added random access indices

[SVN r32644]

example/random_access.cpp

@@ -0,0 +1,102 @@
+/* Boost.MultiIndex example of use of random access indices.
+ *
+ * Copyright 2003-2006 Joaquín M López Muñoz.
+ * 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)
+ *
+ * See http://www.boost.org/libs/multi_index for library home page.
+ */
+
+#if !defined(NDEBUG)
+#define BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING
+#define BOOST_MULTI_INDEX_ENABLE_SAFE_MODE
+#endif
+
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/identity.hpp>
+#include <boost/multi_index/ordered_index.hpp>
+#include <boost/multi_index/random_access_index.hpp>
+#include <boost/tokenizer.hpp>
+#include <algorithm>
+#include <iostream>
+#include <iterator>
+#include <string>
+
+using boost::multi_index_container;
+using namespace boost::multi_index;
+
+/* text_container holds words as inserted and also keep them indexed
+ * by dictionary order.
+ */
+
+typedef multi_index_container<
+  std::string,
+  indexed_by<
+    random_access<>,
+    ordered_non_unique<identity<std::string> >
+  >
+> text_container;
+
+/* ordered index */
+
+typedef nth_index<text_container,1>::type ordered_text;
+
+/* Helper function for obtaining the position of an element in the
+ * container.
+ */
+
+template<typename IndexIterator>
+text_container::size_type text_position(
+  const text_container& tc,IndexIterator it)
+{
+  /* project to the base index and calculate offset from begin() */
+
+  return project<0>(tc,it)-tc.begin();
+}
+
+typedef boost::tokenizer<boost::char_separator<char> > text_tokenizer;
+
+int main()
+{
+  std::string text=
+    "'Oh, you wicked little thing!' cried Alice, catching up the kitten, "
+    "and giving it a little kiss to make it understand that it was in "
+    "disgrace. 'Really, Dinah ought to have taught you better manners! You "
+    "ought, Dinah, you know you ought!' she added, looking reproachfully at "
+    "the old cat, and speaking in as cross a voice as she could manage "
+    "-- and then she scrambled back into the armchair, taking the kitten and "
+    "the worsted with her, and began winding up the ball again. But she "
+    "didn't get on very fast, as she was talking all the time, sometimes to "
+    "the kitten, and sometimes to herself. Kitty sat very demurely on her "
+    "knee, pretending to watch the progress of the winding, and now and then "
+    "putting out one paw and gently touching the ball, as if it would be glad "
+    "to help, if it might.";
+
+  /* feed the text into the container */
+
+  text_container tc;
+  tc.reserve(text.size()); /* makes insertion faster */
+  text_tokenizer tok(text,boost::char_separator<char>(" \t\n.,;:!?'\"-"));
+  std::copy(tok.begin(),tok.end(),std::back_inserter(tc));
+
+  std::cout<<"enter a position (0-"<<tc.size()-1<<"):";
+  text_container::size_type pos=tc.size();
+  std::cin>>pos;
+  if(pos>=tc.size()){
+    std::cout<<"out of bounds"<<std::endl;
+  }
+  else{
+    std::cout<<"the word \""<<tc[pos]<<"\" appears at position(s): ";
+
+    std::pair<ordered_text::iterator,ordered_text::iterator> p=
+      get<1>(tc).equal_range(tc[pos]);
+    while(p.first!=p.second){
+      std::cout<<text_position(tc,p.first++)<<" ";
+    }
+
+    std::cout<<std::endl;
+  }
+
+  return 0;
+}