move files

backend/v3/storage/database/change.go

@@ -0,0 +1,51 @@
+package database
+
+type Change interface {
+	Write(builder *StatementBuilder)
+}
+
+type change[V Value] struct {
+	column Column
+	value  V
+}
+
+var _ Change = (*change[string])(nil)
+
+func NewChange[V Value](col Column, value V) Change {
+	return &change[V]{
+		column: col,
+		value:  value,
+	}
+}
+
+func NewChangePtr[V Value](col Column, value *V) Change {
+	if value == nil {
+		return NewChange(col, NullInstruction)
+	}
+	return NewChange(col, *value)
+}
+
+// Write implements [Change].
+func (c change[V]) Write(builder *StatementBuilder) {
+	c.column.Write(builder)
+	builder.WriteString(" = ")
+	builder.WriteArg(c.value)
+}
+
+type Changes []Change
+
+func NewChanges(cols ...Change) Change {
+	return Changes(cols)
+}
+
+// Write implements [Change].
+func (m Changes) Write(builder *StatementBuilder) {
+	for i, col := range m {
+		if i > 0 {
+			builder.WriteString(", ")
+		}
+		col.Write(builder)
+	}
+}
+
+var _ Change = Changes(nil)