stringexpression.hpp

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/*****************************************************************************
    NumeRe: Framework fuer Numerische Rechnungen
    Copyright (C) 2020  Erik Haenel et al.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    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 General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/
 
#ifndef STRINGEXPRESSION_HPP
#define STRINGEXPRESSION_HPP
 
#include <string>
#include "../utils/tools.hpp"
 
namespace NumeRe
{
 
    struct StringExpression
    {
        std::string& sLine;
        std::string sAssignee;
        size_t nEqPos;
 
 
        StringExpression(std::string& _sLine, const std::string& sCache = "") : sLine(_sLine), sAssignee(sCache), nEqPos(1)
        {
            findAssignmentOperator();
        }
 
 
        bool isAssignmentOperator(size_t eq_pos) const
        {
            if (!eq_pos || eq_pos >= sLine.length())
                return false;
 
            return sLine[eq_pos - 1] != '!' && sLine[eq_pos - 1] != '<' && sLine[eq_pos - 1] != '>' && sLine[eq_pos + 1] != '=' && sLine[eq_pos - 1] != '=';
        }
 
 
        void findAssignmentOperator()
        {
            // Do nothing, if the position is already 0
            if (!nEqPos)
                return;
 
            nEqPos = 0;
 
            if (sLine.find('=') == std::string::npos)
                return;
 
            size_t nQuotes = 0;
 
            // Search for the operator while considering the
            // quotation marks in the expression
            for (size_t i = 0; i < sLine.length(); i++)
            {
                if (sLine[i] == '"' && (!i || sLine[i-1] != '\\'))
                    nQuotes++;
 
                if (nQuotes % 2)
                    continue;
 
                if (sLine[i] == '(' || sLine[i] == '[' || sLine[i] == '{')
                    i += getMatchingParenthesis(sLine.substr(i));
 
                if (sLine[i] == '=' && isAssignmentOperator(i))
                {
                    nEqPos = i;
                    break;
                }
            }
        }
 
 
        void split()
        {
            if (nEqPos)
            {
                sAssignee = sLine.substr(0, nEqPos);
                sLine.erase(0, nEqPos+1);
                nEqPos = 0;
            }
 
            StripSpaces(sAssignee);
        }
    };
 
}
 
#endif // STRINGEXPRESSION_HPP