6 files changed, 6 insertions, 6 deletions
diff --git a/extractor/grammar_extractor.cc b/extractor/grammar_extractor.cc
index 1fbdee5b..487abcaf 100644
--- a/extractor/grammar_extractor.cc
+++ b/extractor/grammar_extractor.cc
@@ -34,7 +34,7 @@ GrammarExtractor::GrammarExtractor(
     vocabulary(vocabulary),
     rule_factory(rule_factory) {}
 
-Grammar GrammarExtractor::GetGrammar(const string& sentence, const unordered_set<int> blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) {
+Grammar GrammarExtractor::GetGrammar(const string& sentence, const unordered_set<int>& blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) {
   vector<string> words = TokenizeSentence(sentence);
   vector<int> word_ids = AnnotateWords(words);
   return rule_factory->GetGrammar(word_ids, blacklisted_sentence_ids, source_data_array);
diff --git a/extractor/grammar_extractor.h b/extractor/grammar_extractor.h
index 6c0aafbf..ae407b47 100644
--- a/extractor/grammar_extractor.h
+++ b/extractor/grammar_extractor.h
@@ -45,7 +45,7 @@ class GrammarExtractor {
 
   // Converts the sentence to a vector of word ids and uses the RuleFactory to
   // extract the SCFG rules which may be used to decode the sentence.
-  Grammar GetGrammar(const string& sentence, const unordered_set<int> blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array);
+  Grammar GetGrammar(const string& sentence, const unordered_set<int>& blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array);
 
  private:
   // Splits the sentence in a vector of words.
diff --git a/extractor/rule_factory.cc b/extractor/rule_factory.cc
index e52019ae..6ae2d792 100644
--- a/extractor/rule_factory.cc
+++ b/extractor/rule_factory.cc
@@ -101,7 +101,7 @@ HieroCachingRuleFactory::HieroCachingRuleFactory() {}
 
 HieroCachingRuleFactory::~HieroCachingRuleFactory() {}
 
-Grammar HieroCachingRuleFactory::GetGrammar(const vector<int>& word_ids, const unordered_set<int> blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) {
+Grammar HieroCachingRuleFactory::GetGrammar(const vector<int>& word_ids, const unordered_set<int>& blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) {
   Clock::time_point start_time = Clock::now();
   double total_extract_time = 0;
   double total_intersect_time = 0;
diff --git a/extractor/rule_factory.h b/extractor/rule_factory.h
index c7332720..df63a9d8 100644
--- a/extractor/rule_factory.h
+++ b/extractor/rule_factory.h
@@ -72,7 +72,7 @@ class HieroCachingRuleFactory {
 
   // Constructs SCFG rules for a given sentence.
   // (See class description for more details.)
-  virtual Grammar GetGrammar(const vector<int>& word_ids, const unordered_set<int> blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array);
+  virtual Grammar GetGrammar(const vector<int>& word_ids, const unordered_set<int>& blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array);
 
  protected:
   HieroCachingRuleFactory();
diff --git a/extractor/sampler.cc b/extractor/sampler.cc
index d332dd90..963afa7a 100644
--- a/extractor/sampler.cc
+++ b/extractor/sampler.cc
@@ -12,7 +12,7 @@ Sampler::Sampler() {}
 
 Sampler::~Sampler() {}
 
-PhraseLocation Sampler::Sample(const PhraseLocation& location, unordered_set<int> blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) const {
+PhraseLocation Sampler::Sample(const PhraseLocation& location, const unordered_set<int>& blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) const {
   vector<int> sample;
   int num_subpatterns;
   if (location.matchings == NULL) {
diff --git a/extractor/sampler.h b/extractor/sampler.h
index 30e747fd..de450c48 100644
--- a/extractor/sampler.h
+++ b/extractor/sampler.h
@@ -23,7 +23,7 @@ class Sampler {
   virtual ~Sampler();
 
   // Samples uniformly at most max_samples phrase occurrences.
-  virtual PhraseLocation Sample(const PhraseLocation& location, const unordered_set<int> blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) const;
+  virtual PhraseLocation Sample(const PhraseLocation& location, const unordered_set<int>& blacklisted_sentence_ids, const shared_ptr<DataArray> source_data_array) const;
 
  protected:
   Sampler();