sugar support, start

include/cif++/Cif++.hpp

@@ -287,7 +287,7 @@ namespace detail
 
 		void swap(ItemReference& b);
 		
-		template<typename T>
+		template<typename T = std::string>
 		T as() const
 		{
 			return item_value_as<T>::convert(*this);
@@ -1332,6 +1332,9 @@ class conditional_iterator_proxy
 	iterator end() const;
 
 	bool empty() const;
+
+	explicit operator bool() const	{ return not empty(); }
+
 	size_t size() const				{ return std::distance(begin(), end()); }
 
 	RowType front()					{ return *begin(); }

include/cif++/Structure.hpp

@@ -242,6 +242,10 @@ class Residue
 	bool isEntity() const;
 	
 	bool isWater() const					{ return mCompoundID == "HOH"; }
+
+	bool isSugar() const;
+	bool isPyranose() const;
+	bool isFuranose() const;
 	
 	const Structure& structure() const		{ return *mStructure; }
 

src/PDB2Cif.cpp

@@ -4268,7 +4268,7 @@ void PDBFileParser::ConstructEntities()
 				{ "polymer_flag",	isPolymer ? "Y" : "N" },
 				{ "occupancy_flag",	1 },
 				{ "PDB_model_num",	unobs.modelNr ? unobs.modelNr : 1 },
-				{ "auth_asym_id",	unobs.chain },
+				{ "auth_asym_id",	std::string{ unobs.chain } },
 				{ "auth_comp_id",	unobs.res },
 				{ "auth_seq_id",	unobs.seq },
 				{ "PDB_ins_code",	unobs.iCode == ' ' ? "" : std::string{ unobs.iCode } },
@@ -4286,7 +4286,7 @@ void PDBFileParser::ConstructEntities()
 					{ "polymer_flag",	isPolymer ? "Y" : "N" },
 					{ "occupancy_flag",	1 },
 					{ "PDB_model_num",	unobs.modelNr ? unobs.modelNr : 1 },
-					{ "auth_asym_id",	unobs.chain },
+					{ "auth_asym_id",	std::string { unobs.chain } },
 					{ "auth_comp_id",	unobs.res },
 					{ "auth_seq_id",	unobs.seq },
 					{ "PDB_ins_code",	unobs.iCode == ' ' ? "" : std::string{ unobs.iCode } },
@@ -4296,7 +4296,6 @@ void PDBFileParser::ConstructEntities()
 					{ "label_seq_id",	seqNr > 0 ? std::to_string(seqNr) : "" },
 					{ "label_atom_id",	atom }
 				});
-				
 			}
 		}
 	}

src/Structure.cpp

@@ -946,6 +946,21 @@ bool Residue::isEntity() const
 	return a1.size() == a2.size();
 }
 
+bool Residue::isSugar() const
+{
+	return compound().isSugar();
+}
+
+bool Residue::isPyranose() const
+{
+	return cif::iequals(compound().group(), "pyranose");
+}
+
+bool Residue::isFuranose() const
+{
+	return cif::iequals(compound().group(), "furanose");
+}
+
 std::string Residue::authID() const
 {
 	std::string result;
@@ -1857,21 +1872,19 @@ std::tuple<char,int,char> Structure::MapLabelToAuth(
 						
 	if (not found)
 	{
-		for (auto r: db["pdbx_nonpoly_scheme"].find(
-							cif::Key("asym_id") == asymID and
-							cif::Key("seq_id") == seqID))
+		auto r = db["pdbx_nonpoly_scheme"].find(cif::Key("asym_id") == asymID);
+		if (r.size() == 1)
 		{
 			std::string pdb_strand_id, pdb_ins_code;
 			int pdb_seq_num;
 			
 			cif::tie(pdb_strand_id, pdb_seq_num, pdb_ins_code) =
-				r.get("pdb_strand_id", "pdb_seq_num", "pdb_ins_code");
+				r.front().get("pdb_strand_id", "pdb_seq_num", "pdb_ins_code");
 	
 			result = std::make_tuple(pdb_strand_id.front(), pdb_seq_num,
 				pdb_ins_code.empty() ? ' ' : pdb_ins_code.front());
 	
 			found = true;
-			break;
 		}
 	}