1 files changed, 204 insertions, 0 deletions
diff --git a/source/20-codegen-compiler/SQLiteHelper.hpp b/source/20-codegen-compiler/SQLiteHelper.hpp
new file mode 100644
index 0000000..c33c2a3
--- /dev/null
+++ b/source/20-codegen-compiler/SQLiteHelper.hpp
@@ -0,0 +1,204 @@
+#pragma once
+
+#include <fmt/format.h>
+#include <sqlite3.h>
+#include <cassert>
+#include <chrono>
+#include <cstddef>
+#include <cstdint>
+#include <sstream>
+#include <stdexcept>
+#include <string_view>
+#include <tuple>
+#include <type_traits>
+
+struct SQLiteDatabase {
+	sqlite3* database = nullptr;
+
+	~SQLiteDatabase() {
+		// NOTE: calling with NULL is a harmless no-op
+		int result = sqlite3_close(database);
+		assert(result == SQLITE_OK);
+	}
+
+	operator sqlite3*() const { return database; }
+	sqlite3** operator&() { return &database; }
+};
+
+struct SQLiteStatement {
+	sqlite3_stmt* stmt = nullptr;
+
+	SQLiteStatement(const SQLiteStatement&) = delete;
+	SQLiteStatement& operator=(const SQLiteStatement&) = delete;
+
+	SQLiteStatement() = default;
+
+	SQLiteStatement(sqlite3* database, std::string_view sql) {
+		Initialize(database, sql);
+	}
+
+	~SQLiteStatement() {
+		// NOTE: calling with NULL is a harmless no-op
+		// NOTE: we don't care about the error code, because they are returned if the statement has errored in the most recent execution
+		//       but deleting it will succeeed anyways
+		sqlite3_finalize(stmt);
+	}
+
+	operator sqlite3_stmt*() const { return stmt; }
+	sqlite3_stmt** operator&() { return &stmt; }
+
+	void Initialize(sqlite3* database, std::string_view sql) {
+		int result = sqlite3_prepare_v2(database, sql.data(), sql.size(), &stmt, nullptr);
+		if (result != SQLITE_OK) {
+			auto msg = fmt::format(
+				"Failed to prepare SQLite3 statement, error message: {}",
+				sqlite3_errmsg(sqlite3_db_handle(stmt)));
+			throw std::runtime_error(msg);
+		}
+	}
+
+	bool InitializeLazily(sqlite3* database, std::string_view sql) {
+		if (!stmt) {
+			Initialize(database, sql);
+			return true;
+		}
+		return false;
+	}
+};
+
+struct SQLiteRunningStatement {
+	sqlite3_stmt* stmt;
+
+	SQLiteRunningStatement(sqlite3_stmt* stmt)
+		: stmt{ stmt } {
+	}
+
+	SQLiteRunningStatement(const SQLiteStatement& stmt)
+		: stmt{ stmt.stmt } {
+	}
+
+	~SQLiteRunningStatement() {
+		sqlite3_clear_bindings(stmt);
+		sqlite3_reset(stmt);
+	}
+
+	void BindArgument(int index, int32_t value) {
+		sqlite3_bind_int(stmt, index, (int)value);
+	}
+
+	void BindArgument(int index, uint32_t value) {
+		sqlite3_bind_int(stmt, index, (int)value);
+	}
+
+	void BindArgument(int index, int64_t value) {
+		sqlite3_bind_int64(stmt, index, value);
+	}
+
+	void BindArgument(int index, uint64_t value) {
+		sqlite3_bind_int64(stmt, index, (int64_t)value);
+	}
+
+	void BindArgument(int index, const char* value) {
+		sqlite3_bind_text(stmt, index, value, -1, nullptr);
+	}
+
+	void BindArgument(int index, std::string_view value) {
+		sqlite3_bind_text(stmt, index, value.data(), value.size(), nullptr);
+	}
+
+	void BindArgument(int index, std::nullptr_t) {
