commit 7cddf9609df427c0a87d759cfeab2a6a34ef211b
author Mike Kaganski <mike.kaganski@collabora.com> Tue Feb 01 07:48:48 2022 +0100
committer Xisco Fauli <xiscofauli@libreoffice.org> Thu Feb 10 16:36:13 2022 +0100
tree bd8c3a8df5a43d19e359310d2ad00505a05726be
parent ea02ca06de604370061a59dd3084f7cfacccbe39

tdf#147109: Optimize ScInterpreter::ScSubstitute

Avoid multiple reallocations, making it freeze for e.g.

  =SUBSTITUTE(REPT(" ";1000000);" ";"")

Change-Id: I269c0b06a0b3cbf9369cc47f33c2eea026b12903
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/129252
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
(cherry picked from commit 0b397d8ef0a2615e8e6202804ca2f6cb58436fa5)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/129262
Tested-by: Jenkins
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

sc/source/core/tool/interpr1.cxx

diff --git a/sc/source/core/tool/interpr1.cxx b/sc/source/core/tool/interpr1.cxx
index 4467239..131f76c 100644
--- a/sc/source/core/tool/interpr1.cxx
+++ b/sc/source/core/tool/interpr1.cxx
@@ -9696,32 +9696,27 @@ void ScInterpreter::ScSubstitute()
    OUString sStr    = GetString().getString();
    sal_Int32 nPos = 0;
    sal_Int32 nCount = 0;
    sal_Int32 nNewLen = sNewStr.getLength();
    sal_Int32 nOldLen = sOldStr.getLength();
    while( true )
    std::optional<OUStringBuffer> oResult;
    for (sal_Int32 nEnd = sStr.indexOf(sOldStr); nEnd >= 0; nEnd = sStr.indexOf(sOldStr, nEnd))
    {
        nPos = sStr.indexOf( sOldStr, nPos );
        if (nPos != -1)
        if (nCnt == 0 || ++nCount == nCnt) // Found a replacement cite
        {
            nCount++;
            if( !nCnt || nCount == nCnt )
            {
                sStr = sStr.replaceAt(nPos,nOldLen, u"");
                if ( CheckStringResultLen( sStr, sNewStr ) )
                {
                    sStr = sStr.replaceAt(nPos, 0, sNewStr);
                    nPos = sal::static_int_cast<sal_Int32>( nPos + nNewLen );
                }
                else
                    break;
            }
            else
                nPos++;
            if (!oResult) // Only allocate buffer when needed
                oResult.emplace(sStr.getLength() + sNewStr.getLength() - sOldStr.getLength());

            oResult->append(sStr.subView(nPos, nEnd - nPos)); // Copy leading unchanged text
            if (!CheckStringResultLen(*oResult, sNewStr))
                return PushError(GetError());
            oResult->append(sNewStr); // Copy  the replacement
            nPos = nEnd + sOldStr.getLength();
            if (nCnt > 0) // Found the single replacement site - end the loop
                break;
        }
        else
            break;
        nEnd += sOldStr.getLength();
    }
    PushString( sStr );
    if (oResult) // If there were prior replacements, copy the rest, otherwise use original
        oResult->append(sStr.subView(nPos, sStr.getLength() - nPos));
    PushString(oResult ? oResult->makeStringAndClear() : sStr);
}

void ScInterpreter::ScRept()