feat: generated and identity columns for mssql, sqlite, drizzle, typeorm, bun and gorm readers

- mssql: write computed columns (AS (expr) PERSISTED) and identity; read computed definition and identity
- sqlite: write GENERATED ALWAYS AS (expr) STORED; read generated columns via table_xinfo and parse the expression
- drizzle: generatedAlwaysAs / generated(Always|ByDefault)AsIdentity, read and write
- typeorm: asExpression/generatedType and identity decorators, read and write; decorator scan is now quote-aware
- bun, gorm readers: read generated and identity markers
- readmes updated

pkg/readers/drizzle/README.md

@@ -85,6 +85,7 @@ export const postsRelations = relations(posts, ({ one }) => ({
 
 ## Notes
 
+- `.generatedAlwaysAs(sql`expr`)` sets `Generated` + `GenerationExpression`; `.generatedAlwaysAsIdentity()` / `.generatedByDefaultAsIdentity()` set `Identity` + `IdentityGeneration`
 - Supports both PostgreSQL and MySQL Drizzle schemas
 - Extracts relationship information from `relations` definitions
 - Schema defaults to `public` for PostgreSQL

pkg/readers/drizzle/reader.go

@@ -495,9 +495,24 @@ func (r *Reader) parseColumnModifiers(line string, column *models.Column, table
 		}
 	}
 
-	// Check for .generatedAlwaysAsIdentity()
+	// Check for .generatedAlwaysAsIdentity() / .generatedByDefaultAsIdentity()
 	if strings.Contains(line, ".generatedAlwaysAsIdentity()") {
 		column.AutoIncrement = true
+		column.Identity = true
+		column.IdentityGeneration = "ALWAYS"
+	}
+	if strings.Contains(line, ".generatedByDefaultAsIdentity()") {
+		column.AutoIncrement = true
+		column.Identity = true
+		column.IdentityGeneration = "BY DEFAULT"
+	}
+
+	// Check for .generatedAlwaysAs(sql`expr`) (generated column)
+	if idx := strings.Index(line, ".generatedAlwaysAs("); idx != -1 {
+		if expr, ok := parseGeneratedAlwaysAs(line[idx+len(".generatedAlwaysAs("):]); ok {
+			column.Generated = true
+			column.GenerationExpression = expr
+		}
 	}
 
 	// Check for .references(() => otherTable.column)
@@ -615,3 +630,34 @@ func (r *Reader) varNameToTableName(varName string) string {
 	// For now, assume variable name matches table name
 	return varName
 }
+
+// parseGeneratedAlwaysAs extracts the SQL expression from the argument list of
+// generatedAlwaysAs(...), which follows the opening parenthesis in rest. The expression is
+// the contents of a sql`...` template (backticks inside it are escaped with a backslash)
+// or, failing that, a quoted string.
+func parseGeneratedAlwaysAs(rest string) (string, bool) {
+	rest = strings.TrimSpace(rest)
+	rest = strings.TrimPrefix(rest, "sql")
+	if rest == "" {
+		return "", false
+	}
+	quote := rest[0]
+	if quote != '`' && quote != '\'' && quote != '"' {
+		return "", false
+	}
+
+	var sb strings.Builder
+	for i := 1; i < len(rest); i++ {
+		ch := rest[i]
+		if ch == '\\' && i+1 < len(rest) {
+			i++
+			sb.WriteByte(rest[i])
+			continue
+		}
+		if ch == quote {
+			return strings.TrimSpace(sb.String()), true
+		}
+		sb.WriteByte(ch)
+	}
+	return "", false
+}