+		// Noop
+	}
+
+	template <typename... Ts>
+	void BindArguments(Ts... args) {
+		// NOTE: SQLite3 argument index starts at 1
+		size_t idx = 1;
+		auto HandleEachArgument = [this, &idx](auto arg) {
+			BindArgument(idx, arg);
+			++idx;
+		};
+		(HandleEachArgument(std::forward<Ts>(args)), ...);
+	}
+
+	int Step() {
+		return sqlite3_step(stmt);
+	}
+
+	void StepAndCheck(int forErr) {
+		int err = sqlite3_step(stmt);
+		assert(err == forErr);
+	}
+
+	int StepAndCheckError() {
+		int err = sqlite3_step(stmt);
+		if (err != SQLITE_DONE || err != SQLITE_ROW) {
+			auto msg = fmt::format(
+				"Error {} executing SQLite3 statement, error message: {}",
+				sqlite3_errstr(err),
+				sqlite3_errmsg(sqlite3_db_handle(stmt)));
+			throw std::runtime_error(msg);
+		}
+	}
+
+	void StepUntilDone() {
+		while (true) {
+			int err = sqlite3_step(stmt);
+			// SQLITE_OK is never returned for sqlite3_step() //TODO fact check this
+			if (err == SQLITE_DONE) {
+				break;
+			}
+			if (err == SQLITE_ROW) {
+				continue;
+			}
+
+			auto msg = fmt::format(
+				"Error {} executing SQLite3 statement, error message: {}",
+				sqlite3_errstr(err),
+				sqlite3_errmsg(sqlite3_db_handle(stmt)));
+			throw std::runtime_error(msg);
+		}
+	}
+
+	using TimePoint = std::chrono::time_point<std::chrono::system_clock>;
+	using TpFromUnixTimestamp = std::pair<TimePoint, int64_t>;
+	using TpFromDateTime = std::pair<TimePoint, const char*>;
+
+	// TODO replace with overloads?
+	template <typename T>
+	auto ResultColumn(int column) const {
+		if constexpr (std::is_enum_v<T>) {
+			auto value = sqlite3_column_int64(stmt, column);
+			return static_cast<T>(value);
+		} else if constexpr (std::is_same_v<T, int>) {
+			return sqlite3_column_int(stmt, column);
+		} else if constexpr (std::is_same_v<T, int64_t>) {
+			return sqlite3_column_int64(stmt, column);
+		} else if constexpr (std::is_same_v<T, const char*>) {
+			return (const char*)sqlite3_column_text(stmt, column);
+		} else if constexpr (std::is_same_v<T, std::string> || std::is_same_v<T, std::string_view>) {
+			auto cstr = (const char*)sqlite3_column_text(stmt, column);
+			return T(cstr);
+		} else if constexpr (std::is_same_v<T, TpFromUnixTimestamp>) {
+			auto unixTimestamp = sqlite3_column_int64(stmt, column);
+			auto chrono = std::chrono::seconds(unixTimestamp);
+			return TimePoint(chrono);
+		} else if constexpr (std::is_same_v<T, TpFromDateTime>) {
+			// TODO wait for libstdc++ and libc++ implement c++20 std::chrono addition
+			static_assert(false && sizeof(T), "Unimplemented");
+		} else {
+			static_assert(false && sizeof(T), "Unknown type");
+		}
+	}
+
+	template <typename... Ts>
+	auto ResultColumns() {
+		// NOTE: SQLite3 column index starts at 0
+		// NOTE: ((size_t)-1) + 1 == 0
+		size_t idx = -1;
+		// NOTE: std::make_tuple() -- variadic template function
+		//       std::tuple() -- CTAD constructor
+		//       Both of these cause make the comma operator unsequenced, not viable here
+		return std::tuple{ (++idx, ResultColumn<Ts>(idx))... };
+	}
+};