Read fields as std::optional, if available.

New field method: get<T>(), returns an optional.  If the field is null,
the optional is empty.  Otherwise, it contains the field's value.

ChangeLog

@@ -1,3 +1,7 @@
+2016-12-11  Jeroen T. Vermeulen <jtv@xs4all.nl>
+ configitems, configure.ac.in, include/pqxx/field.hxx:
+ - Support std::optional or std::experimental::optional if available.
+ - New field::get returns optional.
 2016-12-11  Jeroen T. Vermeulen <jtv@xs4all.nl>
  include/pqxx/binarystring.hxx, include/pqxx/result.hxx, include/pqxx/row.hxx,
  src/result.cxx, src/row.cxx:

config/ltmain.sh

@@ -31,7 +31,7 @@
 
 PROGRAM=libtool
 PACKAGE=libtool
-VERSION="2.4.6 Debian-2.4.6-0.1"
+VERSION="2.4.6 Debian-2.4.6-1"
 package_revision=2.4.6
 
 
@@ -1977,7 +1977,7 @@ func_version ()
 # End:
 
 # Set a version string.
-scriptversion='(GNU libtool) 2.4.6'
+scriptversion='(GNU libtool) 2.4.6 Debian-2.4.6-1'
 
 
 # func_echo ARG...
@@ -2068,7 +2068,7 @@ include the following information:
        compiler:       $LTCC
        compiler flags: $LTCFLAGS
        linker:         $LD (gnu? $with_gnu_ld)
-       version:        $progname (GNU libtool) 2.4.6
+       version:        $progname $scriptversion
        automake:       `($AUTOMAKE --version) 2>/dev/null |$SED 1q`
        autoconf:       `($AUTOCONF --version) 2>/dev/null |$SED 1q`
 

config/m4/libtool.m4

@@ -728,7 +728,6 @@ _LT_CONFIG_SAVE_COMMANDS([
     cat <<_LT_EOF >> "$cfgfile"
 #! $SHELL
 # Generated automatically by $as_me ($PACKAGE) $VERSION
-# Libtool was configured on host `(hostname || uname -n) 2>/dev/null | sed 1q`:
 # NOTE: Changes made to this file will be lost: look at ltmain.sh.
 
 # Provide generalized library-building support services.

configitems

@@ -20,6 +20,8 @@ PQXX_HAVE_FINAL	public	compiler
 PQXX_HAVE_GCC_VISIBILITY	internal	compiler
 PQXX_HAVE_ISINF	internal	compiler
 PQXX_HAVE_ISNAN	internal	compiler
+PQXX_HAVE_OPTIONAL	public	compiler
+PQXX_HAVE_EXP_OPTIONAL	public	compiler
 PQXX_HAVE_MOVE	public	compiler
 PQXX_HAVE_NOEXCEPT	public	compiler
 PQXX_HAVE_NORETURN	public	compiler

configure

@@ -16602,6 +16602,56 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $final_keyword" >&5
 $as_echo "$final_keyword" >&6; }
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for C++17 std::optional support" >&5
+$as_echo_n "checking for C++17 std::optional support... " >&6; }
+have_optional=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <optional>
+int
+main ()
+{
+return std::optional<int>(0).value()
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+
+$as_echo "#define PQXX_HAVE_OPTIONAL 1" >>confdefs.h
+
+else
+  have_optional=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_optional" >&5
+$as_echo "$have_optional" >&6; }
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for experimental C++17 std::optional support" >&5
+$as_echo_n "checking for experimental C++17 std::optional support... " >&6; }
+have_exp_optional=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <experimental/optional>
+int
+main ()
+{
+return std::experimental::optional<int>(0).value()
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+
+$as_echo "#define PQXX_HAVE_EXP_OPTIONAL 1" >>confdefs.h
+
+else
+  have_exp_optional=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_exp_optional" >&5
+$as_echo "$have_exp_optional" >&6; }
+
 boost_smart_ptr=yes
 
 ac_fn_cxx_check_header_mongrel "$LINENO" "boost/smart_ptr.hpp" "ac_cv_header_boost_smart_ptr_hpp" "$ac_includes_default"
@@ -19715,7 +19765,6 @@ $as_echo X"$file" |
     cat <<_LT_EOF >> "$cfgfile"
 #! $SHELL
 # Generated automatically by $as_me ($PACKAGE) $VERSION
-# Libtool was configured on host `(hostname || uname -n) 2>/dev/null | sed 1q`:
 # NOTE: Changes made to this file will be lost: look at ltmain.sh.
 
