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

/* Copyright (C) 2021 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. */

#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;

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

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

  const auto& nstr = fp[0]->data()->getStrVal(row, isNull);
  if (nstr.isNull())
    return "";
  const auto& str = nstr.unsafeStringRef();
  size_t strLen = str.length();

  const auto& nfromstr = fp[1]->data()->getStrVal(row, isNull);
  if (nfromstr.isNull())
    return "";
  const auto& fromstr = nfromstr.unsafeStringRef();

  if (fromstr.length() == 0)
    return str;
  size_t fromLen = fromstr.length();

  const auto& ntostr = fp[2]->data()->getStrVal(row, isNull);
  if (ntostr.isNull())
    return "";
  
  const auto& tostr = ntostr.unsafeStringRef();

  size_t toLen = tostr.length();

  bool binaryCmp = (cs->state & MY_CS_BINSORT) || !cs->use_mb();
  string newstr;
  size_t pos = 0;
  if (binaryCmp)
  {
    // Count the number of fromstr in strend so we can reserve buffer space.
    int count = 0;
    do
    {
      ++count;
      pos = str.find(fromstr, pos + fromLen);
    } while (pos != string::npos);

    newstr.reserve(strLen + (count * ((int)toLen - (int)fromLen)) + 1);

    uint32_t i = 0;
    pos = str.find(fromstr);
    if (pos == string::npos)
      return str;
    // Move the stuff into newstr
    do
    {
      if (pos > i)
        newstr = newstr + str.substr(i, pos - i);

      newstr = newstr + tostr;
      i = pos + fromLen;
      pos = str.find(fromstr, i);
    } while (pos != string::npos);

    newstr = newstr + str.substr(i, string::npos);
  }
  else
  {
    // UTF
    const char* src = str.c_str();
    const char* srcEnd = src + strLen;
    const char* srchEnd = srcEnd - fromLen + 1;
    const char* from = fromstr.c_str();
    const char* fromEnd = from + fromLen;
    const char* to = tostr.c_str();
    const char* ptr = src;
    char *i, *j;
    size_t count = 10;  // Some arbitray number to reserve some space to start.
    int growlen = (int)toLen - (int)fromLen;
    growlen = growlen < 1 ? 1 : growlen;
    growlen *= count;
    newstr.reserve(strLen + (count * growlen) + 1);
    size_t maxsize = newstr.capacity();
    uint32_t l;

    // We don't know where byte patterns might match so
    // we start at the beginning of the string and move forward
    // one character at a time until we find a match. Then we can
    // move the src bytes and add in the to bytes,then try again.
    while (ptr < srchEnd)
    {
      bool found = false;
      if (*ptr == *from)  // If the first byte matches, maybe we have a match
      {
        // Do a byte by byte compare of src at that spot against from
        i = const_cast<char*>(ptr) + 1;
        j = const_cast<char*>(from) + 1;
        found = true;
        while (j != fromEnd)
        {
          if (*i++ != *j++)
          {
            found = false;
            break;
          }
        }
      }
      if (found)
      {
        if (ptr < i)
        {
          int mvsize = ptr - src;
          if (newstr.length() + mvsize + toLen > maxsize)
          {
            // We need a re-alloc
            newstr.reserve(maxsize + growlen);
            maxsize = newstr.capacity();
            growlen *= 2;
          }
          newstr.append(src, ptr - src);
          src += mvsize + fromLen;
          ptr = src;
        }
        newstr.append(to, toLen);
      }
      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;
      }
    }
    // Copy in the trailing src chars.
    newstr.append(src, srcEnd - src);
  }
  return newstr;
}

}  // namespace funcexp