CodeQL library for Python
codeql/python-all 0.8.2 ( changelog , source )
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Module API :: Impl

Provides the actual implementation of API graphs, cached for performance.

Ideally, we’d like nodes to correspond to (global) access paths, with edge labels corresponding to extending the access path by one element. We also want to be able to map nodes to their definitions and uses in the data-flow graph, and this should happen modulo (inter-procedural) data flow.

This, however, is not easy to implement, since access paths can have unbounded length and we need some way of recognizing cycles to avoid non-termination. Unfortunately, expressing a condition like “this node hasn’t been involved in constructing any predecessor of this node in the API graph” without negative recursion is tricky.

So instead most nodes are directly associated with a data-flow node, representing either a use or a definition of an API component. This ensures that we only have a finite number of nodes. However, we can now have multiple nodes with the same access path, which are essentially indistinguishable for a client of the API.

On the other hand, a single node can have multiple access paths (which is, of course, unavoidable). We pick as canonical the alphabetically least access path with shortest length.

Import path

import semmle.python.ApiGraphs

Predicates

distanceFromRoot

Gets the shortest distance from the root to nd in the API graph.

edge

Holds if there is an edge from pred to succ in the API graph that is labeled with lbl.

isImported

Holds if the module name is imported.

prefix_member

Holds if the dotted module name sub refers to the member member of base.

rhs

Holds if rhs is the right-hand side of a definition of a node that should have an incoming edge from base labeled lbl in the API graph.

rhs

Holds if rhs is the right-hand side of a definition of node nd.

trackDefNode

Gets a node that inter-procedurally flows into nd, which is a definition of some node.

trackUseNode

Gets a data-flow node to which src, which is a use of an API-graph node, flows.

use

Holds if ref is a use of a node that should have an incoming edge from base labeled lbl in the API graph.

use

Holds if ref is a use of node nd.

Datatypes

Aliases