- merged -r4458:4466 of query_columns branch

- this branch changes query.values() to immediately return an iterator, adds a new "aliased" construct which will be the primary method to get at aliased columns when using values()
- tentative ORM versions of _join and _outerjoin are not yet public, would like to integrate with Query better (work continues in the branch)
- lots of fixes to expressions regarding cloning and correlation.  Some apparent ORM bug-workarounds removed.
- to fix a recursion issue with anonymous identifiers, bind parameters generated against columns now just use the name of the column instead of the tablename_columnname label (plus the unique integer counter).  this way expensive recursive schemes aren't needed for the anon identifier logic.   This, as usual, impacted a ton of compiler unit tests which needed a search-n-replace for the new bind names.

1 files changed, 36 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/util.py b/lib/sqlalchemy/sql/util.py
index 5b9ffd4fa..dd29cb42b 100644
--- a/lib/sqlalchemy/sql/util.py
+++ b/lib/sqlalchemy/sql/util.py
@@ -130,7 +130,43 @@ def criterion_as_pairs(expression, consider_as_foreign_keys=None, consider_as_re
     pairs = []
     visitors.traverse(expression, visit_binary=visit_binary)
     return pairs
+
+def folded_equivalents(join, equivs=None):
+    """Returns the column list of the given Join with all equivalently-named,
+    equated columns folded into one column, where 'equated' means they are
+    equated to each other in the ON clause of this join.
+
+    This function is used by Join.select(fold_equivalents=True).
     
+    TODO: deprecate ?
+    """
+
+    if equivs is None:
+        equivs = util.Set()
+    def visit_binary(binary):
+        if binary.operator == operators.eq and binary.left.name == binary.right.name:
+            equivs.add(binary.right)
+            equivs.add(binary.left)
+    visitors.traverse(join.onclause, visit_binary=visit_binary)
+    collist = []
+    if isinstance(join.left, expression.Join):
+        left = folded_equivalents(join.left, equivs)
+    else:
+        left = list(join.left.columns)
+    if isinstance(join.right, expression.Join):
+        right = folded_equivalents(join.right, equivs)
+    else:
+        right = list(join.right.columns)
+    used = util.Set()
+    for c in left + right:
+        if c in equivs:
+            if c.name not in used:
+                collist.append(c)
+                used.add(c.name)
+        else:
+            collist.append(c)
+    return collist
+
 class AliasedRow(object):
     
     def __init__(self, row, map):