source: NonGTP/Boost/boost/pending/stringtok.hpp @ 857

Revision 857, 3.4 KB checked in by igarcia, 19 years ago (diff)
Line 
1//  (C) Copyright Jeremy Siek 2004
2//  Distributed under the Boost Software License, Version 1.0. (See
3//  accompanying file LICENSE_1_0.txt or copy at
4//  http://www.boost.org/LICENSE_1_0.txt)
5
6/*
7 * stringtok.hpp -- Breaks a string into tokens.  This is an example for lib3.
8 *
9 * Template function looks like this:
10 *
11 *    template <typename Container>
12 *    void stringtok (Container &l,
13 *                    string const &s,
14 *                    char const * const ws = " \t\n");
15 *
16 * A nondestructive version of strtok() that handles its own memory and can
17 * be broken up by any character(s).  Does all the work at once rather than
18 * in an invocation loop like strtok() requires.
19 *
20 * Container is any type that supports push_back(a_string), although using
21 * list<string> and deque<string> are indicated due to their O(1) push_back.
22 * (I prefer deque<> because op[]/at() is available as well.)  The first
23 * parameter references an existing Container.
24 *
25 * s is the string to be tokenized.  From the parameter declaration, it can
26 * be seen that s is not affected.  Since references-to-const may refer to
27 * temporaries, you could use stringtok(some_container, readline("")) when
28 * using the GNU readline library.
29 *
30 * The final parameter is an array of characters that serve as whitespace.
31 * Whitespace characters default to one or more of tab, space, and newline,
32 * in any combination.
33 *
34 * 'l' need not be empty on entry.  On return, 'l' will have the token
35 * strings appended.
36 *
37 *
38 * [Example:
39 *       list<string>       ls;
40 *       stringtok (ls, " this  \t is\t\n  a test  ");
41 *       for (list<string>::const_iterator i = ls.begin();
42 *            i != ls.end(); ++i)
43 *       {
44 *            cerr << ':' << (*i) << ":\n";
45 *       }
46 *
47 *  would print
48 *       :this:
49 *       :is:
50 *       :a:
51 *       :test:
52 * -end example]
53 *
54 * pedwards@jaj.com  May 1999
55*/
56
57
58#include <string>
59#include <cstring>    // for strchr
60
61
62/*****************************************************************
63 * This is the only part of the implementation that I don't like.
64 * It can probably be improved upon by the reader...
65*/
66namespace {
67    inline bool
68    isws (char c, char const * const wstr)
69    {
70        using namespace std;
71        return (strchr(wstr,c) != NULL);
72    }
73}
74
75namespace boost {
76
77/*****************************************************************
78 * Simplistic and quite Standard, but a bit slow.  This should be
79 * templatized on basic_string instead, or on a more generic StringT
80 * that just happens to support ::size_type, .substr(), and so on.
81 * I had hoped that "whitespace" would be a trait, but it isn't, so
82 * the user must supply it.  Enh, this lets them break up strings on
83 * different things easier than traits would anyhow.
84*/
85template <typename Container>
86void
87stringtok (Container &l, std::string const &s, char const * const ws = " \t\n")
88{
89  typedef std::string::size_type size_type;
90    const size_type  S = s.size();
91          size_type  i = 0;
92
93    while (i < S) {
94        // eat leading whitespace
95        while ((i < S) && (isws(s[i],ws)))  ++i;
96        if (i == S)  return;  // nothing left but WS
97
98        // find end of word
99        size_type  j = i+1;
100        while ((j < S) && (!isws(s[j],ws)))  ++j;
101
102        // add word
103        l.push_back(s.substr(i,j-i));
104
105        // set up for next loop
106        i = j+1;
107    }
108}
109
110
111} // namespace boost
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