ircd::db: Add json::tuple related and utils to row.

include/ircd/db/row.h

@@ -51,13 +51,14 @@ struct ircd::db::row
 	using pointer = cell *;
 	using difference_type = size_t;
 
-  private:
+  private: public:
 	std::vector<cell> its;
 
-	template<class pos> friend void seek(row &, const pos &);
-	friend void seek(row &, const string_view &key);
-
   public:
+	auto empty() const                           { return its.empty();                             }
+	auto size() const                            { return its.size();                              }
+	bool valid() const;                          // true on any cell valid; false on empty
+
 	// [GET] Iterations
 	const_iterator begin() const;
 	const_iterator end() const;
@@ -68,16 +69,20 @@ struct ircd::db::row
 	const_iterator find(const string_view &column) const;
 	iterator find(const string_view &column);
 
-	auto empty() const                           { return its.empty();                             }
-	auto size() const                            { return its.size();                              }
-
 	// [GET] Get cell
 	const cell &operator[](const string_view &column) const;
 	cell &operator[](const string_view &column);
 
+	// [GET] Object conversion
+	template<class tuple> explicit operator tuple() const;
+	template<class tuple> explicit operator tuple();
+
     // [SET] Perform operation
 	void operator()(const op &, const string_view &col, const string_view &val = {}, const sopts & = {});
 
+	// All cells
+	void load(const gopts & = {});               // !DANGER! not atomic
+
 	row(std::vector<cell> cells = {})
 	:its{std::move(cells)}
 	{}
@@ -87,6 +92,12 @@ struct ircd::db::row
 	    const vector_view<string_view> &columns = {},
 	    gopts opts = {});
 
+	template<class... T>
+	row(database &,
+	    const string_view &key = {},
+	    const json::tuple<T...> & = {},
+	    gopts opts = {});
+
 	template<class pos> friend bool seeka(row &, const pos &);
 	template<class pos> friend bool seek(row &, const pos &);
 	friend size_t trim(row &, const std::function<bool (cell &)> &);
@@ -180,6 +191,42 @@ struct ircd::db::row::delta
 	{}
 };
 
+template<class... T>
+ircd::db::row::row(database &d,
+                   const string_view &key,
+                   const json::tuple<T...> &t,
+                   gopts opts)
+:row{[&d, &key, &t, &opts]
+() -> row
+{
+	std::array<string_view, t.size()> cols;
+	json::_key_transform(t, std::begin(cols), std::end(cols));
+	return { d, key, cols, opts };
+}()}
+{
+}
+
+template<class tuple>
+ircd::db::row::operator tuple()
+{
+	tuple ret;
+	for(auto &cell : *this)
+		json::set(ret, cell.col(), cell.val());
+
+	return ret;
+}
+
+template<class tuple>
+ircd::db::row::operator tuple()
+const
+{
+	tuple ret;
+	for(const auto &cell : *this)
+		json::set(ret, cell.col(), cell.val());
+
+	return ret;
+}
+
 inline ircd::db::cell &
 ircd::db::row::operator[](const string_view &column)
 {

ircd/db.cc

@@ -1733,6 +1733,27 @@ const
 	return ret;
 }
 
+bool
+ircd::db::row::valid()
+const
+{
+	return std::any_of(std::begin(its), std::end(its), []
+	(const auto &cell)
+	{
+		return cell.valid();
+	});
+}
+
+void
+ircd::db::row::load(const gopts &opts)
+{
+	std::for_each(std::begin(its), std::end(its), [&opts]
+	(auto &cell)
+	{
+		cell.load(opts);
+	});
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // db/column.h