diff options
Diffstat (limited to 'lib/sqlalchemy/sql')
| -rw-r--r-- | lib/sqlalchemy/sql/expression.py | 72 |
1 files changed, 37 insertions, 35 deletions
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py index f59ed7afd..e9786cbe1 100644 --- a/lib/sqlalchemy/sql/expression.py +++ b/lib/sqlalchemy/sql/expression.py @@ -26,7 +26,8 @@ to stay the same in future releases. """ -import itertools, re +import itertools +import re from operator import attrgetter from .. import util, exc, inspection @@ -1403,8 +1404,12 @@ def _labeled(element): # there is some inconsistency here between the usage of # inspect() vs. checking for Visitable and __clause_element__. # Ideally all functions here would derive from inspect(), -# this is a work in progress. In some cases performance is a concern -# also. +# however the inspect() versions add significant callcount +# overhead for critical functions like _interpret_as_column_or_from(). +# Generally, the column-based functions are more performance critical +# and are fine just checking for __clause_element__(). it's only +# _interpret_as_from() where we'd like to be able to receive ORM entities +# that have no defined namespace, hence inspect() is needed there. def _column_as_key(element): if isinstance(element, basestring): @@ -1445,9 +1450,8 @@ def _no_literals(element): return element def _is_literal(element): - insp = inspection.inspect(element, raiseerr=False) - - return insp is None and not isinstance(element, Visitable) + return not isinstance(element, Visitable) and \ + not hasattr(element, '__clause_element__') def _only_column_elements_or_none(element, name): if element is None: @@ -1456,51 +1460,49 @@ def _only_column_elements_or_none(element, name): return _only_column_elements(element, name) def _only_column_elements(element, name): - insp = inspection.inspect(element, raiseerr=False) - if insp is None or \ - not hasattr(insp, "expression") or \ - not isinstance(insp.expression, ColumnElement): + if hasattr(element, '__clause_element__'): + element = element.__clause_element__() + if not isinstance(element, ColumnElement): raise exc.ArgumentError( "Column-based expression object expected for argument " "'%s'; got: '%s', type %s" % (name, element, type(element))) - return insp.expression + return element + def _literal_as_binds(element, name=None, type_=None): - insp = inspection.inspect(element, raiseerr=False) - if insp is None: + if hasattr(element, '__clause_element__'): + return element.__clause_element__() + elif not isinstance(element, Visitable): if element is None: - return _const_expr(element) + return null() else: - return BindParameter(name, element, type_=type_, unique=True) - elif insp.is_clause_element: - return insp + return _BindParamClause(name, element, type_=type_, unique=True) else: - return insp.expression + return element +def _interpret_as_column_or_from(element): + if isinstance(element, Visitable): + return element + elif hasattr(element, '__clause_element__'): + return element.__clause_element__() -def _interpret_as_from(element): insp = inspection.inspect(element, raiseerr=False) if insp is None: if isinstance(element, (util.NoneType, bool)): return _const_expr(element) - elif isinstance(element, basestring): - return TextClause(unicode(element)) elif hasattr(insp, "selectable"): return insp.selectable - else: - raise exc.ArgumentError("FROM expression expected") -def _literal_as_column(element): - insp = inspection.inspect(element, raiseerr=False) - if insp is not None: - if hasattr(insp, "expression"): - return insp.expression - elif hasattr(insp, "selectable"): - return insp.selectable - elif insp.is_clause_element: - return insp return literal_column(str(element)) +def _interpret_as_from(element): + insp = inspection.inspect(element, raiseerr=False) + if insp is None: + if isinstance(element, basestring): + return TextClause(unicode(element)) + elif hasattr(insp, "selectable"): + return insp.selectable + raise exc.ArgumentError("FROM expression expected") def _const_expr(element): if element is None: @@ -4911,7 +4913,7 @@ class Select(SelectBase): if cols_present: self._raw_columns = [] for c in columns: - c = _literal_as_column(c) + c = _interpret_as_column_or_from(c) if isinstance(c, ScalarSelect): c = c.self_group(against=operators.comma_op) self._raw_columns.append(c) @@ -5238,7 +5240,7 @@ class Select(SelectBase): self._reset_exported() rc = [] for c in columns: - c = _literal_as_column(c) + c = _interpret_as_column_or_from(c) if isinstance(c, ScalarSelect): c = c.self_group(against=operators.comma_op) rc.append(c) @@ -5382,7 +5384,7 @@ class Select(SelectBase): """ self._reset_exported() - column = _literal_as_column(column) + column = _interpret_as_column_or_from(column) if isinstance(column, ScalarSelect): column = column.self_group(against=operators.comma_op) |