Refactor dialect subpackage: rename fields and methods for clarity

commands.go

@@ -94,10 +94,10 @@ func (ss *session) beginTx(ctx context.Context, w io.Writer) error {
 }
 
 func doDescTables(ctx context.Context, ss *session, commandIn commandIn) error {
-	if ss.Dialect.SqlForTab == "" {
+	if ss.Dialect.SQLForTables == "" {
 		return fmt.Errorf("desc: %w", ErrNotSupported)
 	}
-	query := ss.Dialect.SqlToQueryTables()
+	query := ss.Dialect.BuildSQLForTables()
 	var name string
 
 	handler := func(e *csvi.KeyEventArgs) (*csvi.CommandResult, error) {
@@ -106,7 +106,7 @@ func doDescTables(ctx context.Context, ss *session, commandIn commandIn) error {
 		}
 		header := e.Front()
 		for i, c := range header.Cell {
-			if strings.EqualFold(c.Text(), ss.Dialect.TableField) {
+			if strings.EqualFold(c.Text(), ss.Dialect.TableNameField) {
 				name = e.CursorRow.Cell[i].Text()
 				return &csvi.CommandResult{Quit: true}, nil
 			}
@@ -155,10 +155,10 @@ func doDescTables(ctx context.Context, ss *session, commandIn commandIn) error {
 }
 
 func doDescColumns(ctx context.Context, ss *session, table string) error {
-	if ss.Dialect.SqlForDesc == "" {
+	if ss.Dialect.SQLForColumns == "" {
 		return fmt.Errorf("desc table: %w", ErrNotSupported)
 	}
-	query := ss.Dialect.SqlToQueryColumns(table)
+	query := ss.Dialect.BuildSQLForColumns(table)
 	if ss.Debug {
 		fmt.Println(query)
 	}

dialect/main.go

@@ -23,24 +23,43 @@ type PlaceHolder interface {
 }
 
 type Entry struct {
-	Usage                 string
-	SqlForDesc            string
-	SqlForTab             string
-	TableField            string
-	ColumnField           string
-	DisplayDateTimeLayout string
-	PlaceHolder           PlaceHolder
-	TypeNameToConv        func(string) func(string) (any, error)
-	DSNFilter             func(string) (string, error)
-	CanUseInTransaction   func(string) bool
-	IsQuerySQL            func(string) bool
-}
-
-func (D *Entry) TypeToConv(typeName string) func(string) (any, error) {
-	if D.TypeNameToConv == nil {
+	// Usage describes how to use this entry or what it represents.
+	Usage string
+
+	// SQLForColumns is the SQL query used to retrieve column information.
+	SQLForColumns string
+
+	// SQLForTables is the SQL query used to retrieve table information.
+	SQLForTables string
+
+	// TableNameField is the field name for table names in SQL results.
+	TableNameField string
+
+	// ColumnNameField is the field name for column names in SQL results.
+	ColumnNameField string
+
+	// PlaceHolder defines how to represent placeholders (e.g., ?, $1) in SQL.
+	PlaceHolder PlaceHolder
+
+	// TypeConverterFor returns a converter function for a given type name.
+	// The returned function converts a string literal to the corresponding Go value.
+	TypeConverterFor func(typeName string) func(literal string) (any, error)
+
+	// DSNFilter adjusts or validates a given DSN string before use.
+	DSNFilter func(dsn string) (string, error)
+
+	// IsTransactionSafe reports whether the given SQL statement is safe to run in a transaction.
+	IsTransactionSafe func(sql string) bool
+
+	// IsQuerySQL reports whether the given SQL statement is a query (e.g., SELECT) or not.
+	IsQuerySQL func(sql string) bool
+}
+
+func (D *Entry) LookupConverter(typeName string) func(string) (any, error) {
+	if D.TypeConverterFor == nil {
 		return nil
 	}
-	return D.TypeNameToConv(typeName)
+	return D.TypeConverterFor(typeName)
 }
 
 const (
@@ -86,8 +105,8 @@ func ParseAnyDateTime(s string) (time.Time, error) {
 
 var registry = map[string]*Entry{}
 
-func Register(name string, setting *Entry) {
-	registry[strings.ToUpper(name)] = setting
+func (e *Entry) Register(name string) {
+	registry[strings.ToUpper(name)] = e
 }
 
