optimize sqlite bind fast path

sqlite3.go

diff --git a/sqlite3.go b/sqlite3.go
index 76b0f23..3ef78d5 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -866,26 +866,12 @@
 		}
 		var res driver.Result
 		if s.(*SQLiteStmt).s != nil {
-			stmtArgs := make([]driver.NamedValue, 0, len(args))
 			na := s.NumInput()
 			if len(args)-start < na {
 				s.Close()
 				return nil, fmt.Errorf("not enough args to execute query: want %d got %d", na, len(args))
 			}
-			// consume the number of arguments used in the current
-			// statement and append all named arguments not
-			// contained therein
-			if na > 0 {
-				stmtArgs = append(stmtArgs, args[start:start+na]...)
-				for i := range args {
-					if (i < start || i >= na) && args[i].Name != "" {
-						stmtArgs = append(stmtArgs, args[i])
-					}
-				}
-				for i := range stmtArgs {
-					stmtArgs[i].Ordinal = i + 1
-				}
-			}
+			stmtArgs := stmtArgs(args, start, na)
 			res, err = s.(*SQLiteStmt).exec(ctx, stmtArgs)
 			if err != nil && err != driver.ErrSkip {
 				s.Close()
@@ -921,7 +907,6 @@
 func (c *SQLiteConn) query(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
 	start := 0
 	for {
-		stmtArgs := make([]driver.NamedValue, 0, len(args))
 		s, err := c.prepare(ctx, query)
 		if err != nil {
 			return nil, err
@@ -932,18 +917,7 @@
 			s.Close()
 			return nil, fmt.Errorf("not enough args to execute query: want %d got %d", na, len(args)-start)
 		}
-		// consume the number of arguments used in the current
-		// statement and append all named arguments not contained
-		// therein
-		stmtArgs = append(stmtArgs, args[start:start+na]...)
-		for i := range args {
-			if (i < start || i >= na) && args[i].Name != "" {
-				stmtArgs = append(stmtArgs, args[i])
-			}
-		}
-		for i := range stmtArgs {
-			stmtArgs[i].Ordinal = i + 1
-		}
+		stmtArgs := stmtArgs(args, start, na)
 		rows, err := s.(*SQLiteStmt).query(ctx, stmtArgs)
 		if err != nil && err != driver.ErrSkip {
 			s.Close()
@@ -1957,6 +1931,36 @@
 
 var placeHolder = []byte{0}
 
+func stmtArgs(args []driver.NamedValue, start, na int) []driver.NamedValue {
+	if na == 0 {
+		return nil
+	}
+
+	end := start + na
+	hasNamedOutside := false
+	for i := range args {
+		if args[i].Name != "" && (i < start || i >= end) {
+			hasNamedOutside = true
+			break
+		}
+	}
+	if start == 0 && !hasNamedOutside {
+		return args[start:end]
+	}
+
+	stmtArgs := make([]driver.NamedValue, 0, len(args))
+	stmtArgs = append(stmtArgs, args[start:end]...)
+	for i := range args {
+		if args[i].Name != "" && (i < start || i >= end) {
+			stmtArgs = append(stmtArgs, args[i])
+		}
+	}
+	for i := range stmtArgs {
+		stmtArgs[i].Ordinal = i + 1
+	}
+	return stmtArgs
+}
+
 func (s *SQLiteStmt) bind(args []driver.NamedValue) error {
 	rv := C.sqlite3_reset(s.s)
 	if rv != C.SQLITE_ROW && rv != C.SQLITE_OK && rv != C.SQLITE_DONE {
@@ -1965,26 +1969,79 @@
 
 	C.sqlite3_clear_bindings(s.s)
 
-	bindIndices := make([][3]int, len(args))
-	prefixes := []string{":", "@", "$"}
-	for i, v := range args {
-		bindIndices[i][0] = v.Ordinal
-		if v.Name != "" {
-			for j := range prefixes {
-				cname := C.CString(prefixes[j] + v.Name)
-				bindIndices[i][j] = int(C.sqlite3_bind_parameter_index(s.s, cname))
-				C.free(unsafe.Pointer(cname))
-			}
-			args[i].Ordinal = bindIndices[i][0]
+	hasNamed := false
+	for i := range args {
+		if args[i].Name != "" {
+			hasNamed = true
+			break
 		}
 	}
 
+	if !hasNamed {
+		for _, arg := range args {
+			n := C.int(arg.Ordinal)
+			switch v := arg.Value.(type) {
+			case nil:
+				rv = C.sqlite3_bind_null(s.s, n)
+			case string:
+				if len(v) == 0 {
+					rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(&placeHolder[0])), C.int(0))
+				} else {
+					b := []byte(v)
+					rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(&b[0])), C.int(len(b)))
+				}
+			case int64:
+				rv = C.sqlite3_bind_int64(s.s, n, C.sqlite3_int64(v))
+			case bool:
+				if v {
+					rv = C.sqlite3_bind_int(s.s, n, 1)
+				} else {
+					rv = C.sqlite3_bind_int(s.s, n, 0)
+				}
+			case float64:
+				rv = C.sqlite3_bind_double(s.s, n, C.double(v))
+			case []byte:
+				if v == nil {
+					rv = C.sqlite3_bind_null(s.s, n)
+				} else {
+					ln := len(v)
+					if ln == 0 {
+						v = placeHolder
+					}
+					rv = C._sqlite3_bind_blob(s.s, n, unsafe.Pointer(&v[0]), C.int(ln))
+				}
+			case time.Time:
+				b := []byte(v.Format(SQLiteTimestampFormats[0]))
+				rv = C._sqlite3_bind_text(s.s, n, (*C.char)(unsafe.Pointer(&b[0])), C.int(len(b)))
+			}
+			if rv != C.SQLITE_OK {
+				return s.c.lastError()
+			}
+		}
+		return nil
+	}
+
+	bindIndices := make([][3]int, len(args))
+	prefixes := [3]string{":", "@", "$"}
+	for i, v := range args {
+		bindIndices[i][0] = v.Ordinal
+		if v.Name == "" {
+			continue
+		}
+		for j := range prefixes {
+			cname := C.CString(prefixes[j] + v.Name)
+			bindIndices[i][j] = int(C.sqlite3_bind_parameter_index(s.s, cname))
+			C.free(unsafe.Pointer(cname))
+		}
+		args[i].Ordinal = bindIndices[i][0]
+	}
+
 	for i, arg := range args {
-		for j := range bindIndices[i] {
-			if bindIndices[i][j] == 0 {
+		for _, idx := range bindIndices[i] {
+			if idx == 0 {
 				continue
 			}
-			n := C.int(bindIndices[i][j])
+			n := C.int(idx)
 			switch v := arg.Value.(type) {
 			case nil:
 				rv = C.sqlite3_bind_null(s.s, n)