin = buffer.begin() + (std::min)(buffer.size(), start_at); #if defined(BOOST_MSVC) #pragma warning(pop) #endif std::copy(begin, buffer.end(), sink); return true; } std::size_t buffer_size() const { return buffer.size(); } private: std::size_t width; std::basic_string<buffer_char_type> buffer; }; /////////////////////////////////////////////////////////////////////////// struct buffering_policy { public: buffering_policy() : buffer(NULL) {} buffering_policy(buffering_policy const& rhs) : buffer(rhs.buffer) {} // functions related to buffering buffer_sink* chain_buffering(buffer_sink* buffer_data) { buffer_sink* prev_buffer = buffer; buffer = buffer_data; return prev_buffer; } template <typename T> bool output(T const& value) { // buffer characters, if appropriate if (NULL != buffer) { buffer->output(value); return false; } return true; } bool has_buffer() const { return NULL != buffer; } private: buffer_sink* buffer; }; struct no_buffering_policy { no_buffering_policy() {} no_buffering_policy(no_counting_policy const&) {} template <typename T> bool output(T const& /*value*/) { return true; } bool has_buffer() const { return false; } }; /////////////////////////////////////////////////////////////////////////// // forward declaration only template <typename OutputIterator> struct enable_buffering; template <typename OutputIterator, typename Properties , typename Derived = unused_type> class output_iterator; /////////////////////////////////////////////////////////////////////////// template <typename Buffering, typename Counting, typename Tracking> struct output_iterator_base : Buffering, Counting, Tracking { typedef Buffering buffering_policy; typedef Counting counting_policy; typedef Tracking tracking_policy; output_iterator_base() {} output_iterator_base(output_iterator_base const& rhs) : buffering_policy(rhs), counting_policy(rhs), tracking_policy(rhs) {} template <typename T> bool output(T const& value) { this->counting_policy::output(value); this->tracking_policy::output(value); return this->buffering_policy::output(value); } }; template <typename Buffering, typename Counting, typename Tracking> struct disabling_output_iterator : Buffering, Counting, Tracking { typedef Buffering buffering_policy; typedef Counting counting_policy; typedef Tracking tracking_policy; disabling_output_iterator() : do_output(true) {} disabling_output_iterator(disabling_output_iterator const& rhs) : buffering_policy(rhs), counting_policy(rhs), tracking_policy(rhs) , do_output(rhs.do_output) {} template <typename T> bool output(T const& value) { if (!do_output) return false; this->counting_policy::output(value); this->tracking_policy::output(value); return this->buffering_policy::output(value); } bool do_output; }; /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator, typename Properties, typename Derived> struct make_output_iterator { // get the most derived type of this class typedef typename mpl::if_< traits::not_is_unused<Derived>, Derived , output_iterator<OutputIterator, Properties, Derived> >::type most_derived_type; enum { properties = Properties::value }; typedef typename mpl::if_c< (properties & generator_properties::tracking) ? true : false , position_policy, no_position_policy >::type tracking_type; typedef typename mpl::if_c< (properties & generator_properties::buffering) ? true : false , buffering_policy, no_buffering_policy >::type buffering_type; typedef typename mpl::if_c< (properties & generator_properties::counting) ? true : false , counting_policy<most_derived_type>, no_counting_policy >::type counting_type; typedef typename mpl::if_c< (properties & generator_properties::disabling) ? true : false , disabling_output_iterator<buffering_type, counting_type, tracking_type> , output_iterator_base<buffering_type, counting_type, tracking_type> >::type type; }; /////////////////////////////////////////////////////////////////////////// // Karma uses an output iterator wrapper for all output operations. This // is necessary to avoid the dreaded 'scanner business' problem, i.e. the // dependency of rules and grammars on the used output iterator. // // By default the user supplied output iterator is wrapped inside an // instance of this internal output_iterator class. // // This output_iterator class normally just forwards to the embedded user // supplied iterator. But it is possible to enable additional functionality // on demand, such as counting, buffering, and position tracking. /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator, typename Properties, typename Derived> class output_iterator : public make_output_iterator<OutputIterator, Properties, Derived>::type { private: // base iterator type typedef typename make_output_iterator< OutputIterator, Properties, Derived>::type base_iterator; public: typedef std::output_iterator_tag iterator_category; typedef void value_type; typedef void difference_type; typedef void pointer; typedef void reference; explicit output_iterator(OutputIterator& sink_) : sink(&sink_) {} output_iterator(output_iterator const& rhs) : base_iterator(rhs), sink(rhs.sink) {} output_iterator& operator*() { return *this; } output_iterator& operator++() { if (!this->base_iterator::has_buffer()) ++(*sink); // increment only if not buffering return *this; } output_iterator operator++(int) { if (!this->base_iterator::has_buffer()) { output_iterator t(*this); ++(*sink); return t; } return *this; } #if defined(BOOST_MSVC) // 'argument' : conversion from '...' to '...', possible loss of data #pragma warning (push) #pragma warning (disable: 4244) #endif template <typename T> void operator=(T const& value) { if (this->base_iterator::output(value)) *(*sink) = value; } #if defined(BOOST_MSVC) #pragma warning (pop) #endif // plain output iterators are considered to be good all the time bool good() const { return true; } // allow to access underlying output iterator OutputIterator& base() { return *sink; } protected: // this is the wrapped user supplied output iterator OutputIterator* sink; }; /////////////////////////////////////////////////////////////////////////// template <typename T, typename Elem, typename Traits, typename Properties> class output_iterator<karma::ostream_iterator<T, Elem, Traits>, Properties> : public output_iterator<karma::ostream_iterator<T, Elem, Traits>, Properties , output_iterator<karma::ostream_iterator<T, Elem, Traits>, Properties> > { private: typedef output_iterator<karma::ostream_iterator<T, Elem, Traits>, Properties , output_iterator<karma::ostream_iterator<T, Elem, Traits>, Properties> > base_type; typedef karma::ostream_iterator<T, Elem, Traits> base_iterator_type; typedef std::basic_ostream<Elem, Traits> ostream_type; public: output_iterator(base_iterator_type& sink) : base_type(sink) {} ostream_type& get_ostream() { return (*this->sink).get_ostream(); } ostream_type const& get_ostream() const { return (*this->sink).get_ostream(); } // expose good bit of underlying stream object bool good() const { return (*this->sink).get_ostream().good(); } }; /////////////////////////////////////////////////////////////////////////// // Helper class for exception safe enabling of character counting in the // output iterator /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator> struct enable_counting { enable_counting(OutputIterator& sink_, std::size_t count = 0) : count_data(sink_, count) {} // get number of characters counted since last enable std::size_t count() const { return count_data.get_count(); } private: counting_sink<OutputIterator> count_data; // for counting }; template <typename OutputIterator> struct disable_counting { disable_counting(OutputIterator& sink_) : count_data(sink_, 0, false) {} private: counting_sink<OutputIterator> count_data; }; /////////////////////////////////////////////////////////////////////////// // Helper class for exception safe enabling of character buffering in the // output iterator /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator> struct enable_buffering { enable_buffering(OutputIterator& sink_ , std::size_t width = std::size_t(-1)) : sink(sink_), prev_buffer(NULL), enabled(false) { buffer_data.enable(width); prev_buffer = sink.chain_buffering(&buffer_data); enabled = true; } ~enable_buffering() { disable(); } // reset buffer chain to initial state void disable() { if (enabled) { BOOST_VERIFY(&buffer_data == sink.chain_buffering(prev_buffer)); enabled = false; } } // copy to the underlying sink whatever is in the local buffer bool buffer_copy(std::size_t maxwidth = std::size_t(-1) , bool disable_ = true) { if (disable_) disable(); return buffer_data.copy(sink, maxwidth) && sink.good(); } // return number of characters stored in the buffer std::size_t buffer_size() const { return buffer_data.buffer_size(); } // copy to the remaining characters to the specified sink template <typename RestIterator> bool buffer_copy_rest(RestIterator& sink, std::size_t start_at = 0) const { return buffer_data.copy_rest(sink, start_at); } // copy the contents to the given output iterator template <typename OutputIterator_> bool buffer_copy_to(OutputIterator_& sink , std::size_t maxwidth = std::size_t(-1)) const { return buffer_data.copy(sink, maxwidth); } private: OutputIterator& sink; buffer_sink buffer_data; // for buffering buffer_sink* prev_buffer; // previous buffer in chain bool enabled; }; /////////////////////////////////////////////////////////////////////////// // Helper class for exception safe disabling of output /////////////////////////////////////////////////////////////////////////// template <typename OutputIterator> struct disable_output { disable_output(OutputIterator& sink_) : sink(sink_), prev_do_output(sink.do_output) { sink.do_output = false; } ~disable_output() { sink.do_output = prev_do_output; } OutputIterator& sink; bool prev_do_output; }; /////////////////////////////////////////////////////////////////////////// template <typename Sink> bool sink_is_good(Sink const&) { return true; // the general case is always good } template <typename OutputIterator, typename Derived> bool sink_is_good(output_iterator<OutputIterator, Derived> const& sink) { return sink.good(); // our own output iterators are handled separately } }}}} #endif