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•  package semanticcpg

  Domain specific language for querying code property graphs

  Domain specific language for querying code property graphs

  This is the API reference for the CPG query language, a language to mine code for defects and vulnerabilities both interactively on a code analysis shell (REPL), or using non-interactive scripts.

  Queries written in the CPG query language express graph traversals (see https://en.wikipedia.org/wiki/Graph_traversal). Similar to the standard graph traversal language "Gremlin" (see https://en.wikipedia.org/wiki/Gremlin_(programming_language))) these traversals are formulated as sequences of primitive language elements referred to as "steps". You can think of a step as a small program, similar to a unix shell utility, however, instead of processing lines one by one, the step processes nodes of the graph.

  Starting a traversal

  All traversals begin by selecting a set of start nodes, e.g.,

  cpg.method

  will start the traversal at all methods, while

  cpg.local

  will start at all local variables. The complete list of starting points can be found at

  io.shiftleft.codepropertygraph.Cpg

  Lazy evaluation

  Queries are lazily evaluated, e.g., cpg.method creates a traversal which you can add more steps to. You can, for example, evaluate the traversal by converting it to a list:

  cpg.method.toList

  Since toList is such a common operation, we provide the shorthand l, meaning that

  cpg.method.l

  provides the same result as the former query.

  Properties

  Nodes have "properties", key-value pairs where keys are strings and values are primitive data types such as strings, integers, or Booleans. Properties of nodes can be selected based on their key, e.g.,

  cpg.method.name

  traverses to all method names. Nodes can also be filtered based on properties, e.g.,

  cpg.method.name(".*exec.*")

  traverse to all methods where name matches the regular expression ".*exec.*". You can see a complete list of properties by browsing to the API documentation of the corresponding step. For example, you can find the properties of method nodes at io.shiftleft.semanticcpg.language.types.structure.Method.

  Side effects

  Useful if you want to mutate something outside the traversal, or simply debug it: This prints all typeDecl names as it traverses the graph and increments i for each one.

  var i = 0
  cpg.typeDecl.sideEffect{typeTemplate => println(typeTemplate.name); i = i + 1}.exec

  [advanced] Selecting multiple things from your traversal

  If you are interested in multiple things along the way of your traversal, you label anything using the as modulator, and use select at the end. Note that the compiler automatically derived the correct return type as a tuple of the labelled steps, in this case with two elements.

  cpg.method.as("method").definingTypeDecl.as("classDef").select.toList
  // return type: List[(nodes.Method, nodes.TypeDecl)]

  [advanced] For comprehensions

  You can always start a new traversal from a node, e.g.,

  val someMethod = cpg.method.head
  someMethod.start.parameter.toList

  You can use this e.g. in a for comprehension, which is (in this context) essentially an alternative way to select multiple intermediate things. It is more expressive, but more computationally expensive.

  val query = for {
    method <- cpg.method
    param <- method.start.parameter
  } yield (method.name, param.name)
  
  query.toList

io

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