diff --git a/libmwereader/mwe.cpp b/libmwereader/mwe.cpp
index 897c80eaac94beb4b94337fae60f9ab8d933e942..6bd065a6751f9079cd9d14cc4b4b8e29da1bda94 100644
--- a/libmwereader/mwe.cpp
+++ b/libmwereader/mwe.cpp
@@ -19,7 +19,7 @@ LexicalUnit::LexicalUnit(const std::string &base,
 }
 
 bool LexicalUnit::IsHere(const Wccl::SentenceContext &sc,
-					std::set<size_t> &out_position)
+					std::set<size_t> &out_position) const
 {
 	boost::shared_ptr<const Wccl::Bool> pResult = condition_->apply(sc);
 	if(pResult->get_value() == false)
@@ -39,6 +39,8 @@ bool LexicalUnit::IsHere(const Wccl::SentenceContext &sc,
 	return true;
 }
 
+////////////////////////////////////////////////////////////////////
+// TODO realy needed?
 
 FixedLU::FixedLU(const std::string &base,
 				boost::shared_ptr<Wccl::Operator<Wccl::Bool> > condition,
@@ -56,12 +58,14 @@ FlexLU::FlexLU(const std::string &base,
 {
 }
 
-MWEIndex::MWEIndex()
-{
+////////////////////////////////////////////////////////////////////
 
+MWEIndex::MWEIndex() : index_(), empty_()
+{
+	// noop
 }
 
-void MWEIndex::add_lexicalunit(LexicalUnitPtr lu)
+void MWEIndex::add_lexicalunit(LexicalUnit::Ptr lu)
 {
 	foreach(const std::string& base, lu->get_potential_bases()){
 		value_type::iterator find = index_.find(base);
@@ -75,4 +79,13 @@ void MWEIndex::add_lexicalunit(LexicalUnitPtr lu)
 	}
 }
 
+const MWEIndex::luvec& MWEIndex::get_potential_lu(const std::string &base){
+	value_type::iterator find = index_.find(base);
+	if(find == index_.end()){ // not found -> return empty
+		return empty_;
+	}
+
+	return (find->second);
+}
+
 }//ns Corpus2
diff --git a/libmwereader/mwe.h b/libmwereader/mwe.h
index 0676ad0036e4135aeae49a54390a24f590a1ee61..e0ee53c3efa747a2ffba418a2a0f300922427fde 100644
--- a/libmwereader/mwe.h
+++ b/libmwereader/mwe.h
@@ -31,14 +31,14 @@ public:
 	  * \returns true if this lexical unit was found here
 	  */
 	virtual bool IsHere(const Wccl::SentenceContext& sc,
-						std::set<size_t> &out_positions) ;
+						std::set<size_t> &out_positions) const;
 
 	const std::string & get_base() const{ return base_;}
 	const strmap & get_variables() const{ return variables_;}
 	const strset& get_potential_bases() const{ return potential_bases_;}
 
 
-
+	typedef boost::shared_ptr<LexicalUnit> Ptr;
 protected:
 
 	boost::shared_ptr<Wccl::Operator<Wccl::Bool> > condition_;
@@ -51,7 +51,7 @@ protected:
 	const Wccl::Position nowhere_;
 };
 
-typedef boost::shared_ptr<LexicalUnit> LexicalUnitPtr;
+
 
 
 // TODO: czy bedzie potrzebny podzial na fix/flex w kodzie?
@@ -59,9 +59,9 @@ class FixedLU : public LexicalUnit
 {
 public:
 	FixedLU(const std::string &base,
-				boost::shared_ptr<Wccl::Operator<Wccl::Bool> > condition,
-				boost::shared_ptr<Wccl::Operator<Wccl::Bool> > head_cond,
-				std::map<std::string, std::string> variables
+				LexicalUnit::BoolOpPtr condition,
+				LexicalUnit::BoolOpPtr head_cond,
+				LexicalUnit::strmap variables
 				);
 };
 
@@ -69,9 +69,9 @@ class FlexLU : public LexicalUnit
 {
 public:
 	FlexLU(const std::string &base,
-				boost::shared_ptr<Wccl::Operator<Wccl::Bool> > condition,
-				boost::shared_ptr<Wccl::Operator<Wccl::Bool> > head_cond,
-				std::map<std::string, std::string> variables
+				LexicalUnit::BoolOpPtr condition,
+				LexicalUnit::BoolOpPtr head_cond,
+				LexicalUnit::strmap variables
 				);
 
 };
@@ -79,16 +79,22 @@ public:
 class MWEIndex // lub base -> vector<LexicalUnit>
 {
 public:
+	typedef std::vector<LexicalUnit::Ptr> luvec;
+
 	MWEIndex();
 
-	void add_lexicalunit(LexicalUnitPtr lu);
+	void add_lexicalunit(LexicalUnit::Ptr lu);
+
+	const luvec& get_potential_lu(const std::string& base);
 
 protected:
-	typedef std::vector<LexicalUnitPtr> luvec;
+
 	typedef boost::unordered_map<std::string,luvec> value_type;
 
 
 	value_type index_;
+
+	const luvec empty_;
 };
 
 }// ns Corpus2
diff --git a/libmwereader/mweparser.cpp b/libmwereader/mweparser.cpp
index c8fd91e5557142e03b38a149d2e181bc75df57e3..cda56745dc33ef33f2798fce26e74aac9a37ac1e 100644
--- a/libmwereader/mweparser.cpp
+++ b/libmwereader/mweparser.cpp
@@ -60,17 +60,18 @@ namespace Corpus2 {
 		MWEBuilder::BoolOpPtr head = mwe_builder_->get_head_condition(
 					head_cond_);
 
-		LexicalUnitPtr lu;
 		if(group_type_ == "fix"){ // group_name_  -> lower case
-			lu = LexicalUnitPtr(new FixedLU(mwe_base_, main, head,
-											  variables_));
+			mwe_index_.add_lexicalunit( LexicalUnit::Ptr(new FixedLU(mwe_base_, main, head,
+											  variables_)));
 		} else if(group_type_ == "flex"){
-			lu = LexicalUnitPtr(new FlexLU(mwe_base_, main, head,
-											variables_));
+			mwe_index_.add_lexicalunit(LexicalUnit::Ptr(new FlexLU(mwe_base_, main, head,
+											variables_)));
 		} else {
 			throw Wccl::WcclError("Unknown type of lexical unit:"
 									+ group_type_);
 		}
+
+
 	}
 
 	std::string MWEParser::get_attribute(const AttributeList& attributes,