//  (C) Copyright Jeremy Siek 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)

 /*

  * stringtok.hpp -- Breaks a string into tokens.  This is an example for lib3.

  *

  * Template function looks like this:

  *

  *    template <typename Container>

  *    void stringtok (Container &l,

  *                    string const &s,

  *                    char const * const ws = " \t\n");

  *

  * A nondestructive version of strtok() that handles its own memory and can

  * be broken up by any character(s).  Does all the work at once rather than

  * in an invocation loop like strtok() requires.

  *

  * Container is any type that supports push_back(a_string), although using

  * list<string> and deque<string> are indicated due to their O(1) push_back.

  * (I prefer deque<> because op[]/at() is available as well.)  The first

  * parameter references an existing Container.

  *

  * s is the string to be tokenized.  From the parameter declaration, it can

  * be seen that s is not affected.  Since references-to-const may refer to

  * temporaries, you could use stringtok(some_container, readline("")) when

  * using the GNU readline library.

  *

  * The final parameter is an array of characters that serve as whitespace.

  * Whitespace characters default to one or more of tab, space, and newline,

  * in any combination.

  *

  * 'l' need not be empty on entry.  On return, 'l' will have the token

  * strings appended.

  *

  *

  * [Example:

  *       list<string>       ls;

  *       stringtok (ls, " this  \t is\t\n  a test  ");

  *       for (list<string>::const_iterator i = ls.begin();

  *            i != ls.end(); ++i)

  *       {

  *            cerr << ':' << (*i) << ":\n";

  *       }

  *

  *  would print

  *       :this:

  *       :is:

  *       :a:

  *       :test:

  * -end example]

  *

  * pedwards@jaj.com  May 1999

 */

 #include <string>

 #include <cstring>    // for strchr

 /*****************************************************************

  * This is the only part of the implementation that I don't like.

  * It can probably be improved upon by the reader...

 */

     inline bool

     isws (char c, char const * const wstr)

     {

         using namespace std;

         return (strchr(wstr,c) != NULL);

     }

 namespace boost {

 /*****************************************************************

  * Simplistic and quite Standard, but a bit slow.  This should be

  * templatized on basic_string instead, or on a more generic StringT

  * that just happens to support ::size_type, .substr(), and so on.

  * I had hoped that "whitespace" would be a trait, but it isn't, so

  * the user must supply it.  Enh, this lets them break up strings on

  * different things easier than traits would anyhow.

 */

 template <typename Container>

 void

 stringtok (Container &l, std::string const &s, char const * const ws = " \t\n")

 {

   typedef std::string::size_type size_type;

     const size_type  S = s.size();

           size_type  i = 0;

     while (i < S) {

         // eat leading whitespace

         while ((i < S) && (isws(s[i],ws)))  ++i;

         if (i == S)  return;  // nothing left but WS

         // find end of word

         size_type  j = i+1;

         while ((j < S) && (!isws(s[j],ws)))  ++j;

         // add word

         l.push_back(s.substr(i,j-i));

         // set up for next loop

         i = j+1;

     }

 }

 } // namespace boost