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libs/multi_index/example/sequenced.cpp

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+/* Boost.MultiIndex example of use of sequenced indices.
+ *
+ * Copyright 2003-2008 Joaquin M Lopez Munoz.
+ * 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/sequenced_index.hpp>
+#include <boost/tokenizer.hpp>
+#include <algorithm>
+#include <iomanip>
+#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<
+    sequenced<>,
+    ordered_non_unique<identity<std::string> >
+  >
+> text_container;
+
+/* ordered index */
+
+typedef nth_index<text_container,1>::type ordered_text;
+
+typedef boost::tokenizer<boost::char_separator<char> > text_tokenizer;
+
+int main()
+{
+  std::string text=
+    "Alice was beginning to get very tired of sitting by her sister on the "
+    "bank, and of having nothing to do: once or twice she had peeped into the "
+    "book her sister was reading, but it had no pictures or conversations in "
+    "it, 'and what is the use of a book,' thought Alice 'without pictures or "
+    "conversation?'";
+
+  /* feed the text into the container */
+
+  text_container tc;
+  text_tokenizer tok(text,boost::char_separator<char>(" \t\n.,;:!?'\"-"));
+  std::copy(tok.begin(),tok.end(),std::back_inserter(tc));
+
+  /* list all words in alphabetical order along with their number
+   * of occurrences
+   */
+
+  ordered_text& ot=get<1>(tc);
+  for(ordered_text::iterator it=ot.begin();it!=ot.end();){
+    std::cout<<std::left<<std::setw(14)<<*it<<":";  /* print the word */
+    ordered_text::iterator it2=ot.upper_bound(*it); /* jump to next   */
+    std::cout<<std::right<<std::setw(3)   /* and compute the distance */
+             <<std::distance(it,it2)<<" times"<<std::endl;
+    it=it2;
+  }
+
+  /* reverse the text and print it out */
+
+  tc.reverse();
+  std::cout<<std::endl;
+  std::copy(
+    tc.begin(),tc.end(),std::ostream_iterator<std::string>(std::cout," "));
+  std::cout<<std::endl;
+  tc.reverse(); /* undo */
+
+  /* delete most common English words and print the result */
+
+  std::string common_words[]=
+    {"the","of","and","a","to","in","is","you","that","it",
+     "he","for","was","on","are","as","with","his","they","at"};
+
+  for(std::size_t n=0;n<sizeof(common_words)/sizeof(common_words[0]);++n){
+    ot.erase(common_words[n]);
+  }
+  std::cout<<std::endl;
+  std::copy(
+    tc.begin(),tc.end(),std::ostream_iterator<std::string>(std::cout," "));
+  std::cout<<std::endl;
+
+  return 0;
+}