From 45c23ec13e3a7322cb446207e6994ae0d932bb94 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 7 Nov 2015 23:56:14 +0000
Subject: Add utility function for passing each row of a result set to a
 function accepting one parameter per column

---
 libdbpp/selectcommand.h          |  4 ++++
 libdbpp/selectcommandUtil.impl.h | 35 +++++++++++++++++++++++++++++++++++
 libdbpp/unittests/Jamfile.jam    | 14 ++++++++++++++
 libdbpp/unittests/testUtils.cpp  | 37 +++++++++++++++++++++++++++++++++++++
 libdbpp/unittests/util.sql       |  8 ++++++++
 5 files changed, 98 insertions(+)
 create mode 100644 libdbpp/selectcommandUtil.impl.h
 create mode 100644 libdbpp/unittests/testUtils.cpp
 create mode 100644 libdbpp/unittests/util.sql

diff --git a/libdbpp/selectcommand.h b/libdbpp/selectcommand.h
index 31ef9ca..1586357 100644
--- a/libdbpp/selectcommand.h
+++ b/libdbpp/selectcommand.h
@@ -7,6 +7,7 @@
 #include <boost/multi_index/indexed_by.hpp>
 #include <boost/multi_index/ordered_index_fwd.hpp>
 #include <boost/multi_index/member.hpp>
+#include <boost/function/function_fwd.hpp>
 #include <boost/shared_ptr.hpp>
 #include <visibility.h>
 
@@ -31,6 +32,9 @@ namespace DB {
 			unsigned int columnCount() const;
 			/// Get the index of a column by name.
 			unsigned int getOrdinal(const Glib::ustring &) const;
+			/// Push each row through a function accepting one value per column
+			template<typename ... Fn, typename Func = boost::function<void(Fn...)>>
+			void forEachRow(const Func & func);
 
 		protected:
 			/// Helper function so clients need not know about boost::multi_index_container.
diff --git a/libdbpp/selectcommandUtil.impl.h b/libdbpp/selectcommandUtil.impl.h
new file mode 100644
index 0000000..26ff1b7
--- /dev/null
+++ b/libdbpp/selectcommandUtil.impl.h
@@ -0,0 +1,35 @@
+#ifndef DB_SELECTCOMMANDUTIL_IMPL_H
+#define DB_SELECTCOMMANDUTIL_IMPL_H
+
+#include "selectcommand.h"
+#include <boost/function.hpp>
+#include <boost/utility/enable_if.hpp>
+
+namespace DB {
+	template<typename Fields, typename Func, unsigned int field, typename ... Fn>
+	inline typename boost::disable_if_c<field < std::tuple_size<Fields>::value>::type
+	forEachField(DB::SelectCommand *, const Func & func, const Fn & ... args)
+	{
+		func(args...);
+	}
+
+	template<typename Fields, typename Func, unsigned int field, typename ... Fn, typename ... Args>
+	inline typename boost::enable_if_c<field < std::tuple_size<Fields>::value>::type
+	forEachField(DB::SelectCommand * sel, const Func & func, const Args & ... args)
+	{
+		typename std::tuple_element<field, Fields>::type a;
+		(*sel)[field] >> a;
+		forEachField<Fields, Func, field + 1, Fn...>(sel, func, args..., a);
+	}
+
+	template<typename ... Fn, typename Func>
+	inline void SelectCommand::forEachRow(const Func & func)
+	{
+		while (fetch()) {
+			forEachField<std::tuple<Fn...>, Func, 0>(this, func);
+		}
+	}
+}
+
+#endif
+
diff --git a/libdbpp/unittests/Jamfile.jam b/libdbpp/unittests/Jamfile.jam
index 0739af1..ad90ec6 100644
--- a/libdbpp/unittests/Jamfile.jam
+++ b/libdbpp/unittests/Jamfile.jam
@@ -17,3 +17,17 @@ run
 	testConnection
 	;
 
+run
+	testUtils.cpp
+	: : :
+	<define>ROOT=\"$(me)\"
+	<define>BOOST_TEST_DYN_LINK
+	<library>..//dbppcore
+	<library>..//adhocutil
+	<library>../../libpqpp//dbpp-postgresql
+	<library>boost_utf
+	<dependency>util.sql
+	:
+	testUtils
+	;
+
diff --git a/libdbpp/unittests/testUtils.cpp b/libdbpp/unittests/testUtils.cpp
new file mode 100644
index 0000000..79506cf
--- /dev/null
+++ b/libdbpp/unittests/testUtils.cpp
@@ -0,0 +1,37 @@
+#define BOOST_TEST_MODULE DbUtil
+#include <boost/test/unit_test.hpp>
+
+#include <factory.h>
+#include <connection.h>
+#include <selectcommand.h>
+#include <selectcommandUtil.impl.h>
+#include <definedDirs.h>
+#include <fstream>
+#include <vector>
+#include <mock.h>
+#include <boost/date_time/posix_time/posix_time_io.hpp>
+
+class StandardMockDatabase : public PQ::Mock {
+	public:
+		StandardMockDatabase() : PQ::Mock("user=postgres dbname=postgres", "pqmock", {
+				rootDir / "util.sql" })
+		{
+		}
+};
+
+BOOST_GLOBAL_FIXTURE( StandardMockDatabase );
+
+BOOST_AUTO_TEST_CASE( forEachRow )
+{
+	auto db = DB::ConnectionPtr(DB::MockDatabase::openConnectionTo("pqmock"));
+	auto sel = DB::SelectCommandPtr(db->newSelectCommand("SELECT a, b, c, d, e FROM forEachRow ORDER BY a LIMIT 1"));
+	sel->forEachRow<int64_t, double, std::string, boost::posix_time::ptime, boost::posix_time::time_duration>(
+			[](auto a, auto b, auto c, auto d, auto e) {
+				BOOST_REQUIRE_EQUAL(1, a);
+				BOOST_REQUIRE_EQUAL(2.3, b);
+				BOOST_REQUIRE_EQUAL("Some text", c);
+				BOOST_REQUIRE_EQUAL(boost::posix_time::ptime_from_tm({ 17, 39, 13, 7, 10, 115, 0, 0, 0, 0, 0}), d);
+				BOOST_REQUIRE_EQUAL(boost::posix_time::time_duration(4, 3, 2), e);
+			});
+}
+
diff --git a/libdbpp/unittests/util.sql b/libdbpp/unittests/util.sql
new file mode 100644
index 0000000..a3c5ac8
--- /dev/null
+++ b/libdbpp/unittests/util.sql
@@ -0,0 +1,8 @@
+CREATE TABLE foreachrow (
+		a int,
+		b numeric(4,2),
+		c text,
+		d timestamp without time zone,
+		e interval);
+INSERT INTO foreachrow(a, b, c, d, e) VALUES(1, 2.3, 'Some text', '2015-11-07 13:39:17', '04:03:02');
+
-- 
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