From 6e726340e23a97480b17065a633c36a9ba53cf14 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Thu, 3 Jun 2021 00:17:28 +0100
Subject: Determine parameter mode at point of call by DB type property

It's still constexpr, so that's all good.
---
 lib/dbConn.h           |  2 ++
 lib/dbStmt.h           | 17 ++++++++---------
 lib/input/mysqlConn.h  |  2 ++
 lib/output/pq/pqConn.h |  2 ++
 4 files changed, 14 insertions(+), 9 deletions(-)

(limited to 'lib')

diff --git a/lib/dbConn.h b/lib/dbConn.h
index e4b056c..3f14dcb 100644
--- a/lib/dbConn.h
+++ b/lib/dbConn.h
@@ -15,6 +15,8 @@ namespace MyGrate {
 	};
 	using DbPrepStmtPtr = std::unique_ptr<DbPrepStmt>;
 
+	enum class ParamMode { None, DollarNum, QMark };
+
 	class DbConn {
 	public:
 		virtual ~DbConn() = default;
diff --git a/lib/dbStmt.h b/lib/dbStmt.h
index 81621de..80dbd71 100644
--- a/lib/dbStmt.h
+++ b/lib/dbStmt.h
@@ -9,17 +9,16 @@
 #include <type_traits>
 
 namespace MyGrate {
-	class DbConn;
-	enum class ParamMode { None, DollarNum, QMark };
-
-	template<Support::basic_fixed_string S, ParamMode pm = ParamMode::None> class DbStmt {
+	template<Support::basic_fixed_string S> class DbStmt {
 	public:
 		// This don't account for common table expressions, hopefully won't need those :)
 		static constexpr auto isSelect {S.v().starts_with("SELECT") || S.v().starts_with("SHOW")
 				|| S.v().find("RETURNING") != std::string_view::npos};
 
 		// These don't account for string literals, which we'd prefer to avoid anyway :)
-		static constexpr auto paramCount {[]() -> std::size_t {
+		static constexpr std::size_t
+		paramCount(ParamMode pm)
+		{
 			switch (pm) {
 				case ParamMode::None:
 					return 0LU;
@@ -42,15 +41,15 @@ namespace MyGrate {
 						return c == '?';
 					});
 			}
-		}()};
+		}
 
 		using Return = std::conditional_t<isSelect, RecordSetPtr, std::size_t>;
 
-		template<typename... P>
+		template<typename ConnType, typename... P>
 		static Return
-		execute(DbConn * c, P &&... p)
+		execute(ConnType * c, P &&... p)
 		{
-			static_assert(sizeof...(P) == paramCount);
+			static_assert(sizeof...(P) == paramCount(ConnType::paramMode));
 			auto stmt {c->prepare(S, sizeof...(P))};
 			stmt->execute({std::forward<P...>(p)...});
 			if constexpr (isSelect) {
diff --git a/lib/input/mysqlConn.h b/lib/input/mysqlConn.h
index 2f71262..29a34db 100644
--- a/lib/input/mysqlConn.h
+++ b/lib/input/mysqlConn.h
@@ -10,6 +10,8 @@
 namespace MyGrate::Input {
 	class MySQLConn : public MYSQL, public DbConn {
 	public:
+		static constexpr auto paramMode {ParamMode::QMark};
+
 		MySQLConn(const char * const host, const char * const user, const char * const pass, unsigned short port);
 		~MySQLConn();
 
diff --git a/lib/output/pq/pqConn.h b/lib/output/pq/pqConn.h
index 856683d..ae5fc9a 100644
--- a/lib/output/pq/pqConn.h
+++ b/lib/output/pq/pqConn.h
@@ -14,6 +14,8 @@
 namespace MyGrate::Output::Pq {
 	class PqConn : public DbConn {
 	public:
+		static constexpr auto paramMode {ParamMode::DollarNum};
+
 		explicit PqConn(const char * const str);
 		virtual ~PqConn() = default;
 
-- 
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