Added boost header

test/external/boost/program_options/eof_iterator.hpp

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+// 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
+