 func Find(name string) (*Entry, bool) {

dialect/mysql/main.go

@@ -65,7 +65,7 @@ func mySQLDSNFilter(dsn string) (string, error) {
 
 var mySqlSpec = &dialect.Entry{
 	Usage: `sqlbless mysql <USERNAME>:<PASSWORD>@/<DBNAME>`,
-	SqlForDesc: `
+	SQLForColumns: `
         select ordinal_position as "ID",
                column_name as "NAME",
                case
@@ -82,19 +82,18 @@ var mySqlSpec = &dialect.Entry{
           from information_schema.columns
          where table_name = ?
          order by ordinal_position`,
-	SqlForTab: `
+	SQLForTables: `
         select * from information_schema.tables
          where table_type = 'BASE TABLE'
            and table_schema 
         not in ('mysql', 'information_schema', 'performance_schema', 'sys')`,
-	DisplayDateTimeLayout: dialect.DateTimeTzLayout,
-	TypeNameToConv:        mySQLTypeNameToConv,
-	PlaceHolder:           &dialect.PlaceHolderQuestion{},
-	DSNFilter:             mySQLDSNFilter,
-	TableField:            "TABLE_NAME",
-	ColumnField:           "NAME",
+	TypeConverterFor: mySQLTypeNameToConv,
+	PlaceHolder:      &dialect.PlaceHolderQuestion{},
+	DSNFilter:        mySQLDSNFilter,
+	TableNameField:   "TABLE_NAME",
+	ColumnNameField:  "NAME",
 }
 
 func init() {
-	dialect.Register("MYSQL", mySqlSpec)
+	mySqlSpec.Register("MYSQL")
 }

dialect/oracle/main.go

@@ -19,7 +19,7 @@ func oracleTypeNameToConv(typeName string) func(string) (any, error) {
 
 var oracleSpec = &dialect.Entry{
 	Usage: "sqlbless oracle://<USERNAME>:<PASSWORD>@<HOSTNAME>:<PORT>/<SERVICE>",
-	SqlForDesc: `
+	SQLForColumns: `
   select column_id as "ID",
 		 column_name as "NAME",
 		 case 
@@ -35,14 +35,13 @@ var oracleSpec = &dialect.Entry{
 	from all_tab_columns
    where table_name = UPPER(:1)
    order by column_id`,
-	SqlForTab:             `select * from tab where tname not like 'BIN$%'`,
-	DisplayDateTimeLayout: dialect.DateTimeTzLayout,
-	TypeNameToConv:        oracleTypeNameToConv,
-	TableField:            "tname",
-	ColumnField:           "name",
-	PlaceHolder:           &dialect.PlaceHolderName{Prefix: ":", Format: "v"},
+	SQLForTables:     `select * from tab where tname not like 'BIN$%'`,
+	TypeConverterFor: oracleTypeNameToConv,
+	TableNameField:   "tname",
+	ColumnNameField:  "name",
+	PlaceHolder:      &dialect.PlaceHolderName{Prefix: ":", Format: "v"},
 }
 
 func init() {
-	dialect.Register("ORACLE", oracleSpec)
+	oracleSpec.Register("ORACLE")
 }

dialect/postgresql/main.go

@@ -44,7 +44,7 @@ func (ph *placeHolder) Values() (result []any) {
 
 var postgresSpec = &dialect.Entry{
 	Usage: "sqlbless postgres://<USERNAME>:<PASSWORD>@<HOSTNAME>:<PORT>/<DBNAME>?sslmode=disable",
-	SqlForDesc: `
+	SQLForColumns: `
       select a.attnum as "ID",
              a.attname as "NAME",
              case
@@ -63,17 +63,16 @@ var postgresSpec = &dialect.Entry{
          and t.oid = a.atttypid
          and a.attisdropped is false
        order by a.attnum`,
-	SqlForTab: `
+	SQLForTables: `
       select *
         from information_schema.tables
        where table_type = 'BASE TABLE'
          and table_schema not in ('pg_catalog', 'information_schema')`,
-	DisplayDateTimeLayout: dialect.DateTimeTzLayout,
-	TypeNameToConv:        postgresTypeNameToConv,
-	PlaceHolder:           &placeHolder{},
-	TableField:            "table_name",
-	ColumnField:           "name",
-	CanUseInTransaction:   canUseInTransaction,
+	TypeConverterFor:  postgresTypeNameToConv,
+	PlaceHolder:       &placeHolder{},
+	TableNameField:    "table_name",
+	ColumnNameField:   "name",
+	IsTransactionSafe: canUseInTransaction,
 }
 
 func canUseInTransaction(sql string) bool {
@@ -91,5 +90,5 @@ func canUseInTransaction(sql string) bool {
 }
 
 func init() {
-	dialect.Register("POSTGRES", postgresSpec)
+	postgresSpec.Register("POSTGRES")
 }

dialect/query.go

@@ -66,18 +66,25 @@ func queryOneColumn(ctx context.Context, conn CanQuery, sqlStr, columnName strin
 	}
 }
 
-func (e *Entry) SqlToQueryTables() string {
-	return e.SqlForTab
+// BuildSQLForTables returns the SQL statement used to retrieve the list of tables.
+func (e *Entry) BuildSQLForTables() string {
+	return e.SQLForTables
 }
 
-func (e *Entry) SqlToQueryColumns(table string) string {
-	return strings.ReplaceAll(e.SqlForDesc, "{table_name}", table)
+// BuildSQLForColumns returns the SQL statement used to retrieve the list of columns
+// for the given table name. The placeholder "{table_name}" in the template will be replaced.
+func (e *Entry) BuildSQLForColumns(table string) string {
+	return strings.ReplaceAll(e.SQLForColumns, "{table_name}", table)
 }
 
-func (e *Entry) Tables(ctx context.Context, conn CanQuery) ([]string, error) {
-	return queryOneColumn(ctx, conn, e.SqlToQueryTables(), e.TableField)
+// Tables executes the SQL to list all table names defined by the dialect.
+// It returns a slice of table names or an error if the query fails.
+func (e *Entry) FetchTables(ctx context.Context, conn CanQuery) ([]string, error) {
+	return queryOneColumn(ctx, conn, e.BuildSQLForTables(), e.TableNameField)
 }
 
-func (e *Entry) Columns(ctx context.Context, conn CanQuery, table string) ([]string, error) {
-	return queryOneColumn(ctx, conn, e.SqlToQueryColumns(table), e.ColumnField, table)
+// Columns executes the SQL to list column names for the specified table.
+// It returns a slice of column names or an error if the query fails.
+func (e *Entry) FetchColumns(ctx context.Context, conn CanQuery, table string) ([]string, error) {
+	return queryOneColumn(ctx, conn, e.BuildSQLForColumns(table), e.ColumnNameField, table)
 }

dialect/sqlite/main.go

@@ -15,19 +15,18 @@ const dateTimeTzLayout = "2006-01-02 15:04:05.999999999 -07:00"
 
 var Entry = &dialect.Entry{
 	Usage: "sqlbless sqlite3 :memory: OR <FILEPATH>",
-	SqlForTab: `
+	SQLForTables: `
 	select      'master' AS schema,name,rootpage,sql FROM sqlite_master
 	where type = 'table'
 	union all
 	select 'temp_schema' AS schema,name,rootpage,sql FROM sqlite_temp_schema
 	where type = 'temp_schema'`,
-	DisplayDateTimeLayout: dateTimeTzLayout,
-	TypeNameToConv:        typeNameToConv,
-	PlaceHolder:           &placeHolder{},
-	SqlForDesc:            `PRAGMA table_info({table_name})`,
-	TableField:            "name",
-	ColumnField:           "name",
-	CanUseInTransaction:   canUseInTransaction,
+	TypeConverterFor:  typeNameToConv,
+	PlaceHolder:       &placeHolder{},
+	SQLForColumns:     `PRAGMA table_info({table_name})`,
+	TableNameField:    "name",
+	ColumnNameField:   "name",
+	IsTransactionSafe: canUseInTransaction,
 	IsQuerySQL: func(s string) bool {
 		s, _ = misc.CutField(s)
 		return strings.EqualFold(s, "PRAGMA")
@@ -94,5 +93,5 @@ func (ph *placeHolder) Values() (result []any) {
 }
 
 func init() {
-	dialect.Register("SQLITE3", Entry)
+	Entry.Register("SQLITE3")
 }

dialect/sqlserver/main.go

@@ -22,7 +22,7 @@ func sqlServerTypeNameToConv(typeName string) func(string) (any, error) {
 
 var sqlServerSpec = &dialect.Entry{
 	Usage: "sqlbless sqlserver://@<HOSTNAME>?database=<DBNAME>",
-	SqlForDesc: `
+	SQLForColumns: `
 	select c.column_id as "ID",
 		   c.name as "NAME",
 		   case
@@ -42,14 +42,13 @@ var sqlServerSpec = &dialect.Entry{
 	   and o.name = @p1
 	   and c.user_type_id = t.user_type_id
 	 order by c.column_id`,
-	SqlForTab:             `select * from sys.tables`,
-	DisplayDateTimeLayout: dialect.DateTimeTzLayout,
-	TypeNameToConv:        sqlServerTypeNameToConv,
-	PlaceHolder:           &dialect.PlaceHolderName{Prefix: "@", Format: "v"},
-	TableField:            "name",
-	ColumnField:           "name",
+	SQLForTables:     `select * from sys.tables`,
+	TypeConverterFor: sqlServerTypeNameToConv,
+	PlaceHolder:      &dialect.PlaceHolderName{Prefix: "@", Format: "v"},
+	TableNameField:   "name",
+	ColumnNameField:  "name",
 }
 
 func init() {
-	dialect.Register("SQLSERVER", sqlServerSpec)
+	sqlServerSpec.Register("SQLSERVER")
 }

edit.go

@@ -97,7 +97,7 @@ func doEdit(ctx context.Context, ss *session, command string, pilot commandIn) e
 	// replace `edit ` to `select * from `
 	_, tableAndWhere := misc.CutField(command)
 	if tableAndWhere == "" {
-		tables, err := ss.Dialect.Tables(ctx, ss.conn)
+		tables, err := ss.Dialect.FetchTables(ctx, ss.conn)
 		if err != nil {
 			return err
 		}

internal/sqlcompletion/main.go

@@ -123,7 +123,7 @@ func (C *completeType) getCandidates(ctx context.Context, fields []string) ([]st
 
 func (C *completeType) tables(ctx context.Context) []string {
 	if len(C.tableCache) <= 0 {
-		C.tableCache, _ = C.Dialect.Tables(ctx, C.Conn)
+		C.tableCache, _ = C.Dialect.FetchTables(ctx, C.Conn)
 	}
 	return C.tableCache
 }
@@ -138,7 +138,7 @@ func (C *completeType) columns(ctx context.Context, tables []string) (result []s
 		}
 		values, ok := C.columnCache[tableName]
 		if !ok {
-			values, _ = C.Dialect.Columns(ctx, C.Conn, tableName)
+			values, _ = C.Dialect.FetchColumns(ctx, C.Conn, tableName)
 			C.columnCache[tableName] = values
 		}
 		result = append(result, values...)

loop.go

@@ -208,7 +208,7 @@ func (ss *session) Loop(ctx context.Context, commandIn commandIn) error {
 			} else {
 				if ss.tx == nil {
 					_, err = ss.conn.ExecContext(ctx, query)
-				} else if f := ss.Dialect.CanUseInTransaction; f != nil && f(query) {
+				} else if f := ss.Dialect.IsTransactionSafe; f != nil && f(query) {
 					_, err = ss.tx.ExecContext(ctx, query)
 				} else {
 					err = ErrTransactionIsNotClosed

release_note_en.md

@@ -1,5 +1,7 @@
 ( **English** / [Japanese](release_note_ja.md) )
 
+- Refactor `dialect` subpackage: rename fields and methods for clarity (#8)
+
 v0.25.0
 =======
 Nov 3, 2025

release_note_ja.md

@@ -1,5 +1,7 @@
 ( [English](release_note_en.md) / **Japanese** )
 
+- サブパッケージ `dialect` をリファクタリング: フィールド・メソッドを改名 (#8)
+
 v0.25.0
 =======
 Nov 3, 2025

spread/edit.go

@@ -126,7 +126,7 @@ func (editor *Editor) Edit(ctx context.Context, tableAndWhere string, termOut io
 		name := strings.ToUpper(ct.DatabaseTypeName())
 		var v func(string) (string, error)
 		_ct := ct
-		if conv := editor.TypeToConv(name); conv != nil {
+		if conv := editor.LookupConverter(name); conv != nil {
 			quoteFunc = append(quoteFunc, conv)
 			v = func(s string) (string, error) {
 				if s == editor.Null || s == "" {