- consolidate "constraints.py" into the more general "ext.py",

for all assorted PG SQL extensions

1 files changed, 91 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/ext.py b/lib/sqlalchemy/dialects/postgresql/ext.py
index 57592bac2..8b08cc498 100644
--- a/lib/sqlalchemy/dialects/postgresql/ext.py
+++ b/lib/sqlalchemy/dialects/postgresql/ext.py
@@ -7,6 +7,7 @@
 
 from ...sql import expression
 from ...sql import elements
+from ...sql.schema import ColumnCollectionConstraint
 
 
 class aggregate_order_by(expression.ColumnElement):
@@ -61,3 +62,93 @@ class aggregate_order_by(expression.ColumnElement):
     @property
     def _from_objects(self):
         return self.target._from_objects + self.order_by._from_objects
+
+
+class ExcludeConstraint(ColumnCollectionConstraint):
+    """A table-level EXCLUDE constraint.
+
+    Defines an EXCLUDE constraint as described in the `postgres
+    documentation`__.
+
+    __ http://www.postgresql.org/docs/9.0/\
+static/sql-createtable.html#SQL-CREATETABLE-EXCLUDE
+    """
+
+    __visit_name__ = 'exclude_constraint'
+
+    where = None
+
+    def __init__(self, *elements, **kw):
+        """
+        :param \*elements:
+          A sequence of two tuples of the form ``(column, operator)`` where
+          column must be a column name or Column object and operator must
+          be a string containing the operator to use.
+
+        :param name:
+          Optional, the in-database name of this constraint.
+
+        :param deferrable:
+          Optional bool.  If set, emit DEFERRABLE or NOT DEFERRABLE when
+          issuing DDL for this constraint.
+
+        :param initially:
+          Optional string.  If set, emit INITIALLY <value> when issuing DDL
+          for this constraint.
+
+        :param using:
+          Optional string.  If set, emit USING <index_method> when issuing DDL
+          for this constraint. Defaults to 'gist'.
+
+        :param where:
+          Optional string.  If set, emit WHERE <predicate> when issuing DDL
+          for this constraint.
+
+        """
+        columns = []
+        render_exprs = []
+        self.operators = {}
+
+        expressions, operators = zip(*elements)
+
+        for (expr, column, strname, add_element), operator in zip(
+                self._extract_col_expression_collection(expressions),
+                operators
+        ):
+            if add_element is not None:
+                columns.append(add_element)
+
+            name = column.name if column is not None else strname
+
+            if name is not None:
+                # backwards compat
+                self.operators[name] = operator
+
+            expr = expression._literal_as_text(expr)
+
+            render_exprs.append(
+                (expr, name, operator)
+            )
+
+        self._render_exprs = render_exprs
+        ColumnCollectionConstraint.__init__(
+            self,
+            *columns,
+            name=kw.get('name'),
+            deferrable=kw.get('deferrable'),
+            initially=kw.get('initially')
+        )
+        self.using = kw.get('using', 'gist')
+        where = kw.get('where')
+        if where:
+            self.where = expression._literal_as_text(where)
+
+    def copy(self, **kw):
+        elements = [(col, self.operators[col])
+                    for col in self.columns.keys()]
+        c = self.__class__(*elements,
+                           name=self.name,
+                           deferrable=self.deferrable,
+                           initially=self.initially)
+        c.dispatch._update(self.dispatch)
+        return c