split.hpp

//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2022 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

// General string-splitting methods.  These methods along with lexical analyzer
// classes (such as those defined in lex.hpp and OptionList::LexComment) can be
// used as a basis for parsers.

#ifndef OPENVPN_COMMON_SPLIT_H
#define OPENVPN_COMMON_SPLIT_H

#include <string>
#include <vector>
#include <utility>

#include <openvpn/common/size.hpp>
#include <openvpn/common/lex.hpp>
#include <openvpn/common/clamp_typerange.hpp>


using namespace openvpn::numeric_util;

namespace openvpn::Split {

enum
{
    TRIM_LEADING_SPACES = (1 << 0),
    TRIM_SPECIAL = (1 << 1), // trims quotes (but respects their content)
};

struct NullLimit
{
    void add_term()
    {
    }
};

// Split a string using a character (such as ',') as a separator.
// Types:
//   V : string vector of return data
//   LEX : lexical analyzer class such as StandardLex
//   LIM : limit class such as OptionList::Limits
// Args:
//   ret : return data -- a list of strings
//   input : input string to be split
//   split_by : separator
//   flags : TRIM_LEADING_SPACES, TRIM_SPECIAL
//   max_terms : the size of the returned string list will be, at most, this value + 1.  Pass
//               ~0 to disable.
//   lim : an optional limits object such as OptionList::Limits
template <typename V, typename LEX, typename LIM>
inline void by_char_void(V &ret, const std::string &input, const char split_by, const unsigned int flags = 0, const unsigned int max_terms = ~0, LIM *lim = nullptr)
{
    LEX lex;
    unsigned int nterms = 0;
    std::string term;
    for (std::string::const_iterator i = input.begin(); i != input.end(); ++i)
    {
        const char c = *i;
        lex.put(c);
        if (!lex.in_quote() && c == split_by && nterms < max_terms)
        {
            if (lim)
                lim->add_term();
            ret.push_back(std::move(term));
            ++nterms;
            term = "";
        }
        else if ((!(flags & TRIM_SPECIAL) || lex.available())
                 && (!(flags & TRIM_LEADING_SPACES) || !term.empty() || !SpaceMatch::is_space(c)))
            term += c;
    }
    if (lim)
        lim->add_term();
    ret.push_back(std::move(term));
}

// convenience method that returns data rather than modifying an in-place argument
template <typename V, typename LEX, typename LIM>
inline V by_char(const std::string &input, const char split_by, const unsigned int flags = 0, const unsigned int max_terms = ~0, LIM *lim = nullptr)
{
    V ret;
    by_char_void<V, LEX, LIM>(ret, input, split_by, flags, max_terms, lim);
    return ret;
}

// Split a string using spaces as a separator.
// Types:
//   V : string vector of return data
//   LEX : lexical analyzer class such as StandardLex
//   SPACE : class that we use to differentiate between space and non-space chars
//   LIM : limit class such as OptionList::Limits
// Args:
//   ret : return data -- a list of strings
//   input : input string to be split
//   lim : an optional limits object such as OptionList::Limits
template <typename V, typename LEX, typename SPACE, typename LIM>
inline void by_space_void(V &ret, const std::string &input, LIM *lim = nullptr)
{
    LEX lex;

    std::string term;
    bool defined = false;
    for (std::string::const_iterator i = input.begin(); i != input.end(); ++i)
    {
        const char c = *i;
        lex.put(c);
        if (lex.in_quote())
            defined = true;
        if (lex.available())
        {
            const char tc = clamp_to_default<char>(lex.get(), '?');
            if (!SPACE::is_space(tc) || lex.in_quote())
            {
                defined = true;
                term += tc;
            }
            else if (defined)
            {
                if (lim)
                    lim->add_term();
                ret.push_back(std::move(term));
                term = "";
                defined = false;
            }
        }
    }
    if (defined)
    {
        if (lim)
            lim->add_term();
        ret.push_back(std::move(term));
    }
}

// convenience method that returns data rather than modifying an in-place argument
template <typename V, typename LEX, typename SPACE, typename LIM>
inline V by_space(const std::string &input, LIM *lim = nullptr)
{
    V ret;
    by_space_void<V, LEX, SPACE, LIM>(ret, input, lim);
    return ret;
}
} // namespace openvpn::Split

#endif // OPENVPN_COMMON_SPLIT_H