dbf9e800
 Hu Chunming
提交_GLIBCXX_USE_CX...
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// (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)
#ifndef BOOST_STRINGTOK_HPP
#define BOOST_STRINGTOK_HPP
/*
* 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
#endif // BOOST_STRINGTOK_HPP
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