Add assert and tweak comments.

sqlite3cpp.cpp

@@ -68,9 +68,15 @@ row_iter &row_iter::operator++() {
   return *this;
 }
 
-row const &row_iter::operator*() const noexcept { return m_row; }
+row const &row_iter::operator*() const noexcept {
+  assert(is_valid());
+  return m_row;
+}
 
-row const *row_iter::operator->() const noexcept { return &m_row; }
+row const *row_iter::operator->() const noexcept {
+  assert(is_valid());
+  return &m_row;
+}
 
 bool row_iter::operator==(row_iter const &i) const noexcept {
   return m_session.lock() == i.m_session.lock();

sqlite3cpp.h

@@ -123,6 +123,7 @@ struct SQLITE3CPP_EXPORT row_iter {
   row const &operator*() const noexcept;
   row const *operator->() const noexcept;
   bool is_valid() const noexcept;
+
  private:
   friend struct cursor;
   row_iter() noexcept {}
@@ -140,9 +141,9 @@ struct SQLITE3CPP_EXPORT cursor {
   // cursor csr = db.make_cursor();
   // csr.execute("insert into MyTable values(?)", 123);
   //
-  // Binded text types, i.e. string, string_view, char const*, are referenced by
-  // row_iter and cursor. They need to be valid until next call to |execute()|,
-  // cursor reaches end of life.
+  // Binded text types, i.e. string, string_view, and char const*, are
+  // referenced by row_iter and cursor. They need to be valid until next call to
+  // |execute()| or cursor reaches end of life.
   //
   // Only poisitioned binding is supported currently. Named
   // binding is not supported yet.
@@ -152,8 +153,9 @@ struct SQLITE3CPP_EXPORT cursor {
   // Execute multiple SQL statements.
   cursor &executescript(std::string const &sql);
 
-  // Row iterator to begin of **reamin** query results. This row_iter becomes
-  // invalid after the cursor it referenced has been detroyed.
+  // Row iterator to begin query results. This row_iter becomes
+  // invalid after the cursor it referenced has been detroyed or another
+  // |begin()| has been called.
   row_iter begin() noexcept;
 
   // Row itertor to end of query results (next to the last one of result).
@@ -200,18 +202,15 @@ struct SQLITE3CPP_EXPORT transaction {
 
   // Issue `commit;` or `end;` when this transaction instance being destroyed.
   void commit() noexcept;
+
  private:
   database &m_db;
   params_t m_params;
 };
 
 struct SQLITE3CPP_EXPORT database {
-  using xfunc_t = std::function<void(sqlite3_context *, int, sqlite3_value **)>;
-  using xfinal_t = std::function<void(sqlite3_context *)>;
-  using xreset_t = std::function<void()>;
-
-  // Create a database connection to |urn|. |urn| could be `:memory:` or a filename.
-  // |urn| should be encoded in UTF-8.
+  // Create a database connection to |urn|. |urn| could be `:memory:` or a
+  // filename. |urn| should be encoded in UTF-8.
   database(std::string const &urn);
 
   // Create a cursor per current database for executing SQL statements.
@@ -263,11 +262,15 @@ struct SQLITE3CPP_EXPORT database {
   std::string version() const;
 
  private:
-  struct aggregate_wrapper_t {
-    xfunc_t step;
-    xfinal_t fin;
-    xreset_t reset;
-    xreset_t release;
+   using xfunc_t = std::function<void(sqlite3_context *, int, sqlite3_value **)>;
+   using xfinal_t = std::function<void(sqlite3_context *)>;
+   using xreset_t = std::function<void()>;
+
+   struct aggregate_wrapper_t {
+     xfunc_t step;
+     xfinal_t fin;
+     xreset_t reset;
+     xreset_t release;
   };
 
   static void forward(sqlite3_context *ctx, int argc, sqlite3_value **argv);

sqlite3cpp.ipp

@@ -157,7 +157,7 @@ inline int bind_val(sqlite3_stmt *stmt, int index, std::string const &val) {
   return sqlite3_bind_text(stmt, index, val.c_str(), val.size(), SQLITE_STATIC);
 }
 
-inline int bind_val(sqlite3_stmt *stmt, int index, std::string_view const &val) {
+inline int bind_val(sqlite3_stmt *stmt, int index, std::string_view val) {
   return sqlite3_bind_text(stmt, index, val.data(), val.size(), SQLITE_STATIC);
 }
 
@@ -172,7 +172,8 @@ inline int bind_val(sqlite3_stmt *stmt, int index, std::nullptr_t _) {
 template <typename T, typename... Args>
 void bind_to_stmt(sqlite3_stmt *stmt, int index, T &&val, Args &&... args) {
   int ec = 0;
-  if (0 != (ec = bind_val(stmt, index, std::forward<T>(val)))) throw error(ec);
+  if (0 != (ec = bind_val(stmt, index, std::forward<T>(val))))
+    throw error(ec);
   bind_to_stmt(stmt, index + 1, std::forward<Args>(args)...);
 }
 
@@ -241,7 +242,7 @@ R invoke(std::function<R(Args...)> func, int argc, sqlite3_value **argv) {
 }
 
 template <typename R, typename... Args>
-database::xfunc_t make_invoker(std::function<R(Args...)> &&func) {
+auto make_invoker(std::function<R(Args...)> &&func) {
   if constexpr (std::is_void_v<R>) {
     return [func](sqlite3_context *ctx, int argc, sqlite3_value **argv) {
       invoke(func, argc, argv);
@@ -305,7 +306,6 @@ namespace sqlite3cpp {
  */
 template <typename... Cols>
 std::tuple<Cols...> row::to() const {
-  // TODO: Report errors
   std::tuple<Cols...> result;
   detail::enumerate(
       [this](int index, auto &&tuple_value) {
@@ -320,8 +320,7 @@ std::tuple<Cols...> row::to() const {
  */
 template <typename... Args>
 cursor &cursor::execute(std::string const &sql, Args &&... args) {
-  // TODO: Support rebind params (which means step() error for not binded params
-  // should be ignored.
+  // TODO: Support rebind params
   sqlite3_stmt *stmt = 0;
   int ec = 0;