adding check if alignment is empty

Author: guilhermesena1

sam_record.cpp

@@ -131,6 +131,11 @@ sam_rec::sam_rec(const string &line) {
     tags.push_back(tmp);
 }
 
+bool
+sam_rec::empty() const {
+  return pos == 0;
+}
+
 void
 inflate_with_cigar(const sam_rec &sr, string &to_inflate,
                    const char inflation_symbol) {

sam_record.hpp

@@ -117,6 +117,7 @@ class sam_rec {
     seq(_seq),
     qual(_qual) {}
   void add_tag(const std::string &the_tag) {tags.push_back(the_tag);}
+  bool empty() const;
   std::string tostring() const;
 };