From 51ac5d2007f1caf6bc6e65b485ba896357696654 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 6 Jun 2021 00:59:03 +0100
Subject: Add RecordSet RowView

This represents a view into a recordset by row number and provides easy
access to values in a column by index and the ability to create a new
object instance by N columns which are passed to the object's
constructor.
---
 lib/dbRecordSet.cpp              | 17 +++++++++++++++++
 lib/dbRecordSet.h                | 26 ++++++++++++++++++++++++++
 lib/input/replStream.cpp         |  4 ++--
 lib/input/replStream.h           |  2 +-
 lib/output/pq/updateDatabase.cpp |  3 ++-
 5 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 lib/dbRecordSet.cpp

diff --git a/lib/dbRecordSet.cpp b/lib/dbRecordSet.cpp
new file mode 100644
index 0000000..66ade0e
--- /dev/null
+++ b/lib/dbRecordSet.cpp
@@ -0,0 +1,17 @@
+#include "dbRecordSet.h"
+
+namespace MyGrate {
+	RowView::RowView(const RecordSet * rs, std::size_t rw) : recordSet {rs}, row {rw} { }
+
+	DbValue
+	RowView::operator[](std::size_t col) const
+	{
+		return recordSet->at(row, col);
+	}
+
+	RowView
+	RecordSet::operator[](std::size_t row) const
+	{
+		return {this, row};
+	}
+}
diff --git a/lib/dbRecordSet.h b/lib/dbRecordSet.h
index 9bddc01..5bd6967 100644
--- a/lib/dbRecordSet.h
+++ b/lib/dbRecordSet.h
@@ -5,6 +5,31 @@
 #include <memory>
 
 namespace MyGrate {
+	class RecordSet;
+
+	class RowView {
+	public:
+		RowView(const RecordSet * rs, std::size_t rw = 0);
+
+		DbValue operator[](std::size_t col) const;
+
+		template<typename S, std::size_t N, typename Indices = std::make_index_sequence<N>>
+		auto
+		create() const
+		{
+			return create<S>(Indices {});
+		}
+
+		template<typename S, std::size_t... I> auto create(std::index_sequence<I...>) const
+		{
+			return std::make_unique<S>((*this)[I]...);
+		}
+
+	private:
+		const RecordSet * recordSet;
+		std::size_t row;
+	};
+
 	class RecordSet {
 	public:
 		virtual ~RecordSet() = default;
@@ -12,6 +37,7 @@ namespace MyGrate {
 		virtual std::size_t rows() const = 0;
 		virtual std::size_t columns() const = 0;
 		virtual DbValue at(std::size_t, std::size_t) const = 0;
+		RowView operator[](std::size_t row) const;
 	};
 	using RecordSetPtr = std::unique_ptr<RecordSet>;
 }
diff --git a/lib/input/replStream.cpp b/lib/input/replStream.cpp
index c3dea9a..1ec696a 100644
--- a/lib/input/replStream.cpp
+++ b/lib/input/replStream.cpp
@@ -9,9 +9,9 @@
 #include <utility>
 
 namespace MyGrate::Input {
-	ReplicationStream::ReplicationStream(const char * const host, const char * const user, const char * const pass,
+	ReplicationStream::ReplicationStream(const std::string & host, const std::string & user, const std::string & pass,
 			unsigned short port, uint64_t sid, std::string fn, uint64_t pos) :
-		MySQLConn {host, user, pass, port},
+		MySQLConn {host.c_str(), user.c_str(), pass.c_str(), port},
 		serverid {sid}, filename {std::move(fn)}, position {pos}
 	{
 	}
diff --git a/lib/input/replStream.h b/lib/input/replStream.h
index 01c9ef3..bc47267 100644
--- a/lib/input/replStream.h
+++ b/lib/input/replStream.h
@@ -13,7 +13,7 @@ namespace MyGrate {
 namespace MyGrate::Input {
 	class ReplicationStream : public EventSourceBase, MySQLConn {
 	public:
-		ReplicationStream(const char * const host, const char * const user, const char * const pass,
+		ReplicationStream(const std::string & host, const std::string & user, const std::string & pass,
 				unsigned short port, uint64_t serverid, std::string filename, uint64_t position);
 
 		void readEvents(EventHandlerBase &) override;
diff --git a/lib/output/pq/updateDatabase.cpp b/lib/output/pq/updateDatabase.cpp
index ebcabb3..352517e 100644
--- a/lib/output/pq/updateDatabase.cpp
+++ b/lib/output/pq/updateDatabase.cpp
@@ -4,6 +4,7 @@
 #include <dbRecordSet.h>
 #include <eventSourceBase.h>
 #include <helpers.h>
+#include <input/replStream.h>
 #include <memory>
 #include <output/pq/sql/selectSource.h>
 #include <stdexcept>
@@ -16,6 +17,6 @@ namespace MyGrate::Output::Pq {
 	{
 		auto srcrec = output::pq::sql::selectSource::execute(this, source);
 		verify<std::runtime_error>(srcrec->rows() == 1, "Wrong number of source config rows");
-		return {};
+		return (*srcrec)[0].create<Input::ReplicationStream, 7>();
 	}
 }
-- 
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