Initial commit of Python queries and QL libraries.

python/ql/src/analysis/ContextEfficiency.ql

@@ -0,0 +1,25 @@
+/** Compute the total points-to facts, the total size of the points-to relation and 
+ * the ratio of the two in relation to the depth of context.
+ */
+
+
+import python
+import semmle.python.pointsto.PointsTo
+import semmle.python.pointsto.PointsToContext
+
+from int total_facts, int total_size, int depth, float efficiency
+where 
+total_facts = strictcount(ControlFlowNode f, Object value, ClassObject cls |
+    exists(PointsToContext ctx |
+        PointsTo::points_to(f, ctx, value, cls, _) and
+        depth = ctx.getDepth()
+    )
+)
+and
+total_size = strictcount(ControlFlowNode f, Object value, ClassObject cls, PointsToContext ctx, ControlFlowNode orig |
+    PointsTo::points_to(f, ctx, value, cls, orig) and
+    depth = ctx.getDepth()
+)
+and
+efficiency = 100.0 * total_facts / total_size
+select depth, total_facts, total_size, efficiency