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Diffstat (limited to '3rdParty/Boost/src/boost/program_options/eof_iterator.hpp')
-rw-r--r-- | 3rdParty/Boost/src/boost/program_options/eof_iterator.hpp | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/3rdParty/Boost/src/boost/program_options/eof_iterator.hpp b/3rdParty/Boost/src/boost/program_options/eof_iterator.hpp new file mode 100644 index 0000000..0efa6f7 --- /dev/null +++ b/3rdParty/Boost/src/boost/program_options/eof_iterator.hpp @@ -0,0 +1,97 @@ +// Copyright Vladimir Prus 2004. +// 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) + +#ifndef BOOST_EOF_ITERATOR_VP_2004_03_12 +#define BOOST_EOF_ITERATOR_VP_2004_03_12 + +#include <boost/iterator/iterator_facade.hpp> + +namespace boost { + + /** The 'eof_iterator' class is useful for constructing forward iterators + in cases where iterator extract data from some source and it's easy + to detect 'eof' -- i.e. the situation where there's no data. One + apparent example is reading lines from a file. + + Implementing such iterators using 'iterator_facade' directly would + require to create class with three core operation, a couple of + constructors. When using 'eof_iterator', the derived class should define + only one method to get new value, plus a couple of constructors. + + The basic idea is that iterator has 'eof' bit. Two iterators are equal + only if both have their 'eof' bits set. The 'get' method either obtains + the new value or sets the 'eof' bit. + + Specifically, derived class should define: + + 1. A default constructor, which creates iterator with 'eof' bit set. The + constructor body should call 'found_eof' method defined here. + 2. Some other constructor. It should initialize some 'data pointer' used + in iterator operation and then call 'get'. + 3. The 'get' method. It should operate this way: + - look at some 'data pointer' to see if new element is available; + if not, it should call 'found_eof'. + - extract new element and store it at location returned by the 'value' + method. + - advance the data pointer. + + Essentially, the 'get' method has the functionality of both 'increment' + and 'dereference'. It's very good for the cases where data extraction + implicitly moves data pointer, like for stream operation. + */ + template<class Derived, class ValueType> + class eof_iterator : public iterator_facade<Derived, const ValueType, + forward_traversal_tag> + { + public: + eof_iterator() + : m_at_eof(false) + {} + + protected: // interface for derived + + /** Returns the reference which should be used by derived + class to store the next value. */ + ValueType& value() + { + return m_value; + } + + /** Should be called by derived class to indicate that it can't + produce next element. */ + void found_eof() + { + m_at_eof = true; + } + + + private: // iterator core operations + friend class iterator_core_access; + + void increment() + { + static_cast<Derived&>(*this).get(); + } + + bool equal(const eof_iterator& other) const + { + if (m_at_eof && other.m_at_eof) + return true; + else + return false; + } + + const ValueType& dereference() const + { + return m_value; + } + + bool m_at_eof; + ValueType m_value; + }; +} + +#endif + |