 # Provide generalized library-building support services.

configure.ac

@@ -261,6 +261,30 @@ AC_TRY_COMPILE(
 	final_keyword=no)
 AC_MSG_RESULT($final_keyword)
 
+AC_MSG_CHECKING([for C++17 std::optional support])
+have_optional=yes
+AC_TRY_COMPILE(
+	[#include <optional>],
+	[return std::optional<int>(0).value()],
+	AC_DEFINE(
+		[PQXX_HAVE_OPTIONAL],
+		1,
+		[Define if the compiler supports std::optional.]),
+	have_optional=no)
+AC_MSG_RESULT($have_optional)
+
+AC_MSG_CHECKING([for experimental C++17 std::optional support])
+have_exp_optional=yes
+AC_TRY_COMPILE(
+	[#include <experimental/optional>],
+	[return std::experimental::optional<int>(0).value()],
+	AC_DEFINE(
+		[PQXX_HAVE_EXP_OPTIONAL],
+		1,
+		[Define if the compiler supports std::experimental::optional.]),
+	have_exp_optional=no)
+AC_MSG_RESULT($have_exp_optional)
+
 boost_smart_ptr=yes
 AC_CHECK_HEADER(boost/smart_ptr.hpp, AC_DEFINE(PQXX_HAVE_BOOST_SMART_PTR, 1,
 	[Define if you have the <boost/smart_ptr.hpp> header]),

configure.ac.in

@@ -261,6 +261,30 @@ AC_TRY_COMPILE(
 	final_keyword=no)
 AC_MSG_RESULT($final_keyword)
 
+AC_MSG_CHECKING([for C++17 std::optional support])
+have_optional=yes
+AC_TRY_COMPILE(
+	[#include <optional>],
+	[return std::optional<int>(0).value()],
+	AC_DEFINE(
+		[PQXX_HAVE_OPTIONAL],
+		1,
+		[Define if the compiler supports std::optional.]),
+	have_optional=no)
+AC_MSG_RESULT($have_optional)
+
+AC_MSG_CHECKING([for experimental C++17 std::optional support])
+have_exp_optional=yes
+AC_TRY_COMPILE(
+	[#include <experimental/optional>],
+	[return std::experimental::optional<int>(0).value()],
+	AC_DEFINE(
+		[PQXX_HAVE_EXP_OPTIONAL],
+		1,
+		[Define if the compiler supports std::experimental::optional.]),
+	have_exp_optional=no)
+AC_MSG_RESULT($have_exp_optional)
+
 boost_smart_ptr=yes
 AC_CHECK_HEADER(boost/smart_ptr.hpp, AC_DEFINE(PQXX_HAVE_BOOST_SMART_PTR, 1,
 	[Define if you have the <boost/smart_ptr.hpp> header]),

include/pqxx/config.h.in

@@ -75,6 +75,9 @@
 /* Define if distance() works according to the standard */
 #undef PQXX_HAVE_DISTANCE
 
+/* Define if the compiler supports std::experimental::optional. */
+#undef PQXX_HAVE_EXP_OPTIONAL
+
 /* Define if the compiler supports the final keyword. */
 #undef PQXX_HAVE_FINAL
 
@@ -108,6 +111,9 @@
 /* Define if compiler supports [[noreturn]] attribute */
 #undef PQXX_HAVE_NORETURN
 
+/* Define if the compiler supports std::optional. */
+#undef PQXX_HAVE_OPTIONAL
+
 /* Define if the compiler supports the override keyword. */
 #undef PQXX_HAVE_OVERRIDE
 

include/pqxx/field.hxx

@@ -22,6 +22,14 @@
 #include "pqxx/compiler-public.hxx"
 #include "pqxx/compiler-internal-pre.hxx"
 
+#if defined(PQXX_HAVE_OPTIONAL)
+#include <optional>
+#endif
+
+#if defined(PQXX_HAVE_EXP_OPTIONAL)
+#include <experimental/optional>
+#endif
+
 #include "pqxx/strconv"
 
 
@@ -165,7 +173,33 @@ public:
     return Obj;
   }
 
+#if defined(PQXX_HAVE_OPTIONAL)
+  /// Return value as std::optional, or blank value if null.
+  template<typename T> std::optional<T> get() const
+  {
+    typedef std::optional<T> optional;
+    if (is_null()) return optional();
+    else return optional(as<T>());
+  }
+#endif
+
+#if defined(PQXX_HAVE_EXP_OPTIONAL)
+  /// Return value as std::experimental::optional, or blank value if null.
+  template<typename T> std::experimental::optional<T> get() const
+  {
+    typedef std::experimental::optional<T> optional;
+    if (is_null()) return optional();
+    else return optional(as<T>());
+  }
+#endif
+
+  /// Is this field's value null?
   bool is_null() const PQXX_NOEXCEPT;					//[t12]
+
+  /// Return number of bytes taken up by the field's value.
+  /**
+   * Includes the terminating zero byte.
+   */
   size_type size() const PQXX_NOEXCEPT;					//[t11]
   //@}
 

