reorganize code

1 files changed, 41 insertions, 0 deletions

diff --git a/internal/dialect.go b/internal/dialect.go
new file mode 100644
index 0000000..0cf90a2
--- /dev/null
+++ b/internal/dialect.go
@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
+// SPDX-License-Identifier: Apache-2.0
+
+package internal
+
+import (
+	"strconv"
+	"strings"
+)
+
+// Dialect is a copy of the interface of the same name in package oblast.
+// We cannot refer to that interface within this package because that would constitute a cyclic dependency.
+type Dialect interface {
+	Placeholder(i int) string
+	QuoteIdentifier(name string) string
+	UsesLastInsertID() bool
+	InsertSuffixForAutoColumns(columns []string) string
+}
+
+// PostgresDialect is the dialect of PostgreSQL databases.
+type PostgresDialect struct{}
+
+func (PostgresDialect) Placeholder(i int) string           { return "$" + strconv.Itoa(i) }
+func (PostgresDialect) QuoteIdentifier(name string) string { return `"` + name + `"` }
+func (PostgresDialect) UsesLastInsertID() bool             { return false }
+
+func (p PostgresDialect) InsertSuffixForAutoColumns(columns []string) string {
+	quotedColumns := make([]string, len(columns))
+	for idx, name := range columns {
+		quotedColumns[idx] = p.QuoteIdentifier(name)
+	}
+	return ` RETURNING ` + strings.Join(quotedColumns, ", ")
+}
+
+// SqliteDialect is the dialect of SQLite databases.
+type SqliteDialect struct{}
+
+func (SqliteDialect) Placeholder(_ int) string                           { return "?" }
+func (SqliteDialect) QuoteIdentifier(name string) string                 { return `"` + name + `"` }
+func (SqliteDialect) UsesLastInsertID() bool                             { return true }
+func (SqliteDialect) InsertSuffixForAutoColumns(columns []string) string { return "" }