optimise find/insert calls to maps

Instead of doing two lookups, we can just call insert and
then update the mapped-to value if the insert actually succeeded.

Change-Id: I3df3b98f0debe6bf74c739dd5850e7714d9c2789
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/151030
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

configmgr/source/valueparser.cxx

@@ -352,12 +352,11 @@ bool ValueParser::endElement() {
             case Node::KIND_LOCALIZED_PROPERTY:
                 {
                     NodeMap & members = node_->getMembers();
-                    NodeMap::iterator i(members.find(localizedName_));
+                    auto [i, bInserted] = members.insert(NodeMap::value_type(localizedName_, nullptr));
                     LocalizedValueNode *pLVNode;
-                    if (i == members.end()) {
+                    if (bInserted) {
                         pLVNode = new LocalizedValueNode(layer_);
-                        members.insert(
-                            NodeMap::value_type(localizedName_, pLVNode ));
+                        i->second = pLVNode;
                     } else {
                         pLVNode = static_cast< LocalizedValueNode * >(i->second.get());
                     }

oox/source/export/chartexport.cxx

@@ -3345,10 +3345,8 @@ void ChartExport::_exportAxis(
     }
 
     // only export each axis only once non-deleted
-    bool bDeleted = maExportedAxis.find(rAxisIdPair.nAxisType) != maExportedAxis.end();
-
-    if (!bDeleted)
-        maExportedAxis.insert(rAxisIdPair.nAxisType);
+    auto aItInsertedPair = maExportedAxis.insert(rAxisIdPair.nAxisType);
+    bool bDeleted = !aItInsertedPair.second;
 
     pFS->singleElement(FSNS(XML_c, XML_delete), XML_val, !bDeleted && bVisible ? "0" : "1");
 

sc/source/core/opencl/opbase.cxx

@@ -114,12 +114,9 @@ int DynamicKernelArgument::GetStringId( const rtl_uString* string )
         return 0;
     if( stringIdsMap == nullptr )
         stringIdsMap = new std::unordered_map<const rtl_uString*, int>;
-    std::unordered_map<const rtl_uString*, int>::iterator it = stringIdsMap->find( string );
-    if( it != stringIdsMap->end())
-        return it->second;
     int newId = stringIdsMap->size() + 1;
-    stringIdsMap->insert( std::pair( string, newId ));
-    return newId;
+    auto aItInsertedPair = stringIdsMap->insert( std::pair( string, newId ));
+    return aItInsertedPair.first->second;
 }
 
 void DynamicKernelArgument::ClearStringIds()

sc/source/filter/html/htmlpars.cxx

@@ -768,8 +768,7 @@ void ScHTMLLayoutParser::SetWidths()
             for (auto it = pLocalColOffset->begin(); it != pLocalColOffset->end(); ++it)
             {
                 // Only exact offsets, do not use MakeColNoRef().
-                if (maColOffset.find(*it) == maColOffset.end())
-                    maColOffset.insert(*it);
+                maColOffset.insert(*it);
             }
         }
     }

sfx2/source/control/shell.cxx

@@ -170,8 +170,7 @@ void SfxShell::PutItem
     if (it != pImpl->m_Items.end())
     {
         // Replace Item
-        pImpl->m_Items.erase( it );
-        pImpl->m_Items.insert(std::make_pair(nWhich, std::unique_ptr<SfxPoolItem>(pItem)));
+        it->second = std::unique_ptr<SfxPoolItem>(pItem);
 
         // if active, notify Bindings
         SfxDispatcher *pDispat = GetDispatcher();

svx/source/dialog/framelinkarray.cxx

@@ -1379,10 +1379,10 @@ drawinglayer::primitive2d::Primitive2DContainer Array::CreateB2DPrimitiveRange(
                     GetMergedRange(nColLeft, nRowTop, nColRight, nRowBottom, nCol, nRow);
                     const sal_Int32 nIndexOfMergedCell(mxImpl->GetIndex(nColLeft, nRowTop));
 
-                    if(aMergedCells.end() == aMergedCells.find(nIndexOfMergedCell))
+                    auto aItInsertedPair = aMergedCells.insert(nIndexOfMergedCell);
+                    if(aItInsertedPair.second)
                     {
-                        // not found, so not yet handled. Add now to mark as handled
-                        aMergedCells.insert(nIndexOfMergedCell);
+                        // not found, so not yet handled.
 
                         // Get and check if diagonal styles are used
                         // Note: For GetCellStyleBLTR below I tried to use nRowBottom

sw/source/filter/html/svxcss1.cxx

@@ -925,11 +925,9 @@ void SvxCSS1Parser::InsertMapEntry( const OUString& rKey,
                                     const SvxCSS1PropertyInfo& rProp,
                                     CSS1Map& rMap )
 {
-    CSS1Map::iterator itr = rMap.find(rKey);
-    if (itr == rMap.end())
-    {
-        rMap.insert(std::make_pair(rKey, std::make_unique<SvxCSS1MapEntry>(rItemSet, rProp)));
-    }
+    auto [itr,inserted] = rMap.insert(std::make_pair(rKey, nullptr));
+    if (inserted)
+        itr->second = std::make_unique<SvxCSS1MapEntry>(rItemSet, rProp);
     else
     {
         SvxCSS1MapEntry *const p = itr->second.get();

sw/source/filter/ww8/rtfexport.cxx

@@ -1432,13 +1432,11 @@ OString* RtfExport::GetStyle(sal_uInt16 nId)
 
 sal_uInt16 RtfExport::GetRedline(const OUString& rAuthor)
 {
-    auto it = m_aRedlineTable.find(rAuthor);
-    if (it != m_aRedlineTable.end())
-        return it->second;
-
     const sal_uInt16 nId = m_aRedlineTable.size();
-    m_aRedlineTable.insert(std::pair<OUString, sal_uInt16>(rAuthor, nId));
-    return nId;
+    // insert if we don't already have one
+    auto[it, inserted] = m_aRedlineTable.insert(std::pair<OUString, sal_uInt16>(rAuthor, nId));
+    (void)inserted;
+    return it->second;
 }
 
 const OUString* RtfExport::GetRedline(sal_uInt16 nId)