added PerBaseInfo.constructFront method

bio/bam/baseinfo.d

@@ -199,6 +199,14 @@ struct PerBaseInfo(R, TagsAndOptions...) {
         return _seq.empty;
     }
 
+    /// Allows to construct front element in-place, avoiding a copy.
+    void constructFront(Result* addr)
+    {
+        addr.base = _seq.front;
+        foreach (t; Extensions)
+            populate!t(*addr);
+    }
+
     Result front() @property {
         Result r = void;
         r.base = _seq.front;

test/unittests.d

@@ -365,14 +365,17 @@ unittest {
         auto bases = basesWith!Options(read, 
                                        arg!"flowOrder"(flow_order),
                                        arg!"keySequence"(key_sequence));
-      
-        assert(bases.front.md_operation.is_match);
-        assert(bases.front.md_operation.match == 309);
-        assert(bases.front.md_operation_offset == 0);
-        assert(bases.front.previous_md_operation.isNull);
-        assert(bases.front.next_md_operation.is_deletion);
-        assert(equal(bases.front.next_md_operation.deletion, "G"));
-        assert(equal(bases.front.cigar_after, read.cigar[1 .. $]));
+     
+        typeof(bases.front) bfront;
+        bases.constructFront(&bfront);
+
+        assert(bfront.md_operation.is_match);
+        assert(bfront.md_operation.match == 309);
+        assert(bfront.md_operation_offset == 0);
+        assert(bfront.previous_md_operation.isNull);
+        assert(bfront.next_md_operation.is_deletion);
+        assert(equal(bfront.next_md_operation.deletion, "G"));
+        assert(equal(bfront.cigar_after, read.cigar[1 .. $]));
         assert(equal(drop(map!"a.reference_base"(bases.save), 191),
                      "-CCCGATTGGTCGTTGCTTTACGCTGATTGGCGAGTCCGGGGAACGTACCTTTGCTATCAGTCCAGGCCACATGAACCAGCTGCGGGCTGAAAGCATTCCGGAAGATGTGATTGCCGGACCTCGGCACTGGTTCTCACCTCATATCTGGTGCGTTGCAAGCCGGGTGAACCCATGCCGGAAGCACCATGAAAGCCATTGAGTACGCGAAGAAATATA"));
         assert(equal(bases.save, read.sequence));