test/unit/Makefile.am

@@ -34,7 +34,9 @@ runner_SOURCES = \
   test_pipeline.cxx \
   test_prepared_statement.cxx \
   test_read_transaction.cxx \
+  test_result_iteration.cxx \
   test_result_slicing.cxx \
+  test_row.cxx \
   test_simultaneous_transactions.cxx \
   test_sql_cursor.cxx \
   test_stateless_cursor.cxx \

test/unit/Makefile.in

@@ -126,8 +126,9 @@ am_runner_OBJECTS = test_binarystring.$(OBJEXT) \
 	test_exceptions.$(OBJEXT) test_float.$(OBJEXT) \
 	test_notification.$(OBJEXT) test_parameterized.$(OBJEXT) \
 	test_pipeline.$(OBJEXT) test_prepared_statement.$(OBJEXT) \
-	test_read_transaction.$(OBJEXT) test_result_slicing.$(OBJEXT) \
-	test_simultaneous_transactions.$(OBJEXT) \
+	test_read_transaction.$(OBJEXT) \
+	test_result_iteration.$(OBJEXT) test_result_slicing.$(OBJEXT) \
+	test_row.$(OBJEXT) test_simultaneous_transactions.$(OBJEXT) \
 	test_sql_cursor.$(OBJEXT) test_stateless_cursor.$(OBJEXT) \
 	test_string_conversion.$(OBJEXT) test_subtransaction.$(OBJEXT) \
 	test_test_helpers.$(OBJEXT) test_thread_safety_model.$(OBJEXT) \
@@ -560,7 +561,9 @@ runner_SOURCES = \
   test_pipeline.cxx \
   test_prepared_statement.cxx \
   test_read_transaction.cxx \
+  test_result_iteration.cxx \
   test_result_slicing.cxx \
+  test_row.cxx \
   test_simultaneous_transactions.cxx \
   test_sql_cursor.cxx \
   test_stateless_cursor.cxx \
@@ -637,7 +640,9 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_pipeline.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_prepared_statement.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_read_transaction.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_result_iteration.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_result_slicing.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_row.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_simultaneous_transactions.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_sql_cursor.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/test_stateless_cursor.Po@am__quote@

win32/vc-test-unit.mak

@@ -92,7 +92,9 @@ OBJS= \
   $(INTDIR)\test_pipeline.obj \
   $(INTDIR)\test_prepared_statement.obj \
   $(INTDIR)\test_read_transaction.obj \
+  $(INTDIR)\test_result_iteration.obj \
   $(INTDIR)\test_result_slicing.obj \
+  $(INTDIR)\test_row.obj \
   $(INTDIR)\test_simultaneous_transactions.obj \
   $(INTDIR)\test_sql_cursor.obj \
   $(INTDIR)\test_stateless_cursor.obj \
@@ -158,8 +160,12 @@ $(INTDIR)\test_prepared_statement.obj:
 	@$(CXX) $(CXX_FLAGS) test/unit/test_prepared_statement.cxx /Fo"$(INTDIR)\\" /Fd"$(INTDIR)\\"
 $(INTDIR)\test_read_transaction.obj:
 	@$(CXX) $(CXX_FLAGS) test/unit/test_read_transaction.cxx /Fo"$(INTDIR)\\" /Fd"$(INTDIR)\\"
+$(INTDIR)\test_result_iteration.obj:
+	@$(CXX) $(CXX_FLAGS) test/unit/test_result_iteration.cxx /Fo"$(INTDIR)\\" /Fd"$(INTDIR)\\"
 $(INTDIR)\test_result_slicing.obj:
 	@$(CXX) $(CXX_FLAGS) test/unit/test_result_slicing.cxx /Fo"$(INTDIR)\\" /Fd"$(INTDIR)\\"
+$(INTDIR)\test_row.obj:
+	@$(CXX) $(CXX_FLAGS) test/unit/test_row.cxx /Fo"$(INTDIR)\\" /Fd"$(INTDIR)\\"
 $(INTDIR)\test_simultaneous_transactions.obj:
 	@$(CXX) $(CXX_FLAGS) test/unit/test_simultaneous_transactions.cxx /Fo"$(INTDIR)\\" /Fd"$(INTDIR)\\"
 $(INTDIR)\test_sql_cursor.obj: