From 63b2ca0dbdae190941d60a55c9cff99d4a75a0e1 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 31 May 2021 13:18:17 +0100
Subject: Initial commit of prepstmt, selects, record sets

This is full of holes, but all the basics are covered.
---
 lib/dbStmt.h | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 lib/dbStmt.h

(limited to 'lib/dbStmt.h')

diff --git a/lib/dbStmt.h b/lib/dbStmt.h
new file mode 100644
index 0000000..3e98b34
--- /dev/null
+++ b/lib/dbStmt.h
@@ -0,0 +1,66 @@
+#ifndef MYGRATE_DBSTMT_H
+#define MYGRATE_DBSTMT_H
+
+#include <compileTimeFormatter.h>
+#include <dbConn.h>
+#include <dbRecordSet.h>
+#include <memory>
+#include <string_view>
+#include <type_traits>
+
+namespace MyGrate {
+	class DbConn;
+	enum class ParamMode { None, DollarNum, QMark };
+
+	template<AdHoc::support::basic_fixed_string S, ParamMode pm = ParamMode::None> 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 {
+			switch (pm) {
+				case ParamMode::None:
+					return 0LU;
+				case ParamMode::DollarNum: {
+					const auto pn = [](const char * c, const char * const e) {
+						std::size_t n {0};
+						while (++c != e && *c >= '0' && *c <= '9') {
+							n = (n * 10) + (*c - '0');
+						}
+						return n;
+					};
+					return pn(std::max_element(S.v().begin(), S.v().end(),
+									  [pn, e = S.v().end()](const char & a, const char & b) {
+										  return (a == '$' ? pn(&a, e) : 0) < (b == '$' ? pn(&b, e) : 0);
+									  }),
+							S.v().end());
+				}
+				case ParamMode::QMark:
+					return std::count_if(S.v().begin(), S.v().end(), [](char c) {
+						return c == '?';
+					});
+			}
+		}()};
+
+		using Return = std::conditional_t<isSelect, RecordSetPtr, std::size_t>;
+
+		template<typename... P>
+		static Return
+		execute(DbConn * c, P &&... p)
+		{
+			static_assert(sizeof...(P) == paramCount);
+			auto stmt {c->prepare(S, sizeof...(P))};
+			stmt->execute({std::forward<P...>(p)...});
+			if constexpr (isSelect) {
+				return stmt->recordSet();
+			}
+			else {
+				return stmt->rows();
+			}
+		}
+	};
+}
+
+#endif
-- 
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