Python: Remove points-to from Expr

python/ql/lib/LegacyPointsTo.qll

@@ -119,3 +119,75 @@ private predicate varHasCompletePointsToSet(SsaVariable var) {
     )
   )
 }
+
+/**
+ * An extension of `Expr` that provides points-to predicates.
+ */
+class ExprWithPointsTo extends Expr {
+  /**
+   * NOTE: `refersTo` will be deprecated in 2019. Use `pointsTo` instead.
+   * Gets what this expression might "refer-to". Performs a combination of localized (intra-procedural) points-to
+   *  analysis and global module-level analysis. This points-to analysis favours precision over recall. It is highly
+   *  precise, but may not provide information for a significant number of flow-nodes.
+   *  If the class is unimportant then use `refersTo(value)` or `refersTo(value, origin)` instead.
+   * NOTE: For complex dataflow, involving multiple stages of points-to analysis, it may be more precise to use
+   * `ControlFlowNode.refersTo(...)` instead.
+   */
+  predicate refersTo(Object obj, ClassObject cls, AstNode origin) {
+    this.refersTo(_, obj, cls, origin)
+  }
+
+  /**
+   * NOTE: `refersTo` will be deprecated in 2019. Use `pointsTo` instead.
+   * Gets what this expression might "refer-to" in the given `context`.
+   */
+  predicate refersTo(Context context, Object obj, ClassObject cls, AstNode origin) {
+    this.getAFlowNode()
+        .(ControlFlowNodeWithPointsTo)
+        .refersTo(context, obj, cls, origin.getAFlowNode())
+  }
+
+  /**
+   * NOTE: `refersTo` will be deprecated in 2019. Use `pointsTo` instead.
+   * Holds if this expression might "refer-to" to `value` which is from `origin`
+   * Unlike `this.refersTo(value, _, origin)`, this predicate includes results
+   * where the class cannot be inferred.
+   */
+  pragma[nomagic]
+  predicate refersTo(Object obj, AstNode origin) {
+    this.getAFlowNode().(ControlFlowNodeWithPointsTo).refersTo(obj, origin.getAFlowNode())
+  }
+
+  /**
+   * NOTE: `refersTo` will be deprecated in 2019. Use `pointsTo` instead.
+   * Equivalent to `this.refersTo(value, _)`
+   */
+  predicate refersTo(Object obj) { this.refersTo(obj, _) }
+
+  /**
+   * Holds if this expression might "point-to" to `value` which is from `origin`
+   * in the given `context`.
+   */
+  predicate pointsTo(Context context, Value value, AstNode origin) {
+    this.getAFlowNode()
+        .(ControlFlowNodeWithPointsTo)
+        .pointsTo(context, value, origin.getAFlowNode())
+  }
+
+  /**
+   * Holds if this expression might "point-to" to `value` which is from `origin`.
+   */
+  predicate pointsTo(Value value, AstNode origin) {
+    this.getAFlowNode().(ControlFlowNodeWithPointsTo).pointsTo(value, origin.getAFlowNode())
+  }
+
+  /**
+   * Holds if this expression might "point-to" to `value`.
+   */
+  predicate pointsTo(Value value) { this.pointsTo(value, _) }
+
+  /** Gets a value that this expression might "point-to". */
+  Value pointsTo() { this.pointsTo(result) }
+
+  override string getAQlClass() { none() }
+}