mariadb-columnstore-engine/utils/funcexp/func_substring_index.cpp

/* Copyright (C) 2014 InfiniDB, Inc.
   Copyright (C) 2019 MariaDB Corporation

   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; version 2 of
   the License.

   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, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

/****************************************************************************
* $Id: func_substring_index.cpp 2477 2011-04-01 16:07:35Z rdempsey $
*
*
****************************************************************************/
#include <string>
using namespace std;

#include "functor_str.h"
#include "functioncolumn.h"
using namespace execplan;

#include "rowgroup.h"
using namespace rowgroup;

#include "joblisttypes.h"
using namespace joblist;

#include "collation.h"

namespace funcexp
{

CalpontSystemCatalog::ColType Func_substring_index::operationType(FunctionParm& fp, CalpontSystemCatalog::ColType& resultType)
{
    // operation type is not used by this functor
    return fp[0]->data()->resultType();
}

std::string Func_substring_index::getStrVal(rowgroup::Row& row,
        FunctionParm& fp,
        bool& isNull,
        execplan::CalpontSystemCatalog::ColType& ct)
{
    CHARSET_INFO* cs = ct.getCharset();

    const string& str = fp[0]->data()->getStrVal(row, isNull);
    if (isNull)
        return "";
    int64_t strLen = str.length();
    
    const string& delimstr = fp[1]->data()->getStrVal(row, isNull);
    if (isNull)
        return "";
    int64_t delimLen = delimstr.length();
    
    int64_t count = fp[2]->data()->getIntVal(row, isNull);
    if (isNull)
        return "";

    if (strLen == 0 || delimLen == 0 || count == 0)
        return "";

    if (count > strLen)
        return str;

    if ((count < 0) && ((count * -1) > strLen))
        return str;

    bool binaryCmp = (cs->state & MY_CS_BINSORT) || !cs->use_mb();
    std::string value; // Only used if !use_mb()
     
    if (!binaryCmp) // Charset supports multibyte characters
    {
        const char* src = str.c_str();
        const char* srcEnd = src + strLen;
        const char* srchEnd = srcEnd - delimLen + 1;
        const char* delim = delimstr.c_str();
        const char* delimEnd = delim + delimLen;
        char* ptr = const_cast<char*>(src);
        char *i,*j;
        uint32_t l;
        int32_t n = 0, c = count, pass;
        // For count > 0, this loop goes once.
        // For count < 0, it goes twice
        for (pass = (count > 0 ? 1 : 0); pass<2; ++pass)
        {
            while (ptr < srchEnd)
            {
                bool found = false;
                if (*ptr == *delim)  // If the first byte matches, maybe we have a match
                {
                    // Do a byte by byte compare of src at that spot against delim
                    i = ptr + 1; 
                    j = const_cast<char*>(delim) + 1;
                    found = true;
                    while (j != delimEnd)
                    {
                        if (*i++ != *j++)
                        {
                            found = false;
                            break;
                        }
                    }
                }
                if (found)
                {
                    if (pass==0) 
                        ++n;
                    else if (!--c) 
                        break;
                    
                    ptr += delimLen;
                    continue;
                }
                else
                {
                    // move to the next character
                    if ((l = my_ismbchar(cs, ptr, srcEnd))) // returns the number of bytes in the leading char or zero if one byte
                        ptr += l;
                    else
                        ++ptr;
                }
            }
            if (pass == 0) /* count<0 */
            {
                c += n + 1;
                if (c <= 0)
                {
                    return str; // not found, return the original string
                }
                // Go back and do a second pass
                ptr = const_cast<char*>(src);
            }
            else
            {
                if (c)
                {
                    return str; // not found, return the original string
                }
            }
        }
        
        if ( count > 0) /* return left part */
        {
            std::string ret(src, ptr - src);
            return ret;
        }
        else /* return right part */
        {
            ptr+= delimLen;
            std::string ret(ptr, srcEnd - ptr);
            return ret;
        }
    }
    else
    {
        if (count > 0)
        {
            int pointer = 0;
            int64_t end = strLen;
            for ( int64_t i = 0 ; i < count ; i ++ )
            {
                string::size_type pos = str.find(delimstr, pointer);

                if (pos != string::npos)
                    pointer = pos + 1;

                end = pos;
            }

            value = str.substr(0, end);
        }
        else
        {
            count = -count;
            int pointer = strLen;
            int start = 0;

            for ( int64_t i = 0 ; i < count ; i ++ )
            {
                string::size_type pos = str.rfind(delimstr, pointer);

                if (pos != string::npos)
                {
                    if ( count > strLen )
                        return "";

                    pointer = pos - 1;
                    start = pos + 1;
                }
                else
                    start = 0;
            }

            value = str.substr(start, strLen);
        }
    }
    return value;
}


} // namespace funcexp
// vim:ts=4 sw=4: