##### SQL code objects

def as_Table(table):

    if table == None or isinstance(table, Table): return table

    elif isinstance(table, tuple):

        schema, table = table

        return Table(table, schema)

    else: return Table(table)

##### Old-style format support

def unescape_table(table):

    '''Currently only works with PostgreSQL.'''

    if table == None: return table

    assert table.count('.') <= 1

    parts = tuple((v.replace('"', '') for v in table.split('"."', 2)))

    if len(parts) == 1: parts, = parts

    return parts

def value2sql_gen(value, default_table=None, table_is_esc=False):

    '''Converts old-style (tuple-based) values to sql_gen-compatible values.

    @param table_is_esc If False, assumes any table name is not escaped or that

        re-escaping it will produce the same value.

    '''

    if isinstance(value, Code): return value # already in sql_gen form

    if table_is_esc: default_table = unescape_table(default_table)

    is_tuple = isinstance(value, tuple)

    if is_tuple and len(value) == 1: return Literal(value[0]) # value is literal

    elif is_tuple and len(value) == 2: # value is col with table

        table, col = value

        if table_is_esc: table = unescape_table(table)

        return Col(col, as_Table(table))

    else: return Col(value, as_Table(default_table)) # value is col name