Cache the result of default column compose

Use this cache now lots of things are const refs

3 files changed, 30 insertions, 10 deletions

diff --git a/libodbcpp/column.cpp b/libodbcpp/column.cpp
index 31e9642..6f45617 100644
--- a/libodbcpp/column.cpp
+++ b/libodbcpp/column.cpp
@@ -7,12 +7,14 @@
 ODBC::Column::Column(const Glib::ustring & n, unsigned int i) :
 	colNo(i),
 	name(n),
+	composeCache(NULL),
 	bindSize(0)
 {
 }
 
 ODBC::Column::~Column()
 {
+	delete composeCache;
 }
 
 bool
@@ -91,10 +93,13 @@ namespace ODBC {
 		return writeToBuf(buf, "%g");
 	}
 	template <>
-	Glib::ustring
+	const Glib::ustring &
 	_Column<SQLDOUBLE>::compose() const
 	{
-		return Glib::ustring::compose("%1", value);
+		if (!composeCache) {
+			composeCache = new Glib::ustring(Glib::ustring::compose("%1", value));
+		}
+		return *composeCache;
 	}
 	template <>
 	Glib::ustring
@@ -115,10 +120,13 @@ namespace ODBC {
 		return writeToBuf(buf, "%ld");
 	}
 	template <>
-	Glib::ustring
+	const Glib::ustring &
 	_Column<SQLINTEGER>::compose() const
 	{
-		return Glib::ustring::compose("%1", value);
+		if (!composeCache) {
+			composeCache = new Glib::ustring(Glib::ustring::compose("%1", value));
+		}
+		return *composeCache;
 	}
 	template <>
 	Glib::ustring
@@ -139,10 +147,13 @@ namespace ODBC {
 		return writeToBuf(buf, "%s");
 	}
 	template <>
-	Glib::ustring
+	const Glib::ustring &
 	_Column<SQLCHAR*>::compose() const
 	{
-		return Glib::ustring((const char *)value);
+		if (!composeCache) {
+			composeCache = new Glib::ustring((const char *)value);
+		}
+		return *composeCache;
 	}
 	template <>
 	Glib::ustring
@@ -176,10 +187,13 @@ namespace ODBC {
 		return Glib::ustring(buf, len);
 	}
 	template <>
-	Glib::ustring
+	const Glib::ustring &
 	_Column<SQL_TIMESTAMP_STRUCT>::compose() const
 	{
-		return compose("%F %T");
+		if (!composeCache) {
+			composeCache = new Glib::ustring(Glib::ustring(compose("%F %T")));
+		}
+		return *composeCache;
 	}
 }
 
diff --git a/libodbcpp/column.h b/libodbcpp/column.h
index 3b3370f..67dd0c4 100644
--- a/libodbcpp/column.h
+++ b/libodbcpp/column.h
@@ -22,7 +22,7 @@ namespace ODBC {
 			operator Glib::ustring () const;
 			operator struct tm () const;
 			virtual void rebind(Command *, unsigned int col) const = 0;
-			virtual Glib::ustring compose() const = 0;
+			virtual const Glib::ustring & compose() const = 0;
 			virtual Glib::ustring compose(const Glib::ustring & fmt) const = 0;
 			virtual int writeToBuf(char ** buf) const = 0;
 			virtual int writeToBuf(char ** buf, const char * fmt) const = 0;
@@ -30,6 +30,8 @@ namespace ODBC {
 
 			const unsigned int		colNo;
 			const Glib::ustring		name;
+		protected:
+			mutable Glib::ustring * composeCache;
 		private:
 			SQLUINTEGER		bindSize;			// Allocated memory
 			friend class SelectCommand;
@@ -40,7 +42,7 @@ namespace ODBC {
 			_Column(const Glib::ustring &, unsigned int);
 			~_Column() {}
 			void			rebind(Command *, unsigned int col) const;
-			Glib::ustring	compose() const;
+			const Glib::ustring &	compose() const;
 			Glib::ustring	compose(const Glib::ustring & fmt) const;
 			int				writeToBuf(char ** buf) const;
 			int				writeToBuf(char ** buf, const char * fmt) const;
diff --git a/libodbcpp/selectcommand.cpp b/libodbcpp/selectcommand.cpp
index a1a5531..97102ab 100644
--- a/libodbcpp/selectcommand.cpp
+++ b/libodbcpp/selectcommand.cpp
@@ -34,6 +34,10 @@ ODBC::SelectCommand::fetch()
 	RETCODE rc = SQLFetch(hStmt);
 	switch (rc) {
 		case SQL_SUCCESS:
+			for (Columns::iterator i = columns.begin(); i != columns.end(); i++) {
+				delete (*i)->composeCache;
+				(*i)->composeCache = NULL;
+			}
 			return true;
 		case SQL_NO_DATA:
 			return false;