merged 0.2 branch into trunk; 0.1 now in sqlalchemy/branches/rel_0_1

1 files changed, 59 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql_util.py b/lib/sqlalchemy/sql_util.py
new file mode 100644
index 000000000..e3170ebce
--- /dev/null
+++ b/lib/sqlalchemy/sql_util.py
@@ -0,0 +1,59 @@
+import sqlalchemy.sql as sql
+import sqlalchemy.schema as schema
+
+"""utility functions that build upon SQL and Schema constructs"""
+
+
+class TableCollection(object):
+    def __init__(self):
+        self.tables = []
+    def add(self, table):
+        self.tables.append(table)
+    def sort(self, reverse=False ):
+        import sqlalchemy.orm.topological
+        tuples = []
+        class TVisitor(schema.SchemaVisitor):
+            def visit_foreign_key(self, fkey):
+                parent_table = fkey.column.table
+                child_table = fkey.parent.table
+                tuples.append( ( parent_table, child_table ) )
+        vis = TVisitor()        
+        for table in self.tables:
+            table.accept_schema_visitor(vis)
+        sorter = sqlalchemy.orm.topological.QueueDependencySorter( tuples, self.tables )
+        head =  sorter.sort()
+        sequence = []
+        def to_sequence( node, seq=sequence):
+            seq.append( node.item )
+            for child in node.children:
+                to_sequence( child )
+        to_sequence( head )
+        if reverse:
+            sequence.reverse()
+        return sequence
+        
+
+class TableFinder(TableCollection, sql.ClauseVisitor):
+    """given a Clause, locates all the Tables within it into a list."""
+    def __init__(self, table, check_columns=False):
+        TableCollection.__init__(self)
+        self.check_columns = check_columns
+        if table is not None:
+            table.accept_visitor(self)
+    def visit_table(self, table):
+        self.tables.append(table)
+    def __len__(self):
+        return len(self.tables)
+    def __getitem__(self, i):
+        return self.tables[i]
+    def __iter__(self):
+        return iter(self.tables)
+    def __contains__(self, obj):
+        return obj in self.tables
+    def __add__(self, obj):
+        return self.tables + list(obj)
+    def visit_column(self, column):
+        if self.check_columns:
+            column.table.accept_visitor(self)
+
+    
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