CodeQL library for C#
codeql/csharp-all 0.10.0 (changelog, source)
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Module Make

Provides a shared interface for constructing control-flow graphs (CFGs) from abstract syntax trees (ASTs).

The implementation is centered around the concept of a completion, which models how the execution of a statement or expression terminates.

The CFG is built by structural recursion over the AST, using the abstract class ControlFlowTree. To achieve this, the CFG edges related to a given AST node, n, are divided into three categories:

  1. The in-going edge that points to the first CFG node to execute when n is going to be executed.
  2. The out-going edges for control flow leaving n that are going to some other node in the surrounding context of n.
  3. The edges that have both of their end-points entirely within the AST node and its children.

The edges in (1) and (2) are inherently non-local and are therefore initially calculated as half-edges, that is, the single node, k, of the edge contained within n, by the predicates k = n.first() and k = n.last(_), respectively. The edges in (3) can then be enumerated directly by the predicate succ by calling first and last recursively on the children of n and connecting the end-points. This yields the entire CFG, since all edges are in (3) for some AST node.

The parameter of last is the completion, which is necessary to distinguish the out-going edges from n. Note that the completion changes as the calculation of last proceeds outward through the AST; for example, a completion representing a loop break will be caught up by its surrounding loop and turned into a normal completion.

Import path

import codeql.controlflow.Cfg

Imports

Predicates

first

Holds if first is the first element executed within control flow element cft.

last

Holds if last with completion c is a potential last element executed within control flow element cft.

succ

Holds if succ is a control flow successor for pred, given that pred finishes with completion c.

Classes

AnnotatedExitNode

An exit node for a given scope, annotated with the type of exit.

AstCfgNode

A node for an AST node.

ControlFlowTree

An element with associated control flow.

EntryNode

An entry node for a given scope.

ExitNode

An exit node for a given scope.

LeafTree

An element that is a leaf in the control flow graph.

Node

A control flow node.

PostOrderTree

An element that is executed in post-order, typically used for expressions.

PreOrderTree

An element that is executed in pre-order, typically used for statements.

SplitImpl

An interface for implementing an entity to split on.

SplitKind

A split kind. Each control flow node can have at most one split of a given kind.

Splits

A set of control flow node splits. The set is represented by a list of splits, ordered by ascending rank.

StandardPostOrderTree

A standard element that is executed in post-order.

StandardPreOrderTree

A standard element that is executed in pre-order.

StandardTree

An element where the children are evaluated following a standard left-to-right evaluation. The actual evaluation order is determined by the predicate getChildNode().

Modules

Consistency

Provides a set of consistency queries.

TestOutput

Import this module into a .ql file of @kind graph to render a CFG. The graph is restricted to nodes from RelevantNode.

ViewCfgQuery

Provides an implementation for a View CFG query.

Type signatures

RelevantNodeSig

A node to be included in the output of TestOutput.

Module signatures

ViewCfgQueryInputSig

Provides the input to ViewCfgQuery.

Parameters