From 3f8b480ba0ed92b9c17797761666efc16a313ea6 Mon Sep 17 00:00:00 2001
From: Nuno Cruces <ncruces@users.noreply.github.com>
Date: Thu, 14 Dec 2023 14:02:41 +0000
Subject: [PATCH] Optimize declared types.

---
 driver/driver.go | 50 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/driver/driver.go b/driver/driver.go
index eb29891..efd7503 100644
--- a/driver/driver.go
+++ b/driver/driver.go
@@ -377,7 +377,7 @@ func (s *stmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driv
 	if err != nil {
 		return nil, err
 	}
-	return &rows{s, ctx}, nil
+	return &rows{ctx: ctx, stmt: s}, nil
 }
 
 func (s *stmt) setupBindings(args []driver.NamedValue) error {
@@ -479,8 +479,10 @@ func (r resultRowsAffected) RowsAffected() (int64, error) {
 }
 
 type rows struct {
-	*stmt
 	ctx context.Context
+	*stmt
+	names []string
+	types []string
 }
 
 func (r *rows) Close() error {
@@ -489,22 +491,35 @@ func (r *rows) Close() error {
 }
 
 func (r *rows) Columns() []string {
-	count := r.Stmt.ColumnCount()
-	columns := make([]string, count)
-	for i := range columns {
-		columns[i] = r.Stmt.ColumnName(i)
+	if r.names == nil {
+		count := r.Stmt.ColumnCount()
+		r.names = make([]string, count)
+		for i := range r.names {
+			r.names[i] = r.Stmt.ColumnName(i)
+		}
 	}
-	return columns
+	return r.names
+}
+
+func (r *rows) declType(index int) string {
+	if r.types == nil {
+		count := r.Stmt.ColumnCount()
+		r.types = make([]string, count)
+		for i := range r.types {
+			r.types[i] = strings.ToUpper(r.Stmt.ColumnDeclType(i))
+		}
+	}
+	return r.types[index]
 }
 
 func (r *rows) ColumnTypeDatabaseTypeName(index int) string {
-	decltype := r.Stmt.ColumnDeclType(index)
+	decltype := r.declType(index)
 	if len := len(decltype); len > 0 && decltype[len-1] == ')' {
 		if i := strings.LastIndexByte(decltype, '('); i >= 0 {
 			decltype = decltype[:i]
 		}
 	}
-	return strings.ToUpper(strings.TrimSpace(decltype))
+	return strings.TrimSpace(decltype)
 }
 
 func (r *rows) Next(dest []driver.Value) error {
@@ -519,11 +534,12 @@ func (r *rows) Next(dest []driver.Value) error {
 	}
 
 	for i := range dest {
-		if t, ok := r.decodeTime(i); ok {
-			dest[i] = t
+		t := r.Stmt.ColumnType(i)
+		if tm, ok := r.decodeTime(i, t); ok {
+			dest[i] = tm
 			continue
 		}
-		switch r.Stmt.ColumnType(i) {
+		switch t {
 		case sqlite3.INTEGER:
 			dest[i] = r.Stmt.ColumnInt64(i)
 		case sqlite3.FLOAT:
@@ -542,21 +558,21 @@ func (r *rows) Next(dest []driver.Value) error {
 	return r.Stmt.Err()
 }
 
-func (s *stmt) decodeTime(i int) (_ time.Time, _ bool) {
-	if s.tmRead == sqlite3.TimeFormatDefault {
+func (r *rows) decodeTime(i int, typ sqlite3.Datatype) (_ time.Time, _ bool) {
+	if r.tmRead == sqlite3.TimeFormatDefault {
 		return
 	}
-	switch s.Stmt.ColumnType(i) {
+	switch typ {
 	case sqlite3.INTEGER, sqlite3.FLOAT, sqlite3.TEXT:
 		// maybe
 	default:
 		return
 	}
-	switch strings.ToUpper(s.Stmt.ColumnDeclType(i)) {
+	switch r.declType(i) {
 	case "DATE", "TIME", "DATETIME", "TIMESTAMP":
 		// maybe
 	default:
 		return
 	}
-	return s.Stmt.ColumnTime(i, s.tmRead), s.Stmt.Err() == nil
+	return r.Stmt.ColumnTime(i, r.tmRead), r.Stmt.Err() == nil
 }