From bf55ecaeb6849eab89fdb9bc5da51ff32dd1ea33 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Fri, 21 May 2021 08:43:43 +0100
Subject: Unpack row data into a vector or vector pair

---
 lib/row.cpp   | 34 +++++++++++++++++++++++++++-------
 lib/row.h     | 18 ++++++++++++++----
 main/main.cpp | 16 ++++++++++++++--
 3 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/lib/row.cpp b/lib/row.cpp
index d59cdba..45e2959 100644
--- a/lib/row.cpp
+++ b/lib/row.cpp
@@ -3,13 +3,21 @@
 #include <string>
 
 namespace MyGrate {
-	Row::Row(const st_mariadb_rpl_rows_event & r, const st_mariadb_rpl_table_map_event & t) : row {r}, tm {t} { }
+	Row::Row(const st_mariadb_rpl_rows_event & row, const st_mariadb_rpl_table_map_event & tm) :
+		Row(row, tm, RawDataReader {tm.metadata}, RawDataReader {row.row_data, row.row_data_size})
+	{
+	}
+
+	Row::Row(const st_mariadb_rpl_rows_event & row, const st_mariadb_rpl_table_map_event & tm,
+			MyGrate::RawDataReader && md, MyGrate::RawDataReader && data) :
+		Row {row, tm, md, data}
+	{
+	}
 
-	void
-	Row::forEachField(const std::function<void(MySQL::FieldValue)> & cb)
+	Row::Row(const st_mariadb_rpl_rows_event & row, const st_mariadb_rpl_table_map_event & tm,
+			MyGrate::RawDataReader & md, MyGrate::RawDataReader & data)
 	{
-		MyGrate::RawDataReader md {tm.metadata};
-		MyGrate::RawDataReader data {row.row_data, row.row_data_size};
+		reserve(tm.column_count);
 		const size_t flagBytes {(tm.column_count + 7) / 8};
 		MyGrate::BitSet nullFlags {data.viewValue<std::span<const std::byte>>(flagBytes)};
 		MyGrate::BitSet columnFlags {{reinterpret_cast<const std::byte *>(row.column_bitmap), flagBytes}};
@@ -44,13 +52,13 @@ namespace MyGrate {
 							break;
 						default:;
 					}
-					cb(nullptr);
+					emplace_back(nullptr);
 				}
 				else {
 					switch (type) {
 #define TYPE_CALLBACK(T) \
 	case T: \
-		cb(MySQL::Type<T>::read(md, data)); \
+		emplace_back(MySQL::Type<T>::read(md, data)); \
 		break
 						TYPE_CALLBACK(MYSQL_TYPE_DECIMAL);
 						TYPE_CALLBACK(MYSQL_TYPE_TINY);
@@ -98,4 +106,16 @@ namespace MyGrate {
 			++colIter;
 		}
 	}
+
+	RowPair::RowPair(const st_mariadb_rpl_rows_event & row, const st_mariadb_rpl_table_map_event & tm) :
+		RowPair(row, tm, RawDataReader {tm.metadata}, RawDataReader {tm.metadata},
+				RawDataReader {row.row_data, row.row_data_size})
+	{
+	}
+
+	RowPair::RowPair(const st_mariadb_rpl_rows_event & row, const st_mariadb_rpl_table_map_event & tm,
+			MyGrate::RawDataReader && md1, MyGrate::RawDataReader && md2, MyGrate::RawDataReader && data) :
+		std::pair<Row, Row> {Row {row, tm, md1, data}, Row {row, tm, md2, data}}
+	{
+	}
 }
diff --git a/lib/row.h b/lib/row.h
index ac2c135..4191644 100644
--- a/lib/row.h
+++ b/lib/row.h
@@ -6,15 +6,25 @@
 #include <functional>
 
 namespace MyGrate {
-	class Row {
+	class Row : public std::vector<MySQL::FieldValue> {
 	public:
 		Row(const st_mariadb_rpl_rows_event &, const st_mariadb_rpl_table_map_event &);
 
-		void forEachField(const std::function<void(MySQL::FieldValue)> & callback);
+	private:
+		friend class RowPair;
+		Row(const st_mariadb_rpl_rows_event &, const st_mariadb_rpl_table_map_event &, MyGrate::RawDataReader && md,
+				MyGrate::RawDataReader && data);
+		Row(const st_mariadb_rpl_rows_event &, const st_mariadb_rpl_table_map_event &, MyGrate::RawDataReader & md,
+				MyGrate::RawDataReader & data);
+	};
+
+	class RowPair : public std::pair<Row, Row> {
+	public:
+		RowPair(const st_mariadb_rpl_rows_event &, const st_mariadb_rpl_table_map_event &);
 
 	private:
-		const st_mariadb_rpl_rows_event & row;
-		const st_mariadb_rpl_table_map_event & tm;
+		RowPair(const st_mariadb_rpl_rows_event &, const st_mariadb_rpl_table_map_event &,
+				MyGrate::RawDataReader && md1, MyGrate::RawDataReader && md2, MyGrate::RawDataReader && data);
 	};
 }
 
diff --git a/main/main.cpp b/main/main.cpp
index d976a0a..b5d5a4c 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -51,7 +51,19 @@ struct write {
 static void
 dumpRowData(const st_mariadb_rpl_rows_event & row)
 {
-	MyGrate::Row {row, tableMaps.at(row.table_id)->event.table_map}.forEachField([](auto && fv) {
+	MyGrate::Row r {row, tableMaps.at(row.table_id)->event.table_map};
+	std::for_each(r.begin(), r.end(), [](auto && fv) {
+		std::visit(write {}, fv);
+	});
+}
+static void
+dumpRowPairData(const st_mariadb_rpl_rows_event & row)
+{
+	MyGrate::RowPair rp {row, tableMaps.at(row.table_id)->event.table_map};
+	std::for_each(rp.first.begin(), rp.first.end(), [](auto && fv) {
+		std::visit(write {}, fv);
+	});
+	std::for_each(rp.second.begin(), rp.second.end(), [](auto && fv) {
 		std::visit(write {}, fv);
 	});
 }
@@ -80,7 +92,7 @@ doUpdate(MariaDB_Event_Ptr event)
 {
 	const auto & rs = event->event.rows;
 	AdHoc::scprintf<"Update %?\n">(std::cout, rs.table_id);
-	dumpRowData(event->event.rows);
+	dumpRowPairData(event->event.rows);
 }
 
 static void
-- 
cgit v1.2.3