Python: Implement ParameterPosition et al

Author: hvitved

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -6,8 +6,29 @@ private import semmle.python.essa.SsaCompute
 /** Gets the callable in which this node occurs. */
 DataFlowCallable nodeGetEnclosingCallable(Node n) { result = n.getEnclosingCallable() }
 
+/** A parameter position represented by an integer. */
+class ParameterPosition extends int {
+  ParameterPosition() { exists(any(DataFlowCallable c).getParameter(this)) }
+}
+
+/** An argument position represented by an integer. */
+class ArgumentPosition extends int {
+  ArgumentPosition() { exists(any(DataFlowCall c).getArg(this)) }
+}
+
+/** Holds if arguments at position `apos` match parameters at position `ppos`. */
+pragma[inline]
+predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) { ppos = apos }
+
 /** Holds if `p` is a `ParameterNode` of `c` with position `pos`. */
-predicate isParameterNode(ParameterNode p, DataFlowCallable c, int pos) { p.isParameterOf(c, pos) }
+predicate isParameterNode(ParameterNode p, DataFlowCallable c, ParameterPosition pos) {
+  p.isParameterOf(c, pos)
+}
+
+/** Holds if `arg` is an `ArgumentNode` of `c` with position `pos`. */
+predicate isArgumentNode(ArgumentNode arg, DataFlowCall c, ArgumentPosition pos) {
+  arg.argumentOf(c, pos)
+}
 
 //--------
 // Data flow graph