diff --git a/libwccl/parser/Parser.h b/libwccl/parser/Parser.h
index c06273348e9b3bcb5d49d0a71e75b5fffb12baf7..365b7b90ca884fc70087b16612079159713a3ece 100644
--- a/libwccl/parser/Parser.h
+++ b/libwccl/parser/Parser.h
@@ -35,58 +35,58 @@ public:
 	// ---------------------------------------------------------------------------
 	// methods for parsing string operators
 	boost::shared_ptr<Operator<StrSet> >
-			parseStringOperator(const std::string&) const;
+			parseStringOperator(const std::string& operator_string) const;
 	boost::shared_ptr<Operator<StrSet> >
-			parseStringOperator(std::istream&) const;
+			parseStringOperator(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// methods for parsing bool operators
 	boost::shared_ptr<Operator<Bool> >
-			parseBoolOperator(const std::string&) const;
+			parseBoolOperator(const std::string& operator_string) const;
 	boost::shared_ptr<Operator<Bool> >
-			parseBoolOperator(std::istream&) const;
+			parseBoolOperator(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// methods for parsing bool operators
 	boost::shared_ptr<Operator<TSet> >
-			parseSymSetOperator(const std::string&) const;
+			parseSymSetOperator(const std::string& operator_string) const;
 	boost::shared_ptr<Operator<TSet> >
-			parseSymSetOperator(std::istream&) const;
+			parseSymSetOperator(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// methods for parsing position operators
 	boost::shared_ptr<Operator<Position> >
-			parsePositionOperator(const std::string&) const;
+			parsePositionOperator(const std::string& operator_string) const;
 	boost::shared_ptr<Operator<Position> >
-			parsePositionOperator(std::istream&) const;
+			parsePositionOperator(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// methods for parsing any operators
 	boost::shared_ptr<FunctionalOperator>
-			parseAnyOperator(const std::string&) const;
+			parseAnyOperator(const std::string& operator_string) const;
 	boost::shared_ptr<FunctionalOperator>
-			parseAnyOperator(std::istream&) const;
+			parseAnyOperator(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// Parsing rule sequence from input string
 	boost::shared_ptr<RuleSequence>
-			parseRuleSequence(const std::string&) const;
+			parseRuleSequence(const std::string& operator_string) const;
 	boost::shared_ptr<RuleSequence>
-			parseRuleSequence(std::istream&) const;
+			parseRuleSequence(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// Parsing single rule from input string
 	boost::shared_ptr<TagRule>
-			parseSingleRule(const std::string&) const;
+			parseSingleRule(const std::string& operator_string) const;
 	boost::shared_ptr<TagRule>
-			parseSingleRule(std::istream&) const;
+			parseSingleRule(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	// Parsing match rule from input string
 	boost::shared_ptr<Expression>
-			parseMatchRule(const std::string&) const;
+			parseMatchRule(const std::string& operator_string) const;
 	boost::shared_ptr<Expression>
-			parseMatchRule(std::istream&) const;
+			parseMatchRule(std::istream& is) const;
 
 	// ---------------------------------------------------------------------------
 	const Corpus2::Tagset& tagset() const {