//  (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